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The natural history of urinary tract infection in women
Medical Hypotheses 74 (2010) 802–806
Contents lists available at ScienceDirect
Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy
The natural history of urinary tract infection in women R.M. Maskell *,1 84 Bowes Hill, Rowlands Castle, Hampshire PO9 6BS, UK
a r t i c l e
i n f o
Article history: Received 6 December 2009 Accepted 9 December 2009
s u m m a r y Many women who suffer from the symptoms of urinary tract infection have a negative urine culture when conventional methods are used. Their condition is described as ‘urethral’ (or ‘dysuria/frequency’) syndrome’ (US). As they may be indistinguishable clinically from those with positive cultures antibiotics are often prescribed. Their symptoms are usually recurrent and they may receive many courses of treatment. Some women are said to have ‘interstitial cystitis’ (IC); they have a long history of symptoms and antibacterial treatment. The urine contains white blood cells (pyuria) and biopsy of the bladder wall shows the histological changes of chronic inflammation. Additional culture techniques applied to urine from these two groups of patients consistently yield bacteria, most commonly lactobacilli in those with US. From the urine of women with IC, lactobacilli and some other ‘fastidious’ bacteria are isolated from catheter specimens and also from bladder wall biopsies. These bacteria are known to be constituents of the mixed commensal flora of the distal one-third of the urethra. It is proposed that these two syndromes are different stages in the natural history of UTI, and that antibacterial agents, by selection of resistant bacteria in the urethral commensal flora, are an important aetiological factor. It is possible that these bacteria may invade the paraurethral glands via their ducts – a situation analogous to invasion of the prostate in men. There is a considerable body of evidence supporting this hypothesis, but as it all emanates from one centre it needs to be confirmed elsewhere. Acceptance would bring great clinical benefit and considerable financial savings. A laboratory protocol which requires only small additional expenditure, and a clinical management regimen are proposed. At present, much antibacterial treatment is prescribed and many patients undergo radiological and invasive investigations such as cystoscopy and urethral dilatation, the latter incurring the risk of post-instrumentation UTI. There is evidence that ‘US’ responds gradually if antibiotics are withheld. ‘IC’ is a more difficult problem because bacteria may have invaded the bladder wall. Carefully targeted antibacterial treatment given for at least 10–14 days might be effective, but there are no data on this. Rational management of ‘US’ might prevent the development of ‘IC’. A recent thorough review of published work on this condition states that the aetiology is still unknown. It appears, however, that no attempt has been made in any recent studies to use urine culture techniques capable of detecting bacteria other than the recognised aerobic pathogens. Ó 2009 Elsevier Ltd. All rights reserved.
Introduction The normal urinary tract is sterile above the distal one-third of the urethra, which has a mixed commensal flora [1] the purpose of which is to protect the bladder and kidneys from ascending infection from the bowel. With the advent of antibacterial agents in the middle of the last century and the likelihood that they would be used for treatment of urinary tract infection (UTI), for which there was no effective treatment at the time, it became necessary to introduce some rigour and greater accuracy into a diagnosis that had previously been made on clinical and, sometimes dubious, laboratory grounds.
* Tel.: +44 02392413729. E-mail address: [email protected]. 1 Formerly at St. Mary’s Hospital, Portsmouth, UK. 0306-9877/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.mehy.2009.12.011
Hitherto, diagnostic specimens of urine from women and children had been collected direct from the bladder by catheter (CSU), with the attendant risk of introducing bacteria into the urinary tract. Laboratory investigations were only available for hospital patients. With the possibility of effective treatment of the very common condition of ‘cystitis’, as the symptom complex of UTI (frequency, dysuria, pain, and sometimes haematuria) was known colloquially, it was important to validate the culture findings of specimens obtained by a non-invasive method of specimen collection – the midstream specimen (MSU) – and to make laboratory facilities more widely available. Kass [2,3] compared quantitative culture results from CSUs and MSUs collected in the early morning from symptom-free women, and demonstrated that when there were bacteria in the bladder (+ve CSU) the MSU yielded a bacterial count of >108/l. From these data he defined a numerical criterion indicative of UTI – ‘significant bacteriuria’ – as ‘a finding of >108 colony
R.M. Maskell / Medical Hypotheses 74 (2010) 802–806
forming units/l on culture of a fresh, carefully collected MSU’. Lower counts, even when they were of an organism in pure culture, were dismissed as due to contamination of the specimen (despite the fact that contamination from the urethra or bowel would yield a mixed culture as both these structures have a mixed commensal flora) and not indicative of infection. Collection of urine by MSU, and the application of Kass’s numerical criterion of significance were adopted by laboratories thenceforth, thus making this investigation available to the large number of women with symptoms of UTI. In early studies using MSUs and Kass’s criterion it came as a surprise that only about 50% of women with symptoms had significant bacteriuria, and that the patients with negative urine cultures were indistinguishable clinically from those with positive cultures [4,5]. This figure is still reported from recent studies [6]. The diagnostic label ‘Urethral Syndrome’ was coined for women with symptoms and negative urine cultures. Most of these patients are seen initially in the community by General Practitioners (GPs). There was a considerable time-lag, in some places more than 10 years, between the availability of antibacterial agents and the provision of laboratory facilities to GPs. During this time treatment with antibacterial agents for UTI, one of the commonest infections seen in general practice, was promoted enthusiastically by the pharmaceutical companies, with the consequence that they were given to a very large number of women without confirmation of infection. Some whose symptoms failed to respond were given repeated and longer courses of treatment, often in higher dosage or with a different agent. The effect of this on the commensal urethral flora could be significant in determining the natural history of the condition.
