The Effects of Negative Ions and Ozone on Various Bacteria and The Evaluation of Their Use in Hospital Wastewater Disinfection

Introduction: In recent years, there has been an increase in hospital and/or community-acquired infections caused by antibiotic-resistant microorganisms. To prevent or to reduce these infections, reliable, effective disinfection methods are needed to be used in disinfecting the hospital wastewater. In this study, the sensitivity of multidrug resistant strains of Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii and Staphylococcus aureus bacteria, which are often encountered as hospital infection agents to ozone gas and/or negative ions, is investigated, and the use of these disinfection methods in our hospital’s waste water systems is evaluated. Materials and Methods: Our study included multidrug resistant clinical isolates identified by our hospital infection control committee as agents of hospital-acquired infection. Bacterial suspensions were prepared from the isolates at a concentration of 1.5 x 108 cfu/mL and serial dilutions were then made to 1.5 x 102 cfu/mL. Two different ozone generators with an ozone generating capacity at concentrations of 10.5 mg/h and 6.6 mg/h and a negative ionizer with a negative ion output of 3.3 million/cm3 were used. For a total of seven different bacterial concentrations, ozone and/or negative ion application was performed at different application times, and the changes observed in the number of bacteria were recorded. The effectiveness of the ozone on the agar plate surface and in the aqueous medium were examined, and finally, the disinfection efficiency on the waste water treatment system was evaluated by applying ozone to the water samples taken from the entrance and exit points of the hospital wastewater treatment system. Results: It was determined that all bacterial species studied were highly susceptible to ozone gas, and their growth was inhibited in a short exposure time. However, it was observed that high concentrations of ozone gas and/or continuous ozone application might be required, especially at high bacterial concentrations. It was also found that the activity of ozone in the aqueous environment was much higher. It was observed that the negative ions were ineffective at high bacterial concentrations and therefore the use of this method in the disinfection of wastewater systems with high pathogen load was not beneficial. Conclusion: It is concluded that the use of ozone gas in the disinfection of hospital wastewater systems is effective and reliable

Investigation of Extended Spectrum Beta-Lactamase (ESBL) Genes in ESBL-Producing Escherichia coli and Klebsiella pneumoniae Strains

Introduction: Extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae is an important health problem all over the world. In this study, it was aimed to determine the ESBL genes in Escherichia coli and Klebsiella pneumoniae strains isolated for approximately four-year period. Materials and Methods: A total 100 ESBL-producing E. coli and 100 ESBL-producing K. pneumoniae strains which were isolated between January 2008 and October 2012 were included into this study. The strains were identified using classical bacteriologic methods and BD Phoenix (Becton Dickinson, US) automatized bacterial identification device. CTX-M, TEM, SHV, VEB, GES, PER and OXA beta-lactamase genes were analyzed with the PCR method. Results: The beta-lactamase genes detected in ESBL-positive K. pneumoniae strains were as follows: 99% for CTX-M, 91% for SHV, 71% for TEM, 10% for OXA-10 group, and 5% for OXA-2 group. In E. coli strains, the prevalence of CTX-M was 92%; TEM was 70%, SHV was 21%, and OXA-2 group was 3%. CTX-M alone was found to be positive in 25 of the 98 (25.5%) in E. coli strains; TEM alone was found to be positive in 2 of 98 (2%) and SHV alone was found in 2 of 98 (2%). CTX-M alone was found positive in 3 of 100 (3%) K. pneumoniae strains. No other resistance genes alone were found in the strains. No GES, VEB and PER-producing strains were determined in this study. Conclusion: In the study, high prevalence of CTX-M beta-lactamase was found in ESBL-producing strains. It was thought that the high potential of mobility with CTX-M genes was the most possible reason for this result. Determination of ESBL genes will be useful to understand resistance epidemiology, develop effective therapeutic strategies, and plan the appropriate preventive measurements

The Optimization of a Rapid Pulsed-Field Gel Electrophoresis Protocol for the Typing of Acinetobacter baumannii, Escherichia coli and Klebsiella spp.

