J Infect Chemother 21 (2015) 176e181
Contents lists available at ScienceDirect
Journal of Infection and Chemotherapy journal homepage: http://www.elsevier.com/locate/jic
Original article
Evaluation of a rapid immunochromatographic ODK0501 assay for detecting Streptococcus pneumoniae antigens in the sputum of pneumonia patients with positive S. pneumoniae urinary antigens Hiroshi Mukae a, *, Kazuhiro Yatera a, Shingo Noguchi a, b, Toshinori Kawanami a, Kei Yamasaki a, Susumu Tokuyama c, Naoyuki Inoue c, Chinatsu Nishida a, Yukiko Kawanami a, Takaaki Ogoshi a, Takeshi Orihashi a, b, Chiharu Yoshii b, Hiroshi Ishimoto a a
Department of Respiratory Medicine, University of Occupational and Environmental Health, Japan Department of Respiratory Medicine, Wakamatsu Hospital of University of Occupational and Environmental Health, Japan c Department of Internal Medicine, Kyushu Rosai Hospital, Japan b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 23 June 2014 Received in revised form 29 October 2014 Accepted 5 November 2014 Available online 20 November 2014
Background: A novel, rapid and noninvasive test (ODK0501, RAPIRUN® Streptococcus pneumoniae) uses polyclonal antibodies to detect C polysaccharide of S. pneumoniae derived from sputum samples using an immunochromatographic assay. We evaluated its usefulness in Japanese patients with pneumonia who exhibited positive urinary antigen tests for S. pneumoniae (BinaxNOW® S. pneumoniae). Patients and methods: Forty adult patients with pneumonia treated between May 2011 and August 2013 were enrolled. Bacterial cultures, Gram staining and ODK0501 assays of sputum as well as urinary antigen tests for S. pneumoniae using urine samples obtained from the same patients were performed upon admission, the fourth day after starting antimicrobial treatment and at the end of the antimicrobial treatment. Results: Twenty-seven of the 40 patients were positive for ODK0501, while a negative result for ODK0501 was associated with low-quality sputum samples according to the Geckler classification of sputum. The sensitivity and specificity of the ODK0501 assay in the 40 patients were 90.9% and 61.1%, respectively, based on the culture results. The results obtained with this kit were more favorable than those observed on Gram staining. The ODK0501 assay also showed a rapid reaction to the disappearance of S. pneumoniae in the sputum samples, while approximately 80% of the patients exhibited persistent positive results on the urinary antigen detection tests at the end of treatment. Conclusions: The ODK0501 test is a noninvasive, rapid and accurate tool for diagnosing respiratory infections caused by S. pneumoniae, although good quality sputum must be obtained prior to adequate treatment with antibiotics. © 2014, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Keywords: Sputum antigen detection ODK0501 Urinary antigen detection Pneumococcal pneumonia Streptococcus pneumoniae
1. Introduction Pneumonia is a common illness and currently the third leading cause of mortality in Japan, with approximately 90% of patients with
* Corresponding author. Department of Respiratory Medicine, University of Occupational and Environment Health, Japan, 1-1, Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka 807-8555, Japan. Tel.: þ81 93 691 7453; fax: þ81 93 602 9373. E-mail address: [email protected] (H. Mukae).
