Antimicrobial Resistance in Gram-Negative Bacterial Pneumonia After the COVID-19 Pandemic in Northern Iran

The irrational use of antibiotics has become a significant factor in the escalating global crisis of antimicrobial resistance (AMR). AMR is linked to an increasing burden of healthcare-associated infections caused by multidrug-resistant pathogens, which present substantial challenges for infection control and patient management. During the COVID-19 pandemic, the widespread use of antibiotics for treating and preventing secondary bacterial infections further exacerbated the threat of AMR worldwide. This study aimed to determine the antibiotic resistance profile of Gram-negative bacteria (GNB) causing pneumonia after COVID-19 in Northern Iran.

In this cross-sectional study, respiratory specimens were collected from hospitalized patients with bacterial pneumonia at four hospitals in Northern Iran. The antimicrobial susceptibility profiles were assessed using the standard microdilution method in accordance with CLSI guidelines (2020). Additionally, resistance-associated genetic determinants were evaluated using multiplex PCR.

A total of 120 MDR GNB isolates were identified, primarily from sputum specimens (75.8%). Pseudomonas aeruginosa was the most common pathogen in the ICU, representing 35% of isolates. Resistance rates to antibiotics were high: Ciprofloxacin (85%), Ceftazidime (85%), Gentamicin (80%), and Colistin (77.5%), while Piperacillin-Tazobactam had a lower resistance rate of 33.3%.

The present study highlights the increasing AMR among GNB causing pneumonia in ICU settings post COVID-19 pandemic in hospitals in Northern Iran. The prevalence of Pseudomonas aeruginosa and high resistance rates to new antibiotics such as Colistin pose significant challenges to treatment, while Piperacillin-Tazobactam shows relatively lower resistance and may be a potential option.