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New rapid antigen test for diagnosis of pneumococcal meningitis
RESEARCH LETTERS
Research letters
New rapid antigen test for diagnosis of pneumococcal meningitis María A Marcos, Esteban Martínez, Manel Almela, Josep Mensa, María T Jiménez de Anta Conventional diagnostic methods for bacterial meningitis are frequently not rapid or sensitive enough to guide initial antimicrobial therapy. Streptococcus pneumoniae is the most frequent and severe cause of communityacquired bacterial meningitis and treatment is complicated by the increasing prevalence of antimicrobial resistance to third-generation cephalosporins. We used a new rapid antigen test in the cerebrospinal fluid and urine of patients with suspected bacterial meningitis, and found it to be highly sensitive and specific for the detection of pneumococci. This test might help guide initial therapy for bacterial meningitis according to the local rates of pneumococcal antimicrobial resistance.
Initial antimicrobial therapy for suspected bacterial meningitis should be guided by the results of gram staining or bacterial antigen tests in cerebrospinal fluid (CSF). However, the sensitivity of CSF gram staining can decrease from 75% to 50% in patients who have already been given antimicrobial therapy.1 Additionally, the sensitivities of current bacterial antigen tests in CSF samples vary from 50% to 100% dependent on the commercial assays used and the organisms studied.2 In many instances, antimicrobial therapy must be started empirically because no causative agent can be identified in advance. Streptococcus pneumoniae has become the main cause of communityacquired acute bacterial meningitis. Recommendations on empirical treatment in the emergency setting for presumed bacterial meningitis have been modified recently because of the increasing rates of pneumococcal resistance to penicillin and thirdgeneration cephalosporins such as cefotaxime or ceftriaxone.1,3 Rapid and accurate diagnosis of pneumococcal bacterial meningitis would therefore be very welcome.
Representative results of of Binax NOW Streptococcus pneumoniae antigen test Left=positive result, right=negative result from CSF samples.
THE LANCET • Vol 357 • May 12, 2001
Diagnosis by conventional methods
Total
CSF gram staining
Patients with meningitis (n=25) Streptococcus 8 6 pneumoniae Neisseria 4 4 meningitidis Haemophilus 1 0 influenzae Listeria 1 0 monocytogenes No diagnosis 11 0 Controls (n=32) No diagnosis 32
0
CSF culture
Blood culture
Urinary antigen test
8
6
8
3
3
0
1
0
0
1
1
0
0
0
4
0
0
0
CSF=cerebrospinal fluid.
Comparison of results obtained with conventional diagnostic methods and new urinary antigen test
A rapid immunochromatographic membrane assay (Binax NOW Streptococcus pneumoniae Urinary Antigen Test, Binax, Portland, ME, USA) has been approved for the diagnosis of pneumococcal pneumonia.4 In our experience, this test increases the diagnostic yield for pneumococci in patients with community-acquired pneumonia.5 By contrast with other less sensitive bacterial antigen tests that detect capsular antigens, this rapid test detects S pneumoniae C-polysaccharide, which is found in the cell wall and is common to all serotypes. To use this test device, a swab is dipped in the urine sample and placed on a nitrocellulose membrane containing complexes consisting of rabbit antibody against S pneumoniae conjugated with colloidal gold particles. Two lines of immobilised antibodies are adsorbed onto this membrane. The first line (sample line) contains a rabbit antibody against S pneumoniae, and the second (control line) contains goat antibody against rabbit antibodies. If S pneumoniae antigen is present in the urine sample, it binds to the conjugated antibody, and the resulting antigen–conjugate complexes are captured by the immobilised antibody, forming a visible line (figure). Immobilised goat antibody against rabbit antibody captures excess visualising conjugate, forming the control line (figure). Since there are no data on the potential applicability of this test in samples other than urine or in infections other than pneumonia, we explored its usefulness in the CSF and urine of adult patients with suspected bacterial meningitis.
1499
For personal use. Only reproduce with permission from The Lancet Publishing Group.
