Naslov
Effect of inoculum size of enterobacteriaceae producing SHV and CTX-M extended spectrum β- lactamases on the susceptibility to β-lactam combinations with inhibitors and carbapene

Autori
Bedenić, Branka ; Vraneš, Jasmina ; Beader, Nataša ; Jajić-Benčić, Ines ; Plečko, Vanda ; Uzunović- Kamberović, Selma ; Kalenić, Smilja

Izvornik
Medicinski glasnik Ljekarske komore Zeničko- dobojskog kantona (1840-0132) 6 (2009), 2; 166-172

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
inoculum effect; extended spectrum β-lactamases; carbapenems; β-lactam/inhibitor combinations

Sažetak
Background and aim: Many extended-spectrum β- lactamases (ESBL) producing isolates of E. coli and K. pneumoniae are susceptible in vitro to amoxycillin-clavulanate (AMC), ceftazidime- clavulanate (CAZ/cl), and piperacillin-tazobactam (TZP), but MICs increase substantially when higher inoculum is applied. The aim of this study was to determine the effect of inoculum size on the susceptibility of E. coli and K. pneumoniae isolates with well characterized ESBLs, to amoxycillin (AMX), AMC, ceftazidime (CAZ), CAZ/cl, piperacillin (PIP), TZP, imipenem (IMI) and meropenem (MEM). Material and methods: Minimum inhibitory concentrations (MIC) were determined by broth microdilution method using inocula that differed 100 fold in density. Results: Inoculum effect for CAZ/cl was detected in 52% of SHV-2 producing K. pneumoniae strains followed by AMC (43%) and TZP (38%). SHV-5 producing K. pneumoniae strains showed the most pronounced inoculum effect with CAZ/cl and AMC and to lesser extent with TZP. Inoculum effect was observed for AMC, CAZ/cl and TZP in 71% of SHV-12 producers. E. coli producing SHV-5 β-lactamase showed the most pronounced inoculum effect with AMC, followed by CAZ/cl and TZP. Strains producing CTX-M β-lactamases had a marked inoculum effect with CAZ/cl, AMC and TZP . Carbapenems did not show inoculum effect with any type of ESBLs. Conclusions: According to the results of this study, carbapenems remain the antibiotics of choice for the treatment of infections caused by ESBL producing Enterobacteriaceae.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

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