Major biologic characteristics of Acinetobacter baumannii isolates from hospital environmental and patients' respiratory tract sources

This prospective study investigated major biologic characteristics of Acinetobacter baumannii isolates from hospital environment and respiratory tract samples of patients admitted to adult intensive care units (ICUs) at the Jordan University Hospital.

A baumannii isolates from both sources were examined for antimicrobial susceptibility and for presence of specific metallo-β-lactamase genes (VIM-2, IMP-1) and OXA-type β-lactamase genes (OXA-type) using polymerase chain reaction and biofilm formation and surviving under various temperatures and pH conditions.

The majority of A baumannii isolates from environmental and patients sources was multidrug resistant (MDR), except for colistin and tigecycline. All A baumannii examined carried a blaOXA51-like gene, 58% has a blaOXA23-like gene, and 38.8% has a blaOXA24-like gene. Representative MDR A baumannii isolates from both sources were capable to form biofilm. A baumannii environmental isolates were capable to survive for a longer time in tap, normal saline, and distilled water than respiratory tract isolates with pH range of 4.5 to 8 and temperature between 18°C to 37°C.

This study demonstrates that A baumannii isolates from the patients' respiratory tract and hospital environment carried much similar multidrug resistance patterns and biologic characteristics. In conclusion, this study shows that all MDR A baumannii strains survived well in the hospital environment, especially in water and moist environment and produced biofilm, which might be responsible for high colonization in the respiratory tract of patients in ICU.