Assessment of the Coagulase Test in the Identification of Staphylococcus Aureus Strains (original) (raw)
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Assessment of the Coagulase Test in the Identification of Staphylococcus Aureus Strains Citation
Introduction: Staphylococcus aureus are among the most important and several pathogens in human infections. The objectives of this study are to evaluate the efficacy of the coagulase test in the detection of Staphylococcus aureus in the laboratory and to identify the factors associated with Staphylococcal infections. Methods: It is a prospective study of 69 strains of Staphylococci in a period of six months from January Results: Among of the 69 strains of Staphylococci, 47 (68%) were represented by Staphylococcus aureus. Concerning the prediction performance of the catalase test, It has a sensitivity of 93.6%, a specificity of 100%, a positive predictive value (PPV) of 100% and a negative predictive value (NPV) of 88%. Concerning the associated factors, the men (71.1%) (p=0.46; NS), the patients aged 60 and over (76.5%) (p=0.63; NS), in resuscitation department (93.3%) (p=0.01) and with suppuration (100%) (p=10-3) were the most affected by Staphylococcus aureus. Conclusion: Coagulase test can replace the standard gold test for the detection of Staphylococcus aureus. In case of doubt, the bacteriological characteristics and the factors associated with Staphylococcal infections may be helpful in the diagnosis of Staphylococcus aureus infection.
Journal of Medical Sciences, 2015
Objective: To evaluate performance (sensitivity & specificity) of a range of phenotypic tests which are currently used in tertiary care hospitals for the indentification of S aureus and to identify an optimal phenotypic test that is reliagle and cost effective and can be used with confidence for confirmation of S. aureus.Material and Methods: The present study was conducted at clinical microbiology laboratory department of Pathology of Northwest General Hospital and Research Centre, Peshawar from January 2012 to September 2013. The study group consisted of 300 samples were collected from different clinical sources i.e. patient’s blood, body fluids, pus swabs, wound swabs, urine and sputum. During sampling safety methods were adopted and data were collect regarding age, sex, types of specimens and present health condition were also recorded.Results: All clinical samples evaluated with slide coagulase (SCT), mannitol salt fermented test (MSA) and DNase test the result were 95%, 87% an...
Journal of Gandaki Medical College-Nepal
Introduction: The accurate identification of Staphylococcus aureus clinical isolates requires a series of tests. Morphological features and slide coagulase test are two criteria on which S. aureus are identified. Resort to tube coagulase test is sought when results of slide coagulase test are equivocal or doubtful. Both coagulase tests detect the enzymes that convert fibrinogen into fibrin. Human, rabbit or sheep pooled plasma is used as substrate for both tests. Slide coagulase test is simpler and faster as compared to tube coagulase test. The plasma could be carrier of many human and animal pathogens like HIV, HBV, HCV etc. Storage of plasma for longer duration is fraught with chances of contamination. Improperly stored plasma can lead to false positive or negative results. Citrated plasma may be unsuitable for this test if contaminated with citrate utilizing bacteria. Considering the role of S. aureus as a common etiological agent in nosocomial and community infections, there is a need of implementing rapid, easy and cost-effective phenotypic test. Objectives: Considering the disadvantages and risks associated with fresh plasma, this study aims to launch for safer, more reliable substitute with longer shelf life that may provide reliable results for prompt identification of S. aureus by slide coagulase test. Methods: The present work evaluates slide coagulase test (SCT), and urea fibrinogen slide coagulase test (UF-SCT) for S. aureus detection considering Tube coagulase test (TCT) as the reference method. Sensitivity, specificity, positive predictive value and negative predictive values of SCT and UF-SCT were calculated using TCT as gold standard. Results: A total of 150 staphylococcal isolates from different clinical specimens were selected for the evaluation of coagulase tests. All the specimens were subjected to SCT, UF-SCT and TCT. The UF-SCT showed better sensitivity (95.04%), specificity (100%), PPV (100%), and NPV (82.85%) with reference to TCT. UF-SCT showed similar sensitivity and specificity to SCT. None of the isolates were negative in UF-SCT
Asian Journal of Research in Infectious Diseases
The test for coagulase activity is a simple and non-expensive test for the identification of S. aureus strains from clinical samples in resource-poor settings. The results of these tests have been reported to vary with the source of plasma and with some atypical strains that test negative with the coagulase test. The study was carried out to determine if misidentification of strains of S. aureus exists on account of the reliance on the coagulase tests. Clinical isolates of Staphylococci that tested negative by the coagulase tests from wounds, pus, aspirates, blood cultures and urogenital samples were collected and re-tested by the slide and tube coagulase tests and confirmed to be negative. Each isolate was inoculated onto mannitol sat agar and DNAse agar plates and incubated at 37oC for 18 h. Isolates that fermented mannitol and showed a positive DNAse test were 25/366 (6.8%). The highest number of coagulase-negative Staphylococcus aureus (CNSA) occurred within blood culture sample...
