Mbl Producing Bacteria

Background: The emergence of extended-spectrum-beta-lactamase (ESBL) and metallo-beta-lactamase (MBL) producing bacterial isolates has resulted in fewer therapeutic options in treatment modalities. However, no studies regarding MBLs had been done so far in Nepal and a few researches on ESBLs were also pilot studies. Therefore, this study was carried out to assess the current status of ESBL- and MBL-producing bacteria among patients attending Tribhuvan University Teaching Hospital (TUTH), Nepal.

Methods: This was a cross-sectional study conducted at Bacteriology laboratory of TUTH. A total of 1120 sputum, endotracheal secretion and bronchial washing specimens from patients suspected of lower respiratory tract infection (LRTI) were processed according to the standard methodology. Double disk synergy test (DDST) and Combination disk (CD) methods were used for the detection of ESBL- and MBL-producing isolates.

Results: Respiratory pathogens were recovered from 44.4% cases. Haemophilus influenzae (112, 21.0%) was the predominant isolate followed by Klebsiella pneumoniae, Pseudomonads, Acinetobacter calcoaceticus baumannii complex, Streptococcus pneumoniae, Escherichia coli and others. Multidrug resistance (MDR) was found in 53.6% of the total bacterial isolates. Twenty-four percent of the Enterobacteriaceae and nonfermentative isolates were ESBL-producers, majority of which included K. pneumoniae (43, 42.2%), Pseudomonads (8, 8.8%), E. coli (13, 41.9%) and Acinetobacter spp. For ESBL-producers, the most effective drug was found to be carbapenems, followed by cefoperazone-sulbactam and amikacin. MBL was present in 1.34% of the total gram-negative isolates (3 isolates each of P. aeruginosa and Acinetobacter spp). All ESBL- and MBL-producers were MDR. Forty-two percent of S. aureus were resistant to methicillin. Besides, one vancomycin resistant S. aureus (VRSA) was also encountered.

Conclusion: A high level of antibiotic resistance in LRTI pathogens was exacerbated by the association of ESBL and MBL. Though carbapenems were effective for ESBL-producers, the emergence of MBL-producing bacteria has resulted in confounding scene in antibiotic armamentarium. This is the first report of MBL-producing isolates from Nepal. The data can be taken as the baseline level of MBL in our set-up. The regular surveillance of resistant clones is important in developing countries like Nepal so that effective measures could be undertaken to reduce the emergence and dissemination of such strains.