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Aims: The antibiotic colistin, which had been previously abandoned, is being brought back as a last line of defense against bacterial infection. However, colistin resistance was reported shortly after its reintroduction. This study evaluated the risk factors for colonization/infections due to colistin-resistant Acinetobacter baumannii (ColR-Ab) and Klebsiella pneumoniae (ColR-Kp) strains and characterized the molecular epidemiology of these two strains., Results: Age, previous hospitalization duration, and previous use of carbapenem and colistin were risk factors for ColR-Kp, whereas previous use of carbapenem and colistin was a risk factor for ColR-Ab. According to pulsed-field gel electrophoresis analysis, most ColR-Kp strains could be grouped into two major pulsotypes. This appears to be an indicator of cross contamination of ColR-Kp strain, since different isolates appeared to be belonging to the same clones. The existence of colistin-susceptible (ColS) and colistin-resistant (ColR) strains in the same pulsotypes might also be an indicator of the recent emergence of resistance mechanisms., Conclusions: The results highlight the emergence of ColR pathogens in Turkey, which is considered to be developing country, and that carbapenem use coupled with insufficient infection control measures might increase the risk of ColR outbreaks.

Objectives: To compare the efficacy of colistin (COL) monotherapy versus non-COL based combinations in the treatment of bloodstream infections (BSIs) due to multidrug resistant Acinetobacter spp.(MDR-A)., Materials and Methods: Retrospective data of 107 MDR-A BSI cases from 27 tertiary centers in Turkey were included., Primary End-Point: 14-day mortality., Secondary End-Points: Microbial eradication and clinical improvement., Results: Thirty-six patients in the COL monotherapy (CM) group and 71 in the non-COL based combinations (NCC) group were included in the study. Mean age was 59.98 ± 20 years (range: 18-89) and 50.5% were male. Median duration of follow-up was 40 days (range: 9-297). The 14-day survival rates were 52.8% in CM and 47.23% in NCC group (P = 0.36). Microbiological eradication was achieved in 69% of CM and 83% of NCC group (P = 0.13). Treatment failure was detected in 22.9% of cases in both CM and NCC groups. Univariate analysis revealed that mean age (P = 0.001), Charlson comorbidity index (P = 0.03), duration of hospital stay before MDR-A BSI (P = 0.04), Pitt bacteremia score (P = 0.043) and Acute Physiology and Chronic Health Evaluation II score (P = 0.05) were significant in terms of 14-day mortality. Advanced age (P = 0.01) and duration of hospital stay before MDR-A BSI (P = 0.04) were independently associated with 14-day mortality in multivariate analysis., Conclusion: No significant difference was detected between CM and non-COL based combinations in the treatment of MDR-A BSIs in terms of efficacy and 14-day mortality.

Background: Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as one of the most troublesome pathogens in healthcare settings worldwide. The present study was conducted to analyze the genes encoding resistance to carbapenems and to determine in vitro activity of colistin and tigecycline against CRAB isolates from blood culture of hospitalized patients at Istanbul University Cerrahpasa Medical School hospital., Methods: Between January 2012 and June 2014, a total of 72 CRAB isolates were isolated by conventional methods from blood cultures of patients with bacteremia who were hospitalized in intensive care units and in various departments of the hospital. The isolates were confirmed using a Phoenix automated system. Antibiotic susceptibilities were determined by disk diffusion method and Etest. Molecular detection of resistance genes were screened by multiplex real time polymerase chain reaction (qPCR) and PCR parameters., Results: CRAB isolates were highly resistant to tetracycline (86.1%), trimethoprim/sulfamethoxazole (84.7%), ceftazidime (83.3%), cefepime (81.9%), ciprofloxacin (81.9%), amikacin (75.0%), piperacillin/tazobactam (75.0%), cefotaxime (72.2%), and gentamicin (69.4%). Tigecycline and colistin resistance were not detected. MIC50 and MIC90 of tigecycline (MIC ranges 0.016-1 µg/mL) and colistin (MIC ranges 0.125-1.5 µg/mL) were found to be 0.5 µg/mL and 1 µg/mL, respectively. All isolates were positive for OXA-51 that shows molecular identification of A. baumannii. Fifty-one (70.8%) and 2 (2.8%) of these isolates were positive for OXA-23 and OXA-58 genes, re- spectively., Conclusions: This study indicated the most of the CRAB isolates in our hospital carry the OXA-23 gene. Colistin and tigecycline resistance were not detected. However, significant effort must be done to prevent the spread of OXA-23-producing CRAB-isolates and continuous monitoring of drug resistance is necessary in clinical settings.

