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P1343 Molecular epidemiology of pandrug-resistant Acinetobacter baumannii infection at a university hospital in Taiwan
S372 one of 5 strains. Strains of the first two groups were dispersed in all wards, while the majority (80%) of the strains of the third group was isolated from the internal medicine ward. All strains presented similar multi-resistant patterns, with the exception of the third group which was susceptible to aminoglycosides. Class 1 integrons were missing from the strains of the third group, while it was present in all other strains. Class 2 or 3 integrons were not detected. Conclusions: Three different clonal groups of A. baumannii strains are present in the hospital during the last year. The main difference among them is the resistance to aminoglycosides combined with the presence of intI gene in strains of two of the three groups. Results of this study gave an insight into the molecular diversity of multiresistant A. baumannii strains isolated in Papageorgiou hospital during the last year. P1343 Molecular epidemiology of pandrug-resistant Acinetobacter baumannii infection at a university hospital in Taiwan L.H. Su, T.L. Wu, J.H. Chia, A.J. Kuo, C.F. Sun (Taoyuan, TW) Objectives: Acinetobacter baumannii has constituted as an important clinical pathogen causing an increasing number of respiratory infections at the Chang Gung Memorial Hospital, Taiwan. Moreover, approximately 50% of the isolates were multidrug-resistant A. baumannii (MDRAB) that were multiply resistant to all antibiotics commonly used to treat infections caused by Gram-negative bacteria except imipenem. The incidence of pandrug-resistant A. baumannii (PDRAB), which is resistant to all antibiotics including imipenem, had been kept low at 2.7% before 2002, but a sudden increase to 16%-20% was noticed during 2003–2006. Methods: A total of 597 isolates of A. baumannii collected from 287 patients during 1998–2006 were retrospectively studied. Antimicrobial susceptibilities of A. baumannii isolates to amikacin, aztreonam, ceftazidime, ciprofloxacin, cefepime, gentamicin, imipenem, and piperacillin were analysed by a standard disk diffusion method and interpreted according to the criteria suggested by the Clinical and Laboratory Standard Institutes. Genotypes of the isolates were determined by pulsed-field gel electrophoresis (PFGE) and infrequentrestriction-site PCR (IRS-PCR). Results: A total of 303 (50.8%) PDRAB isolates and 135 (22.6%) MDRAB isolates were identified from the 597 isolates studied. Genotyping analysis by PFGE and IRS-PCR produced compatible results and 82 genotypes, including 17 from the PDRAB isolates and 13 from the MDRAB isolates, were identified. The majority (78.4%) of the isolates belonged to a predominant genotype 7, the prevalence of which was significantly higher among the PDRAB (93.4%) and MDRAB (88.1%) isolates compared to isolates of other antibiograms (41.5%; P < 0.00000005). Among 50 of the 56 patients from whom multiple isolates of different antibiograms were available for comparison, genotypes of their isolates remained the same when MDRAB became PDRAB (in 38 patients) or vice versa (in 22 patients) during their hospital stay. Conclusions: The recent upsurge of PDRAB isolates at this hospital was closely associated with a predominant clone, genotype 7, which had been prevalent among MDRAB isolates prior to the PDRAB era. During the hospital stay, MDRAB from the same patients may become PDRAB, some of which may subsequently turn back to MDRAB again. Infection control strategies to contain PDRAB infections may not be effective if patients with imipenem-susceptible MDRAB infections were not included in the isolation policies. P1344 Multidrug-resistant Acinetobacter baumannii susceptible only to colistin outbreak in a cardiac surgical intensive care unit A. Mastoraki, E. Douka, I. Kriaras, G. Stravopodis, G. Saroglou, H. Manoli, S. Geroulanos (Athens, GR) Objectives: The aim of this study was to determine the incidence and mortality of Multi-Drug Resistant Acinetobacter baumannii (MDR-AB) in patients undergoing cardiac surgery, to elucidate the effectiveness of
17th ECCMID / 25th ICC, Posters treating them with colistin and to identify if the additional measures to the recommended procedures were able to control the dissemination of MDR-AB isolates in our institution. Methods: A prospective study was conducted among 1,451 patients who were submitted to cardiovascular surgery from 1 September 2005 to 31 August 2006. All case histories of infected patients were objected to meticulous analysis. We reviewed the prophylactic measures of the SICU and implemented a two scale multiple programme. Scale 1 included classical infection control measures, i.e. strict contact and droplet isolation, surveillance of throat, nasal and anal flora for MDR pathogens on all patients transferred from other hospitals, separate nursing staff for each infected or colonised case and strict antibiotic policy, while Scale 2 referred to the geographic isolation of all positive MDR-AB cases in distinct hospital units with exclusive medical and nursing personnel, use of separate supplies and facilities and environmental intense surveillance. Results: Among 121/1,451 infected patients 15 were colonised by strains of MDR-AB susceptible only to colistin. All patients were mechanically ventilated; 13 presented respiratory tract infection, 1 patient suffered deep surgical site infection and 1 patient catheter related infection. Transmission of the pathogen into the hospital occurred via 2 patients transferred from 2 other institutions. They were all treated with colistin. Cure or clinical improvement was observed only in 4 patients (27%). Scale 1 measures were implemented for the whole 12-month period while Scale 2 for 2 separate periods of 3 weeks. Environmental specimens (n > 350) sampled on several occasions proved negative. Conclusions: The increasing prevalence of MDR-AB in SICU patients creates demand on strict screening and contact precautions. Following this infection control strategy we were able to achieve intermittent eradication of the pathogen during a 12-month period with continuous function of the SICU. Despite the significant “in vitro” activity of colistin against MDR-AB the results were discouraging. Due to the significant mortality of MDR-AB infected patients additional measurements are highly