Diversity of Carbapenem Resistance Mechanisms in Clinical Gram-Negative Bacteria in Pakistan

Antibiotic resistance is a health challenge worldwide. Carbapenem resistance in Gram-negative bacteria is a major problem since treatment options are very limited. Tigecycline and colistin are drugs of choice in this case, but resistance to these drugs is also high. The aim of this study was to describe the diversity of resistance mechanisms in carbapenem-resistant clinical Gram-negative bacteria from Pakistan. Carbapenem-hydrolyzing enzyme-encoding genes were detected using PCR and DNA sequencing and clonal types determined by multilocus sequence typing (MLST). Forty-four carbapenem-resistant isolates were collected from the microbiology laboratory of Fauji Foundation Hospital and Al-Syed Hospital, Rawalpindi, Pakistan, including Klebsiella spp., Escherichia coli, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter cloacae, and Achromobacter xylosoxidans. bla(NDM-1), bla(NDM-4,) bla(NDM-5,) bla(NDM-7), bla(OXA-48), and bla(OXA-181) were detected in Enterobacteriaceae; bla(OXA-23,) bla(OXA-72), and bla(NDM-1) in A. baumannii, and bla(VIM-6) and bla(VIM-11) in P. aeruginosa. MLST analysis revealed several predominant clonal types: ST167 in E. coli, ST147 in Klebsiella pneumoniae, ST2 in Acinetobacter, and ST664 in P. aeruginosa. In Acinetobacter, a new clonal type was observed for the first time. To the best of our knowledge, this is the first study describing the clonality and resistance mechanisms of carbapenem-resistant Gram-negative bacteria in Pakistan.

Automated summary

This study investigated diverse resistance mechanisms in carbapenem-resistant Gram-negative bacteria in Pakistan, identifying multiple carbapenem-hydrolyzing enzyme-encoding genes and predominant clonal types. It is the first study to describe clonality and resistance mechanisms of these bacteria in Pakistan, shedding light on the resistance situation in the region.