The hypothesis A large number of women have symptoms which suggest urinary tract infection (UTI), but only about one half of them yield a positive urine culture when standard laboratory methods are used. Some of those with negative cultures have objective signs of infection such as pyuria or inflammatory changes in the bladder wall. Diagnostic labels such as ‘Urethral Syndrome’ (US), ‘Dysuria/Frequency Syndrome (D/FS)’, ‘Detrusor Instability (DI)’, and ‘Interstitial Cystitis’ (IC) have been applied to them. There have been no widely accepted advances in the management of these patients during the past 30 years. Many are still subjected to repeated courses of antibacterial treatment, to radiological investigations and to invasive procedures such as cystoscopy and urethral dilatation. Clinical and laboratory experience of these patients suggested to the author that a more thorough search for bacteria in the urine, especially those of the commensal flora of the distal urethra, and consideration of a possible role for the urethra and the paraurethral glands in the natural history of UTI, might provide the basis for a rational management regimen, with considerable clinical benefit and large savings on antibiotic treatment and investigations. In 1967 the author assumed a combined clinical and laboratory role in the field of UTI. The laboratory protocol at that time was to culture urine specimens on a primary isolation medium, cystine lactose electrolyte deficient (CLED) agar, incubate the plates overnight in air and read them the next morning. This technique detected the presence of the Gram negative coliform bowel organisms such as Escherichia coli, various species of staphylococci, Enterococcus faecalis and Streptococcus agalactiae. Kass’s criterion of significance was applied; all other cultures were reported to the clinician as showing ‘no growth’ or ’no significant growth’. This protocol had some important drawbacks:
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Kass’s criterion was derived from a finding of bacteriuria in early morning specimens from symptom-free women. Therefore it might not be applicable to daytime specimens from women with frequency and thirst who were constantly diluting the bacterial count in the bladder. It dismissed from the minds of microbiologists and clinicians the possibility of pathological infective processes in the structures below the bladder, the urethra and those organs in communication with it, the prostate in men and the paraurethral glands in women. There is no reason to suppose that bacteria in these tissues would multiply at the same rate as in the favourable environment of bladder urine. Overnight incubation in air of cultures on a primary isolation medium does not detect organisms other than the aerobic pathogens. Many organisms with other requirements, for example anaerobes and CO2-requiring bacteria and those species that need longer incubation, are well recognised as pathogens in sites other than the urinary tract. They are sought in laboratories, using appropriate methods, in all specimens other than urine. If present, they might explain the symptoms of women with a long history of UTIs and antibiotic treatment whose overnight cultures were negative. They might also explain the presence of leucocytes in apparently ‘sterile’ urine and/or other objective evidence of infection, for example inflammatory changes in the bladder wall or prostate. Some of the diagnostic labels attached to such patients include ‘US’, ‘Dysuria/Frequency Syndrome (DFS)’, IC’, ‘Detrusor Instability’ (DI), and ‘Chronic Prostatitis’. The hypothesis evolved as a consequence of: observations made by the author at the laboratory bench; an initial study using a conventional culture technique which confirmed the findings of other studies [7]; the author’s experience of conducting a clinic to which GPs referred patients whom they had treated for proven or suspected UTI; discussion with clinical and laboratory colleagues. It was soon apparent that many women with symptoms and/ or objective evidence of UTI were not obtaining a diagnosis and, for lack of a satisfactory and logical alternative, were being given antibiotic treatment and often subjected to potentially harmful investigations. We decided to seek the presence of bacteria other than the aerobic pathogens in urine specimens and, in collaborative clinical and laboratory studies, to assess their clinical relevance. We considered it important that each investigation should actively involve the appropriate clinicians and laboratory staff. To this end we collaborated with GPs, nephrologists, urologists, a histopathologist, an electron microscopist and a virologist. A microbiological scientist was an integral part of each study; in addition to her laboratory work she acted as a channel of communication between the patients, the clinicians and the laboratory. At that time we also began to consider a possible role for the commensal flora of the distal urethra. Collaborative clinical and laboratory studies Studies in which bacteria other than the aerobic pathogens were sought in groups of patients. 1981–1983 2-year prospective study of 51 women to determine the clinical significance of the presence of bacteria other than the recognised aerobic pathogens in urine [8].
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51 women were referred to the study by their GPs because they had suffered from repeated episodes of symptoms suggestive of UTI, some of which had yielded ‘negative’ urine cultures, and had received several courses of antibacterial treatment. In a clinic reserved for the study a careful history including a detailed description of the symptoms was taken. The average length of the period during which they had experienced urinary symptoms was 10 years. In addition to those symptoms which are characteristic of UTI, (dysuria frequency etc.) many complained of a feeling of perineal pressure, dyspareunia and post-micturition dribble. They had received an average of 3.3 (range 1–9) courses of antibacterial treatment during the 2 years before referral to the study. Carefully collected MSUs were obtained from a control group of 56 women, matched with the patients in the study for age and contraceptive status, none of whom had suffered from urinary symptoms in the previous 2 years, or received any antibiotics during the previous 3 months. They were asked specifically about dyspareunia and post-micturition dribble; eight had experienced one or more of these symptoms. When the patients were examined particular attention was paid to palpation of the urethra and the paraurethral tissues per vaginam. No abnormality was found in 20(39%); 12(24%)complained of excessive discomfort on swabbing of the distal urethra; 10(20%) had abnormalities of the urethral meatus due to age, previous surgery or obstetric experience; 15(30%) had paraurethral tenderness on palpation per vaginam, and the paraurethral tissues were thickened in 4(8%) patients. More than one of these signs were detected in some patients. At their first attendance urine was collected directly from the bladder of every patient by suprapubic aspiration (SPA). At each visit to the clinic a urethral swab and a fresh, carefully collected MSU were refrigerated and transported to the laboratory. All urine specimens and urethral swabs were cultured using the following protocol: Inoculation of CLED agar for overnight incubation in a CO2 incubator (7%CO2); plate read at 24 h. If negative it was reincubated for a further 24 h. Inoculation of chocolated blood agar (CBA) and of blood agar containing 16 lg/ml nalidixic acid (BAN). The CBA plate was incubated in 7% CO2 and read at 18 and 24 h. The BAN plate was incubated for 48 h in an anaerobic cabinet. All bacterial isolates were identified using standard methods. The same procedure was used for the MSUs from the controls. The term ‘fastidious’ was used to indicate that the bacteria were not detected by overnight culture. Fifty-seven SPAs were examined. Eight yielded aerobic pathogens; a fastidious streptococcus was isolated on two occasions from one patient. The remainder were negative on all media. Of the 258 urethral swabs cultured during the study 210 (81%) yielded large numbers of a predominant fastidious species; 200 (95%) of these isolates were lactobacilli and from 40% of specimens this was the only species isolated. Lactobacillus spp. were isolated in high counts and pure culture from MSUs from the patients significantly more often than from those from the controls. The presence of this organism was significantly related to the development of symptoms. Even when the patient was symptom-free between attacks their MSUs yielded lactobacilli, often in pure culture, significantly more often than those from the controls. Over the course of 2 years antibacterial treatment was withheld, unless a patient had a proven episode of infection with an aerobic pathogen, for which a 3 day course of an appropriate agent was given. All other episodes of symptoms were managed with a high fluid intake and administration of a palatable
