- Email: [email protected]
Antimicrobial resistance of Salmonella enterica group C strains isolated from humans in Turkey, 2000–2002
International Journal of Antimicrobial Agents 26 (2005) 33–37
Antimicrobial resistance of Salmonella enterica group C strains isolated from humans in Turkey, 2000–2002 B. Erdem a,∗ , S. Ercis b , G. Hascelik b , D. Gur c , A.D. Aysev d a
Department of Microbiology and Clinical Microbiology, Ankara University School of Medicine, Bilkent 3 Konutları, F3 Blok, No. 42, Bilkent, 06800 Ankara, Turkey b Department of Microbiology and Clinical Microbiology, Hacettepe University School of Medicine, Ankara, Turkey c Hacettepe University School of Medicine, Children’s Hospital, Clinical Microbiology Laboratory, Ankara, Turkey d Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey Received 28 December 2004; accepted 10 March 2005
Abstract Fifty-three Salmonella enterica group C isolates obtained from various human samples (47 stool, 4 blood and 2 urine) in ten provinces of Turkey between 1 July 2000 and 30 June 2002 were serotyped and resistance to antimicrobials was investigated by agar dilution tests. The isolates were identified as S. Choleraesuis (11), S. Hadar (7), S. Irumu (4), S. Virchow (3), S. Tallahassee (3), S. Paratyphi C (2), S. Braenderup (2), S. Othmarschen (2), S. Menston (2), S. Concord (2), S. Infantis (2), S. Kottbus (2), S. Edinburg (1), S. Oranienburg (1), S. Muenchen (1) and S. Malmoe (1). Antimicrobial resistance rates of S. enterica groups C1 and C2 were high for ampicillin (26% and 60%, respectively), amoxicillin/clavulanic acid (11% and 40%), chloramphenicol (16% and 27%) and tetracycline (3% and 40%). The percentages of strains sensitive to all antimicrobials were 58% and 33%, respectively. Multiresistance was not observed in group C1 isolates, but the rate of multiresistant isolates was 13% in group C2 . The rate of decreased ciprofloxacin susceptibility (CipL ) was 61% in serogroup C1 and 20% in serogroup C2 . These results indicated that S. enterica group C infections in humans were not infrequent in Turkey and that multiple antimicrobial resistance was common within these strains. © 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. Keywords: Salmonella group C; Salmonella Choleraesuis; Salmonella Hadar; Antimicrobial resistance
1. Introduction Salmonella infections are very common and are an important public health problem in Turkey as well as in many parts of the world [1,2]. Non-typhoidal salmonellae are the major agents of food poisoning and acute gastroenteritis; however, they can cause severe diseases such as septicaemia and local infections at the any site of body [3]. The main source of human salmonellosis is food products of animal origin, especially those from poultry. Non-typhoidal salmonellae are important zoonotic pathogens [4]. Very little statistical data on salmonella infections and salmonella serotypes collected from individual stud∗
Corresponding author. Tel.: +90 312 266 2655; fax: +90 312 310 6370. E-mail address: [email protected] (B. Erdem).
ies are available in Turkey [1]. Salmonella Enteritidis, S. Typhimurium, S. Paratyphi B and S. Typhi are the most common serotypes isolated from humans in Turkey. Other salmonella serotypes are extremely rare in clinical samples [5]. In Turkey, the number of reported salmonella serotypes isolated from any samples (human, animal or other) was 116 by the end of the year 2000. Only 37 of these belong to Salmonella enterica group C [1,5]. Data regarding common salmonella serotypes isolated from clinical human samples and their antimicrobial resistance patterns are available in Turkey, but there are only a few reports on the antimicrobial resistance of group C serotypes isolated from humans and/or food animals [6,7]. The aim of this study was to investigate serotype distribution and antimicrobial resistance of S. enterica group C isolates from humans in Turkey during the period 1 July 2000 to 30 June 2002.
0924-8579/$ – see front matter © 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. doi:10.1016/j.ijantimicag.2005.03.007
34
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37
2. Materials and methods Salmonella enterica strains were consecutively isolated from various clinical samples by standard procedures [8] at 13 clinical microbiology laboratories of tertiary care hospitals in ten provinces (Ankara, Antalya, Bursa, Edirne, Eskis¸ehir, Istanbul, Izmir, Kayseri, Konya and Trabzon) between 1 July 2000 and 30 June 2002. All strains were serotyped using standard methods according to the Kauffmann–White scheme [9]. Antimicrobial susceptibility tests were performed on Mueller–Hinton agar (Difco Laboratories, Detroit, USA) by agar dilution tests following the National Committee for Clinical Laboratory Standards (NCCLS) guidelines [10]. In vitro activities of ampicillin (Fako, Istanbul, Turkey), amoxicillin/clavulanic acid (Fako, Istanbul, Turkey), cefotaxime (Eczacıbası, Istanbul, Turkey), gentamicin (Fako, Istanbul, Turkey), chloramphenicol (Sigma, Deisenhofen, Germany), tetracycline (Fako, Istanbul, Turkey), trimethoprim/sulphamethoxazole (Roche, Istanbul, Turkey) and ciprofloxacin (Bayer, Istanbul, Turkey) were determined in all isolates. Escherichia coli (ATCC 25922) was used as a quality control strain. Decreased susceptibility to ciprofloxacin (CipL ) was defined as a minimum inhibitory concentration (MIC) of 0.125–1 mg/L. Intermediately resistant strains were included in the resistant category. Isolates that were resistant to four or more antimicrobials were defined as multiresistant.