RESEARCH LETTERS
All adult patients admitted to our hospital from Oct 1, 1999, to July 31, 2000, with a clinical picture consistent with acute bacterial meningitis and CSF pleocytosis of at least 100 neutrophils/L were enrolled. A group of 32 neurosurgical patients undergoing CSF diagnostic procedures for reasons other than CSF infection were used as controls. Blood cultures and CSF chemistry, cell counts, gram staining, and cultures were routinely done at admission in the patients with meningitis. CSF samples from the control group were gram stained and cultured. CSF and urine samples from all patients were tested for the presence of S pneumoniae antigen with the Binax NOW urinary antigen test. 25 patients met the inclusion criteria for communityacquired acute bacterial meningitis, and an organism was identified through CSF gram staining or blood or CSF cultures in 14. Minimum inhibitory concentrations (g/mL) of penicillin and cefotaxime in the S pneumoniae isolates from the eight patients with bacterial meningitis were 0·03 and 0·25, respectively, in six; 1·00 and 0·25, respectively, in one; and 2·00 and 1·00, respectively, in another. At least two patients with, and six patients without, a causative diagnosis had received antimicrobial therapy before hospital admission. The detection of S pneumoniae antigen in CSF and urine samples showed a sensitivity and specificity of 100% for the diagnosis of pneumococcal meningitis (table). The specificity of this test was further confirmed by the negative results from all controls with no suspected bacterial infection. In four of 11 patients with bacterial meningitis and no established bacterial cause, the results of the test were positive, suggesting pneumococcal infection (table). Since three of these four patients had received antimicrobial therapy before admission, we assume that the sensitivity of the conventional tests had been compromised, and that these patients did, in fact, have pneumococcal meningitis. We found a 100% correlation between the results in CSF and urine of the S pneumoniae antigen test. Our study shows that testing for S pneumoniae antigen with the Binax NOW test in CSF from patients with suspected bacterial meningitis allows a rapid diagnosis of the pneumococcal infection and increases the efficiency of conventional methods. However, these results should be regarded with caution because of the small numbers of patients studied. Although this test may give similar results in urine and in CSF, we believe that CSF should be the preferred sample for the diagnosis of pneumococcal meningitis because the diagnosis of meningitis must be confirmed on CSF samples and because a positive result in urine may be also found in invasive pneumococcal infections other than meningitis. The rapid and accurate identification of pneumococcal infection in patients presenting with bacterial meningitis might be useful in the adjustment of initial antimicrobial therapy to cover S pneumoniae according to local rates of antimicrobial resistance. The study was partly supported by grant FIS 98/1250 from the Spanish Ministry of Health. 1 2 3
Tunkel AR, Scheld WM. Acute bacterial meningitis. Lancet 1995; 346: 1675–80. Gray LD, Fedorko DP. Laboratory diagnosis of bacterial meningitis. Clin Microbiol Rev 1992; 5: 130–45. Paris MM, Ramilo O, McCracken GH. Management of meningitis caused by penicillin-resistant Streptococcus pneumoniae. Antimicrob Agents Chemother 1995; 39: 2171–75.
1500
4 5
Henney JE. Quick test for pneumonia. JAMA 1999; 282: 1218. Marcos MA, Gonzalez J, Angrill J, et al. The S pneumoniae urinary antigen test for improvement of the diagnosis of communityacquired pneumonia. Am J Respir Crit Care Med 2000; 161: A294 (abstr).
Units of Microbiology (Prof M A Marcos PhD, M Almela MD, Prof M T Jiménez de Anta PhD) and Infectious Diseases (E Martínez PhD, J Mensa MD); Clinical Institute of Infections and Immunology, Institut d´Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic Universitari, Barcelona 08036, Spain Correspondence to: Prof María A Marcos (e-mail: [email protected])
Absence of the inferior labial and lingual frenula in Ehlers-Danlos syndrome Claudio De Felice, Paolo Toti, Giovanni Di Maggio, Stefano Parrini, Franco Bagnoli The diagnosis of Ehlers-Danlos syndrome is based on distinctive phenotypical characteristics such as hyperelastic skin and hypermobile joints. To date, no congenital physical markers exist for identifying patients with Ehlers-Danlos syndrome. Absence of the inferior labial (100% sensitivity; 99·4% specificity) and lingual frenulum (71·4% sensitivity; 100% specificity) was found to be associated with classical and hypermobility types of EhlersDanlos syndrome.
Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inheritable connective tissue disorders, featuring skin hyperextensibility and joint hypermobility.1 It has been estimated that approximately one in 5000 individuals is affected by EDS.2 The diagnosis is usually made clinically.1 A variety of diagnostic signs has been described in EDS patients, including dystrophic “cigarette paper” scarring, tongue hypermobility (Gorlin’s sign), eyelid extensibility (Metenier’s sign), and postural acrocyanosis.3,4 However, none of these clinical features allows a diagnosis at birth, since they develop later in life. As labial and lingual frenula are mainly connective tissue structures, we tested the hypothesis that developmental abnormalities of the oral frenula are associated with EDS. 12 consecutive patients (five male, seven female, mean age 29·7 years; range 15–45 years) belonging to seven unrelated families and fulfilling the clinical criteria1 for classical EDS (formerly type II/Mitis, Online Mendelian Inheritance in Man [OMIM] 130010, autosomal dominant inheritance; n=4) or hypermobility EDS (formerly type III/hypermobile, OMIM 130020, autosomal dominant inheritance; n=8) were recruited for the study. All patients had velvety skin with severe hyperelasticity, which was tested at a neutral site, and joint hypermobility, which was determined by a score of 5/9 or greater by use of Beighton’s 9-point scale (mean 7·4 [SD 1·2]).1 All patients with classical EDS had atrophic scars, and two out of four had subcutaneous nodules and pseudotumours, whereas none of the hypermobility patients had any of these characteristics. Three of four classical and seven of eight hypermobility patients
THE LANCET • Vol 357 • May 12, 2001
For personal use. Only reproduce with permission from The Lancet Publishing Group.
Research letters
New rapid antigen test for diagnosis of pneumococcal meningitis María A Marcos, Esteban Martínez, Manel Almela, Josep Mensa, María T Jiménez de Anta Conventional diagnostic methods for bacterial meningitis are frequently not rapid or sensitive enough to guide initial antimicrobial therapy. Streptococcus pneumoniae is the most frequent and severe cause of communityacquired bacterial meningitis and treatment is complicated by the increasing prevalence of antimicrobial resistance to third-generation cephalosporins. We used a new rapid antigen test in the cerebrospinal fluid and urine of patients with suspected bacterial meningitis, and found it to be highly sensitive and specific for the detection of pneumococci. This test might help guide initial therapy for bacterial meningitis according to the local rates of pneumococcal antimicrobial resistance.
Initial antimicrobial therapy for suspected bacterial meningitis should be guided by the results of gram staining or bacterial antigen tests in cerebrospinal fluid (CSF). However, the sensitivity of CSF gram staining can decrease from 75% to 50% in patients who have already been given antimicrobial therapy.1 Additionally, the sensitivities of current bacterial antigen tests in CSF samples vary from 50% to 100% dependent on the commercial assays used and the organisms studied.2 In many instances, antimicrobial therapy must be started empirically because no causative agent can be identified in advance. Streptococcus pneumoniae has become the main cause of communityacquired acute bacterial meningitis. Recommendations on empirical treatment in the emergency setting for presumed bacterial meningitis have been modified recently because of the increasing rates of pneumococcal resistance to penicillin and thirdgeneration cephalosporins such as cefotaxime or ceftriaxone.1,3 Rapid and accurate diagnosis of pneumococcal bacterial meningitis would therefore be very welcome.
Representative results of of Binax NOW Streptococcus pneumoniae antigen test Left=positive result, right=negative result from CSF samples.
