| Mohsen Mohammadi | 3 Articles |
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<b>Objectives</b>
<p>Genetic determinants conferring resistance to macrolide, lincosamide, and streptogramin B (MLS<sub>B</sub>) via ribosomal modification such as, <italic>erm</italic>, <italic>msrA/B</italic> and <italic>ereA/B</italic> genes are distributed in bacteria. The main goals of this work were to evaluate the dissemination of MLS<sub>B</sub> resistance phenotypes and genotypes in methicillin-resistant <italic>Staphylococcus aureus</italic> (MRSA) isolates collected from clinical samples.</p></sec>
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<b>Methods</b>
<p>A total of 106 MRSA isolates were studied. Isolates were recovered from 3 hospitals in Tehran between May 2016 to July 2017. The prevalence of MLS<sub>B</sub>-resistant strains were determined by D-test, and then M-PCR was performed to identify genes encoding resistance to macrolides, lincosamides, and streptogramins in the tested isolates.</p></sec>
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<b>Results</b>
<p>The frequency of constitutive resistance MLS<sub>B</sub>, inducible resistance MLS<sub>B</sub> and MS<sub>B</sub> resistance were 56.2%, 22.9%, and 16.6%, respectively. Of 11 isolates with the inducible resistance MLS<sub>B</sub> phenotype, <italic>ermC</italic>, <italic>ermB</italic>, <italic>ermA</italic> and <italic>ereA</italic> were positive in 81.8%, 63.6%, 54.5% and 18.2% of these isolates, respectively. In isolates with the constitutive resistance MLS<sub>B</sub> phenotype, the prevalence of <italic>ermA</italic>, <italic>ermB</italic>, <italic>ermC</italic>, <italic>msrA</italic>, <italic>msrB</italic>, <italic>ereA</italic> and <italic>ereB</italic> were 25.9%, 18.5%, 44.4%, 0.0%, 0.0%, 11.1% and 0.0%, respectively.</p></sec>
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<b>Conclusion</b>
<p>Clindamycin is commonly administered in severe MRSA infections depending upon the antimicrobial susceptibility findings. This study showed that the D-test should be used as an obligatory method in routine disk diffusion assay to detect inducible clindamycin resistance in MRSA so that effective antibiotic treatment can be provided.</p></sec>
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<sec><b>Objectives</b><p>Brucellosis is a major zoonotic disease that poses a significant public health threat worldwide. The classical bacteriological detection process used to identify <italic>Brucella</italic> spp. is difficult and time-consuming. This study aimed to develop a novel molecular assay for detecting brucellosis.</p></sec><sec><b>Methods</b><p>All complete sequences of chromosome 1 with 2.1-Mbp lengths were compared among all available <italic>Brucella</italic> sequences. A unique repeat sequence (URS) locus on chromosome 1 could differentiate <italic>Brucella abortus</italic> from <italic>Brucella melitensis</italic>. A primer set was designed to flank the unique locus. A total of 136 lymph nodes and blood samples were evaluated and classified by the URS-polymerase chain reaction (PCR) method in 2013–2014.</p></sec><sec><b>Results</b><p>Biochemical tests and bacteriophage typing as the golden standard indicated that all <italic>Brucella</italic> spp. isolates were <italic>B. melitensis</italic> biovar 1 and <italic>B. abortus</italic> biovar 3. The PCR results were the same as the bacteriological method for detecting <italic>Brucella</italic> spp. The sensitivity and specificity of the URS-PCR method make it suitable for detecting <italic>B. abortus</italic> and <italic>B. melitensis</italic>.</p></sec><sec><b>Conclusion</b><p>Quick detection of <italic>B. abortus</italic> and <italic>B. melitensis</italic> can provide the most effective strategies for control of these bacteria. The advantage of this method over other presented methods is that both <italic>B. abortus</italic> and <italic>B. melitensis</italic> are detectable in a single test tube. Furthermore, this method covered 100% of all <italic>B. melitensis</italic> and <italic>B. abortus</italic> biotypes. The development of this URS-PCR method is the first step toward the development of a novel kit for the molecular identification of <italic>B. abortus</italic> and <italic>B. melitensis</italic>.</p></sec>
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<b>Objectives</b><br/>
Gastrointestinal tract infection is still one of the serious public health problems in many geographic areas and is endemic in most countries including Iran. Early detection of the gastrointestinal tract pathogens can be extremely important. The aim of the current study was to apply a shortened time-multiplex polymerase chain reaction (PCR) for rapid and simultaneous detection of <i>Salmonella</i> spp., <i>Shigella</i> spp., and <i>Vibrio cholera</i>.<br/><b>Methods</b><br/>
The standard and clinical strains of <i>Salmonella</i> spp., <i>Shigella</i> spp., and <i>V. cholerae</i> were used in the assay. Multiplex PCR was performed and optimized based on amplification of <i>invA</i>, putative integrase, and <i>ompW</i> genes for detecting <i>Salmonella</i> spp., <i>Shigella</i> spp., and <i>V. cholerae</i>, respectively. The specificity of the assay was evaluated by testing 12 different bacterial species.<br/><b>Results</b><br/>
Only <i>Salmonella</i> spp., <i>Shigella</i> spp., and <i>V. cholerae</i> strains had positive results when subjected to the assay using multiplex PCR. The assay showed a high sensitivity, and no amplification products were observed in multiplex PCR with any of the other microorganisms.<br/><b>Conclusion</b><br/>
Our study indicated that the <i>invA</i>, putative integrase, and <i>ompW</i>-based multiplex PCR assay appears to be an efficient method for rapid and simultaneous detection of <i>Salmonella</i> spp., <i>Shigella</i> spp., and <i>V. cholerae.</i>
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