Investigation of Ciprofloxacin Resistance and Its Mechanisms in Clinical Pseudomonas aeruginosa Isolates

Pseudomonas aeruginosa is one of the most important causes of hospital infections. Although different antibiotic groups are used for the treatment of P.aeruginosa infections, quinolone groups are distinguished by the advantages of oral administration. However, in recent years, resistance against members of this group has made treatment more difficult. The aim of this study was to investigate the epidemiological relationship and possible mechanisms of resistance in ciprofloxacin resistant P. aeruginosa isolates from Ege University Hospital. The identification of P.aeruginosa bacteria isolated from clinical samples in Ege University Medical Faculty Medical Microbiology Laboratory was determined by VITEK MS automated systems by VITEK compact, antimicrobial susceptibility. The epidemiological relationships of the ciprofloxacin resistant isolates were determined by Enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR). The presence of qnrA, qnrB, qnrS, qepA genes, the quinolone resistance genes and nfxB, mexR, the regulatory genes of the efflux pump, was determined by PCR. The phenylalanine-arginine β-naphthylamide (PAβN) assay was used to determine the activation of the efflux pump. Twenty-two isolates (26.5 %) were found resistant to ciprofloxacin. According to the ERIC-PCR results, 11 unrelated clones were detected. Ciprofloxacin minimum inhibitory concentration (MIC) values were decreased 2-64 times in 10 isolates in the presence of PAIN. No ciprofloxacin MIC change was detected in one isolate. The presence of pump regulatory genes was determined in 10 of the 11 representative isolates, while only qnrB of the genes associated with quinolone resistance was detected in seven representative isolates. qnrA, qnrS, qepA genes were not detected in any isolate. Ciprofloxacin resistant P.aeruginosa isolates are isolated from our hospital. It is noteworthy that the isolates belonging to different genetic groups are in circulation in clinics. Basic resistance mechanisms are thought to be efflux pumps and qnrB genes.

Microorganisms Isolated from Wound Samples and Their Antibiotic Resistance Rates

In this study, it was aimed to contribute to available epidemiological data and guide empirical treatment by determining the distribution and antibiotic susceptibility of pathogenic microorganisms isolated from wound samples sent to the microbiology laboratory of our hospital. The agents of wound infection sent to our laboratory between 02.01.2017 and 20.07.2020 were retrospectively analyzed. The microorganisms grown were identified by conventional microbiological methods together with automated system. Antibiotic susceptibility testing was done by Kirby-Bauer disk diffusion method and an automated system and evaluated according to EUCAST criteria. Of the 956 bacteria isolated from 722 samples, 370 (39 %) were order Enterobacterales, 286 (30 %) were Gram positive cocci, 134 (14 %) were Pseudomonas spp., 83 (9 %) were Acinetobacter baumannii and 27 (3 %) were Candida spp. Vancomycin, teicoplanin and linezolid resistance were not found in staphylococci and enterococci. The most effective antibiotic against Staphylococcus aureus was trimethoprim-sulfamethoxazole (TMP-SXT) (11 %), and gentamicin (30 %) and TMP-SXT (28 %) for coagulase negative staphylococci (CNS). Ciprofloxacin (48 %) and levofloxacin (58 %) resistance was higher in enterococci compared to other antibiotics. In addition, Klebsiella spp. strains have higher resistance rates than other Enterobacterales genus strains while A. baumannii and Pseudomonas spp. strains had the lowest resistance rate against colistin (1 %). Antibiotic resistance was higher in intensive care units than in other clinics, except for enterococci. In our study, it was observed that many species of bacteria and fungi could be an agent in wound infection, and high rates of resistance developed against antibiotics. Therefore, it was thought that the treatments should be regulated by performing culture and antibiogram procedures on all samples for which wound infection is suspected.

First Food-Borne Cases of Vibrio Parahaemolyticus in Turkey

ABSTRACT Vibrio parahaemolyticus (V.parahaemolyticus) is detected in many parts of the world. It is one of the most common causes of food-borne infections in Asian countries and Japan, and is usually seen as minor outbreaks involving less than ten cases. In this study, it is aimed to investigate V.parahaemolyticus in diarrhea cases in our laboratory in order to draw attention to the possible cases of this agent due to the increase in the consumption of shellfish. In the period of July-August 2018; patients who applied to the emergency service of our hospital with gastrointestinal tract infection symptoms following seafood consumption were investigated by stool microscopy and culture as part of routine procedures. Stool samples were cultured on Hektoen enteric agar, MacConkey agar, and sheep blood agar and were incubated at 37°C for 24 hours. After the incubation period, lactose negative and oxidase-positive colonies were identified by classical biochemical tests, VITEK 2 and MALDI-TOF MS (bioMérieux, France). In seven patients aged between 12-59, clinical symptoms associated with gastroenteritidis started after consuming stuffed mussels in four, eating fish in one, and in a patient after consuming fast food. One patient could not be contacted. In the microscopic examination of the macroscopically watery and mucous stool samples, abundant leukocytes in all samples, and abundant erythrocytes in addition to leukocytes in one sample were seen. The bacteria grown in culture were identified as V.parahaemolyticus by conventional methods and automated systems, Vitek 2 with 96 % and MALDITOF MS with 99 % accuracy. The results were also confirmed by the General Directorate of Public Health, National Enteric Pathogens Reference Laboratory by conventional methods, API 20 E and MALDI-TOF MS (BrukerDaltonics, USA). It should be kept in mind that V.parahaemolyticus can be isolated as a cause of gastroenteritis in diarrhea cases during the summer months, especially in the presence of a history of seafood consumption, and further investigations should be performed in this direction.