fatal pneumonia being elderly (over 65 years of age) [1]. Streptococcus pneumoniae is the most frequent cause of communityacquired pneumonia (CAP), a well-recognized common and potentially severe infection. Mortality from this disease is particularly high in infants and the elderly, suggesting the need for the early administration of appropriate pathogen-oriented antibacterial therapy. Therefore, rapidly and precisely identifying the causative agents of infectious diseases is critical, although obtaining microbiological confirmation is often difficult. The use of bacterial cultures to identify causative microorganisms requires several days to yield a
http://dx.doi.org/10.1016/j.jiac.2014.11.003 1341-321X/© 2014, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
H. Mukae et al. / J Infect Chemother 21 (2015) 176e181
result and is thus unhelpful for initially selecting appropriate antibacterial agents. In addition, even when using sputum of adequate quality, the sensitivity of detection of predominant Gram-positive cocci in pairs and chains on Gram staining in patients with blood culture-proven pneumococcal pneumonia is only 57% [2]. On the other hand, urinary antigen detection is a rapid diagnostic technique for identifying antigens of S. pneumoniae and Legionella pneumophila serogroup 1 and is currently widely used in clinical practice. The BinaxNOW® S. pneumoniae urinary antigen test (BinaxNOW®) (Binax, Inc., Portland, ME) detects cell wall antigens secreted in urine using an immunochromatographic method to separate the capsular polysaccharide (C-ps) of S. pneumoniae [3]. This BinaxNOW® test is noninvasive, easy to perform and rapid (taking approximately 15 min), with a reported pooled specificity and sensitivity for detecting pneumococcal infections in adult patients with pneumonia in a meta-analysis of 0.95 (95% confidence interval: 0.71e0.79) and 0.75 (95% confidence interval: 0.92e0.98), respectively [4], although considerable variance in results has also been reported among previous studies [5e9]. Moreover, even when S. pneumoniae is not identified in a bacterial culture after the initiation of antibiotic therapy, urinary assays may still detect the antigen of this organism [5]. However, the BinaxNOW® has significant limitations, including cross-reaction with other closely related streptococci [10], false-positive results due to the presence of indigenous S. pneumoniae, especially in children [4,11], and the detection of antigens even one to three months after treatment for pneumococcal infections [5,6,12]. In addition, the kit may yield positive findings due to the effects of the pneumococcal vaccine [13]. ODK0501, RAPIRUN® S. pneumoniae (Otsuka Pharmaceutical Co., Ltd., Tokyo, Japan) is another diagnostic kit that uses polyclonal antibodies to detect pneumococcal C-ps, a cell wall antigen of S. pneumoniae [14,15]. This immunochromatographic method is also rapid (taking less than 25 min) and noninvasive using sputum derived directly from local sites of infection. In this study, we evaluated the ability of the ODK0501 assay to detect S. pneumoniae in patients with pneumonia who showed positive results for urinary antigens of S. pneumoniae among several Japanese medical institutions. The goal of this study was to assess the usefulness and performance of the ODK0501 assay in comparison with sputum Gram staining and the BinaxNOW® test in the clinical setting. 2. Materials and methods
177
also evaluated. A history of prior treatment with antibiotics was not a criterion for exclusion. 2.2. Sample collection and microbiological investigation When a diagnosis of pneumonia was made, urine samples were immediately evaluated using the BinaxNOW®, and patients with positive results for this test were enrolled in the present study. Expectorated sputum and urine samples were also collected from the patients immediately before the commencement of therapy, on the fourth day after the start of antimicrobial treatment and at the end of treatment. Sputum samples were immediately analyzed using Gram staining and the ODK0501 assay, as described below. “Negative” results for Gram staining were defined as the absence of bacteria on Gram staining at a magnification of X1,000. The sputum samples were also cultured at 37 C for 24 h on blood and chocolate agar. Following incubation, presumptive colonies of S. pneumoniae were removed and identified using biochemical testing. In addition, bronchoalveolar lavage fluid (BALF) samples were obtained from the affected lung lesions in some patients. Blood cultures were also performed when available. 2.3. Criteria for the identification of bacterial isolates The isolates were inoculated onto the appropriate Vitek identification strip using the Vitek 2 apparatus (bioMerieux) with or without the associated API identification strip (bioMerieux). Accurate identification of the isolates using the Vitek system was confirmed based on a percentage of identification of equal to or more than 90%, whereas subsequent identification of the bacteria using API was performed if the percentage of identification using the Vitek strip was less than 90%. Bacterial identification using the API system was confirmed when the percentage of identification was equal to or more than 90%. Each bacterial colony was evaluated, and colonies macroscopically recognized to contain normal bacteria were recorded as normal floral bacteria. In cases of Streptococcus species, the detected species were reported when the items of the Vitek system were matched at a rate above 90%, whereas only Streptococcus species were recorded when the rate of matching items was less than 90%. 2.4. Measurement and interpretation of the results obtained with the ODK0501 and BinaxNOW® for S. pneumoniae
