Moiz Ahmed Khan

Abstract

Carbapenem-resistant Acinetobacter baumannii (CRAB) represents a significant threat in healthcare settings, particularly in high-risk environments such as cardiac surgery units. Healthcare-associated outbreaks require systematic investigation to identify sources and implement effective control measures. A comprehensive outbreak investigation was conducted at a cardiac tertiary care center in Karachi, Pakistan following seven cases of CRAB infections in post-cardiac surgery patients from 15th to 30th June, 2025. Investigation methods included direct observation of infection control practices, environmental surveillance cultures, staff microbial screening through fingerprint cultures and surface sampling from operation rooms (ORs) and intensive care units (ICUs). Seven patients developed CRAB infections of which four were ventilator-associated pneumonias (VAP), two central line-associated bloodstream infections (CLABSI) and one surgical site infection. Four patients (57.1%) died, including two VAP and two CLABSI cases. All isolates were resistant to carbapenems but susceptible to tigecycline and minocycline. Environmental cultures were negative but CRAB was isolated from one OR staff member's fingerprint culture. Critical infection control breaches were identified including inadequate hand hygiene, insufficient environmental cleaning between procedures and non-compliance with personal protective equipment (PPE) protocols. The outbreak was successfully controlled through enhanced infection control measures including strict hand hygiene protocols, enhanced cleaning procedures and comprehensive staff education. This investigation demonstrates the critical importance of systematic outbreak investigation and adherence to established infection control protocols in high-risk healthcare environments.