3. Results Fifty-three S. enterica group C strains were isolated from various human samples (47 stool, 4 blood and 2 urine). The S.
enterica group C isolates constituted 8.5% of all salmonella strains isolated from various clinical samples of salmonellosis patients during the study period. The distribution of clinical diseases was 85% gastroenteritis, 9% septicaemia and/or local infections, and 6% paratyphoid. Thirty-eight strains were group C1 and 15 were group C2 . Group C1 strains were isolated in the provinces of Ankara (26), Bursa (3), Edirne (2), Eskis¸ehir (1), Istanbul (1), Izmir (1), Kayseri (2) and Konya (2). Group C2 strains were obtained in Ankara (6), Antalya (2), Edirne (4) and Konya (3). The serotype distribution of salmonella group C isolates in clinical diseases is shown in Table 1. Six group C1 isolates and one group C2 isolate could not be serotyped. In this study, the group C isolates from human samples were found to be S. Choleraesuis (11), S. Hadar (7), S. Irumu (4), S. Virchow (3), S. Tallahassee (3), S. Paratyphi C (2), S. Braenderup (2), S. Othmarschen (2), S. Menston (2), S. Concord (2), S. Infantis (2), S. Kottbus (2), S. Edinburg (1), S. Oranienburg (1), S. Muenchen (1) and S. Malmoe (1) (Table 1). During the study period, S. Choleraesuis was the most common S. enterica group C serotype in Turkey; these isolates were obtained from patients with gastroenteritis (8), septicaemia and/or local infection (2) and paratyphoid (1) in the provinces of Ankara (7), Bursa (1), Eskis¸ehir (1) and Kayseri (2). The second common serotype was S. Hadar isolated from gastroenteritis cases in the provinces of Ankara (3), Antalya (2) and Edirne (2). Antimicrobial resistance rates of S. enterica group C1 and C2 were high for ampicillin (26% and 60%, respectively), amoxicillin/clavulanic acid (11% and 40%), chloramphenicol (16% and 27%) and tetracycline (3% and 40%). Table 2 displays the range, MIC50 and MIC90 values and resistance rates of salmonella group C1 and C2 isolates to antimicrobials obtained by agar dilution tests. The resistance patterns of salmonella group C isolates are shown in Table 3.
Table 1 Serotype distribution of Salmonella enterica group C isolates in clinical diseases Serotype, antigenic formulae
N
S. Edinburg 6,7:b:1,5 S. Paratyphi C 6,7:c:1,5 S. Choleraesuis 6,7:–:1,5 S. Braenderup 6,7:eh:enz15 S. Othmarschen 6,7:gm:− S. Menston 6,7:gst:– S. Oranienburg 6,7:mt:– S. Virchow 6,7:r:1,2 S. Infantis 6,7:r:1,5 S. Concord 6,7:Iv:1,2 S. Irumu 6,7:Iv:1,5 Serogroup C1 (untypeble) S. Muenchen 6,8:d:1,2 S. Kottbus 6,8:eh:1,5 S. Malmoe 6,8:i:1,7 S. Tallahassee 6,8:z4 z32 :– S. Hadar 6,8:z10 :enx Serogroup C2 (untypeble)
1 2 11 2 2 2 1 3 2 2 4 6 1 2 1 3 7 1
Total N %
53
Paratyphoid 1 1
Septicaemia/local infection
2
1 2
Gastroenteritis 1 1 8 2 2 2 1 3 2 2 3 4 1 2
1 3 7 1 3 6
5 9
45 85
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37
35
Table 2 Range, MIC50 and MIC90 values, and percentages of resistance to antimicrobials of Salmonella enterica group C1 and C2 strains in agar dilution tests (mg/L) Antimicrobials
Serogroup C1 Range
A A/C Cf G C T T/S Cip
1 to >256 0.5–64 0.03–32 0.5–4 4–64 0.25–8 0.06 to >8 0.008–0.5
Serogroup C2 MIC50
4 2 0.125 1 8 2 0.125 0.125
MIC90
16 8 0.25 1 16 4 0.5 0.25
Resistance
Range
s
%
10 4 0 0 6 1 1 0
26 11 0 0 16 3 3 0
2 to >256 1 to >256 0.06–0.25 0.25–2 4 to >64 0.25 to >64 0.06–1 0.08–0.25
MIC50
16 4 0.125 1 4 4 0.25 0.03
MIC90
>256 >256 0.25 2 16 >64 0.5 0.25
Resistance s
%
9 6 0 0 4 6 1 0
60 40 0 0 27 40 7 0
MIC, minimum inhibitory concentration; A, ampicillin; A/C, amoxicillin/clavulanic acid; Cf, cefotaxime; G, gentamicin; C, chloramphenicol; T, tetracycline; T/S, trimethoprim/sulphamethoxazole; Cip, ciprofloxacin.
