Regional insights on the prevalence and antimicrobial susceptibility pattern of carbapenem and colistin-resistant gram-negative bacteria: an observational cross-sectional study from Karachi, Pakistan

Our study highlights a concerning prevalence of colistin resistance (1.7%) among carbapenem-resistant gram-negative bacteria, particularly Klebsiella species, predominantly affecting male in-patients aged 31-49 and ≥ 50 years. This significant therapeutic challenge is underscored by the limited efficacy of available antibiotics, with only tigecycline showing high susceptibility (96%) and others like fosfomycin (53%) and minocycline (50%) offering moderate alternatives.