The Occurrence and Modified Method for Phenotypic Identification of Ambler Group A and B Extended Spectrum β-Lactamases Production in Urino-Genital Gram Negative Bacterial Isolates from, Nigeria.

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Date
2013
Authors
Enwuru C.A
Iwalokun B.
Enwuru N.V
Ezechi O.
Idika N.
Oluwadun A.
Journal Title
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Abstract
Beta lactamase enzymes production in gram negative bacteria (GNB) grouped into four Ambler classe: A – D, remains a formidable threat to therapeutic interventions and impact negatively on the course and outcome of infections in patients worldwide. Routine β -lactamase screening is a standard for clinical bacteriology laboratories especially for gram negative pathogens of extra-intestinal origin medicated often with third and fourth generation cephalosporins. However, routine phenotypic screening methods (DDT and DDST) as recommended by CLSI for class A and B respectively have been found not sustainable in resource poor settings such as Nigeria, as a result of cost and cumbersomeness. This study was designed to study the occurrence and evaluate the performance of a modified DDT and DDST methods for phenotypic identification of Ambler class A and B - β-lactamase production in GNB for routine use in the clinical laboratories. A total of 63 consecutive non-repetitive gram-negative bacterial isolates from urino-genital specimens of men attending fertility clinic were studied. There were 10 different species of bacteria: with E. coli 23/63 (36.5%) and Enterobacter spp. 12/63 (19%) having the highest occurrence. Groups A and B β-Lactamases were screened with CLIS recommended phenotypic methods (DDT and DDST respectively) for Enterobacteriaceae and a modified agar plate (co-detection in a single lawn culture plate) and the results were compared. Of the 63 bacteria screened, 18 (29%) produced Ambler group A and 7 (11%) demonstrated heteroresistant sub-population. Eleven (17.5%) were Ambler group B positive. One (1.5 %) strain showed hetero-resistant subpopulation and negative for Metallo β-Lactamase production. Out of the 18 group A and 11 group B ESBLs producing isolates by standard methods, 16 (89 %) and 10 (91%) were positive on the modified method respectively. The sensitivity and specificity were 88.9 % and 100% for group A and 91% and 100% for group B β-Lactamases, respectively. The positive predictive values of 100% were recorded for both. The highest co-production of both enzymes was amongst Serratia spp. 2/3. The result has demonstrated 29 % group A and 17.5 % group B ESBLs occurrence and that the modified method (less expensive, time saving and less cumbersome) is comparatively sensitive with the standard DDT and DDST methods recommended by CLSI and is equally recommended.
Description
Scholarly article
Keywords
Bacteria , Antibiotics , ESBLS , Occurrence , Modified , Screening , Research Subject Categories::PHARMACY
Citation
Enwuru CA, Iwalokun B, Enwuru NV, Ezechi O, Idika N, Oluwadun A (2013). The Occurrence and Modified Method for Phenotypic Identification of Ambler Group A and B Extended Spectrum β-Lactamases Production in Urino-Genital Gram Negative Bacterial Isolates from, Nigeria. Nature and Science; 11(8): 48-53.