Isolation and genetic characterization of metallo-p-lactamase and carbapenamase producing strains of Acinetobacter baumannii from patients at Tehran hospitals

Carbapenems are therapeutic choice against infections caused by gram-negative bacilli including strains of Acinetobacter baumannii. Resistance to these antibiotics is mediated by efflux pumps, porins, PBPs and B-lactamases. The aim of this study was to determine the possibility of existence of MBLs, OXAs and GES-1 betalactamase genes among clinical isolates of Acinetobacter collected from Tehran hospitals. Two hundred and three Acinetobacter isolates were collected from patient at Tehran hospitals. The isolates were identified using biochemical tests. The susceptibility to different antibiotics was evaluated by disk diffusion method and MICs of imipenem were determined using Micro broth dilution method [CLSI]. PCR was performed for detection of bla[VIM-2], bla[SPM-1], bla[IMP-2], bla[GES-2], bla[OXA-51, bla[OXA-23] betalactamase genes. Clonal relatedness was estimated by PFGE with the restriction enzyme Smal. Of 100 isolates of imipenem resistant Acinetobacter spp. collected from Tehran hospitals in 2009 and 2010,6 isolates produced metallo-beta-lactamases and 94 isolates produced OXA- type carbapenemase. The bla[spm-1], bla[GES-1], bla[OXA-51, bla[OXA-23] genes were detected by PCR among 6, 2, 94 and 84 isolates of A. baumannii, respectively. The MICs of isolates to imipenem were 8-128 microg/mL. PFGE analysis of 29 bla[OXA-51] and BLA[OXA-23]-positive A baumannii isolates gave 6 different patterns. This is the first report of SPM-1 and GES-1 beta-lactamase producing A. baumannii. Production of the OXA-23, OXA-51, GES-1 and SPM-1 enzyme presents an emerging threat of carbapenem resistance among A. baumannii in Iran

Antimicrobial resistance profile and presence of class I integrongs among Salmonella enterica serovars isolated from human clinical specimens in Tehran, Iran

Salmonella is one of the leading causes of food-borne diseases. Increasing occurrence of antimicrobial resistance, especially multidrug-resistance, in Salmonella serovars is a major public health problem worldwide. This study was carried out to detect class I integrons and antibiotic resistance profiles in clinical isolates of Salmonella serovars collected from seven hospitals in Tehran during November 2009 to June 2010. Antibiotic susceptibility profile of 19 antibiotics against 58 Salmonella isolates commonly used in humans was determined using disk diffusion assay. Minimum inhibitory concentration against ceftriaxone and ciprofloxacin was studied. PCR assays were used to detect class I integrons. Among 58 Salmonella isolates, 72.4% were Salmonella enterica serovar Enteritidis, 8.7% were Salmonella enteric serovar Typhimurium and 18.9% were other serovars. Of the total 58 Salmonella serovars, 43 [74.1%] were multidrug resistant and showed resistance to three or more antibiotic families. Class I integrons were identified in 38 [88.3%] MDR Salmonella isolates. Ciprofloxacin minimum inhibitory concentration ranged between 0.125-2 microg/ml for four isolates and other four isolates exhibited resistance to ceftriaxone [MIC 64-256 microg/ml]. The high prevalence of class I integrons was seen in our MDR Salmonella isolates and class I integrons might play an important role in the dissemination of antimicrobial resistance determinants

[Detection of blaTEM and blaSHV genes among clinical isolates of E. coli from Tehran hospitals]

The pathogenic strains of Escherichia coli cause severe septicemia, urinary tract infection and wound sepsis. Resistance of this organism to the expanded-spectrum cephalosporins occurs via the production of extended-spectrum beta-lactamases [ESBLs] such as TEM and SHV. These enzymes hydrolyze oxyiminocephalosporins [cefotaxime, ceftazidime] and monobactams [aztreonam]. This study was conducted to determine the drug susceptibility and prevalence of ESBL phenotypes of E. coli isolates at Tehran hospitals. Collectively, 200 isolates of E. coli were obtained from 5 hospitals in Tehran. The antibiotic susceptibility patterns of all clinical specimens were determined using disk diffusion method. Phenotypic confirmatory test was used to detect ESBL producing isolates. The MICs of ceftazidime and imipenem were determined using Microbroth dilution assay. Isolates with MIC >/= 2microg/ml were screened by PCR to detect blaTEM and blaSHV genes. Resistance to ceftazidime and cefotaxime were 30.1% and 32.1% respectively. All isolates were susceptible to imipenem. 52.5% of them [n=105] were positive in phenotypic confirmatory test. Resistance to ciprofloxacin among ESBL positive strains was 41%. The blaTEM and blaSHV genes were found among 24% [n=48] and 6% [n=12] of isolates respectively. Six isolates [3%] contained both genes. At Tehran hospitals, the rate of resistance to ceftazidime and prevalence of ESBL phenotype among the isolates of E. coli are high. It is necessary to seek a remedy for monitoring the ESBLs in these health settings. TEM is the dominant enzyme among the ESBL producing strains of E. coli in Iran

clinical efficacy of QAC [micro 10 and Deconex 53 Plus] on contaminated dental instruments

[Micro 10] and [Deconex 53 plus] are current samples of new QAC generation. Although these compounds have been widely evaluated, there are still some doubts about their disinfecting power. The purpose of this investigation was to evaluate the clinical efficiency of Micro 10 and Deconex 53 plus. In this single blinded study, the microorganisms' suspension was prepared according to AOAC guidelines [containing standard and resistant pseudomonas aeruginosa, staphylococcus aureous, salmonella typhi muriom, bacillus subtillis, mycobacterium bovis, trichophyton menta grophit]. The instruments [syringes] were contaminated using a sampler and the above mentioned suspension. After cleaning and disinfecting the instruments according to manufacture's instructions, samples were collected for cultivation and incubation. The colony formation units were observed and data was analyzed using fisher's exact, chi square and Mann Whitney tests in order to identify the group differences and significance levels. Micro 10 5% and Deconex 53 plus 2% had similar bactericidal effect on pseudomonas aeruginosa, staphylococcus aureous, salmonella typhimuriom and fungicidal effect on trichopyton menta grophit with no significant difference compared to autoclave. However, in comparison with Deconex 53 plus 2% and autoclave, the Micro 10 5% showed significant effect against bacillus subtilis and mycobacterium bovis [P < 0.001]. Deconex 53 plus can be classified as an intermediate level disinfectant