In this study, 283 multidrug-resistant Acinetobacter baumannii (MDR-AB) bloodstream isolates were collected between 1996 and 2004, from three teaching hospitals located in different regions of Taiwan. Susceptibility data showed that strains carrying class 1 integrons were significantly more resistant (p <0.01) to all tested antibiotics (except aztreonam and chloramphenicol) than strains lacking integrons, Seven types of gene cassette were identified among these strains, including two that have not been previously reported. The vast majority of the cassettes encoded aminoglycoside resistance genes, including aacA4, aacC1, aac(6')-II, aadA1, aadA2, aadA4 and aadDA1. Sixteen distinct ribotypes were identified in MDR-AB isolates carrying class 1 integrons. Only one strain was found to produce an extended-spectrum beta-lactamase, i.e. VEB-3. In the 18 imipenem-resistant strains, two carbapenenmase genes, bla(VIM-11) and bla(OXA-58), were found concomitantly in one isolate. An island-wide epidemic clone and an endemic clone from a hospital located in the northern region were identified by ribotyping. On the basis of the susceptibility data among the different ribogroups, the epidemic clone was associated more significantly with resistance to cefepime and ampicillin-sulbactam than was the endemic clone. In conclusion, the presence of class 1 integrons was significantly associated with resistance in MDR-AB, and the epidemic, class 1 integron-carrying MDR-AB clone was found to be widespread in Taiwan.

Repeated isolation of multidrug-resistant Acinetobacter baumannii (MDRAB) from respiratory secretions poses a great challenge for infection control. We conducted a retrospective case-control study to evaluate the efficacy and adverse effect of inhaled colistin methanesulfonate (CMS) in the eradication of MDRAB from the respiratory tract. Patients who were admitted to Taipei Veterans General Hospital between February 2009 and June 2010, had at least two sets of monomicrobial culture of MDRAB from respiratory secretions, and remained in hospital for at least 14 days after the first isolation of MDRAB (index day) were included. Patients who received intravenous CMS were excluded. Patients who received CMS inhalation for ≥ 3 days were selected as cases whereas the controls were matched for age and Acute Physiology and Chronic Health Evaluation II score. Thirty-nine cases and controls were identified. The duration of CMS inhalation was 10.9 ± 3.6 days. The use of inhaled CMS was the only independent factor associated with the eradication of MDRAB within 14 days after the index day (OR 266.33; 95% CI 11.26-6302.18, p <0.001), and shortened the duration of MDRAB recovery from the respiratory tract by 13.3 ± 1.45 days. The adverse effects were similar for both groups. The increase of colistin minimal inhibitory concentrations in the last isolate compared with the index isolate from the same patient did not differ between the two groups. In conclusion, our study demonstrated that inhaled CMS enhanced the eradication of MDRAB from the respiratory tract without significant clinical adverse effect or impact on colistin resistance.

Klebsiella pneumoniae is the major cause of community-acquired pyogenic infections in Taiwan and is becoming an increasing problem in acute thoracic empyema. This study evaluated the clinical and microbiological characteristics of community-acquired thoracic empyema or complicated parapneumonic effusion caused by K. pneumoniae in Taiwanese adults treated during the period 2001-2008 at a tertiary medical center. All clinical isolates were examined for capsular serotypes K1/K2, and pulsed-field gel electrophoresis (PFGE) was performed on strains of the same serotype. K. pneumoniae was the most frequent cause of community-acquired thoracic empyema or complicated parapneumonic effusion. It was associated with high mortality (32.4%) and was an independent risk factor for fatal outcome. Diabetes mellitus, liver cirrhosis, and bronchogenic carcinoma were independent risk factors for K. pneumoniae infection. Serotypes K1 (9/37, 24.3%) and K2 (13/37, 35.1%) were the prevalent strains but did not predispose patients to poor outcome compared with other non-K1/K2 serotypes. There was no major cluster of isolates found among serotype K1/K2 strains. In summary, physicians should be aware of the risk factors for thoracic empyema or complicated parapneumonic effusion caused by K. pneumoniae and the associated high mortality, and monitor these patients more closely.