proprietary preparation of Potassium Citrate. During the study lactobacilli gradually disappeared from the MSUs of most of the patients, the majority of whom became symptom-free. At the end of the study 55% of the patients were symptom-free; 18% were symptom-free for most of the time, but had a recurrence of symptoms only at times of proven infection with an aerobic pathogen; 12% had improved considerably. The symptoms of the remaining 15% persisted unchanged. Two of the eight patients in the last group had had previous urethral surgery, two still had episodes of aerobic infection, five had urethral tenderness at the beginning of the study which was still present at the end in four. Lactobacilli were isolated from the urine of six and a fastidious streptococcus from two. Comment: This study suggests that lactobacilli multiply at the expense of the other, more sensitive, urethral commensal organisms in response to treatment with antibacterial agents, and that they may extend into the proximal urethra and thence to the paraurethral glands. Repeated and longer courses of treatment increase the likelihood that this will occur. The agent that is widely recommended for treatment of UTI is trimethoprim, to which lactobacilli are intrinsically resistant. They are also resistant to the fluoroquinolones. Their presence may be accompanied by symptoms suggesting UTI, but, on careful questioning, these symptoms are usually related to the urethra – urgency, urge incontinence, dyspareunia and post-micturition dribble – rather than to the bladder. Isolation of a fastidious streptococcus from the SPA from one patient on two occasions indicated that some fastidious organisms can invade the bladder. The symptoms and signs related to the urethra and paraurethral tissues would support the supposition that bacteria from the distal urethra had migrated proximally. Their presence is not always accompanied by symptoms and they disappear gradually from MSUs if antibacterial agents are withheld. These should be given in short (3 days) courses only if there is a proven infection with an aerobic pathogen. We did not repeat the urethral swabs at the end of the study because we did not wish to prejudice the improving situation, but it could be argued that we should have done so. We would have expected to find that a normal mixed flora had become re-established. So far as I can ascertain, no comparable study has been undertaken since. In a shorter study [9] which concluded that ‘Lactobacilli do not cause frequency and dysuria syndrome.’, lactobacilli were isolated from the MSUs of patients with symptoms, but their significance was dismissed because they were isolated equally often from controls who were symptom-free when the MSU was collected. However, the controls were either pregnant women from whom it is known that various species of fastidious bacteria including lactobacilli have been isolated from bladder urine collected by SPA [10], or women who were subject to UTI and had received antibacterial treatment. 1988 Study of 20 patients, of whom 19 were women, with a diagnosis of ‘interstitial cystitis’ i.e. a long history of frequency and dysuria, many courses of antibacterial treatment and a repeated finding of apparently ‘sterile’ pyuria [11]. A urethral swab and an MSU were collected from all the patients before cystoscopy, at which a CSU was collected and a bladder biopsy performed. All bladder biopsy specimens were examined by the same histopathologist who was unaware that the patient was in the study. All were reported as showing the non-specific inflammatory changes usually associated with the diagnosis of ‘Interstitial Cystitis’ [12]. Bacteria were isolated from the bladder biopsy and/or CSU of 12 patients. Eight of these isolates were fastidious bacteria: Gardnerella vaginalis 6, Lactobacillus spp. 2. Fastidious bacteria were isolated from the MSU and/or the urethral swab of these patients and of 6 other patients.
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Comment: It is widely believed that ‘interstitial cystitis’ is not caused by infection [13]. This study, which demonstrated the presence of bacteria in the bladder urine and bladder tissue, suggests that it is an infective process and could be an advanced stage in the natural history of UTI in women. Elliot [14], using scanning electron microscopy, has also reported the presence of bacteria in the bladder wall. The number of isolates of G. vaginalis (an organism that was previously known as Corynebacterium vaginale) is interesting. This organism is a recognised vaginal pathogen. We have also isolated it from the CSU of a sexually active young man with the clinical diagnosis of ‘Acute Abacterial Cystitis of Young Men’ [15]. It can be argued that it should be sought in specimens from the vagina and treated appropriately. A recent extensive review of publications on ‘Interstitial Cystitis’ concluded that it is not caused by infection [13]. However, the urine culture techniques used in the studies quoted were not stated. 1988 Study of the microbiology of urine in 88 patients (66 F, 22 M) undergoing urodynamic studies [16]. CSUs were collected from all the patients. Using techniques capable of detecting fastidious organisms bacteria were isolated from 25 (38%) of the women: aerobic coliforms from 4, lactobacilli from 10, and other fastidious species from the remainder. MSUs were collected for culture before the investigation and 48 h afterwards. The commonest urodynamic diagnoses in women were detrusor instability + sensory frequency (DI + SF) 42, urge incontinence (UI) 15, and stress incontinence only (SI) 2. Only 5 of the 42 women with DI + SF and 3 of the 15 with UI had negative urine cultures. Twenty-three of the 25 with positive CSUs complained of UI. Comment: The symptoms of many of these women could be due to infection and inflammatory change in the paraurethral glands, sometimes extending into the bladder. Laboratory study of isolates from urine specimens 1986 Prospective study of streptococci as urinary pathogens [17]. During a 2-month period all catalase-negative Gram positive cocci or coccobacilli isolated in pure culture from 11,725 urine specimens received in the laboratory were identified to species level. Our ‘routine’ technique of culture on a primary isolation medium and overnight incubation in a CO2 incubator (7% CO2) was used. Any cultures that left symptoms or pyuria unexplained after overnight incubation were reincubated for a further 24 h. If the culture was still negative, a further specimen with an accompanying form asking for culture for fastidious organisms, was requested. These specimens were then cultured on 2 additional media (chocolated blood agar (CBA) and blood agar containing 16 lg/ml (BAN)). The CBA plate was incubated in 7% CO2 and read at 18 and 48 h; the BAN plate was incubated for 48 h in an anaerobic cabinet and read at 48hr. All isolates of Gram negative cocci and coccobacilli detected on any medium at any stage of this protocol were identified to species level using API 20 STREP. 242 such organisms were isolated; they comprised 10% of the total number of significant isolates from the 11,725 specimens. 168 were E. faecalis or S. agalactiae, both of which were detected by ‘routine’ culture after 24 h incubation. The other 74 isolates were fastidious i.e. they were not detected by 48 h incubation in 7% CO2. Twenty of the 24 isolates of coccobacilli were G. vaginalis. The remainder were various species of streptococci. Thirty-three (44%) of the 74 fastidious isolates were accompanied by pyuria.
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After completion of the study streptococci isolated only on the additional media were reported as ‘fastidious streptococci’ and were not identified to species level. Comment: The findings of this study enabled us to devise a protocol for urine culture which is practicable in a busy laboratory and requires only small additional expenditure. Lactobacilli are detected by incubation of the primary isolation medium in a CO2 incubator, sometimes overnight but always after 48 h. As lactobacilli are by far the commonest fastidious isolate from urine specimens, repeat specimens for additional culture techniques are required comparatively rarely. The presence of G. vaginalis in urine was also noted.