2.1. Patients and diagnostic criteria Adult patients with signs of pneumonia who underwent sputum exploration and were found to be positive on the BinaxNOW® S. pneumoniae urinary antigen test between May 2011 and August 2013 were eligible for inclusion in this study. The study protocol was approved by the Institutional Review Board of the University of Occupational and Environmental Health, Japan (UOEH11-003, UMIN000012326). All patients provided their written informed consent for sample collection. Pneumonia was diagnosed based on the fulfillment of all three of the following criteria: (1) positive findings for at least one of the assessed clinical symptoms (fever, cough, purulent sputum, moist rales, pleural pain, dyspnea, tachypnea), (2) the presence of new infiltrates on chest radiography and/or computed tomography and (3) positive findings for at least one sign of inflammation, (white blood cell (WBC) count >10,000/ mm3 or
Contents lists available at ScienceDirect
Journal of Infection and Chemotherapy journal homepage: http://www.elsevier.com/locate/jic
Original article
Evaluation of a rapid immunochromatographic ODK0501 assay for detecting Streptococcus pneumoniae antigens in the sputum of pneumonia patients with positive S. pneumoniae urinary antigens Hiroshi Mukae a, *, Kazuhiro Yatera a, Shingo Noguchi a, b, Toshinori Kawanami a, Kei Yamasaki a, Susumu Tokuyama c, Naoyuki Inoue c, Chinatsu Nishida a, Yukiko Kawanami a, Takaaki Ogoshi a, Takeshi Orihashi a, b, Chiharu Yoshii b, Hiroshi Ishimoto a a
Department of Respiratory Medicine, University of Occupational and Environmental Health, Japan Department of Respiratory Medicine, Wakamatsu Hospital of University of Occupational and Environmental Health, Japan c Department of Internal Medicine, Kyushu Rosai Hospital, Japan b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 23 June 2014 Received in revised form 29 October 2014 Accepted 5 November 2014 Available online 20 November 2014
Background: A novel, rapid and noninvasive test (ODK0501, RAPIRUN® Streptococcus pneumoniae) uses polyclonal antibodies to detect C polysaccharide of S. pneumoniae derived from sputum samples using an immunochromatographic assay. We evaluated its usefulness in Japanese patients with pneumonia who exhibited positive urinary antigen tests for S. pneumoniae (BinaxNOW® S. pneumoniae). Patients and methods: Forty adult patients with pneumonia treated between May 2011 and August 2013 were enrolled. Bacterial cultures, Gram staining and ODK0501 assays of sputum as well as urinary antigen tests for S. pneumoniae using urine samples obtained from the same patients were performed upon admission, the fourth day after starting antimicrobial treatment and at the end of the antimicrobial treatment. Results: Twenty-seven of the 40 patients were positive for ODK0501, while a negative result for ODK0501 was associated with low-quality sputum samples according to the Geckler classification of sputum. The sensitivity and specificity of the ODK0501 assay in the 40 patients were 90.9% and 61.1%, respectively, based on the culture results. The results obtained with this kit were more favorable than those observed on Gram staining. The ODK0501 assay also showed a rapid reaction to the disappearance of S. pneumoniae in the sputum samples, while approximately 80% of the patients exhibited persistent positive results on the urinary antigen detection tests at the end of treatment. Conclusions: The ODK0501 test is a noninvasive, rapid and accurate tool for diagnosing respiratory infections caused by S. pneumoniae, although good quality sputum must be obtained prior to adequate treatment with antibiotics. © 2014, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
Keywords: Sputum antigen detection ODK0501 Urinary antigen detection Pneumococcal pneumonia Streptococcus pneumoniae
1. Introduction Pneumonia is a common illness and currently the third leading cause of mortality in Japan, with approximately 90% of patients with
* Corresponding author. Department of Respiratory Medicine, University of Occupational and Environment Health, Japan, 1-1, Iseigaoka, Yahatanishiku, Kitakyushu city, Fukuoka 807-8555, Japan. Tel.: þ81 93 691 7453; fax: þ81 93 602 9373. E-mail address: [email protected] (H. Mukae).
fatal pneumonia being elderly (over 65 years of age) [1]. Streptococcus pneumoniae is the most frequent cause of communityacquired pneumonia (CAP), a well-recognized common and potentially severe infection. Mortality from this disease is particularly high in infants and the elderly, suggesting the need for the early administration of appropriate pathogen-oriented antibacterial therapy. Therefore, rapidly and precisely identifying the causative agents of infectious diseases is critical, although obtaining microbiological confirmation is often difficult. The use of bacterial cultures to identify causative microorganisms requires several days to yield a
http://dx.doi.org/10.1016/j.jiac.2014.11.003 1341-321X/© 2014, Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.