Prevalence of Coagulase Negative Strains of Staphylococcus aureus in Clinical Specimens at the
Asian Journal of Research in Infectious Diseases, 2023
The test for coagulase activity is a simple and non-expensive test for the identification of S. aureus strains from clinical samples in resource-poor settings. The results of these tests have been reported to vary with the source of plasma and with some atypical strains that test negative with the coagulase test. The study was carried out to determine if misidentification of strains of S. aureus exists on account of the reliance on the coagulase tests. Clinical isolates of Staphylococci that tested negative by the coagulase tests from wounds, pus, aspirates, blood cultures and urogenital
Annals of Clinical Microbiology and Antimicrobials, 2010
Background: The ideal identification of Staphylococcus aureus clinical isolates requires a battery of tests and this is costly in resource limited settings. In many developing countries, the tube coagulase test is usually confirmatory for S. aureus and is routinely done using either human or sheep plasma. This study evaluated Mannitol salt agar and the deoxyribonuclease (DNase) test for improving the efficiency of the tube coagulase test in resource limited settings. The efficiency of human and sheep plasma with tube coagulase tests was also evaluated. Methods: One hundred and eighty Gram positive, Catalase positive cocci occurring in pairs, short chains or clusters were subjected to growth on Mannitol salt agar, deoxyribonuclease and tube coagulase tests. Of these, isolates that were positive for at least two of the three tests (n = 60) were used to evaluate the performance of the tube coagulase test for identification of S. aureus, using PCR-amplification of the nuc gene as a gold standard.
Evaluation of Hiaureus TM Coagulase Confirmation Kit in Identification of Staphylococcus aureus
JOURNAL OF CLINICAL AND DIAGNOSTIC RESEARCH, 2017
Introduction: Staphylococcus aureus is a facultative anaerobic Gram positive coccal bacterium whose incidence ranges to different infections. It is a cause of various uncomplicated skin infections, abscesses, septicaemia/bacteraemia, gastroenteritis, endocarditis, toxic shock syndrome and food intoxications. Various methods with varied time, sensitivities, specificities and costs are available, but may not be used as a reliable test for the identification and differentiation of S. aureus. Therefore, there is a need to evaluate newer tests. Aim: To compare the conventional tests with a commercial available kit for reliable, cost effective identification and confirmation of S. aureus. Materials and Methods: The current prospective study was conducted in the Department of Clinical Pathology, Haffkine Institute for a period of six months. A total of 341 clinical isolates of staphylococci isolated from pus, urine, blood culture and sterile body fluids were subjected to conventional tests like Tube Coagulase Test (TCT) using Rabbit Plasma (RP) and Human Plasma (HP), culture media such as Mannitol Salt Agar (MSA) and Deoxyribonuclease (DNase) media in parallel to Hiaureus TM Coagulase Confirmation Kit (HACCK), a commercially available kit for identification of S. aureus. Amplification of the femA gene was used as a comparative reference point test to calculate the sensitivity, specificity and concordance values of the conventional tests. Results: Amongst the coagulase based tests, HACCK was 100% sensitive and specific. The TCT using RP was 98.58% sensitive while TCT using HP was less sensitive (95.37%). A total of 100% specificity was observed for TCT using RP while TCT using HP was 96.68% specific. The MSA and DNase media were 97.86% vs 96.44% and 96.67% vs 91.67% sensitive and specific respectively. The combination tests had varying sensitivity and specificity ranges. The HACCK demonstrated 100% concordance with femA amplification and was labelled as an ideal perfect test (κ=1) with MSA as an alternative test for S. aureus identification. Conclusion: The HACCK can be used as an exclusive, reliable and cost effective test for identification of S. aureus. Alter natively, in view of the cost factor MSA either as a single test or in combination with TCT using HP could be used as screening tests and confirm discordant results with HACCK. www.jcdr.net Arunagiri Subramanian et al., Evaluation of Hiaureus TM Coagulase Confirmation Kit in Identification of Staphylococcus aureus
