Molecular investigation of extended-spectrum beta-lactamase genes and potential drug resistance in clinical isolates of Morganella morganii.

BACKGROUND: Resistance to beta-lactam antibiotics has become more common in Morganella morganii, which can cause of outbreaks of bacteremia and septicemia in postoperative patients.

OBJECTIVE: Investigate drug susceptibility of M morganii, identify the gene responsible for extended-spectrum beta-lactamase (ESBL) production and explore treatment options.

DESIGN: Descriptive study.

SETTING: Hospitals in An Najaf, Iraq.

METHODS: M morganii isolates were identified based on morphology, biochemical tests and VITEK® 2 compact system using (GN-ID) card. M morganii isolates were subjected to antibiotic resistance tests using the minimum inhibitory concentration (MIC) technique and an antibiogram was produced. Molecular studies were conducted using the polymerase chain reaction technique.

MAIN OUTCOME MEASURE(S): Minimum inhibitory concentration.

RESULTS: From 395 gram-negative bacteria, only 17 isolates M morganii grew on MacConkey agar. M morganii isolates strongly resistant to several antibiotics were considered multidrug resistant. All M morganii isolates were ESBL producers. Four genes (CTX-M, SHV, TEM and OXA) encoding the b-lactamase enzyme were detected. Meropenem and imipenem were highly active against the M morganii isolates.

CONCLUSIONS: All isolates showed resistance to most common antibiotics, which limits options for treatment. This study provided useful information for selecting antibiotics to precisely target infections caused by M morganii.

LIMITATIONS: Limited to antibiotic susceptibility and genotype.