H. Mukae et al. / J Infect Chemother 21 (2015) 176e181
result and is thus unhelpful for initially selecting appropriate antibacterial agents. In addition, even when using sputum of adequate quality, the sensitivity of detection of predominant Gram-positive cocci in pairs and chains on Gram staining in patients with blood culture-proven pneumococcal pneumonia is only 57% [2]. On the other hand, urinary antigen detection is a rapid diagnostic technique for identifying antigens of S. pneumoniae and Legionella pneumophila serogroup 1 and is currently widely used in clinical practice. The BinaxNOW® S. pneumoniae urinary antigen test (BinaxNOW®) (Binax, Inc., Portland, ME) detects cell wall antigens secreted in urine using an immunochromatographic method to separate the capsular polysaccharide (C-ps) of S. pneumoniae [3]. This BinaxNOW® test is noninvasive, easy to perform and rapid (taking approximately 15 min), with a reported pooled specificity and sensitivity for detecting pneumococcal infections in adult patients with pneumonia in a meta-analysis of 0.95 (95% confidence interval: 0.71e0.79) and 0.75 (95% confidence interval: 0.92e0.98), respectively [4], although considerable variance in results has also been reported among previous studies [5e9]. Moreover, even when S. pneumoniae is not identified in a bacterial culture after the initiation of antibiotic therapy, urinary assays may still detect the antigen of this organism [5]. However, the BinaxNOW® has significant limitations, including cross-reaction with other closely related streptococci [10], false-positive results due to the presence of indigenous S. pneumoniae, especially in children [4,11], and the detection of antigens even one to three months after treatment for pneumococcal infections [5,6,12]. In addition, the kit may yield positive findings due to the effects of the pneumococcal vaccine [13]. ODK0501, RAPIRUN® S. pneumoniae (Otsuka Pharmaceutical Co., Ltd., Tokyo, Japan) is another diagnostic kit that uses polyclonal antibodies to detect pneumococcal C-ps, a cell wall antigen of S. pneumoniae [14,15]. This immunochromatographic method is also rapid (taking less than 25 min) and noninvasive using sputum derived directly from local sites of infection. In this study, we evaluated the ability of the ODK0501 assay to detect S. pneumoniae in patients with pneumonia who showed positive results for urinary antigens of S. pneumoniae among several Japanese medical institutions. The goal of this study was to assess the usefulness and performance of the ODK0501 assay in comparison with sputum Gram staining and the BinaxNOW® test in the clinical setting. 2. Materials and methods
177
also evaluated. A history of prior treatment with antibiotics was not a criterion for exclusion. 2.2. Sample collection and microbiological investigation When a diagnosis of pneumonia was made, urine samples were immediately evaluated using the BinaxNOW®, and patients with positive results for this test were enrolled in the present study. Expectorated sputum and urine samples were also collected from the patients immediately before the commencement of therapy, on the fourth day after the start of antimicrobial treatment and at the end of treatment. Sputum samples were immediately analyzed using Gram staining and the ODK0501 assay, as described below. “Negative” results for Gram staining were defined as the absence of bacteria on Gram staining at a magnification of X1,000. The sputum samples were also cultured at 37 C for 24 h on blood and chocolate agar. Following incubation, presumptive colonies of S. pneumoniae were removed and identified using biochemical testing. In addition, bronchoalveolar lavage fluid (BALF) samples were obtained from the affected lung lesions in some patients. Blood cultures were also performed when available. 2.3. Criteria for the identification of bacterial isolates The isolates were inoculated onto the appropriate Vitek identification strip using the Vitek 2 apparatus (bioMerieux) with or without the associated API identification strip (bioMerieux). Accurate identification of the isolates using the Vitek system was confirmed based on a percentage of identification of equal to or more than 90%, whereas subsequent identification of the bacteria using API was performed if the percentage of identification using the Vitek strip was less than 90%. Bacterial identification using the API system was confirmed when the percentage of identification was equal to or more than 90%. Each bacterial colony was evaluated, and colonies macroscopically recognized to contain normal bacteria were recorded as normal floral bacteria. In cases of Streptococcus species, the detected species were reported when the items of the Vitek system were matched at a rate above 90%, whereas only Streptococcus species were recorded when the rate of matching items was less than 90%. 2.4. Measurement and interpretation of the results obtained with the ODK0501 and BinaxNOW® for S. pneumoniae
2.1. Patients and diagnostic criteria Adult patients with signs of pneumonia who underwent sputum exploration and were found to be positive on the BinaxNOW® S. pneumoniae urinary antigen test between May 2011 and August 2013 were eligible for inclusion in this study. The study protocol was approved by the Institutional Review Board of the University of Occupational and Environmental Health, Japan (UOEH11-003, UMIN000012326). All patients provided their written informed consent for sample collection. Pneumonia was diagnosed based on the fulfillment of all three of the following criteria: (1) positive findings for at least one of the assessed clinical symptoms (fever, cough, purulent sputum, moist rales, pleural pain, dyspnea, tachypnea), (2) the presence of new infiltrates on chest radiography and/or computed tomography and (3) positive findings for at least one sign of inflammation, (white blood cell (WBC) count >10,000/ mm3 or
