Distribution of staphylococcal cassette chromosome mec types among methicillin-resistant coagulase negative staphylococci in central Iran

Background and Objectives: Methicillin-resistant coagulase-negative staphylococci (MR-CoNS) are important nosocomial pathogens. They may serve as a reservoir of SCCmec, the genomic island encoding amongst other methicillin resistance. This study was designed to determine the distribution of different SCCmec types from MR-CoNS isolated from clinical specimens in a tertiary hospital in central Iran, having high frequency of nosocomial methicillin-resistant staphylococcal infections. Materials and Methods: We evaluated isolates from patients attending the Vali-Asr Hospital located in the center of Iran, from February to December 2012. Multiplex PCR was performed for SCCmec typing. For isolates in which SCCmec could not be typed directly, additional ccr and mec complex analyses were performed. Results: Totally, 70 MR-CoNS isolates, comprising of 47 S. epidermidis strains (67%), 10 S. saprophyticus (14.3%), 9 S. hemolyticus (13%) and 4 S. lugdunensis (5.7%) were identified. Thirty-nine were characterized as type IVa 19 (27%), type III 11 (16%), type II 7 (10%) and type V 2 (3%). Only 20 isolates (28.6%) carried the ccr complex, while the current methods could not characterize the 11 remaining isolates. Conclusion: A high level of SCCmec genetic diversity was found among MR-CoNS isolates. MR-CoNS may act as a reservoir of SCCmec IV for MRSA. This issue should be taken into consideration seriously

Characterization of Plasmid-Mediated AmpC and Carbapenemases among Iranain Nosocomial Isolates of Klebsiella pneumoniae Using Phenotyping and Genotyping Methods

Objectives: Plasmid-mediated AmpC β-lactamases (PMABLs) and carbapenemases are emerging groups of antimicrobial-resistance determinants. The aims of the study were to evaluate the occurrence of PMABLs and carbapenemases in clinical isolates of Klebsiella pneumoniae and compare the test performance of various phenotypic methods for detection of these enzymes in Iran. Methods: A total of 100 K. pneumoniae isolates were collected from clinical specimens obtained in Valiasr Hospital. AmpC production in all isolates was determined using the AmpC disk test, the cephamycin Hodge test, the AmpC Etest, and the boronic acid combined-disk test. In addition, carbapenemase production was determined using the modified Hodge test, the EDTA disk synergy test, and the boronic acid combined-disk test. The performances of various phenotypic methods were evaluated by the comparison of their results with polymerase chain reaction (PCR) method as the gold standard. Results: Of the 100 isolates, 19 (19%) were demonstrated to harbor the

Variability in gene cassette patterns of class 1 and 2 integrons associated with multi drug resistance patterns in Staphylococcus aureus clinical isolates in Tehran-Iran

Background: To 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. Results: Among 139S.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. Conclusions: This is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes among in S.aureus isolates from Iran. © 2015 Mostafa et al

Nosocomial Outbreak of Extensively and Pan Drug-Resistant Acinetobacter baumannii in Tertiary Hospital in Central Part of Iran

Background: Acinetobacter baumannii has emerged as a cause of nosocomial infections in hospitalized patients, particularly in intensive care units. Carbapenems are a common choice for treating nosocomial infections caused by A. baumannii strains. Increasing antimicrobial resistance among Acinetobacter isolates has been documented and multidrug-resistant A. baumannii is recognized to be among the most difficult antimicrobial-resistant bacilli to control and treat. Objectives: This study describes carbapenem resistance in A. baumannii isolates obtained during an outbreak from intensive care units of a peripheral hospital in central part of Iran. Patients and Methods: Sixty-three non-repetitive A. baumannii isolates were collected over a six months period. Susceptibility of the isolated bacteria to a panel of 23 different antimicrobial agents was defined by using the standard disk diffusion method. Production of Metallo-beta-lactamases (MBL) and AmpC beta-lactamase were determined by using the E-test MBL strip and AmpC disk tests, respectively. Results: The present study indicates that carbapenems and new cephalosporin antibiotics were practically ineffective against the extensive drug resistance (XDR) strains. Colistin was observed to be more effective, although in seven cases resistance to colistin observed. AmpC beta-lactamase and MBL could be an important contributory factor for imipenem resistance among the isolates in our hospital. The elevated prevalence of XDR and pan drug resistance (PDR) strains indicates that local antibioti Conclusions: The elevated prevalence of XDR and PDR strains indicates that local antibiotic prescription policies should be revised and infection control should be improved