Pulsed-field gel electrophoresis (PFGE) is the most common genotyping method used for the typing of a number of bacterial species. Generally, investigators use their own custom-developed protocol, but a standardized PFGE protocol would allow the comparison of typing results between laboratories and the tracing of strains around the country. In the present study, we optimized a PFGE protocol for subtyping of Acinetobacter baumannii, Escherichia coli and Klebsiella spp., which are commonly isolated from nosocomial infections in many hospitals. Reproducibility of our PFGE procedure was studied three times at 2- to 3-week intervals. Epidemiological concordance of the optimized PFGE procedure was tested on seven isolates of A. baumannii from a previous outbreak and seven A. baumannii isolates randomly selected among the clinical isolates. The optimized PFGE procedure was evaluated on a total of 174 clinical isolates including 62 A. baumannii, 50 E. coli and 62 Klebsiella spp. The inter-laboratory reproducibility of the optimized protocol was tested at four laboratories. The optimized procedure is completed in 28 h after culturing. It is likely to be cost-effective, due to the reduction in the time, reagent volume and enzyme concentration needed. The procedure showed high concordance with epidemiological data. There were no non-typeable isolates among the tested bacteria. It is reproducible and versatile. This protocol can be used to identify outbreaks and monitor the spreading rate of nosocomial infections caused by the tested bacterial isolates. Furthermore, due to its high intra- and inter-laboratory reproducibility, the protocol has the potential to be useful for comparing PFGE fingerprinting profiles of the isolates from different settings

2277. Comparison Of 30-Day Crude Mortality Rates In Patients With Bloodstream Infections (Bsis) Caused By Colistin Susceptible-(Cols-Crkp) Vs. Colistin And Carbapenem-Resistant Klebsiella Pneumoniae(Colr-Crkp)

Background Colistin is a last resort antibiotic against infections with CRKp. Its increased use has led to resistance to this antibiotic. Methods This was a single-center, retrospective, cohort study including all CRKp BSIs treated between January 1, 2014 and July 31, 2018. Antibiotic therapy was appropriate if initiated within 5 days from the onset of BSI including at least an active drug with an adequate dosage. Exclusion criteria were missing key data, death < 24 h after inclusion, subsequent episodes in the same patients, pregnancy, polymicrobial BSI, < 18 years of age, no ID consultation, no carbapenemase gene detection by multiplex PCR for blaKPC, blaNDM, blaVIM, blaIMPand blaOXA48. EUCAST breakpoints were used for antibiotic susceptibilities. Colistin MIC was determined by using broth microdilution. FDA criteria were applied for tigecycline susceptibility Results Among 174 CRKp BSIs, 129 met all inclusion criteria. Susceptibility to antibiotics was as follows: colistin (51.9%), tigecycline (67.4%), gentamicine (38.0%), amikacin (43.0%), meropenem (32.6%), ciprofloxacin (18.6%), TMP-SMX (24.0%), ceftazidime (7.8%), cefepime (7.8%)., 66.1% and 19.4% of the patients received inappropriate therapy in ColR-CRKp and ColS-CRKp groups, respectively (P ≤ 0.001). We incorporated interaction between colistin susceptibility and inappropriate therapy into multivariate logistic regression analysis (MLRA) that was constructed for identification of independent risk factors for 30-day mortality. The variables having P ≤ 0.1 in crude analysis were included in MLRA. After checking correlation between variables by Pearson correlation analysis and multicollinearity analysis, the final model was builded. The results are shown in Table 2. Conclusion Colistin resistance and inappropriate therapy were not associated with decreased mortality individually, however their interaction significantly increased 30-day mortality rate (OR: 4.04; 95% CI: 1.62–10.02; P = 0.003).85.5% of ColR-CRKp isolates produced an OXA-48 enzyme which can be inhibited by ceftazidime–avibactam, but not available in our setting, treatment with this agent may have altered the mortality rates. Thus, high rate colistin resistance among CRKp isolates remains as a significant cause of mortality in our setting., , , , Disclosures All authors: No reported disclosures.PubMe