Analysis of blood stream infections: Antimicrobial susceptibility and associated types of extended spectrum β-lactamases

Purpose: To investigate the antimicrobial susceptibility and extended spectrum beta-lactamase (ESBL) production by clinical isolates of Escherichia coli (ESBL-EC) and Klebsiella species (ESBL-KP) associated with blood stream infections (BSIs). Methods: Bacteria isolation and identification were carried out using basic bacteriological and biochemical techniques. Antimicrobial susceptibility test was performed according to the guidelines of the Clinical Laboratory Standard Institute (CLSI). Vitek 2 Compact automated system was used to confirm the identifications (ID) and antimicrobial susceptibility test (AST). The ESBL produced by E. coli and K. pneumoniae isolates were phenotypically characterised using Modified Double Disc Synergy Test (MDDST), as recommended by CLSI. Results: All (100 %) isolates were sensitive to imipenem and meropenem, while susceptibility to other antibiotics varied. ESBL genotypes, viz, bla(TEM), bla(SHV) and bla(CTX) were encountered in the BSIs. For ESBL-EC, TEM, SHV and CTX producers accounted for 33, 16.67 and 58.3 %, respectively, while 75, 91.7 and 100 % of ESBL-KP were TEM, SHV and CTX producers, respectively. In ESBL-KP, 67 % coexisted with all three genotypes (bla(TEM), bla(SHV), and bla(CTX), while 8.3 % of ESBL-EC coexisted with the three encoding genes (CTX, SHV and TEM). Conclusion: ESBL E. coli and K. pneumoniae associated with BSI have been identified as TEM, SHV and CXT producers, with more ESBL-KP coexisting with all three than ESBL-EC.