4. Discussion Non-typhoidal salmonellae, which are widely distributed in many animal species, continue to produce foodborne salmonellosis in humans in developed and developing countries [2]. Although non-typhoidal salmonellae other than S. Typhimurium and S. Enteritidis were not commonly isolated from human cases, animal sources or the environment, they can cause severe invasive infections, even nosocomial, and foodborne acute gastroenteritis [4,8,11–14]. Salmonella enterica serotype Choleraesuis shows predisposition towards systemic infections in humans, causing severe complications and even death [15]. Salmonella Choleraesuis has previously been reported as an agent of gastroenteritis in Turkey [16]. In the present study, three strains of S. Choleraesuis were isolated from the patients with systemic infections. Salmonella Hadar was the second prevalent group C serotype from humans. The primary reservoirs of S. Hadar are chickens, geese, turkeys and ducks [4]. Isolation of S. Hadar from gastroenteritis cases has been reported in Turkey [5,6]. In this study, all strains of S. Hadar were obtained from stool cultures of gastroenteritis cases. During the study period, a small numbers of other serotypes were isolated from sporadic cases. An interesting finding was the isolation of S. Malmoe from a paratyphoid patient while she had been hospitalised for viral hepatitis. It was a food-derived nosocomial infection. With these isolations, the number of S. enterica serotypes reported in Turkey was up to 117, and the number of group C types reached 38. Antimicrobial therapy of gastroenteritis caused by nontyphoidal salmonellae is not recommended and is indicated only in life-threatening infections such as infections in immunocompromised patients, septicaemia or local infections [2,3]. High antimicrobial resistance rates in S. Typhimurium and S. Enteritidis strains against ampicillin, chloramphenicol, tetracycline and trimethoprim/sulphamethoxazole have been reported in various studies in Turkey [17–19], however, there are no sufficient data on the antimicrobial resistance of group C isolates from humans or food animals. In recent years
there have been several reports of multiresistance to antimicrobials in non-typhoidal salmonellae in different parts of the world [4,15]. In the present study, the rate of multiple resistance is particularly high among S. Hadar serotypes; two of seven strains (29%) of S. Hadar had multiple resistance to antimicrobials (Table 3). In Turkey, the first S. Hadar strains isolated from patients with gastroenteritis were reported in 2001, where five of six strains were multiresistant, although all were susceptible to ciprofloxacin [6]. In this study, MIC90 values for ciprofloxacin in both group C1 and C2 isolates were found to be in the susceptible category (0.25 mg/L) of NCCLS (Table 2). However, during recent years, several treatment failures with quinolones have been reported from different countries and these infections have been caused by ciprofloxacin-susceptible isolates according to the breakpoints (susceptible, ≤1 mg/L and resistant, ≥4 mg/L) used by NCCLS. It has been demonstrated that there was a defined subpopulation with decreased quinolone susceptibility (MIC ≥0.125 mg/L) [20,21]. In the present study, although no resistance to ciprofloxacin was observed in group C isolates, the rates of decreased susceptibility to ciprofloxacin (CipL ) (MIC ≥0.125 mg/L) were 61% in salmonella group C1 and 20% in salmonella group C2 . In particular, 10 of 11 isolates (91%) in S. Choleraesuis and 3 of 7 isolates (43%) in S. Hadar serotype showed decreased susceptibility to ciprofloxacin (CipL ) (Table 3). These results indicated that decreased susceptibility to ciprofloxacin in particular salmonella group C strains is an important problem in Turkey. The results presented here are a reflection of the serotype distribution and prevalence of antimicrobial resistance among salmonella group C isolates from humans. High rates of antimicrobial resistance, multiple resistance and decreased susceptibility to ciprofloxacin among S. enterica group C strains are very important issues in Turkey. Most salmonella infections, and particularly gastroenteritis, improve spontaneously and antibiotic therapy is not necessary. However, some group C serotypes, especially S. Choleraesuis, may cause severe systemic and invasive clinical conditions that require diligent antibiotic therapy [12,15].
36
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37
Table 3 Resistance patterns of salmonella group C isolates Serotype
N
Resistance pattern
N
S. Edinburg S. Paratyphi C
1 2
Susceptiblea CipL b
1 2
S. Choleraesuis
11
CipL A C CipL
8 1 2
S. Braenderup
2
C
2
S. Menston
2
Susceptible AT
1 1
S. Irumu
4
Susceptible CipL A CipL
1 2 1
S. Othmarschen
2
Susceptible
2
S. Virchow
3
Susceptible A CipL
1 1 1
S. Infantis
2
A C CipL
1 1
S. Concord
2
CipL C CipL
1 1
S. Oranienburg
1
A A/C
1
Group C1 (untypeble)
6
Susceptible CipL A A A/C CipL A A/C T/S CipL
1 1 1 2 1
S. Muenchen
1
AC
1
S. Kottbus
2
Susceptible A
1 1
S. Malmoe S. Tallahassee
1 3
Susceptible Susceptible
1 3
S. Hadar
7
A A A/C T A A/C T CipL A A/C C T A A/C C T T/S CipL
1 2 2 1 1
Group C2 (untypeble)
1
C
1
a
Susceptible to all antimicrobials: A, ampicillin; A/C, amoxicillin/clavulanic acid; C, chloramphenicol; T, tetracycline; T/S, trimethoprim/sulphamethoxazole. b Cip , decreased susceptibility to ciprofloxacin. L
Multiresistant salmonella strains spread from farm animals to humans. Resistant bacteria do not respect national boundaries, and with the ease and rapidity of modern travel and the global food market, infections can be disseminated from their origins very quickly [22,23]. Therefore, to reduce the dissemination of multiresistant salmonella isolates, more careful use of antimicrobials and more effective disease prevention of farm animals are very important. To control and reduce the prevalence of multiresistant salmonellae, continuous monitoring of the isolates is necessary. In veterinary medicine, adjusting and practicing the proper rules for lim-
ited and controlled use of antimicrobials in Turkey, with its modern and developed livestock and poultry raising both for local consumption and export to neighbouring and Middle East countries, has vital importance.