Conclusions These studies provide strong evidence that US, D/FS, IC and DI may be due to infection. All the women studied had a history of repeated courses of antibiotic treatment. It is suggested that this may be an important aetiological factor in the natural history of UTI. By disturbing the normal balance of the commensal flora of the distal urethra it may enable resistant species, in particular lactobacilli, to migrate proximally to structures which are normally sterile and to cause inflammatory changes there. It is proposed that: The initial stage in the natural history of UTI in women is infection with the recognised aerobic pathogens, which are constituents of the commensal bowel flora. They invade the urinary tract by the ascending route. Such episodes are treated with antibiotics, and because episodes tend to be recurrent, they are sometimes given in prolonged courses and high dosage. This management may result, in some women, in disproportionate multiplication of one or more constituents of the commensal flora of the distal urethra, most often lactobacilli, which may extend to structures which are normally sterile. A management protocol of withholding antibiotics from patients with a history of recurrent symptoms, reserving them for a 3day course of treatment for a proven infection with an aerobic pathogen, and administration of a palatable Potassium Citrate preparation, may prevent further invasion of the urinary tract and gradually render the patient symptom- free. The earlier in the natural history this management is adopted the more likely it is to be successful. A laboratory protocol for detecting fastidious bacteria in urine does not require much additional expenditure. Good communication between patient and doctor, and doctor and laboratory is vital. Once all those involved understand the pathogenesis of these refractory syndromes, clinicians may be able to make a provisional diagnosis from the history and clinical examination, institute the management protocol suggested, and require laboratory confirmation only if symptoms persist. The GP who took part in the study of 51 women [8] subsequently adopted this protocol in his own practice with considerable success. As most of the evidence for this hypothesis comes from one centre it is essential that it should be confirmed by studies elsewhere. There has been greater understanding recently of the role of bacteria of the commensal flora of the bowel, for example Clostridium difficile, as emerging pathogens in patients treated with broad spectrum antibiotics. This might persuade clinicians and laboratories to think of lactobacilli as potential pathogens. There have been occasional reports recently of their isolation from blood cultures and from other sites of infection in patients who had been treated with broad spectrum antibiotics [18]. We did not consider identification to species level feasible in a busy
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service laboratory, but clearly this is an important investigation if the hypothesis is accepted. Longitudinal studies of urethral flora should also be undertaken. Confirmation and acceptance of this hypothesis would result in much clinical benefit in terms of symptoms. It would also spare a large number of women the radiological and invasive investigations – the latter with the attendant risk of introducing bacteria into the bladder – which they undergo at present. Considerable expenditure on such investigations and on antibiotics would be saved. It is also conceivable that a reduction in the quantity of antibiotics used in the community for one of the commonest infections might have a beneficial effect on the general bacterial environment.
Conflict of interest statement There were no sponsors and no conflicts of interest. Acknowledgements I thank: The Public Health Laboratory Service and the Wessex Kidney Research Fund for financial support. My clinical and laboratory colleagues for their encouragement and loyalty in our efforts to understand this very common problem. In particular, most of our studies would not have been possible without the scientific involvement, and her role of coordinator between patients and doctors, of Mrs. Linda Pead. The patients and their General Practitioners who collaborated so reliably with us. References [1] Marrie TJ, Swantee CA, Hartlen M. Aerobic and anaerobic urethral flora of healthy females in various physiological age groups and of females with urinary tract infection. J Clin Microbiol 1980;11:654–9.
[2] Kass EH. Asymptomatic infections of the urinary tract. Trans Assoc Am Phys 1956;69:56–63. [3] Kass EH. Bacteriuria and the diagnosis of infections of the urinary tract. Arch Intern Med 1957;100:709–14. [4] Gallagher DJA, Montgomerie JZ, North JDK. Acute infections of the urinary tract and the urethral syndrome in general practice. Br Med J 1965;1:622–6. [5] Mond NC, Percival A, Williams JD, Brumfitt W. Presentation, diagnosis and treatment of urinary tract infections in general practice. Lancet 1965;1:514–6. [6] Deville WL, Yzermans JC, van Duijn NP, Bezemer PD, van der Windt DA, Bouter LM, et al. The urine dipstick test useful to rule out infections. A meta-analysis of the accuracy. BMC Urol 2004;4:4. [7] Maskell R, Polak A. Bacteriological facilities for the diagnosis of urinary tract infection in general practice. In: Brumfitt W, Ascher AW, editors. Urinary tract infection. Oxford University Press; 1973. p. 3–10. [8] Maskell R, Pead L, Sanderson RA. Fastidious bacteria and the urethral syndrome: a clinical and bacteriological study of 51 women. Lancet 1983;2:1277–80. [9] Brumfitt W, Hamilton-Miller JMT, Ludlam H, Gooding A. Lactobacilli do not cause frequency and dysuria syndrome. Lancet 1981;2:393–6. [10] McDowall DRM, Buchanan JD, Fairley KF, Gilbert GL. Anaerobic and other fastidious microorganisms in asymptomatic bacteriuria in pregnant women. J Infect Dis 1981;144:114–22. [11] Wilkins EGL, Payne SR, Pead PJ, Moss ST, Maskell R. Interstitial cystitis and urethral syndrome: a possible answer. Br J Urol 1989;64:39–44. [12] Tait J, Peddie BA, Bailey RR, et al. Urethral syndrome (abacterial cystitis) – search for a pathogen. Br J Urol 1985;57:552–6. [13] Marinkovic SP, Maldwin R, Gillen LM, Stanton SL. The management of interstitial cystitis or painful bladder syndrome in women. BMJ 2009;339:b2707. [14] Elliott TSJ, Reed L, Slack RCB, Bishop MC. Bacteriology and ultrastructure of the bladder in patients with urinary tract infections. J Infection 1985;11:191–9. [15] Abercrombie GF, Allen J, Maskell R. Corynebacterium vaginale urinary tract infection in a young man. Lancet 1978;1:766. [16] Payne SR, Timoney AG, McKenning ST, den Hollander D, Pead LJ, Maskell RM. Microbiological look at urodynamic studies. Lancet 1988;2:1123–6. [17] Collins LE, Clarke RW, Maskell R. Streptococci as urinary pathogens. Lancet 1986;2:479–81. [18] Graggen WJZ, Fankhauser H, Lammer F, Bregenzer T, Conen D. Pancreatic necrosis infection due to Lactobacillus paracasei in an immunocompetent patient. Pancreatology 2005;5:108–9.
