| Summary: | 碩士 === 國立臺灣大學 === 流行病學研究所 === 91 === Acinetobacter baumannii is one of the most common opportunistic pathogens in nosocomial infection. It causes a wide range of clinical complications, including pneumonia, septicemia, urinary tract infection, wound infection and meningitis, especially among immunocompromised patients. The first isolate of pandrug-resistant Acinetobacter baumannii (PDRAB), a mutant A. baumannii strain that is resistant to almost all commercially available antibiotics, was discovered in 1993 at National Taiwan University Hospital (NTUH). Since April 1999, clusters of PDRAB have been found throughout the hospital, particularly among patients hospitalized in intensive-care units (ICUs). A resistance rate of more than 1.3% was reported in the year 2000, and this rate is continuing to grow. The increasing rate of PDRAB isolates presents a new challenge to clinical medicine and public health in Taiwan.
To understand the association between antimicrobial treatment and nosocomial infection of PDRAB in ICUs at NTUH, we carried out a one to one matched case-control study. All ICU patients from whom PDRAB were first isolated from clinical specimens were recruited during Jan 2002 to Dec 2002. The control group included patients with no record of PDRAB isolates, but was not limited to patients with pandrug-sensitive A. baumannii isolates. Each control was matched to its case by two variables: ICU type and the nearest duration of ICU stay by the isolation time of the case. Information about possible confounders was collected, including age, sex, underlying disease, major invasive procedure, clinical severity through APACHE Ⅱ score and duration of ICU stay. The following four dimensions were considered when evaluating the impact of previous antimicrobial treatment on the incidence of nosocomial PDRAB infection or colonization: whether using or not, overall dosage, treatment duration and the strength, which was defined by overall dosage over the treatment duration. Using the defined daily dose (DDD) of each antimicrobial agent, we compared the effect of selected antibiotics exposure in different dimensions mentioned above.
The results of conditional logistic regression analysis found that the use of carbapenem (OR=4.6, 95%C.I. = 1.8-12) and the DDD of 3rd generation cephalosporin (OR=1.2, 95%C.I.=1.0 — 1.4) were risk factors for nosocomial PDRAB colonization or infection. Further analysis of selected antibiotics indicates that the use of imipenem and meropenem were consistently the most important risk factors in all drug-related factors examined in this study. The strength of ceftazidime use (OR=5.0, 95%C.I.=1.1 — 22) was also a crucial factor. Study results also showed strong association between higher overall dosage and longer duration of vancomycin use (OR=4.8, 95%C.I.=1.1 — 21), and the PDRAB colonization or infection. Our findings suggest that proper management in the use of carbapenem, ceftazidime and vancomycin is necessary for the control of nosocomial PDRAB colonization or infection in ICUs.
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