Sławomir Lech Czaban

The Occurrence of blaCTX-M, blaSHV, and blaTEM Genes in Extended-Spectrum β-Lactamase-Positive Strains of Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis in Poland

Bacteria belonging to the Enterobacteriaceae family that produce extended-spectrum β-lactamase (ESBL) enzymes are important pathogens of infections. Increasing numbers of ESBL-producing bacterial strains exhibiting multidrug resistance have been observed. The aim of the study was to evaluate the prevalence of , , and genes among ESBL-producing Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis strains and to examine susceptibility to antibiotics of tested strains. In our study, thirty-six of the tested strains exhibited genes , , , and . Moreover, twelve ESBL-positive strains harbored genes , , , and , and the presence of a gene in twenty-five ESBL-positive strains was revealed. Among K. pneumoniae the multiple ESBL genotype composed of , and genes encoding particular ESBL variants was observed. Analysis of bacterial susceptibility to antibiotics revealed that, among β-lactam antibiotics, the most effective against E. coli strains was meropenem (100%), whereas K. pneumoniae were completely susceptible to ertapenem and meropenem (100%), and P. mirabilis strains were susceptible to ertapenem (91.7%). Moreover, among non-β-lactam antibiotics, gentamicin showed the highest activity to E. coli (91.7%) and ciprofloxacin the highest to K. pneumoniae (83.3%). P. mirabilis revealed the highest susceptibility to amikacin (66.7%).

Assessment of serum IGF-1 and adipokines related to metabolic dysfunction in HIV-infected adults.

PURPOSE HIV/HAART associated metabolic syndrome (HAMS) seems to result from direct influence of HIV, adverse effects of combined antiretroviral therapy (cART) and individual genetic predisposition. This study aimed to assess the influence of HIV infection and cART on serum concentration of insulin-like growth factor-1 (IGF-1) and adipokines related to metabolic abnormalities. METHODS Seventy-two HIV infected patients including 48 HIV/HCV coinfected were enrolled in this study. Insulin resistance was evaluated by Homeostatic Model Assessment (HOMA) indexes. Serum concentrations of IGF-1, adiponectin, chemerin and visfatin were measured by ELISA. RESULTS Significant correlation between serum IGF-1 level and CD4 lymphocytes count was demonstrated and the lowest values were observed in subjects with CD4<200 cells/μL. Serum concentration of IGF-1 was significantly higher in patients treated with protease inhibitors based regimen compared to non-nucleoside reverse transcriptase inhibitors and healthy subjects. A significant negative correlation between serum concentration of adiponectin and waist-hip ratio as an indicator of central obesity, was found. There were significant positive correlations between serum concentration of chemerin and HOMA1-IR and serum IGF-1 concentration. Serum chemerin was increased in patients with insulin resistance vs. those with preserved insulin sensitivity. CONCLUSIONS According to these results HAMS is associated with insulin resistance and imbalance of adipokines serum concentration, therefore identification of pathways related to HAMS development might be helpful in management of the syndrome. Serum IGF-1 largely depends on level of immunodeficiency in HIV-infection and may provide a link between immune dysfunction and development of HIV-associated lipodystrophy, AIDS wasting syndrome, diabetes and/or cardiovascular diseases in HIV-infected patients.

Susceptibility, phenotypes of resistance, and extended-spectrum β-lactamases in Acinetobacter baumannii strains.

Acinetobacter baumannii plays an increasing role in the pathogenesis of infections in humans. The bacilli are frequently isolated from patients treated in intensive care units. A growing resistance to antibiotics is leading to the emergence of strains that are multidrug-resistant and resistant to all available agents. The objective of this study was to assess susceptibility to antibiotics and to determine the presence and current level of the extended-spectrum β-lactamases (ESBLs) and attempt to isolate the Acinetobacter baumannii strain carrying the bla PER gene. A total of 51 strains of A. baumannii identified by phenotypic features were examined. That the strains belonged to the species was confirmed by the presence of the bla OXA-51-like ; gene. A broth microdilution method was used for antibacterial susceptibility testing. The occurrence of ESBLs was determined using phenotypic double-disk synergy tests. The PCR technique was used to confirm the presence of the bla PER-1 ; gene encoding ESBL. The most active antibiotics were meropenem, cefepime and ampicillin/sulbactam, with susceptibility shown by 76.5%, 60.8% and 56.9% of the strains, respectively. The strains exhibited the highest resistance (> 75%) to piperacillin, tetracycline, ciprofloxacin and cefotaxime. Phenotypic tests revealed ESBL mechanism of resistance in approximately 20% of Acinetobacter baumannii isolates. However, the PCR technique did not confirm the presence of the bla PER-1 ; gene in any of the Acinetobacter baumannii strains examined in our hospital. Acinetobacter baumannii strains demonstrate considerable resistance to many groups of antibiotics. Our findings indicate the involvement of enzymes belonging to families other than PER β-lactamase in resistance to β-lactams in A. baumannii.