THE LANCET • Vol 357 • May 12, 2001
Diagnosis by conventional methods
Total
CSF gram staining
Patients with meningitis (n=25) Streptococcus 8 6 pneumoniae Neisseria 4 4 meningitidis Haemophilus 1 0 influenzae Listeria 1 0 monocytogenes No diagnosis 11 0 Controls (n=32) No diagnosis 32
0
CSF culture
Blood culture
Urinary antigen test
8
6
8
3
3
0
1
0
0
1
1
0
0
0
4
0
0
0
CSF=cerebrospinal fluid.
Comparison of results obtained with conventional diagnostic methods and new urinary antigen test
A rapid immunochromatographic membrane assay (Binax NOW Streptococcus pneumoniae Urinary Antigen Test, Binax, Portland, ME, USA) has been approved for the diagnosis of pneumococcal pneumonia.4 In our experience, this test increases the diagnostic yield for pneumococci in patients with community-acquired pneumonia.5 By contrast with other less sensitive bacterial antigen tests that detect capsular antigens, this rapid test detects S pneumoniae C-polysaccharide, which is found in the cell wall and is common to all serotypes. To use this test device, a swab is dipped in the urine sample and placed on a nitrocellulose membrane containing complexes consisting of rabbit antibody against S pneumoniae conjugated with colloidal gold particles. Two lines of immobilised antibodies are adsorbed onto this membrane. The first line (sample line) contains a rabbit antibody against S pneumoniae, and the second (control line) contains goat antibody against rabbit antibodies. If S pneumoniae antigen is present in the urine sample, it binds to the conjugated antibody, and the resulting antigen–conjugate complexes are captured by the immobilised antibody, forming a visible line (figure). Immobilised goat antibody against rabbit antibody captures excess visualising conjugate, forming the control line (figure). Since there are no data on the potential applicability of this test in samples other than urine or in infections other than pneumonia, we explored its usefulness in the CSF and urine of adult patients with suspected bacterial meningitis.
1499
For personal use. Only reproduce with permission from The Lancet Publishing Group.
RESEARCH LETTERS
All adult patients admitted to our hospital from Oct 1, 1999, to July 31, 2000, with a clinical picture consistent with acute bacterial meningitis and CSF pleocytosis of at least 100 neutrophils/L were enrolled. A group of 32 neurosurgical patients undergoing CSF diagnostic procedures for reasons other than CSF infection were used as controls. Blood cultures and CSF chemistry, cell counts, gram staining, and cultures were routinely done at admission in the patients with meningitis. CSF samples from the control group were gram stained and cultured. CSF and urine samples from all patients were tested for the presence of S pneumoniae antigen with the Binax NOW urinary antigen test. 25 patients met the inclusion criteria for communityacquired acute bacterial meningitis, and an organism was identified through CSF gram staining or blood or CSF cultures in 14. Minimum inhibitory concentrations (g/mL) of penicillin and cefotaxime in the S pneumoniae isolates from the eight patients with bacterial meningitis were 0·03 and 0·25, respectively, in six; 1·00 and 0·25, respectively, in one; and 2·00 and 1·00, respectively, in another. At least two patients with, and six patients without, a causative diagnosis had received antimicrobial therapy before hospital admission. The detection of S pneumoniae antigen in CSF and urine samples showed a sensitivity and specificity of 100% for the diagnosis of pneumococcal meningitis (table). The specificity of this test was further confirmed by the negative results from all controls with no suspected bacterial infection. In four of 11 patients with bacterial meningitis and no established bacterial cause, the results of the test were positive, suggesting pneumococcal infection (table). Since three of these four patients had received antimicrobial therapy before admission, we assume that the sensitivity of the conventional tests had been compromised, and that these patients did, in fact, have pneumococcal meningitis. We found a 100% correlation between the results in CSF and urine of the S pneumoniae antigen test. Our study shows that testing for S pneumoniae antigen with the Binax NOW test in CSF from patients with suspected bacterial meningitis allows a rapid diagnosis of the pneumococcal infection and increases the efficiency of conventional methods. However, these results should be regarded with caution because of the small numbers of patients studied. Although this test may give similar results in urine and in CSF, we believe that CSF should be the preferred sample for the diagnosis of pneumococcal meningitis because the diagnosis of meningitis must be confirmed on CSF samples and because a positive result in urine may be also found in invasive pneumococcal infections other than meningitis. The rapid and accurate identification of pneumococcal infection in patients presenting with bacterial meningitis might be useful in the adjustment of initial antimicrobial therapy to cover S pneumoniae according to local rates of antimicrobial resistance. The study was partly supported by grant FIS 98/1250 from the Spanish Ministry of Health. 1 2 3
Tunkel AR, Scheld WM. Acute bacterial meningitis. Lancet 1995; 346: 1675–80. Gray LD, Fedorko DP. Laboratory diagnosis of bacterial meningitis. Clin Microbiol Rev 1992; 5: 130–45. Paris MM, Ramilo O, McCracken GH. Management of meningitis caused by penicillin-resistant Streptococcus pneumoniae. Antimicrob Agents Chemother 1995; 39: 2171–75.