Acknowledgments This study was supported by TUBITAK: The Scientific and Technical Research Council of Turkey (Project No.: 199S224 SBAG-2246). We thank members of the Turkish Salmonella Study Group (Co-ordinator: B. Erdem), along with participating hospitals, as follows: S. Gedikoglu (Uludag University School of Medicine), B. Sumerkan (Erciyes University School of Medicine), I. Tuncer (Selcuk University School of Medicine), M. Tugrul (Trakya University School of Medicine), A. Tunger (Ege University School of Medicine), M. Tatman-Otkun (Trakya University School of Medicine), D. Esel (Erciyes University School of Medicine), Y. Akg¨un (Osmangazi University School of Medicine), N. Acar (Ankara Teaching Hospital, Ministry of Health), M. G¨ultekin (Akdeniz University School of Medicine), I. Koksal (Karadeniz University School of Medicine) and G. Soyletir (Marmara University School of Medicine).
References [1] T¨oreci K, Ang O. Turkiye’de saptanmıs olan Salmonella serovarları ve salmonellozların genel degerlendirilmesi. Turk Mikrobiyol Cem Derg 1991;21:1–18. [2] Miller S, Hohmann E, Pegues D. Salmonella species (including Salmonella typhi). In: Mandell GI, Bennet JE, Dolin R, editors. Principles and practice of infectious diseases. London, UK: Churchill Livingstone; 2000. p. 2344–61. [3] Cohen JL, Bartlett JA, Corey GR. Intestinal manifestations of Salmonella infections. Medicine 1987;66:349–85. [4] Hoszowski A, Wasyl D. Salmonella serovars found in animals and feeding stuffs in 2001 and their antimicrobial resistance. Bull Vet Inst Pulawy 2002;46:165–78. [5] Erdem B. 1998–2000 yıllarında serotiplendirilen Salmonella’lar. Infeks Derg 2001;15:137–40. [6] Erdem B, T¨unger A, G¨uriz H, et al. T¨urkiye ic¸in yeni bir Salmonella enterica subsp enterica serotipi: Salmonella Hadar. Infeks Derg 2001;15:107–9. [7] Carli KT, Eyigor A, Caner V. Prevalence of Salmonella serovars in chickens in Turkey. J Food Prot 2001;64:1832–5. [8] Janda JM, Abbott SL. The Enterobacteriaceae. Philadelphia, PA: Lippincott-Raven; 1998. p. 80–109. [9] Popoff MY. Antigenic formulas of the Salmonella serovars. World Health Organization Collaborating Centre for Reference and Research on Salmonella. Paris, France: Institute Pasteur; 2001. [10] National Committee for Clinical Laboratory Standards. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. 4th ed. Approved standard, NCCLS document M7-A4. Wayne, PA: NCCLS; 1997. [11] Vugia DJ, Samuel M, Farley MM, et al. Emerging Infections Program FoodNet Working Group. Invasive Salmonella infections in the United States, FoodNet, 1996–1999: incidence, serotype distribution, and outcome. Clin Infect Dis 2004;38(Suppl 3):S149–56.
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37 [12] Chiu S, Chiu CH, Lin TY. Salmonella enterica serotype Choleraesuis infection in a medical center in northern Taiwan. J Microbiol Immunol Infect 2004;37:99–102. [13] Morosini MI, Blazquez J, Negri MC, et al. Characterization of a nosocomial outbreak involving an epidemic plasmid encoding for TEM-27 in Salmonella enterica subspecies enterica serotype Othmarchen. J Infect Dis 1996;174:1015–20. [14] Urfer E, Rossier P, Mean F, et al. Outbreak of Salmonella braenderup gastroenteritis due to contaminated meat pies: clinical and molecular epidemiology. Clin Microbiol Infect 2000;6:536–42. [15] Cheng-Hsun C, Lin-Hui S, Chishih C. Salmonella enterica serotype Choleraesuis: epidemiology, pathogenesis, clinical diseases, and treatment. Clin Microbiol Rev 2004;17:311–22. [16] Erdem B, Gediko˘glu S, Tibet M, Gerc¸eker D. T¨urkiye’de gastroenterit etkeni olarak Salmonella choleraesuis serovarı. Infeks Derg 1996;10:83–6. [17] Aysev AD, G¨uriz H, Erdem B. Drug resistance of Salmonella strains isolated from community infections in Ankara, Turkey. Scand J Infect Dis 2001;33:420–2.
37
[18] S¨umerkan B, Inan M, Caglayangil A, et al. Klinik o¨ rneklerden izole edilen Salmonella’ların in vitro antimikrobik duyarlılıklarının de˘gerlendirilmesi. Mikrobiyol Bul 1994;28:21–6. [19] Tatman-Otkun M, Ozkan ME, Ozturk D, et al. 1995–1997 yıllarında dıskıdan izole edilen Salmonella serotiplerinin dagılımı ve antibiyotik duyarlılıkları. Infeks Derg 1998;12:181–5. [20] Threlfall EJ, Ward LR, Rowe B. Resistance to ciprofloxacin in non-typhoidal Salmonellas from humans in England and Wales—the current situation. Clin Microbiol Infect 1999;5:130–4. [21] Albayrak F, C¸okc¸a F, Erdem B, Aysev AD. Predictive value of nalidixic acid resistance for detecting salmonellae with decreased ciprofloxacin susceptibility. Int J Antimicrob Agents 2004;23: 332–6. [22] Levy SB, Fitzgerald GB, Maconne AB. Changes in intestinal flora of farm personnel after introduction of a tetracycline-supplemented feed on a farm. N Engl J Med 1976;295:583–8. [23] Molbak K, Baggesen DL, Aaestrup FM, et al. An outbreak of multidrug resistant, quinolone resistant Salmonella enterica serotype Typhimurium DT 104. N Engl J Med 1999;341:1420–5.