Contents lists available at ScienceDirect
Medical Hypotheses journal homepage: www.elsevier.com/locate/mehy
The natural history of urinary tract infection in women R.M. Maskell *,1 84 Bowes Hill, Rowlands Castle, Hampshire PO9 6BS, UK
a r t i c l e
i n f o
Article history: Received 6 December 2009 Accepted 9 December 2009
s u m m a r y Many women who suffer from the symptoms of urinary tract infection have a negative urine culture when conventional methods are used. Their condition is described as ‘urethral’ (or ‘dysuria/frequency’) syndrome’ (US). As they may be indistinguishable clinically from those with positive cultures antibiotics are often prescribed. Their symptoms are usually recurrent and they may receive many courses of treatment. Some women are said to have ‘interstitial cystitis’ (IC); they have a long history of symptoms and antibacterial treatment. The urine contains white blood cells (pyuria) and biopsy of the bladder wall shows the histological changes of chronic inflammation. Additional culture techniques applied to urine from these two groups of patients consistently yield bacteria, most commonly lactobacilli in those with US. From the urine of women with IC, lactobacilli and some other ‘fastidious’ bacteria are isolated from catheter specimens and also from bladder wall biopsies. These bacteria are known to be constituents of the mixed commensal flora of the distal one-third of the urethra. It is proposed that these two syndromes are different stages in the natural history of UTI, and that antibacterial agents, by selection of resistant bacteria in the urethral commensal flora, are an important aetiological factor. It is possible that these bacteria may invade the paraurethral glands via their ducts – a situation analogous to invasion of the prostate in men. There is a considerable body of evidence supporting this hypothesis, but as it all emanates from one centre it needs to be confirmed elsewhere. Acceptance would bring great clinical benefit and considerable financial savings. A laboratory protocol which requires only small additional expenditure, and a clinical management regimen are proposed. At present, much antibacterial treatment is prescribed and many patients undergo radiological and invasive investigations such as cystoscopy and urethral dilatation, the latter incurring the risk of post-instrumentation UTI. There is evidence that ‘US’ responds gradually if antibiotics are withheld. ‘IC’ is a more difficult problem because bacteria may have invaded the bladder wall. Carefully targeted antibacterial treatment given for at least 10–14 days might be effective, but there are no data on this. Rational management of ‘US’ might prevent the development of ‘IC’. A recent thorough review of published work on this condition states that the aetiology is still unknown. It appears, however, that no attempt has been made in any recent studies to use urine culture techniques capable of detecting bacteria other than the recognised aerobic pathogens. Ó 2009 Elsevier Ltd. All rights reserved.
Introduction The normal urinary tract is sterile above the distal one-third of the urethra, which has a mixed commensal flora [1] the purpose of which is to protect the bladder and kidneys from ascending infection from the bowel. With the advent of antibacterial agents in the middle of the last century and the likelihood that they would be used for treatment of urinary tract infection (UTI), for which there was no effective treatment at the time, it became necessary to introduce some rigour and greater accuracy into a diagnosis that had previously been made on clinical and, sometimes dubious, laboratory grounds.
* Tel.: +44 02392413729. E-mail address: [email protected]. 1 Formerly at St. Mary’s Hospital, Portsmouth, UK. 0306-9877/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.mehy.2009.12.011
Hitherto, diagnostic specimens of urine from women and children had been collected direct from the bladder by catheter (CSU), with the attendant risk of introducing bacteria into the urinary tract. Laboratory investigations were only available for hospital patients. With the possibility of effective treatment of the very common condition of ‘cystitis’, as the symptom complex of UTI (frequency, dysuria, pain, and sometimes haematuria) was known colloquially, it was important to validate the culture findings of specimens obtained by a non-invasive method of specimen collection – the midstream specimen (MSU) – and to make laboratory facilities more widely available. Kass [2,3] compared quantitative culture results from CSUs and MSUs collected in the early morning from symptom-free women, and demonstrated that when there were bacteria in the bladder (+ve CSU) the MSU yielded a bacterial count of >108/l. From these data he defined a numerical criterion indicative of UTI – ‘significant bacteriuria’ – as ‘a finding of >108 colony
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forming units/l on culture of a fresh, carefully collected MSU’. Lower counts, even when they were of an organism in pure culture, were dismissed as due to contamination of the specimen (despite the fact that contamination from the urethra or bowel would yield a mixed culture as both these structures have a mixed commensal flora) and not indicative of infection. Collection of urine by MSU, and the application of Kass’s numerical criterion of significance were adopted by laboratories thenceforth, thus making this investigation available to the large number of women with symptoms of UTI. In early studies using MSUs and Kass’s criterion it came as a surprise that only about 50% of women with symptoms had significant bacteriuria, and that the patients with negative urine cultures were indistinguishable clinically from those with positive cultures [4,5]. This figure is still reported from recent studies [6]. The diagnostic label ‘Urethral Syndrome’ was coined for women with symptoms and negative urine cultures. Most of these patients are seen initially in the community by General Practitioners (GPs). There was a considerable time-lag, in some places more than 10 years, between the availability of antibacterial agents and the provision of laboratory facilities to GPs. During this time treatment with antibacterial agents for UTI, one of the commonest infections seen in general practice, was promoted enthusiastically by the pharmaceutical companies, with the consequence that they were given to a very large number of women without confirmation of infection. Some whose symptoms failed to respond were given repeated and longer courses of treatment, often in higher dosage or with a different agent. The effect of this on the commensal urethral flora could be significant in determining the natural history of the condition.