1500
4 5
Henney JE. Quick test for pneumonia. JAMA 1999; 282: 1218. Marcos MA, Gonzalez J, Angrill J, et al. The S pneumoniae urinary antigen test for improvement of the diagnosis of communityacquired pneumonia. Am J Respir Crit Care Med 2000; 161: A294 (abstr).
Units of Microbiology (Prof M A Marcos PhD, M Almela MD, Prof M T Jiménez de Anta PhD) and Infectious Diseases (E Martínez PhD, J Mensa MD); Clinical Institute of Infections and Immunology, Institut d´Investigacions Biomèdiques August Pi i Sunyer, Hospital Clínic Universitari, Barcelona 08036, Spain Correspondence to: Prof María A Marcos (e-mail: [email protected])
Absence of the inferior labial and lingual frenula in Ehlers-Danlos syndrome Claudio De Felice, Paolo Toti, Giovanni Di Maggio, Stefano Parrini, Franco Bagnoli The diagnosis of Ehlers-Danlos syndrome is based on distinctive phenotypical characteristics such as hyperelastic skin and hypermobile joints. To date, no congenital physical markers exist for identifying patients with Ehlers-Danlos syndrome. Absence of the inferior labial (100% sensitivity; 99·4% specificity) and lingual frenulum (71·4% sensitivity; 100% specificity) was found to be associated with classical and hypermobility types of EhlersDanlos syndrome.
Ehlers-Danlos syndrome (EDS) is a heterogeneous group of inheritable connective tissue disorders, featuring skin hyperextensibility and joint hypermobility.1 It has been estimated that approximately one in 5000 individuals is affected by EDS.2 The diagnosis is usually made clinically.1 A variety of diagnostic signs has been described in EDS patients, including dystrophic “cigarette paper” scarring, tongue hypermobility (Gorlin’s sign), eyelid extensibility (Metenier’s sign), and postural acrocyanosis.3,4 However, none of these clinical features allows a diagnosis at birth, since they develop later in life. As labial and lingual frenula are mainly connective tissue structures, we tested the hypothesis that developmental abnormalities of the oral frenula are associated with EDS. 12 consecutive patients (five male, seven female, mean age 29·7 years; range 15–45 years) belonging to seven unrelated families and fulfilling the clinical criteria1 for classical EDS (formerly type II/Mitis, Online Mendelian Inheritance in Man [OMIM] 130010, autosomal dominant inheritance; n=4) or hypermobility EDS (formerly type III/hypermobile, OMIM 130020, autosomal dominant inheritance; n=8) were recruited for the study. All patients had velvety skin with severe hyperelasticity, which was tested at a neutral site, and joint hypermobility, which was determined by a score of 5/9 or greater by use of Beighton’s 9-point scale (mean 7·4 [SD 1·2]).1 All patients with classical EDS had atrophic scars, and two out of four had subcutaneous nodules and pseudotumours, whereas none of the hypermobility patients had any of these characteristics. Three of four classical and seven of eight hypermobility patients
THE LANCET • Vol 357 • May 12, 2001
For personal use. Only reproduce with permission from The Lancet Publishing Group.