Antimicrobial resistance of Salmonella enterica group C strains isolated from humans in Turkey, 2000–2002 B. Erdem a,∗ , S. Ercis b , G. Hascelik b , D. Gur c , A.D. Aysev d a
Department of Microbiology and Clinical Microbiology, Ankara University School of Medicine, Bilkent 3 Konutları, F3 Blok, No. 42, Bilkent, 06800 Ankara, Turkey b Department of Microbiology and Clinical Microbiology, Hacettepe University School of Medicine, Ankara, Turkey c Hacettepe University School of Medicine, Children’s Hospital, Clinical Microbiology Laboratory, Ankara, Turkey d Department of Pediatrics, Ankara University School of Medicine, Ankara, Turkey Received 28 December 2004; accepted 10 March 2005
Abstract Fifty-three Salmonella enterica group C isolates obtained from various human samples (47 stool, 4 blood and 2 urine) in ten provinces of Turkey between 1 July 2000 and 30 June 2002 were serotyped and resistance to antimicrobials was investigated by agar dilution tests. The isolates were identified as S. Choleraesuis (11), S. Hadar (7), S. Irumu (4), S. Virchow (3), S. Tallahassee (3), S. Paratyphi C (2), S. Braenderup (2), S. Othmarschen (2), S. Menston (2), S. Concord (2), S. Infantis (2), S. Kottbus (2), S. Edinburg (1), S. Oranienburg (1), S. Muenchen (1) and S. Malmoe (1). Antimicrobial resistance rates of S. enterica groups C1 and C2 were high for ampicillin (26% and 60%, respectively), amoxicillin/clavulanic acid (11% and 40%), chloramphenicol (16% and 27%) and tetracycline (3% and 40%). The percentages of strains sensitive to all antimicrobials were 58% and 33%, respectively. Multiresistance was not observed in group C1 isolates, but the rate of multiresistant isolates was 13% in group C2 . The rate of decreased ciprofloxacin susceptibility (CipL ) was 61% in serogroup C1 and 20% in serogroup C2 . These results indicated that S. enterica group C infections in humans were not infrequent in Turkey and that multiple antimicrobial resistance was common within these strains. © 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. Keywords: Salmonella group C; Salmonella Choleraesuis; Salmonella Hadar; Antimicrobial resistance
1. Introduction Salmonella infections are very common and are an important public health problem in Turkey as well as in many parts of the world [1,2]. Non-typhoidal salmonellae are the major agents of food poisoning and acute gastroenteritis; however, they can cause severe diseases such as septicaemia and local infections at the any site of body [3]. The main source of human salmonellosis is food products of animal origin, especially those from poultry. Non-typhoidal salmonellae are important zoonotic pathogens [4]. Very little statistical data on salmonella infections and salmonella serotypes collected from individual stud∗
Corresponding author. Tel.: +90 312 266 2655; fax: +90 312 310 6370. E-mail address: [email protected] (B. Erdem).
ies are available in Turkey [1]. Salmonella Enteritidis, S. Typhimurium, S. Paratyphi B and S. Typhi are the most common serotypes isolated from humans in Turkey. Other salmonella serotypes are extremely rare in clinical samples [5]. In Turkey, the number of reported salmonella serotypes isolated from any samples (human, animal or other) was 116 by the end of the year 2000. Only 37 of these belong to Salmonella enterica group C [1,5]. Data regarding common salmonella serotypes isolated from clinical human samples and their antimicrobial resistance patterns are available in Turkey, but there are only a few reports on the antimicrobial resistance of group C serotypes isolated from humans and/or food animals [6,7]. The aim of this study was to investigate serotype distribution and antimicrobial resistance of S. enterica group C isolates from humans in Turkey during the period 1 July 2000 to 30 June 2002.
0924-8579/$ – see front matter © 2005 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved. doi:10.1016/j.ijantimicag.2005.03.007
34
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37
2. Materials and methods Salmonella enterica strains were consecutively isolated from various clinical samples by standard procedures [8] at 13 clinical microbiology laboratories of tertiary care hospitals in ten provinces (Ankara, Antalya, Bursa, Edirne, Eskis¸ehir, Istanbul, Izmir, Kayseri, Konya and Trabzon) between 1 July 2000 and 30 June 2002. All strains were serotyped using standard methods according to the Kauffmann–White scheme [9]. Antimicrobial susceptibility tests were performed on Mueller–Hinton agar (Difco Laboratories, Detroit, USA) by agar dilution tests following the National Committee for Clinical Laboratory Standards (NCCLS) guidelines [10]. In vitro activities of ampicillin (Fako, Istanbul, Turkey), amoxicillin/clavulanic acid (Fako, Istanbul, Turkey), cefotaxime (Eczacıbası, Istanbul, Turkey), gentamicin (Fako, Istanbul, Turkey), chloramphenicol (Sigma, Deisenhofen, Germany), tetracycline (Fako, Istanbul, Turkey), trimethoprim/sulphamethoxazole (Roche, Istanbul, Turkey) and ciprofloxacin (Bayer, Istanbul, Turkey) were determined in all isolates. Escherichia coli (ATCC 25922) was used as a quality control strain. Decreased susceptibility to ciprofloxacin (CipL ) was defined as a minimum inhibitory concentration (MIC) of 0.125–1 mg/L. Intermediately resistant strains were included in the resistant category. Isolates that were resistant to four or more antimicrobials were defined as multiresistant.