The hypothesis A large number of women have symptoms which suggest urinary tract infection (UTI), but only about one half of them yield a positive urine culture when standard laboratory methods are used. Some of those with negative cultures have objective signs of infection such as pyuria or inflammatory changes in the bladder wall. Diagnostic labels such as ‘Urethral Syndrome’ (US), ‘Dysuria/Frequency Syndrome (D/FS)’, ‘Detrusor Instability (DI)’, and ‘Interstitial Cystitis’ (IC) have been applied to them. There have been no widely accepted advances in the management of these patients during the past 30 years. Many are still subjected to repeated courses of antibacterial treatment, to radiological investigations and to invasive procedures such as cystoscopy and urethral dilatation. Clinical and laboratory experience of these patients suggested to the author that a more thorough search for bacteria in the urine, especially those of the commensal flora of the distal urethra, and consideration of a possible role for the urethra and the paraurethral glands in the natural history of UTI, might provide the basis for a rational management regimen, with considerable clinical benefit and large savings on antibiotic treatment and investigations. In 1967 the author assumed a combined clinical and laboratory role in the field of UTI. The laboratory protocol at that time was to culture urine specimens on a primary isolation medium, cystine lactose electrolyte deficient (CLED) agar, incubate the plates overnight in air and read them the next morning. This technique detected the presence of the Gram negative coliform bowel organisms such as Escherichia coli, various species of staphylococci, Enterococcus faecalis and Streptococcus agalactiae. Kass’s criterion of significance was applied; all other cultures were reported to the clinician as showing ‘no growth’ or ’no significant growth’. This protocol had some important drawbacks:
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Kass’s criterion was derived from a finding of bacteriuria in early morning specimens from symptom-free women. Therefore it might not be applicable to daytime specimens from women with frequency and thirst who were constantly diluting the bacterial count in the bladder. It dismissed from the minds of microbiologists and clinicians the possibility of pathological infective processes in the structures below the bladder, the urethra and those organs in communication with it, the prostate in men and the paraurethral glands in women. There is no reason to suppose that bacteria in these tissues would multiply at the same rate as in the favourable environment of bladder urine. Overnight incubation in air of cultures on a primary isolation medium does not detect organisms other than the aerobic pathogens. Many organisms with other requirements, for example anaerobes and CO2-requiring bacteria and those species that need longer incubation, are well recognised as pathogens in sites other than the urinary tract. They are sought in laboratories, using appropriate methods, in all specimens other than urine. If present, they might explain the symptoms of women with a long history of UTIs and antibiotic treatment whose overnight cultures were negative. They might also explain the presence of leucocytes in apparently ‘sterile’ urine and/or other objective evidence of infection, for example inflammatory changes in the bladder wall or prostate. Some of the diagnostic labels attached to such patients include ‘US’, ‘Dysuria/Frequency Syndrome (DFS)’, IC’, ‘Detrusor Instability’ (DI), and ‘Chronic Prostatitis’. The hypothesis evolved as a consequence of: observations made by the author at the laboratory bench; an initial study using a conventional culture technique which confirmed the findings of other studies [7]; the author’s experience of conducting a clinic to which GPs referred patients whom they had treated for proven or suspected UTI; discussion with clinical and laboratory colleagues. It was soon apparent that many women with symptoms and/ or objective evidence of UTI were not obtaining a diagnosis and, for lack of a satisfactory and logical alternative, were being given antibiotic treatment and often subjected to potentially harmful investigations. We decided to seek the presence of bacteria other than the aerobic pathogens in urine specimens and, in collaborative clinical and laboratory studies, to assess their clinical relevance. We considered it important that each investigation should actively involve the appropriate clinicians and laboratory staff. To this end we collaborated with GPs, nephrologists, urologists, a histopathologist, an electron microscopist and a virologist. A microbiological scientist was an integral part of each study; in addition to her laboratory work she acted as a channel of communication between the patients, the clinicians and the laboratory. At that time we also began to consider a possible role for the commensal flora of the distal urethra. Collaborative clinical and laboratory studies Studies in which bacteria other than the aerobic pathogens were sought in groups of patients. 1981–1983 2-year prospective study of 51 women to determine the clinical significance of the presence of bacteria other than the recognised aerobic pathogens in urine [8].
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51 women were referred to the study by their GPs because they had suffered from repeated episodes of symptoms suggestive of UTI, some of which had yielded ‘negative’ urine cultures, and had received several courses of antibacterial treatment. In a clinic reserved for the study a careful history including a detailed description of the symptoms was taken. The average length of the period during which they had experienced urinary symptoms was 10 years. In addition to those symptoms which are characteristic of UTI, (dysuria frequency etc.) many complained of a feeling of perineal pressure, dyspareunia and post-micturition dribble. They had received an average of 3.3 (range 1–9) courses of antibacterial treatment during the 2 years before referral to the study. Carefully collected MSUs were obtained from a control group of 56 women, matched with the patients in the study for age and contraceptive status, none of whom had suffered from urinary symptoms in the previous 2 years, or received any antibiotics during the previous 3 months. They were asked specifically about dyspareunia and post-micturition dribble; eight had experienced one or more of these symptoms. When the patients were examined particular attention was paid to palpation of the urethra and the paraurethral tissues per vaginam. No abnormality was found in 20(39%); 12(24%)complained of excessive discomfort on swabbing of the distal urethra; 10(20%) had abnormalities of the urethral meatus due to age, previous surgery or obstetric experience; 15(30%) had paraurethral tenderness on palpation per vaginam, and the paraurethral tissues were thickened in 4(8%) patients. More than one of these signs were detected in some patients. At their first attendance urine was collected directly from the bladder of every patient by suprapubic aspiration (SPA). At each visit to the clinic a urethral swab and a fresh, carefully collected MSU were refrigerated and transported to the laboratory. All urine specimens and urethral swabs were cultured using the following protocol: Inoculation of CLED agar for overnight incubation in a CO2 incubator (7%CO2); plate read at 24 h. If negative it was reincubated for a further 24 h. Inoculation of chocolated blood agar (CBA) and of blood agar containing 16 lg/ml nalidixic acid (BAN). The CBA plate was incubated in 7% CO2 and read at 18 and 24 h. The BAN plate was incubated for 48 h in an anaerobic cabinet. All bacterial isolates were identified using standard methods. The same procedure was used for the MSUs from the controls. The term ‘fastidious’ was used to indicate that the bacteria were not detected by overnight culture. Fifty-seven SPAs were examined. Eight yielded aerobic pathogens; a fastidious streptococcus was isolated on two occasions from one patient. The remainder were negative on all media. Of the 258 urethral swabs cultured during the study 210 (81%) yielded large numbers of a predominant fastidious species; 200 (95%) of these isolates were lactobacilli and from 40% of specimens this was the only species isolated. Lactobacillus spp. were isolated in high counts and pure culture from MSUs from the patients significantly more often than from those from the controls. The presence of this organism was significantly related to the development of symptoms. Even when the patient was symptom-free between attacks their MSUs yielded lactobacilli, often in pure culture, significantly more often than those from the controls. Over the course of 2 years antibacterial treatment was withheld, unless a patient had a proven episode of infection with an aerobic pathogen, for which a 3 day course of an appropriate agent was given. All other episodes of symptoms were managed with a high fluid intake and administration of a palatable