Expression of MexAB‐OprM efflux pump system and susceptibility to antibiotics of different Pseudomonas aeruginosa clones isolated from patients hospitalized in two intensive care units at University Hospital in Bialystok (northeastern Poland) between January 2002 and December 2009

We investigated the genetic similarities and expression of the MexAB‐OprM efflux pump system in different clones of multiresistant Pseudomonas aeruginosa strains collected from 2002 to 2009 at two intensive care units (ICU). Regulatory and structural genes mexB, mexR, and mexA were found in 99%, 98%, and 94% of tested strains, respectively. The presence of class 1 integron was found in 90% of the strains, while class 2 integron in only one strain (Psa506). Class 3 integron was not found in any of the tested strains. Among the eleven clones identified, only two clones, I and D, exhibited higher levels of mexB gene expression than the other clones. Clone I had the highest expression (FC = 10.36, p < 0.05). The results of our study indicated a high level of MexAB‐OprM pump expression in groups of strains isolated in the years 2008–2009 (FC = 12.92, p < 0.03) and 2002–2006 (FC = 5.14, p < 0.03). There were no statistically significant differences in resistance to all tested antibiotics among the various clones. The high level of antimicrobial resistance may have been due to the coexistence of different resistance mechanisms among the studied P. aeruginosa strains. However, this does not exclude the contribution of the MexAB‐OprM pump, particularly in resistance to meropenem and ciprofloxacin.

Distribution of AdeABC efflux system genes in genotypically diverse strains of clinical Acinetobacter baumannii

Acinetobacter baumannii has emerged as a highly problematic hospital-associated pathogen. Different mechanisms contribute to the formation of multidrug resistance in A. baumannii, including the AdeABC efflux system. Distribution of the structural and regulatory genes encoding the AdeABC efflux system among genetically diverse clinical A. baumannii strains was achieved by using PCR and pulsed-field gel electrophoresis techniques. The distribution of adeABRS genes is extremely high among our A. baumannii strains, except the adeC gene. We have observed a large proportion of strains presenting multidrug-resistance phenotype for several years. The efflux pump could be an important mechanism in these strains in resistance to antibiotics.

Rep-PCR genotyping of infectious Acinetobacter spp. strains from patients treated in Intensive Care Unit of Emergency Department (ICU of ED) - preliminary report

PURPOSE Strains of Acinetobacter spp. are responsible for a considerable percentage of hospital infections. These pathogens have colonized hospital environment and developed resistance to many currently available antibiotics. The aim of this study was one year-long analysis of the occurrence of multiresistant strains of Acinetobacter spp. in population of patients hospitalized in ICU of ED and determination of their genetic similarity. MATERIAL/METHODS Subject of research was the population of patients admitted to ED of University Hospital in Bialystok in the period from 01.08.2010 to 01.08.2011. In the analysed group of patients, infections were identified on the basis of the guidelines of CDC. Identification and drug susceptibility of strains was specified using the automatic methods with the analyzer Vitek 2XL. Genotyping using Rep-PCR method in DiversiLab system was performed on strains of Acinetobacter spp. to determinate their genetic similarity. RESULTS During analyzed period 405 patients were hospitalized, from 14 of them multiresistant strains of Acinetobacter spp. were isolated. Conducted genetic research allowed to detect 5 clones. Rep-PCR method in DiversiLab system enabled to learn that different clone of multiresistant strain of Acinetobacter spp. is responsible for variable forms of infection. CONCLUSIONS Results of conducted research suggest that genotyping with rep-PCR method in DiversiLab system is useful tool in diagnostics of clones of multiresistant pathogens isolated from patients requiring intensive care, hospitalized in ED. Genotyping with rep-PCR method combined with epidemiological investigation enables to establish ways of spreading of multiresistant strains of Acinetobacter spp. in ED.