Applied microbiology, 1975
A total of 91 enterotoxigenic strains of Staphylococcus aureus isolated from foods and tested for production of coagulase and thermostable nuclease and the ability to ferment glucose and mannitol showed, with the exception of four strains, a complete correlation among these properties. A similar correlation was observed with 103 cultures of S. aureus isolated from clinical material. In all instances, the coagulase reactions were sufficiently strong to be scored at either the 3+ or 4+ levels. Presumptive staphylococcal cultures isolated during routine examination of foods and yielding 2+ coagulase reactions or lower were invariably negative for themostable nuclease production. It is suggested that the thermostable nuclease test be performed on cultures with doubtful coagulase reactions before classifying them as S. aureus.
Clinical and antimicrobial profile of Coagulase Negative staphylococci in a tertiary care hospital
International Journal of Research in Medical Sciences
Background: Coagulase negative staphylococci (CoNS) are gaining importance because of their role as pathogens in certain clinical conditions and their marked resistance to antibiotics. Their species distribution and slime production has important correlation with the antimicrobial susceptibility pattern. Aim of this study was to determine clinically significant CoNS, their species distribution, slime production and antimicrobial susceptibility pattern in a tertiary care hospital.Methods: Identification, speciation and antimicrobial sensitivity testing were performed using standard microbiological techniques. Slime production was also tested by microtiter plate. Antimicrobial susceptibility testing was performed by modified Kirby Bauer method as per the CLSI guidelines.Results: A total 204 (49.88%) CoNS were found to be clinically significant. Percentage of clinical significance was high in urine isolates (88.88%) followed by pus (47.78%) and blood (45.56%). The most common CoNS infe...
Staphylococcus aureus is the most important cause of nosocomial and community associated infections as well as the most pronounced species in drug resistance amongst Staphylococcus species. There have been reported cases of inconsistency in presumptive coagulase tests using commercial kits and conventional methods. This study therefore reports a simple, rapid, accurate and cost-effective PCR-RFLP-based molecular technique that separates and identifies to species level S. aureus from other coagulase negative staphylococci. Fifty clinical isolates of staphylococci previously isolated from various specimens were investigated for their ability to clot blood plasma. Of the 50 clinical isolates, 6 (12%) and 44 (88%) isolates yielded positive and negative results, respectively, for conventional tube coagulase test. The PCR-RFLP supplemented with species-specific primers classified these isolates into three distinct species: S. epidermidis (86%), S. aureus (12%) and S. xylosus (2%). Furthermore, the technique applied in this study classified the isolates into two RFLP patterns representing S. aureus and other coagulase negative staphylococci which correlated with coagulase test results. Since coagulase test could be sometimes misleading and inconclusive, this method could be substituted in routine laboratory program.