3. Results Fifty-three S. enterica group C strains were isolated from various human samples (47 stool, 4 blood and 2 urine). The S.
enterica group C isolates constituted 8.5% of all salmonella strains isolated from various clinical samples of salmonellosis patients during the study period. The distribution of clinical diseases was 85% gastroenteritis, 9% septicaemia and/or local infections, and 6% paratyphoid. Thirty-eight strains were group C1 and 15 were group C2 . Group C1 strains were isolated in the provinces of Ankara (26), Bursa (3), Edirne (2), Eskis¸ehir (1), Istanbul (1), Izmir (1), Kayseri (2) and Konya (2). Group C2 strains were obtained in Ankara (6), Antalya (2), Edirne (4) and Konya (3). The serotype distribution of salmonella group C isolates in clinical diseases is shown in Table 1. Six group C1 isolates and one group C2 isolate could not be serotyped. In this study, the group C isolates from human samples were found to be S. Choleraesuis (11), S. Hadar (7), S. Irumu (4), S. Virchow (3), S. Tallahassee (3), S. Paratyphi C (2), S. Braenderup (2), S. Othmarschen (2), S. Menston (2), S. Concord (2), S. Infantis (2), S. Kottbus (2), S. Edinburg (1), S. Oranienburg (1), S. Muenchen (1) and S. Malmoe (1) (Table 1). During the study period, S. Choleraesuis was the most common S. enterica group C serotype in Turkey; these isolates were obtained from patients with gastroenteritis (8), septicaemia and/or local infection (2) and paratyphoid (1) in the provinces of Ankara (7), Bursa (1), Eskis¸ehir (1) and Kayseri (2). The second common serotype was S. Hadar isolated from gastroenteritis cases in the provinces of Ankara (3), Antalya (2) and Edirne (2). Antimicrobial resistance rates of S. enterica group C1 and C2 were high for ampicillin (26% and 60%, respectively), amoxicillin/clavulanic acid (11% and 40%), chloramphenicol (16% and 27%) and tetracycline (3% and 40%). Table 2 displays the range, MIC50 and MIC90 values and resistance rates of salmonella group C1 and C2 isolates to antimicrobials obtained by agar dilution tests. The resistance patterns of salmonella group C isolates are shown in Table 3.
Table 1 Serotype distribution of Salmonella enterica group C isolates in clinical diseases Serotype, antigenic formulae
N
S. Edinburg 6,7:b:1,5 S. Paratyphi C 6,7:c:1,5 S. Choleraesuis 6,7:–:1,5 S. Braenderup 6,7:eh:enz15 S. Othmarschen 6,7:gm:− S. Menston 6,7:gst:– S. Oranienburg 6,7:mt:– S. Virchow 6,7:r:1,2 S. Infantis 6,7:r:1,5 S. Concord 6,7:Iv:1,2 S. Irumu 6,7:Iv:1,5 Serogroup C1 (untypeble) S. Muenchen 6,8:d:1,2 S. Kottbus 6,8:eh:1,5 S. Malmoe 6,8:i:1,7 S. Tallahassee 6,8:z4 z32 :– S. Hadar 6,8:z10 :enx Serogroup C2 (untypeble)
1 2 11 2 2 2 1 3 2 2 4 6 1 2 1 3 7 1
Total N %
53
Paratyphoid 1 1
Septicaemia/local infection
2
1 2
Gastroenteritis 1 1 8 2 2 2 1 3 2 2 3 4 1 2
1 3 7 1 3 6
5 9
45 85
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37
35
Table 2 Range, MIC50 and MIC90 values, and percentages of resistance to antimicrobials of Salmonella enterica group C1 and C2 strains in agar dilution tests (mg/L) Antimicrobials
Serogroup C1 Range
A A/C Cf G C T T/S Cip
1 to >256 0.5–64 0.03–32 0.5–4 4–64 0.25–8 0.06 to >8 0.008–0.5
Serogroup C2 MIC50
4 2 0.125 1 8 2 0.125 0.125
MIC90
16 8 0.25 1 16 4 0.5 0.25
Resistance
Range
s
%
10 4 0 0 6 1 1 0
26 11 0 0 16 3 3 0
2 to >256 1 to >256 0.06–0.25 0.25–2 4 to >64 0.25 to >64 0.06–1 0.08–0.25
MIC50
16 4 0.125 1 4 4 0.25 0.03
MIC90
>256 >256 0.25 2 16 >64 0.5 0.25
Resistance s
%
9 6 0 0 4 6 1 0
60 40 0 0 27 40 7 0
MIC, minimum inhibitory concentration; A, ampicillin; A/C, amoxicillin/clavulanic acid; Cf, cefotaxime; G, gentamicin; C, chloramphenicol; T, tetracycline; T/S, trimethoprim/sulphamethoxazole; Cip, ciprofloxacin.
