Emission of extensively-drug resistant Acinetobacter baumannii from hospital settings to the natural environment

• Published in: The Journal of hospital infection 2017-08, Vol.96 (4), p.323-327
• Main Authors: Seruga Music, Martina, Hrenovic, Jasna, Goic-Barisic, Ivana, Hunjak, Blazenka, Skoric, Dijana, Ivankovic, Tomislav
• Format: Article
• Language: English
• Subjects: Acinetobacter baumannii; Acinetobacter baumannii - classification; Acinetobacter baumannii - drug effects; Acinetobacter baumannii - genetics; Acinetobacter baumannii - isolation & purification; Acinetobacter Infections - microbiology; Cross Infection - microbiology; DNA-Directed RNA Polymerases - genetics; Drug Resistance, Multiple, Bacterial; Environment; Environmental Microbiology; Extensively drug resistant; Humans; Infectious Disease; Microbial Sensitivity Tests; MLST; Multilocus Sequence Typing; Sequence type 1421; Sewage - microbiology; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Wastewater
• ISSN: 0195-6701; 1532-2939
• DOI: 10.1016/j.jhin.2017.04.005

Summary Background Acinetobacter baumannii is a leading emerging pathogen, which is frequently recovered from patients during hospital outbreaks. The role of environmental A. baumannii reservoirs is therefore of great concern worldwide. Aim The aim of this study was to investigate the connection between A. baumannii causing hospital outbreaks and environmental isolates from hospital wastewater, from urban sewage, and from river water as the final natural recipient of wastewaters. Methods Clinical isolates from patients with hospital-acquired pneumonia and environmental isolates from water were collected during a two-month monitoring period. Recovery of A. baumannii was performed on CHROMagar Acinetobacter plates, incubated at 42°C for 48h. Identification was performed by MALDI-TOF MS and analyses of rpoB gene. The antibiotic resistance profiles were interpreted according to criteria given for clinical isolates of A. baumannii . The sequence types (ST) were retrieved by MLST analysis. Results 14 of 19 isolates recovered from patients, hospital wastewaters, urban sewage, and river water belonged to the ST-195. The remaining five isolates recovered from patients and river water were assigned to the new ST-1421. All isolates showed a very strong relatedness and clustered into the CC92 which corresponds to IC2. All isolates were non-susceptible to ≥1 agent in all but ≤2 antimicrobial categories, and thus were classified as extensively drug-resistant (XDR). Heteroresistance to colistin was found in two isolates from hospital wastewater. Conclusion Close relatedness of clinical and environmental isolates suggests the emission of XDR A. baumannii via the untreated hospital wastewater in the natural environment.