recommended. P1345 Multidrug-resistant Acinetobacter baumannii prosthetic joint infection treated with colistin A. Rodr´ıguez Guardado, V. Asensi, M. Lantero, M. Castillo, J. Cart´on (Oviedo, ES) Background: Description of the characteristics of the prosthetic joint infection by A. baumannii treated with colistin emphasizing the factors influencing their outcome Methods: All the episodes of prosthetic joint infection by multidrugresistant A. baumannii diagnosed between 2004–2006 treated with colistin were retrospectively reviewed. The Acinetobacter isolate was defined as MDR if it was resistant to 3classes of antimicrobial agents as tested by commercial system. The dose of parenteral colistin was 160 mg/8 h. Results: Eight cases were reviewed. All the patients had underwent surgery. Five patients were carriers of a knee prosthesis and the rest hip prosthesis. The mean time between the surgery and the onset of the infection was 26.5 days. Five patients had deep wound cultures and the rest had bone tissue cultures. Three patients had mixed infections [methicillin-resistant Staphylococcus aureus (two cases), E. faecium (one case)] coccus aureus (and case each). All the patients had received previous antibiotic treatment which were inadequate in all cases Four patients received IV colistin (160 mg/8 hours) monotherapy. Three received a combined IV therapy with colistin and vancomycin. One patient development a infection by a A. baumannii resistant to colistin and he was treated with a combination of IV colistin 160 mg/8 hours, IV rifampicin (600 mg/day) and IV imipenem (1 g/8 hours) with good evolution. In 3 cases the treatment was associated with removal of the prosthesis and in the rest a surgical drainage was performed. The mean of treatment was 59.7 days. The follow-up period was 9 months (range 6−18 months). Only one patient died a consequence of the infection and the rest cured. The renal function was normal in all the cases. Conclusions: The use of intravenous colistin is safe and effective treatment for prosthetic joint infection due to multiresistant A. baumannii.
17th ECCMID / 25th ICC, Posters treating them with colistin and to identify if the additional measures to the recommended procedures were able to control the dissemination of MDR-AB isolates in our institution. Methods: A prospective study was conducted among 1,451 patients who were submitted to cardiovascular surgery from 1 September 2005 to 31 August 2006. All case histories of infected patients were objected to meticulous analysis. We reviewed the prophylactic measures of the SICU and implemented a two scale multiple programme. Scale 1 included classical infection control measures, i.e. strict contact and droplet isolation, surveillance of throat, nasal and anal flora for MDR pathogens on all patients transferred from other hospitals, separate nursing staff for each infected or colonised case and strict antibiotic policy, while Scale 2 referred to the geographic isolation of all positive MDR-AB cases in distinct hospital units with exclusive medical and nursing personnel, use of separate supplies and facilities and environmental intense surveillance. Results: Among 121/1,451 infected patients 15 were colonised by strains of MDR-AB susceptible only to colistin. All patients were mechanically ventilated; 13 presented respiratory tract infection, 1 patient suffered deep surgical site infection and 1 patient catheter related infection. Transmission of the pathogen into the hospital occurred via 2 patients transferred from 2 other institutions. They were all treated with colistin. Cure or clinical improvement was observed only in 4 patients (27%). Scale 1 measures were implemented for the whole 12-month period while Scale 2 for 2 separate periods of 3 weeks. Environmental specimens (n > 350) sampled on several occasions proved negative. Conclusions: The increasing prevalence of MDR-AB in SICU patients creates demand on strict screening and contact precautions. Following this infection control strategy we were able to achieve intermittent eradication of the pathogen during a 12-month period with continuous function of the SICU. Despite the significant “in vitro” activity of colistin against MDR-AB the results were discouraging. Due to the significant mortality of MDR-AB infected patients additional measurements are highly recommended. P1345 Multidrug-resistant Acinetobacter baumannii prosthetic joint infection treated with colistin A. Rodr´ıguez Guardado, V. Asensi, M. Lantero, M. Castillo, J. Cart´on (Oviedo, ES) Background: Description of the characteristics of the prosthetic joint infection by A. baumannii treated with colistin emphasizing the factors influencing their outcome Methods: All the episodes of prosthetic joint infection by multidrugresistant A. baumannii diagnosed between 2004–2006 treated with colistin were retrospectively reviewed. The Acinetobacter isolate was defined as MDR if it was resistant to 3classes of antimicrobial agents as tested by commercial system. The dose of parenteral colistin was 160 mg/8 h. Results: Eight cases were reviewed. All the patients had underwent surgery. Five patients were carriers of a knee prosthesis and the rest hip prosthesis. The mean time between the surgery and the onset of the infection was 26.5 days. Five patients had deep wound cultures and the rest had bone tissue cultures. Three patients had mixed infections [methicillin-resistant Staphylococcus aureus (two cases), E. faecium (one case)] coccus aureus (and case each). All the patients had received previous antibiotic treatment which were inadequate in all cases Four patients received IV colistin (160 mg/8 hours) monotherapy. Three received a combined IV therapy with colistin and vancomycin. One patient development a infection by a A. baumannii resistant to colistin and he was treated with a combination of IV colistin 160 mg/8 hours, IV rifampicin (600 mg/day) and IV imipenem (1 g/8 hours) with good evolution. In 3 cases the treatment was associated with removal of the prosthesis and in the rest a surgical drainage was performed. The mean of treatment was 59.7 days. The follow-up period was 9 months (range 6−18 months). Only one patient died a consequence of the infection and the rest cured. The renal function was normal in all the cases. Conclusions: The use of intravenous colistin is safe and effective treatment for prosthetic joint infection due to multiresistant A. baumannii.