Phenotypic Distribution of Serine and ZincType Carbapenemases Among Clinical Bacterial Isolates in a Tertiary Hospital in Benin, Nigeria

Background: Serine and zinc type carbapenemases are distributed in many genera of bacteria and are typically associated with specific regions or countries. Objectives: This study phenotypically determined the prevalence of serine and zinctype carbapenemases among Gramnegative bacilli recovered from clinical specimens in Benin, Nigeria. Materials and Methods: Totally, 158 consecutive nonduplicate bacterial isolates (gramnegative bacilli) recovered from clinical samples were screened for serine and zinctype carbapenemases using the simplified carbapenemase inactivation (sCIM) and ethylenediaminetetraacetic acid doubledisc synergy test methods. Results: The isolates recovered from clinical specimens included 126 Enterobacteriaceae (79.7%), 7 Acinetobacter spp (3.7%), and 28oxidase positive gram negative bacilli (17.7%). Twentyeight isolates (17.7%) out of the 158 tested samples were carbapenemase positive. There was no significant difference in the prevalence of serine and zinctype carbapenemases (P=0.0748). However, the prevalence of zinctype carbapenemase was significantly higher in Pseudomonas aeruginosa compared with other isolates (P=0.0028) while that of serinetype carbapenemase was not affected by the type of clinical isolates (P=0.7216). Finally, the prevalence of both serine and zinctype carbapenemases were not affected (P gt;0.05) by clinical specimens and the source of isolates (inpatient vs. outpatient) respectively. Conclusion: In general, the prevalence of zinctype (12%) carbapenemases was insignificantly higher than that of serinetype (5.7%) carbapenemases. The measures to reduce infections caused by carbapenemaseproducing organisms (CPOs) are advocated accordingly.