proprietary preparation of Potassium Citrate. During the study lactobacilli gradually disappeared from the MSUs of most of the patients, the majority of whom became symptom-free. At the end of the study 55% of the patients were symptom-free; 18% were symptom-free for most of the time, but had a recurrence of symptoms only at times of proven infection with an aerobic pathogen; 12% had improved considerably. The symptoms of the remaining 15% persisted unchanged. Two of the eight patients in the last group had had previous urethral surgery, two still had episodes of aerobic infection, five had urethral tenderness at the beginning of the study which was still present at the end in four. Lactobacilli were isolated from the urine of six and a fastidious streptococcus from two. Comment: This study suggests that lactobacilli multiply at the expense of the other, more sensitive, urethral commensal organisms in response to treatment with antibacterial agents, and that they may extend into the proximal urethra and thence to the paraurethral glands. Repeated and longer courses of treatment increase the likelihood that this will occur. The agent that is widely recommended for treatment of UTI is trimethoprim, to which lactobacilli are intrinsically resistant. They are also resistant to the fluoroquinolones. Their presence may be accompanied by symptoms suggesting UTI, but, on careful questioning, these symptoms are usually related to the urethra – urgency, urge incontinence, dyspareunia and post-micturition dribble – rather than to the bladder. Isolation of a fastidious streptococcus from the SPA from one patient on two occasions indicated that some fastidious organisms can invade the bladder. The symptoms and signs related to the urethra and paraurethral tissues would support the supposition that bacteria from the distal urethra had migrated proximally. Their presence is not always accompanied by symptoms and they disappear gradually from MSUs if antibacterial agents are withheld. These should be given in short (3 days) courses only if there is a proven infection with an aerobic pathogen. We did not repeat the urethral swabs at the end of the study because we did not wish to prejudice the improving situation, but it could be argued that we should have done so. We would have expected to find that a normal mixed flora had become re-established. So far as I can ascertain, no comparable study has been undertaken since. In a shorter study [9] which concluded that ‘Lactobacilli do not cause frequency and dysuria syndrome.’, lactobacilli were isolated from the MSUs of patients with symptoms, but their significance was dismissed because they were isolated equally often from controls who were symptom-free when the MSU was collected. However, the controls were either pregnant women from whom it is known that various species of fastidious bacteria including lactobacilli have been isolated from bladder urine collected by SPA [10], or women who were subject to UTI and had received antibacterial treatment. 1988 Study of 20 patients, of whom 19 were women, with a diagnosis of ‘interstitial cystitis’ i.e. a long history of frequency and dysuria, many courses of antibacterial treatment and a repeated finding of apparently ‘sterile’ pyuria [11]. A urethral swab and an MSU were collected from all the patients before cystoscopy, at which a CSU was collected and a bladder biopsy performed. All bladder biopsy specimens were examined by the same histopathologist who was unaware that the patient was in the study. All were reported as showing the non-specific inflammatory changes usually associated with the diagnosis of ‘Interstitial Cystitis’ [12]. Bacteria were isolated from the bladder biopsy and/or CSU of 12 patients. Eight of these isolates were fastidious bacteria: Gardnerella vaginalis 6, Lactobacillus spp. 2. Fastidious bacteria were isolated from the MSU and/or the urethral swab of these patients and of 6 other patients.
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Comment: It is widely believed that ‘interstitial cystitis’ is not caused by infection [13]. This study, which demonstrated the presence of bacteria in the bladder urine and bladder tissue, suggests that it is an infective process and could be an advanced stage in the natural history of UTI in women. Elliot [14], using scanning electron microscopy, has also reported the presence of bacteria in the bladder wall. The number of isolates of G. vaginalis (an organism that was previously known as Corynebacterium vaginale) is interesting. This organism is a recognised vaginal pathogen. We have also isolated it from the CSU of a sexually active young man with the clinical diagnosis of ‘Acute Abacterial Cystitis of Young Men’ [15]. It can be argued that it should be sought in specimens from the vagina and treated appropriately. A recent extensive review of publications on ‘Interstitial Cystitis’ concluded that it is not caused by infection [13]. However, the urine culture techniques used in the studies quoted were not stated. 1988 Study of the microbiology of urine in 88 patients (66 F, 22 M) undergoing urodynamic studies [16]. CSUs were collected from all the patients. Using techniques capable of detecting fastidious organisms bacteria were isolated from 25 (38%) of the women: aerobic coliforms from 4, lactobacilli from 10, and other fastidious species from the remainder. MSUs were collected for culture before the investigation and 48 h afterwards. The commonest urodynamic diagnoses in women were detrusor instability + sensory frequency (DI + SF) 42, urge incontinence (UI) 15, and stress incontinence only (SI) 2. Only 5 of the 42 women with DI + SF and 3 of the 15 with UI had negative urine cultures. Twenty-three of the 25 with positive CSUs complained of UI. Comment: The symptoms of many of these women could be due to infection and inflammatory change in the paraurethral glands, sometimes extending into the bladder. Laboratory study of isolates from urine specimens 1986 Prospective study of streptococci as urinary pathogens [17]. During a 2-month period all catalase-negative Gram positive cocci or coccobacilli isolated in pure culture from 11,725 urine specimens received in the laboratory were identified to species level. Our ‘routine’ technique of culture on a primary isolation medium and overnight incubation in a CO2 incubator (7% CO2) was used. Any cultures that left symptoms or pyuria unexplained after overnight incubation were reincubated for a further 24 h. If the culture was still negative, a further specimen with an accompanying form asking for culture for fastidious organisms, was requested. These specimens were then cultured on 2 additional media (chocolated blood agar (CBA) and blood agar containing 16 lg/ml (BAN)). The CBA plate was incubated in 7% CO2 and read at 18 and 48 h; the BAN plate was incubated for 48 h in an anaerobic cabinet and read at 48hr. All isolates of Gram negative cocci and coccobacilli detected on any medium at any stage of this protocol were identified to species level using API 20 STREP. 242 such organisms were isolated; they comprised 10% of the total number of significant isolates from the 11,725 specimens. 168 were E. faecalis or S. agalactiae, both of which were detected by ‘routine’ culture after 24 h incubation. The other 74 isolates were fastidious i.e. they were not detected by 48 h incubation in 7% CO2. Twenty of the 24 isolates of coccobacilli were G. vaginalis. The remainder were various species of streptococci. Thirty-three (44%) of the 74 fastidious isolates were accompanied by pyuria.
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After completion of the study streptococci isolated only on the additional media were reported as ‘fastidious streptococci’ and were not identified to species level. Comment: The findings of this study enabled us to devise a protocol for urine culture which is practicable in a busy laboratory and requires only small additional expenditure. Lactobacilli are detected by incubation of the primary isolation medium in a CO2 incubator, sometimes overnight but always after 48 h. As lactobacilli are by far the commonest fastidious isolate from urine specimens, repeat specimens for additional culture techniques are required comparatively rarely. The presence of G. vaginalis in urine was also noted.
