Extended-spectrum beta-lactamase (ESBL)-producing isolates of Klebsiella pneumoniae have been increasingly recognized in the hospital settings in Iran as well as throughout the world. The aim of this study was to detect and determine the genes encoding the ESBLs including bla(TEM), bla(SHV), and bla(CTX-M) groups among the K. pneumoniae isolates at Labbafinejad Hospital by polymerase chain reaction (PCR) and characterize them by direct sequencing of PCR products. Eighty-nine isolates were isolated from patients at different wards during March 2008-March 2009. They were identified as K. pneumoniae using biochemical tests. Susceptibility of isolates to 17 different antimicrobial agents was determined using agar disk diffusion method. The phenotypic confirmatory test was used to screen the isolates for production of ESBLs. To amplify the bla(SHV) the template DNA was extracted by boiling method. Plasmid DNA was extracted using minipreparation kit and used as template in PCR for detection of bla(TEM) and bla(CTX-M). The selected PCR products were sequenced and analyzed. All 89 strains were susceptible to imipenem. The rates of resistance to different antibiotics were in the following order: aztronam (79.7%), cefexime (67.4%), cefpodoxime (66.2%), cefotaxime (65.1%), ceftazidime (61.7%). The phenotypic confirmatory test detected 62 isolates (69.7%) as ESBL-producing K. pneumoniae. The prevalence of genes encoding ESBLs were as follows: bla(TEM) 54% (n = 48), bla(SHV) 67.4% (n = 60), bla(CTX-M-I) 46.51% (n = 40), and bla(CTX-M-III) 29% (n = 25). The bla(CTX-M-II) and bla(CTX-M-IV) were not detected. All bla(TEM) types were characterized as bla(TEM-1) and all bla(CTX-M-I) were identified as bla(CTX-M-15). The SHV types were characterized as SHV-5, SHV-11, and SHV-12. The rate of ESBL at Labbafinejad Hospital was 25% increase in a 4-year study that ended in March 2009. It appears that bla(TEM-1), bla(SHV-5), bla(SHV-11), bla(SHV-12), and bla(CTX-M-15) are the dominant ESBLs among the resistant strains of K. pneumoniae in Iran.

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PurposeStaphylococcus aureus is one of the most important causes of nosocomial and community-acquired infections. The increasing incidence of multiple antibiotic-resistant S. aureus strains and the emergence of vancomycin resistant S. aureus strains have placed renewed interest on alternative means of prevention and control of infection. S. aureus produces a variety of virulence factors, so a multi-subunit vaccine will be more successful for preventing S. aureus infections than a mono-subunit vaccine.Materials and MethodsWe selected three important virulence factors of S. aureus, clumping factor A (ClfA), iron-regulated surface determinant (IsdB), and gamma hemolysin (Hlg) that are potential candidates for vaccine development. We designed synthetic genes encoding the clfA, isdB, and hlg and used bioinformatics tools to predict structure of the synthetic construct and its stabilities. VaxiJen analysis of the protein showed a high antigenicity. Linear and conformational B-cell epitopes were identified.ResultsThe proteins encoded by these genes were useful as vaccine candidates against S. aureus infections.ConclusionIn silico tools are highly suited to study, design, and evaluate vaccine strategies.

The existence of infections caused by multidrug resistant (MDR) Acinetobacter baumannii is a growing problem because of the difficulty to treat them. We examined the published literature and focused our analysis on the investigation of the synergism of colistin and rifampin against MDR A. baumannii isolates via systematic review and meta-analysis. A systematic literature search was performed using the following 4 databases (PubMed, Scopus, EMBASE and ISI Web of Sciences). The related articles were evaluated during the period from December 2014 to January 2015. Information based on resistance and sensitivity to antibiotics, the minimum inhibitory concentration and the effects of two antibiotics on each other including synergism, antagonism, relative synergism and additive antagonism were extracted. A meta-analysis of 17 studies including 448 samples was brought into process and 2% (95% CI 0-4%) and 72% (95% CI 56-89%) resistance to colistin and rifampin were observed, respectively. 42% of all isolates showed MIC = 4 µg/ml (95% CI 14-69%) to rifampin and 30% MIC= 2 µg/ml to colistin (95% CI 3.8-78%). MIC50 and MIC90 for both rifampin and colistin were 2 µg/ml and 4 µg/ml, respectively. 63% of the strains demonstrated synergy (95% CI 37-90%), 7% were highlighted as relative synergism (95% CI 0.0- 13%), 3% showed an additive effect (95% CI -0.0-7%) and 14% were indifferent (95% CI 6-23%). The antagonistic effect was not observed in this combination. Synergy rates of time-kill assay in rifampin and colistin combinations were generally higher than those of check bored microdilution and E-test method. The results demonstrated that the combination therapy could be more useful when compared to monotherapy and that this strategy might reduce the resistance rate to rifampin in MDR A. baumannii isolates.