Distribution and drug resistance of pathogenic bacteria in ventilator-associated pneumonia at a local hospital of North-eastern China Yu Wang, Rong Zhang, Wei Liu Department of Emergency, Shengjing Hospital Affiliated to China Medical University, Heping District, Shenyang, Liaoning Province 110004, People’s Republic of China Purpose: To study the distribution of pathogenic bacteria in ventilator-associated pneumonia (VAP), and epidemiological characteristics of extended-spectrum β lactamase (ESBL)-producing bacteria. Patients and methods: Lower respiratory tract secretions from 156 patients with mechanical ventilation were collected using a protective specimen brush (PSB), with quantitative bacterial culture carried out and antibiotic sensitivity measured. ESBLs produced by Gram-negative bacilli were detected using the double disk diffusion method and monitored by plasmid profiles. Results: Gram-negative bacilli accounted for 78.9% of VAP pathogens, with Acinetobacter baumannii (25%), Pseudomonas aeruginosa (19.7%), and Klebsiella pneumoniae (14.5%) as the most common strains. There were 12 Gram-positive strains detected (15.8%); mostly methicillin-resistant. Staphylococcus aureus and methicillin-resistant coagulase-negative Staphylococcus. There were also four strains of Candida albicans detected (5.26%). Most Gram-negative bacilli are sensitive to imipenem, but A. baumannii is serious resistant. ESBLs were detected in nine strains of Gram-negative bacilli; mainly produced by K. pneumoniae and Escherichia coli, to different degrees of multidrug resistance. Five strains of K. pneumoniae-producing ESBLs were from the same clonal origin, as confirmed by plasmid restriction endonuclease analysis. Conclusion: VAP was mainly caused by Gram-negative bacteria, with high antibiotic resistance rates. Plasmids played an important role in the spread of antibiotic resistance among bacteria. Keywords: ventilator-associated pneumonia, pathogenic bacteria, extended-spectrum β lactamases, drug resistance plasmid