Evaluation of Diagnostics Colistin MIC-Strip Test for Colistin Susceptibility Testing

Due to the limited number of antimicrobials to be used in the treatment of infections caused by Gram-negative microorganisms with multi-drug resistance recently, old antibiotics such as colistin have started to be preferred frequently. However, some problems are encountered in antibiotic susceptibility tests (disk diffusion, gradient test, automated systems) which are frequently used in the routine laboratory due to the cationic nature of colistin. For this reason, only the broth microdilution test is recommended by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) for the detection of colistin susceptibility. Since broth microdilution tests are time consuming and inconvenient, tests that can provide fast and reliable colistin susceptibility result is needed in routine laboratories. In this study, it was aimed to evaluate the performance of the commercially produced Diagnostics MIC-COL test (Diagnostics I.n.c, Galanta, Slovakia) for the detection of colistin susceptibility in Klebsiella pneumoniae and Acinetobacter baumannii strains. The strains of K.pneumoniae (n = 22) and A.baumannii (n = 28) isolated from various clinical specimens between 2016 and 2019 in our routine laboratory were included in the study. Colistin minimum inhibitory concentrations (MIC) of the strains were studied with both the reference broth microdilution method and the commercially produced Diagnostics Colistin MIC-COL test. The essential agreement, categorical agreement, major error, and very major error rates of the test were calculated by comparing the obtained results. The essential agreement of the Diagnostics Colistin MIC-Strip test was determined as 84 %, categorical agreement as 98 %, and major error rate as 3.8 %, while no very major error was detected. İt is very important to guide antimicrobial treatment with rapid and reliable detection of colistin susceptibility. The commercial test used in our study is easy to use and not time-consuming. Also, due to its strip from, each isolate can be studied separately. Because of the major error rate being above the expected values, it will be useful to re-evaluate these rates with further studies to be conducted with a larger number of strains with different resistance levels.

The Investigation of OXA-48 and Sub-Derivatives in Klebsiella pneumoniae Strains and Phenotypic Reflection

The number of infections caused by carbapenem-resistant Gram negative bacteria is increasing among nosocomial infections. These bacteria are a serious threat to health because they are usually resistant to other antibiotics. This study was aimed to determine the carbapenemase resistance of OXA-48 and its subderivatives in Klebsiella pneumoniae isolates isolated from various clinical samples by phenotypic and genotypic methods and to investigate the presence of OXA-48 gene region genotypically in isolates without resistance. A total of 127 K.pneumoniae strains isolated from patients treated in various clinics and intensive care units were included in this study from March 2015 to March 2016. The isolates were identified and susceptibilities were tested using BD Phoenix automated system and also with Kirby-Bauer disk diffusion method. The presence of resistance was examined phenotypically with the disk of temosillin, which is considered to indicate the presence of OXA-48 type enzymes. The presence of OXA-48 type enzyme was investigated by “in-house” polymerase chain reaction (PCR) in all isolates and the presence of OXA-48 variant was investigated by DNA sequencing analysis on positive isolates. Carbapenem resistance rate was 35 % and ESBL positivity was determined as 46 %. The sensitivity of temocillin disk method in the identification of OXA-48 gene presence in K. pneumoniae strains was found to be 88 %, and specificity 89 %. Ertapenem was the best carbapenem with sensitivity and specificity balance to detect carbapenem resistance caused by OXA-48. The presence of blaOXA-48 gene region was 80 % in K. pneumoniae isolates detected as resistant to carbapenems by an automated system. All sequences obtained by DNA sequence analysis of 42 OXA-48 positive isolates were OXA-48 and there was no variant OXA-48 gene among the sequences. It was observed that the phenotypic reflection of resistance did not occur immediately in three isolates genotypically having OXA-48 gene region. The presence of blaOXA-48 gene region in carbapenems-resistant K.pneumoniae isolates is common. In addition, in some isolates having OXA-48 gene region, should be kept in mind in patients who do not recover despite treatment, due to phenotypic reflection of resistance does not occur immediately