Nguyen Thi Khanh Nhu 1 , 2 , Nguyen Phu Huong Lan 1 , 3 , James I. Campbell 1 , 4 , Christopher M. Parry 1 , 4 , 5 , Corinne Thompson 1 , 4 , Ha Thanh Tuyen 1 , Nguyen Van Minh Hoang 1 , Pham Thi Thanh Tam 1 , Vien Minh Le 1 , 6 , Tran Vu Thieu Nga 1 , Tran Do Hoang Nhu 1 , Pham Van Minh 1 , Nguyen Thi Thu Nga 1 , Cao Thu Thuy 1 , Le Thi Dung 3 , Nguyen Thi Thu Yen 3 , Nguyen Van Hao 2 , Huynh Thi Loan 3 , Lam Minh Yen 3 , Ho Dang Trung Nghia 1 , 2 , 7 , Tran Tinh Hien 1 , Louise Thwaites 1 , 4 , Guy Thwaites 1 , 4 , Nguyen Van Vinh Chau 2 , Stephen Baker , 1 , 4 , 8
Ventilator-associated pneumonia (VAP) is a serious healthcare-associated infection that affects up to 30 % of intubated and mechanically ventilated patients in intensive care units (ICUs) worldwide. The bacterial aetiology and corresponding antimicrobial susceptibility of VAP is highly variable, and can differ between countries, national provinces and even between different wards in the same hospital. We aimed to understand and document changes in the causative agents of VAP and their antimicrobial susceptibility profiles retrospectively over an 11 year period in a major infectious disease hospital in southern Vietnam. Our analysis outlined a significant shift from Pseudomonas aeruginosa to Acinetobacter spp. as the most prevalent bacteria isolated from quantitative tracheal aspirates in patients with VAP in this setting. Antimicrobial resistance was common across all bacterial species and we found a marked proportional annual increase in carbapenem-resistant Acinetobacter spp. over a 3 year period from 2008 (annual trend; odds ratio 1.656, P = 0.010). We further investigated the possible emergence of a carbapenem-resistant Acinetobacter baumannii clone by multiple-locus variable number tandem repeat analysis, finding a bla OXA-23-positive strain that was associated with an upsurge in the isolation of this pathogen. We additionally identified a single bla NDM-1-positive A. baumannii isolate. This work highlights the emergence of a carbapenem-resistant clone of A. baumannii and a worrying trend of antimicrobial resistance in the ICU of the Hospital for Tropical Diseases in Ho Chi Minh City, Vietnam.