4. Discussion Non-typhoidal salmonellae, which are widely distributed in many animal species, continue to produce foodborne salmonellosis in humans in developed and developing countries [2]. Although non-typhoidal salmonellae other than S. Typhimurium and S. Enteritidis were not commonly isolated from human cases, animal sources or the environment, they can cause severe invasive infections, even nosocomial, and foodborne acute gastroenteritis [4,8,11–14]. Salmonella enterica serotype Choleraesuis shows predisposition towards systemic infections in humans, causing severe complications and even death [15]. Salmonella Choleraesuis has previously been reported as an agent of gastroenteritis in Turkey [16]. In the present study, three strains of S. Choleraesuis were isolated from the patients with systemic infections. Salmonella Hadar was the second prevalent group C serotype from humans. The primary reservoirs of S. Hadar are chickens, geese, turkeys and ducks [4]. Isolation of S. Hadar from gastroenteritis cases has been reported in Turkey [5,6]. In this study, all strains of S. Hadar were obtained from stool cultures of gastroenteritis cases. During the study period, a small numbers of other serotypes were isolated from sporadic cases. An interesting finding was the isolation of S. Malmoe from a paratyphoid patient while she had been hospitalised for viral hepatitis. It was a food-derived nosocomial infection. With these isolations, the number of S. enterica serotypes reported in Turkey was up to 117, and the number of group C types reached 38. Antimicrobial therapy of gastroenteritis caused by nontyphoidal salmonellae is not recommended and is indicated only in life-threatening infections such as infections in immunocompromised patients, septicaemia or local infections [2,3]. High antimicrobial resistance rates in S. Typhimurium and S. Enteritidis strains against ampicillin, chloramphenicol, tetracycline and trimethoprim/sulphamethoxazole have been reported in various studies in Turkey [17–19], however, there are no sufficient data on the antimicrobial resistance of group C isolates from humans or food animals. In recent years
there have been several reports of multiresistance to antimicrobials in non-typhoidal salmonellae in different parts of the world [4,15]. In the present study, the rate of multiple resistance is particularly high among S. Hadar serotypes; two of seven strains (29%) of S. Hadar had multiple resistance to antimicrobials (Table 3). In Turkey, the first S. Hadar strains isolated from patients with gastroenteritis were reported in 2001, where five of six strains were multiresistant, although all were susceptible to ciprofloxacin [6]. In this study, MIC90 values for ciprofloxacin in both group C1 and C2 isolates were found to be in the susceptible category (0.25 mg/L) of NCCLS (Table 2). However, during recent years, several treatment failures with quinolones have been reported from different countries and these infections have been caused by ciprofloxacin-susceptible isolates according to the breakpoints (susceptible, ≤1 mg/L and resistant, ≥4 mg/L) used by NCCLS. It has been demonstrated that there was a defined subpopulation with decreased quinolone susceptibility (MIC ≥0.125 mg/L) [20,21]. In the present study, although no resistance to ciprofloxacin was observed in group C isolates, the rates of decreased susceptibility to ciprofloxacin (CipL ) (MIC ≥0.125 mg/L) were 61% in salmonella group C1 and 20% in salmonella group C2 . In particular, 10 of 11 isolates (91%) in S. Choleraesuis and 3 of 7 isolates (43%) in S. Hadar serotype showed decreased susceptibility to ciprofloxacin (CipL ) (Table 3). These results indicated that decreased susceptibility to ciprofloxacin in particular salmonella group C strains is an important problem in Turkey. The results presented here are a reflection of the serotype distribution and prevalence of antimicrobial resistance among salmonella group C isolates from humans. High rates of antimicrobial resistance, multiple resistance and decreased susceptibility to ciprofloxacin among S. enterica group C strains are very important issues in Turkey. Most salmonella infections, and particularly gastroenteritis, improve spontaneously and antibiotic therapy is not necessary. However, some group C serotypes, especially S. Choleraesuis, may cause severe systemic and invasive clinical conditions that require diligent antibiotic therapy [12,15].
36
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37
Table 3 Resistance patterns of salmonella group C isolates Serotype
N
Resistance pattern
N
S. Edinburg S. Paratyphi C
1 2
Susceptiblea CipL b
1 2
S. Choleraesuis
11
CipL A C CipL
8 1 2
S. Braenderup
2
C
2
S. Menston
2
Susceptible AT
1 1
S. Irumu
4
Susceptible CipL A CipL
1 2 1
S. Othmarschen
2
Susceptible
2
S. Virchow
3
Susceptible A CipL
1 1 1
S. Infantis
2
A C CipL
1 1
S. Concord
2
CipL C CipL
1 1
S. Oranienburg
1
A A/C
1
Group C1 (untypeble)
6
Susceptible CipL A A A/C CipL A A/C T/S CipL
1 1 1 2 1
S. Muenchen
1
AC
1
S. Kottbus
2
Susceptible A
1 1
S. Malmoe S. Tallahassee
1 3
Susceptible Susceptible
1 3
S. Hadar
7
A A A/C T A A/C T CipL A A/C C T A A/C C T T/S CipL
1 2 2 1 1
Group C2 (untypeble)
1
C
1
a
Susceptible to all antimicrobials: A, ampicillin; A/C, amoxicillin/clavulanic acid; C, chloramphenicol; T, tetracycline; T/S, trimethoprim/sulphamethoxazole. b Cip , decreased susceptibility to ciprofloxacin. L
Multiresistant salmonella strains spread from farm animals to humans. Resistant bacteria do not respect national boundaries, and with the ease and rapidity of modern travel and the global food market, infections can be disseminated from their origins very quickly [22,23]. Therefore, to reduce the dissemination of multiresistant salmonella isolates, more careful use of antimicrobials and more effective disease prevention of farm animals are very important. To control and reduce the prevalence of multiresistant salmonellae, continuous monitoring of the isolates is necessary. In veterinary medicine, adjusting and practicing the proper rules for lim-
ited and controlled use of antimicrobials in Turkey, with its modern and developed livestock and poultry raising both for local consumption and export to neighbouring and Middle East countries, has vital importance.
