Epidemiology and antimicrobial resistance among commonly encountered bacteria associated with infections and colonization in intensive care units in a university-affiliated hospital in Shanghai.
OBJECTIVE
The aim of this study was to classify intensive care unit (ICU) bacterial strains as either ICU-acquired or ICU-on-admission and to compare their epidemiological and antibiogram characteristics.


METHODS
The study was performed in a 1300-bed university-affiliated hospital from January 1, 2006 to December 31, 2010. Based on the time of ICU admission, ICU isolates were classified as ICU-acquired strains (appearing more than 48 hours after admission) or ICU-on-admission strains (appearing 48 hours or less from admission). The microbiological data before ICU admission, the microbiological data, and susceptibility testing were compared between the ICU-acquired and ICU-on-admission bacterial isolates.


RESULTS
The most common ICU-acquired strains were Acinetobacter baumannii (19.5%), Pseudomonas aeruginosa (15.6%), Stenotrophomonas maltophilia (11.5%), Staphylococcus aureus (10.7%), Enterococcus spp. (10.6%), and Klebsiella pneumoniae (9.7%). There were significant differences between ICU-acquired and ICU-on-admission isolates in the susceptibility rates of Gram-negative bacteria to antibiotics, especially the susceptibility of A. baumannii to imipenem [23.8% (ICU-acquired) vs. 44.4% (ICU-on-admission), p < 0.001] and meropenem (24.1% vs. 37.8%, p < 0.001), and the susceptibility of P. aeruginosa to imipenem (39.3% vs. 76.1%, p < 0.001) and meropenem (58.5% vs. 76.1%, p < 0.05). Furthermore, decreased susceptibility rates of A. baumannii and P. aeruginosa to carbapenems were correlated with an extended ICU stay (p < 0.05).


CONCLUSIONS
Because of decreasing susceptibility rates of pathogens (especially ICU-acquired strains) and a significant correlation with the length of ICU stay, intensivists should consider a patient's time of ICU admission and previous microbiological data and should distinguish ICU-acquired strains from non-ICU-acquired strains so as to initiate optimized empirical antibiotic therapy against ICU-acquired infections.
Department of Critical Care Medicine and Respiratory Intensive Care Unit, Shanghai Ruijin Hospital Affiliated with Jiaotong University, Shanghai, China.
Ruoming
R
Tan
Department of Critical Care Medicine and Respiratory Intensive Care Unit, Shanghai Ruijin Hospital Affiliated with Jiaotong University, Shanghai, China.
Jialin
J
Liu
Department of Critical Care Medicine and Respiratory Intensive Care Unit, Shanghai Ruijin Hospital Affiliated with Jiaotong University, Shanghai, China.
Meiling
M
Li
Department of Critical Care Medicine and Respiratory Intensive Care Unit, Shanghai Ruijin Hospital Affiliated with Jiaotong University, Shanghai, China.
Jie
J
Huang
Department of Microbiology, Shanghai Ruijin Hospital Affiliated with Jiaotong University, Shanghai, China.
Jingyong
J
Sun
Department of Critical Care Medicine and Respiratory Intensive Care Unit, Shanghai Ruijin Hospital Affiliated with Jiaotong University, Shanghai, China. Electronic address: hongpingqu@yahoo.com.cn.
Hongping
H
Qu
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001419:Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D001424:Bacterial Infections / Q000453:epidemiology* / Q000382:microbiology*; D002353:Carrier State / Q000453:epidemiology* / Q000382:microbiology*; D002681:China / Q000453:epidemiology; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology*; D024881:Drug Resistance, Bacterial; D005260:Female; D006785:Hospitals, University; D006801:Humans; D007362:Intensive Care Units; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015995:Prevalence; D055815:Young Adult
Antibiogram; ICU-acquired infection; Susceptibility rates