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.

We describe two separate outbreaks of blaOXA-48- and blaNDM-1-carrying K. pneumoniae strains associated with dissemination of the ST11 and ST893 clones, with the ICU acting as the epicentre. The spread of plasmids carrying carbapenemase genes resulting in fulminant antimicrobial resistance is a severe concern.

New Delhi metallo-beta-lactamase (NDM-1) is a novel metallo-beta-lactamase (MBL). Sporadic cases of NDM-1 positive strains have been reported from different countries, suggesting a widespread dissemination. The aim of this study was the detection of MBLs in Enterobacteriaceae isolated from patients in Tehran hospitals. After identification tests, the susceptibility to the antibiotics was done by Kirby-Bauer method and broth microdilution. Carbapenem-resistant isolates were tested for carbapenemase production using the modified Hodge test (MHT). Carbapenem-resistant strains screened for bla(KPC) gene and genes encoding MBLs. Twenty-three isolates (6.3%) were resistant to meropenem, eleven isolates (3%) were resistant to ertapenem, and four isolates (1.1%) were resistant to imipenem. MHT was positive in 11 (47.8%) of the carbapenem-resistant isolates. In March 2011, we detected a multiple drug-resistant Klebsiella pneumoniae isolate that was resistant to all tested antibiotics except colistin. PCR confirmed that this isolate contained bla(NDM-1), bla(TEM), bla(SHV), and bla(CTX-M). This is the first report on the detection of MBL NDM-1 in Iran. The rapid spread of NDM-1-positive bacteria proved to be a major challenge for the treatment and control of infectious diseases.

Gastrointestinal colonization of carbapenem-resistant Enterobacteriaceae (CRE) could serve as a reservoir for the transmission of these pathogens in the clinical setting. The aim of this study was to investigate the intestinal carriage of CRE and to analyze risk factors for CRE carriage. Rectal swabs were collected from 95 patients at two Iranian university hospitals. CRE screening was performed using selective media (CHROMagar and MacConkey agar). Polymerase chain reaction (PCR) was used to detect carbapenemase-encoding genes. Clonal relatedness was investigated by pulsed-field gel electrophoresis (PFGE). The rate of carriage of CRE in hospitalized patients was 37.9%. Overall, 54 CRE isolates were identified, of which 47 were carbapenemase-producers. All of the 54 CRE were detected using CHROMagar compared with 52 CRE detected using MacConkey agar. Fifteen patients were colonized by multiple CRE isolates. Three significant risk factors for CRE carriage were detected: intensive care unit (ICU) hospitalization, antibiotic exposure, and mechanical ventilation. bla was the most frequent carbapenemase detected, followed by bla and bla . Eleven carbapenemase-producing Enterobacteriaceae (CPE) isolates co-harbored bla and bla . Also, six CPE isolates co-harbored bla and bla . We did not detect bla, bla , bla, or bla . PFGE analysis showed that Escherichia coli clones were diverse, while Klebsiella pneumoniae isolates were divided into four clusters. Cluster I was the major clone carrying bla and bla genes. In our study, the carriage rate of CRE was high and the emergence of CPE isolates among patients is alarming. The implementation of adequate preventive measures such as active surveillance is urgently needed to control the spread of CPE in the healthcare setting.

This study shows that rhamnolipid mixtures of MR01 and MASH1 have antimicrobial efficacy against Gram positive bacteria and may be evaluated as antimicrobial agent against multidrugresistant clinical pathogenic isolates. Background:In recent decades, biological properties of biosurfactants, particularly glycolipids, including antimicrobial, antifungal, and anti-cellular effects have been projected in many research studies. The unique advantages of these compounds in terms of production and environment made them important as antimicrobial agents. Objectives: This study aims to evaluate probable antibacterial and antifungal properties of MR01 and MASH1 biosurfactants against several specified microorganisms. Materials and Methods:In this article antibacterial activities of two rhamnolipid mixtures of MR01 and MASH1 were studied. MR01 and MASH1 are glycolipid-type biosurfactants that are being produced by two strains of Pseudomonas aeruginosa MR01 and MASH1, respectively. Antibacterial effects of two biosurfactants were assessed by disc diffusion test method and determination of minimum inhibitory concentration (MIC). Results: They exhibit not only excellent surface activity but also remarkable inhibitory effect against Gram-positive bacteria. According to results, although none of two biosurfactants showed significant effects on Gram negative bacteria growth inhibition, both assessing methods confirmed the growth inhibition of Gram-positive bacteria by MR01 and MASH1 biosurfactants. Conclusions: According to results of this study, MR01 and MASH1 biosurfactants had antimicrobial efficacy against Gram positive bacterial groups. This effect is comparable to antibiotics and therefore the future use of these biosurfactants as broad spectrum antibiotics is highly promising. These features of biosurfactants (BS) should broaden its applications in new advanced technologies. Future studies will be performed on characterization and isolation of biologically active fraction of the rhamnolipid biosurfactant produced by P. aeruginosa strains. This bioactive compound may be evaluated as a potent antimicrobial agent to be applied against a panel of pathogenic micro-organisms including a few multidrug-resistant (MDR) clinical pathogenic isolates such as methicillin-resistant Staphylococcus aureus (MRSA) and other MDR pathogenic strains.

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BackgroundTo investigate antibiotic resistance, the occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran.The isolates were examined for susceptibility to antimicrobial agents. The mecA gene, class 1 and 2 integrons were detected by PCR. Integrase positive strains were further analysed for the presence of resistance gene cassettes using specific primers and were sequenced.ResultsAmong 139 S.aureus isolates, 109 (78.4 %) and 112 (80.5 %) strains were considered as multidrug resistant and mecA positive, respectively. Class 1 integrons and internal variable regions were found in 72.6 % (101/139) and 97 % (98/101) and class 2 integrons and variable regions also in 35.2 % (49/139) and 65.3 % (32/49) of S.aureus clinical isolates, respectively. Twelve distinct cassette arrays were found, containing genes encoding resistance to β-lactams, aminoglycosides, streptothricin, trimethoprim, chloramphenicol,a putative glucose dehydrogenase precursor and a protein with unknown function. Gene cassette arrays aadB, aadA2 and dhfrA1-sat2-aadA1 were common in S.aureus isolates. We detected a completely new gene cassettes which contained aadB, oxa2, aacA4, orfD-aacA4-catB8, aadB-catB3, orfD-aacA4 and aadB-aadA1-cmlA6 of class 1 and dhfrA1-sat2-aadA1, dhfrA11, dhfrA1-sat2 of class 2 integrons.ConclusionsThis is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes among in S.aureus isolates from Iran.