Acknowledgments This study was supported by TUBITAK: The Scientific and Technical Research Council of Turkey (Project No.: 199S224 SBAG-2246). We thank members of the Turkish Salmonella Study Group (Co-ordinator: B. Erdem), along with participating hospitals, as follows: S. Gedikoglu (Uludag University School of Medicine), B. Sumerkan (Erciyes University School of Medicine), I. Tuncer (Selcuk University School of Medicine), M. Tugrul (Trakya University School of Medicine), A. Tunger (Ege University School of Medicine), M. Tatman-Otkun (Trakya University School of Medicine), D. Esel (Erciyes University School of Medicine), Y. Akg¨un (Osmangazi University School of Medicine), N. Acar (Ankara Teaching Hospital, Ministry of Health), M. G¨ultekin (Akdeniz University School of Medicine), I. Koksal (Karadeniz University School of Medicine) and G. Soyletir (Marmara University School of Medicine).
References [1] T¨oreci K, Ang O. Turkiye’de saptanmıs olan Salmonella serovarları ve salmonellozların genel degerlendirilmesi. Turk Mikrobiyol Cem Derg 1991;21:1–18. [2] Miller S, Hohmann E, Pegues D. Salmonella species (including Salmonella typhi). In: Mandell GI, Bennet JE, Dolin R, editors. Principles and practice of infectious diseases. London, UK: Churchill Livingstone; 2000. p. 2344–61. [3] Cohen JL, Bartlett JA, Corey GR. Intestinal manifestations of Salmonella infections. Medicine 1987;66:349–85. [4] Hoszowski A, Wasyl D. Salmonella serovars found in animals and feeding stuffs in 2001 and their antimicrobial resistance. Bull Vet Inst Pulawy 2002;46:165–78. [5] Erdem B. 1998–2000 yıllarında serotiplendirilen Salmonella’lar. Infeks Derg 2001;15:137–40. [6] Erdem B, T¨unger A, G¨uriz H, et al. T¨urkiye ic¸in yeni bir Salmonella enterica subsp enterica serotipi: Salmonella Hadar. Infeks Derg 2001;15:107–9. [7] Carli KT, Eyigor A, Caner V. Prevalence of Salmonella serovars in chickens in Turkey. J Food Prot 2001;64:1832–5. [8] Janda JM, Abbott SL. The Enterobacteriaceae. Philadelphia, PA: Lippincott-Raven; 1998. p. 80–109. [9] Popoff MY. Antigenic formulas of the Salmonella serovars. World Health Organization Collaborating Centre for Reference and Research on Salmonella. Paris, France: Institute Pasteur; 2001. [10] National Committee for Clinical Laboratory Standards. Methods for dilution antimicrobial susceptibility tests for bacteria that grow aerobically. 4th ed. Approved standard, NCCLS document M7-A4. Wayne, PA: NCCLS; 1997. [11] Vugia DJ, Samuel M, Farley MM, et al. Emerging Infections Program FoodNet Working Group. Invasive Salmonella infections in the United States, FoodNet, 1996–1999: incidence, serotype distribution, and outcome. Clin Infect Dis 2004;38(Suppl 3):S149–56.
B. Erdem et al. / International Journal of Antimicrobial Agents 26 (2005) 33–37 [12] Chiu S, Chiu CH, Lin TY. Salmonella enterica serotype Choleraesuis infection in a medical center in northern Taiwan. J Microbiol Immunol Infect 2004;37:99–102. [13] Morosini MI, Blazquez J, Negri MC, et al. Characterization of a nosocomial outbreak involving an epidemic plasmid encoding for TEM-27 in Salmonella enterica subspecies enterica serotype Othmarchen. J Infect Dis 1996;174:1015–20. [14] Urfer E, Rossier P, Mean F, et al. Outbreak of Salmonella braenderup gastroenteritis due to contaminated meat pies: clinical and molecular epidemiology. Clin Microbiol Infect 2000;6:536–42. [15] Cheng-Hsun C, Lin-Hui S, Chishih C. Salmonella enterica serotype Choleraesuis: epidemiology, pathogenesis, clinical diseases, and treatment. Clin Microbiol Rev 2004;17:311–22. [16] Erdem B, Gediko˘glu S, Tibet M, Gerc¸eker D. T¨urkiye’de gastroenterit etkeni olarak Salmonella choleraesuis serovarı. Infeks Derg 1996;10:83–6. [17] Aysev AD, G¨uriz H, Erdem B. Drug resistance of Salmonella strains isolated from community infections in Ankara, Turkey. Scand J Infect Dis 2001;33:420–2.
37
[18] S¨umerkan B, Inan M, Caglayangil A, et al. Klinik o¨ rneklerden izole edilen Salmonella’ların in vitro antimikrobik duyarlılıklarının de˘gerlendirilmesi. Mikrobiyol Bul 1994;28:21–6. [19] Tatman-Otkun M, Ozkan ME, Ozturk D, et al. 1995–1997 yıllarında dıskıdan izole edilen Salmonella serotiplerinin dagılımı ve antibiyotik duyarlılıkları. Infeks Derg 1998;12:181–5. [20] Threlfall EJ, Ward LR, Rowe B. Resistance to ciprofloxacin in non-typhoidal Salmonellas from humans in England and Wales—the current situation. Clin Microbiol Infect 1999;5:130–4. [21] Albayrak F, C¸okc¸a F, Erdem B, Aysev AD. Predictive value of nalidixic acid resistance for detecting salmonellae with decreased ciprofloxacin susceptibility. Int J Antimicrob Agents 2004;23: 332–6. [22] Levy SB, Fitzgerald GB, Maconne AB. Changes in intestinal flora of farm personnel after introduction of a tetracycline-supplemented feed on a farm. N Engl J Med 1976;295:583–8. [23] Molbak K, Baggesen DL, Aaestrup FM, et al. An outbreak of multidrug resistant, quinolone resistant Salmonella enterica serotype Typhimurium DT 104. N Engl J Med 1999;341:1420–5.