The purpose of our study was to share experience on demographic characteristics and clinical outcome of the patients infected with extensively drug-resistant Acinetobacter baumannii (XDRAB) in haematology clinics, focusing on the period with a sudden increase in the number of XDRAB cases. A regular patient-based infection control programme was set up in haematology clinics and haematopoietic stem cell transplant centre starting from 2008. An infection control nurse visited all patients daily. A form including demographic data and laboratory results were recorded for all patients. The source of infections was identified according to the criteria proposed by the Centers for Disease Control and Prevention. While haematology ward-acquired XRDAB was rare before 2012, between January 2012 and July 2013, 29 A. baumannii infection episodes were detected in 28 patients. All but one isolate were MDR and 72.4% (21 out of 29) were XDR. Blood cultures revealed A. baumannii in 26 out of 29 episodes. While the haematological malignancy was relapsing or not under remission in 15 patients, four patients were under remission, and 10 patients were newly diagnosed. The mortality rate was 81.2%. All patients with a poor outcome died in the first week after the index blood culture was performed. In 16 out of 29 episodes, the patients died before the culture results became available. Colistin was initiated for the treatment in 11 out of 29 episodes. Three patients received colistin combined with sulbactam or sulbactam containing beta-lactams; the remaining eight patients who received colistin monotherapy were already under carbapenems. In conclusion, XDRAB infections can easily become nightmares for haematology clinics without any reliable treatment option.

Aim: The aim of the present study was to assess the efficacy and safety of colistimethate sodium therapy in multidrug-resistant nosocomial infections caused by Pseudomonas aeruginosa or Acinetobacter baumannii in neonates and children., Methods: Pediatric patients hospitalized at the Uludag University Hospital who had nosocomial infections caused by multidrug-resistant P. aeruginosa or A. baumannii, were enrolled in the study. Colistimethate sodium at a dosage of 50-75 x 10(3) U/kg per day was given i.v. divided into three doses., Results: Fifteen patients received 17 courses of colistimethate sodium for the following infections: ventilator-associated pneumonia (n= 14), catheter-related sepsis (n= 1) and skin and soft-tissue infection (n= 2). The mean age of patients was 53.2 + 74.7 months (range, 8 days-15 years) and 60% were male. Mortality was 26.6%., Conclusion: Colistimethate sodium appears to be safe and effective for the treatment of severe infections caused by multidrug-resistant P. aeruginosa or A. baumannii in pediatric patients.

Background: The nosocomial spread of pan-antibiotic-resistant nonfermentative bacteria is an increasing concern. This study investigated the microbiologic and epidemiologic characteristics of a hospital outbreak due to alginate-producing, pan-antibiotic-resistant Pseudomonas aeruginosa (PAR-Pa)., Methods: All patients with infection with a P. aeruginosa strain that was resistant to all Clinic Laboratory Standards Institute-suggested antimicrobial agents between November 2004 and May 2005 were included in the study. Alginate production detection and pulsed-field gel electrophoresis (PFGE) typing were done for the patient and environmental surveillance isolates. A matched case-control study was performed to identify risk factors and evaluate outcomes., Results: PFGE analysis of a total of 35 PAR-Pa isolates (28 patient and 7 environmental surveillance isolates) identified a single epidemic clone as responsible for the outbreak. All epidemic isolates were alginate-producing and susceptible only to colistin. The Student t-test demonstrated that a longer stay in the intensive care unit (ICU) (6.64 days vs 1.83 days; P < .05) significantly increased the risk of PAR-Pa infection. Systemic PAR-Pa infection resulted in higher mortality (85.7% vs 27.8%; P < .05). Multivariate analysis determined that therapeutic failure (odds ratio = 24.7; 95% confidence interval = 4.144 to 147.221; P < .05) was the independent risk factor related to this high mortality. Localized PAR-Pa infections were associated with longer hospital stays (46.2% vs 14.4%; P < .05) and higher rates of surgery (85.7% vs 15.4%; P < .05) and amputation (42.8% vs 0%; P < .05). The recovery of the pathogen from staff hands and frequently handled surfaces suggests possible handborne transmission. Improved hygienic standards and application of strict contact precautions, including isolation, reduced the spread of the pathogen., Conclusion: This study illustrates the ability of pan-antibiotic-resistant P. aeruginosa to cause an outbreak with significant mortality and stresses the need for precautions to prevent the spread of such highly resistant strains.