Conclusions These studies provide strong evidence that US, D/FS, IC and DI may be due to infection. All the women studied had a history of repeated courses of antibiotic treatment. It is suggested that this may be an important aetiological factor in the natural history of UTI. By disturbing the normal balance of the commensal flora of the distal urethra it may enable resistant species, in particular lactobacilli, to migrate proximally to structures which are normally sterile and to cause inflammatory changes there. It is proposed that: The initial stage in the natural history of UTI in women is infection with the recognised aerobic pathogens, which are constituents of the commensal bowel flora. They invade the urinary tract by the ascending route. Such episodes are treated with antibiotics, and because episodes tend to be recurrent, they are sometimes given in prolonged courses and high dosage. This management may result, in some women, in disproportionate multiplication of one or more constituents of the commensal flora of the distal urethra, most often lactobacilli, which may extend to structures which are normally sterile. A management protocol of withholding antibiotics from patients with a history of recurrent symptoms, reserving them for a 3day course of treatment for a proven infection with an aerobic pathogen, and administration of a palatable Potassium Citrate preparation, may prevent further invasion of the urinary tract and gradually render the patient symptom- free. The earlier in the natural history this management is adopted the more likely it is to be successful. A laboratory protocol for detecting fastidious bacteria in urine does not require much additional expenditure. Good communication between patient and doctor, and doctor and laboratory is vital. Once all those involved understand the pathogenesis of these refractory syndromes, clinicians may be able to make a provisional diagnosis from the history and clinical examination, institute the management protocol suggested, and require laboratory confirmation only if symptoms persist. The GP who took part in the study of 51 women [8] subsequently adopted this protocol in his own practice with considerable success. As most of the evidence for this hypothesis comes from one centre it is essential that it should be confirmed by studies elsewhere. There has been greater understanding recently of the role of bacteria of the commensal flora of the bowel, for example Clostridium difficile, as emerging pathogens in patients treated with broad spectrum antibiotics. This might persuade clinicians and laboratories to think of lactobacilli as potential pathogens. There have been occasional reports recently of their isolation from blood cultures and from other sites of infection in patients who had been treated with broad spectrum antibiotics [18]. We did not consider identification to species level feasible in a busy
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service laboratory, but clearly this is an important investigation if the hypothesis is accepted. Longitudinal studies of urethral flora should also be undertaken. Confirmation and acceptance of this hypothesis would result in much clinical benefit in terms of symptoms. It would also spare a large number of women the radiological and invasive investigations – the latter with the attendant risk of introducing bacteria into the bladder – which they undergo at present. Considerable expenditure on such investigations and on antibiotics would be saved. It is also conceivable that a reduction in the quantity of antibiotics used in the community for one of the commonest infections might have a beneficial effect on the general bacterial environment.
Conflict of interest statement There were no sponsors and no conflicts of interest. Acknowledgements I thank: The Public Health Laboratory Service and the Wessex Kidney Research Fund for financial support. My clinical and laboratory colleagues for their encouragement and loyalty in our efforts to understand this very common problem. In particular, most of our studies would not have been possible without the scientific involvement, and her role of coordinator between patients and doctors, of Mrs. Linda Pead. The patients and their General Practitioners who collaborated so reliably with us. References [1] Marrie TJ, Swantee CA, Hartlen M. Aerobic and anaerobic urethral flora of healthy females in various physiological age groups and of females with urinary tract infection. J Clin Microbiol 1980;11:654–9.
[2] Kass EH. Asymptomatic infections of the urinary tract. Trans Assoc Am Phys 1956;69:56–63. [3] Kass EH. Bacteriuria and the diagnosis of infections of the urinary tract. Arch Intern Med 1957;100:709–14. [4] Gallagher DJA, Montgomerie JZ, North JDK. Acute infections of the urinary tract and the urethral syndrome in general practice. Br Med J 1965;1:622–6. [5] Mond NC, Percival A, Williams JD, Brumfitt W. Presentation, diagnosis and treatment of urinary tract infections in general practice. Lancet 1965;1:514–6. [6] Deville WL, Yzermans JC, van Duijn NP, Bezemer PD, van der Windt DA, Bouter LM, et al. The urine dipstick test useful to rule out infections. A meta-analysis of the accuracy. BMC Urol 2004;4:4. [7] Maskell R, Polak A. Bacteriological facilities for the diagnosis of urinary tract infection in general practice. In: Brumfitt W, Ascher AW, editors. Urinary tract infection. Oxford University Press; 1973. p. 3–10. [8] Maskell R, Pead L, Sanderson RA. Fastidious bacteria and the urethral syndrome: a clinical and bacteriological study of 51 women. Lancet 1983;2:1277–80. [9] Brumfitt W, Hamilton-Miller JMT, Ludlam H, Gooding A. Lactobacilli do not cause frequency and dysuria syndrome. Lancet 1981;2:393–6. [10] McDowall DRM, Buchanan JD, Fairley KF, Gilbert GL. Anaerobic and other fastidious microorganisms in asymptomatic bacteriuria in pregnant women. J Infect Dis 1981;144:114–22. [11] Wilkins EGL, Payne SR, Pead PJ, Moss ST, Maskell R. Interstitial cystitis and urethral syndrome: a possible answer. Br J Urol 1989;64:39–44. [12] Tait J, Peddie BA, Bailey RR, et al. Urethral syndrome (abacterial cystitis) – search for a pathogen. Br J Urol 1985;57:552–6. [13] Marinkovic SP, Maldwin R, Gillen LM, Stanton SL. The management of interstitial cystitis or painful bladder syndrome in women. BMJ 2009;339:b2707. [14] Elliott TSJ, Reed L, Slack RCB, Bishop MC. Bacteriology and ultrastructure of the bladder in patients with urinary tract infections. J Infection 1985;11:191–9. [15] Abercrombie GF, Allen J, Maskell R. Corynebacterium vaginale urinary tract infection in a young man. Lancet 1978;1:766. [16] Payne SR, Timoney AG, McKenning ST, den Hollander D, Pead LJ, Maskell RM. Microbiological look at urodynamic studies. Lancet 1988;2:1123–6. [17] Collins LE, Clarke RW, Maskell R. Streptococci as urinary pathogens. Lancet 1986;2:479–81. [18] Graggen WJZ, Fankhauser H, Lammer F, Bregenzer T, Conen D. Pancreatic necrosis infection due to Lactobacillus paracasei in an immunocompetent patient. Pancreatology 2005;5:108–9.