Detection of Metallo-β –lactamase–producing Psudomonas aeruginosa Strains Isolated from Nosocomial Infections in Suez Canal University Hospital, Ismailia, Egypt

Background: Pseudomonas aeruginosa causes large percentages of nosocomial infections with high rates of treatment failure due to antibiotic resistance. In recent years, metallo beta lactamase (MBL) resistance has emerged in pseudomonas aeruginosa isolates which belong to Ambler class B. Objectives: We have performed this study to find out the frequency of MBL- producing Pseudomonas aeruginosa. Methodology: This study was conducted on 120 clinical specimens isolated from Suez Canal University Hospital. P. aeruginosa were isolated and identified conventionally. All isolates were submitted for antibiotic susceptibility testing, followed by phenotypic screening tests for detection of ESBL production using cefotaxime disc (30µg) and ceftazidime disc (30µg) and then confirmed by using disc combination method of ceftazidime- clavulanic acid and cefotaxime- clavulanic acid discs. Double disc synergy test was performed. MBL was suspected when the isolate was resistant to meropenem and imipenem confirmed by Modified Hodge test (MHT) and EDTA disk synergy test. PCR targeting genes bla IMP and bla VIM was applied for more accurate detection. Results: Out of 120 clinical samples, 26 isolates were diagnosed as pseudomonas aeruginosa. All isolates were considered as potential producer of carbapenemases.The resistance rates were 42.3% for cefepime and reached 88.5% for ceftazidime. We found that 80.8% of the isolates were ESBL producers and 54.8% (14 isolates) were considered as class B carbapenemases (MBL) by using MHT and EDTA synergy test. PCR detected bla IMP and blaVIM in six and seven isolates, respectively. The relation between MBL genes and resistance pattern of the isolates to cephalosprines, Aztreonam and gentamicin was not statistically significant (p=0.9). Conclusion:  ESBLs and MBLs are still playing a major role in marked antibiotic resistance of pseudomonas aeruginosa against the extended beta lactam antibiotics in Ismailia, Egypt. The current study provides a new report for detection of blaIMP and blaVIM in Ismailia, Egypt.