Virulence genes and antimicrobial resistance pattern in Proteus mirabilis strains isolated from patients attended with urinary infections to Tertiary Hospitals, in Iran

Background: Proteus mirabilis is a frequent reason for catheter-associated urinary tract infections (UTIs). The aim of this study was to identify virulence genes and antimicrobial resistance patterns in P. mirabilis strains isolated from patients whoattended a tertiary hospital in Iran. Methods: In this study, 100 P. mirabilis strains from urine samples were isolated. These isolated strains were identified by biochemical and PCR-based tests, and their antibiotic resistance was profiled through a standard procedure using 14 antibiotics.PCR assays were used to detect virulence-related genes in P. mirabilis strains. The biofilm formation of each P. mirabilis strain was examined. Results: Of the 100 P. mirabilis isolates, 16 (16%) were multidrug-resistant. High resistance was observed against cotrimoxazole (97%), nalidixic acid (93%), cefotaxime (77%), and amoxicillin (62%). Sixty of the 100 isolates showed resistance against extended-spectrum cephalosporins. The prevalence rates of the genes related to the virulence factors in this study were mrpH (100%), ucaA (91%), hpmA (94%), zapA (95%), ptaA (100%), ureG (100%), pmfA (100%), fliC (97%), and mrpA (90%) using PCR method. Strong biofilm formation was observed in 20% (5/25) of the strains isolated fromnon-catheterized samples and 80% (20/25) of strains isolated from catheterized samples. Conclusions: Resistance to antibiotics and the prevalence of pathogenicity genes are high in Proteus mirabilis strains iolated from UTIs. Keywords: Antibiotic resistance; Proteus mirabilis; biofilm; virulence factors

Detection of tstH Gene in Staphylococcus aureus Isolates from Hospitalized Burnt Children

Background:    The main cause of toxic shock is TSST-1 toxin which is produced by S. aureus.  Finding of TSST-1 toxin in burnt children is very important to prevent TSS and its consequences.  Methods:     The aim of this study was to investigate the presence of gene encoding TSST-1 toxin in wound specimens by PCR. In this case-control study, 90 children who were admitted to the burn unit, were divided in two groups of 45 patients, namely febrile (cases group) and non-febrile (control group). Samplings were done from the burn wounds and were tested by PCR with specific primers of tstH gene. Finally, all data including demographic characteristics, percentage of burnt surface severity and the PCR results were analyzed, statistically. Results:    The positive PCR results indicated the expression of tstH gene in 37.7% of the febrile children and 11.1% of the non-febrile children with a statistically significant difference (p <0.003). The means and the standard deviations for the percentage of burnt surfaces (i.e. severity) in the samples with the positive and negative PCR results were 30.9±16.93 and 20.09±11.02, respectively with a statistically significant difference (p <0.01). No difference with respect to age and sex could be detected between positive and negative PCR results. Conclusion:    A direct association between the expression of tstH and the occurrence of fever in the burnt children was observed. Furthermore, increased surface area of the wounds was also positively related to the expression of tstH

Molecular Detection of gyrA, parC and oprD Mutation in Pseudomonas aeruginosa Isolates from a University Hospital of Isfahan, Iran during 2016

Background:   Excessive use of broad-spectrum antibiotics in hospitals has led to the emergence of highly resistant strains of Pseudomonas aeruginosa. The main mechanism of resistance of this bacterium to fluoroquinolones and carbapenems are the modification of type II topoisomerases (DNA gyrase and topoisomerase IV) and alterations in the OprD porin, respectively. The aim of this study was to examine for the occurrence of mutations related to fluoroquinolone resistance of gyrA and parC genes and mutational inactivation of oprD gene of clinical isolates using DNA sequencing technique. Methods:  A total of 60 P. aeruginosa isolates were collected from the hospitalized patients in the Intensive Care Units (ICUs) of Al-Zahra hospital located in Isfahan, Iran. The pattern of sensitivity to antibiotics was determined using CLSI disk diffusion and MIC methods. The assay was based on a DNA sequencing method using polymerase chain reaction (PCR) for amplification and sequencing of the selected genes. Results:   The results show that replacement of Ile for Thr-83 in gyrA was the only replacement, while other substitutions not observed. No mutations were found in parC. The most frequent amino acid alterations were E185Q, P186G, and V189T, found in five resistance isolates, However, nucleotide insertions and deletions mutations not observed. Conclusion:  Our study suggested that mutation of gyrA and oprD genes may play a minor role in fluoroquinolone and carbapenem resistance and other mechanisms may contribute to the fluoroquinolone and carbapenem resistance of P. aeruginosa

Comparative Phylogeny of the Genus Bordetella Using Sequence Analysis of 16S rRNA and ompA Genes

Background:   The genus Bordetella harbors 16 species; three of them are well-known for their high medical importance. The phylogenetic diversity of the genus is currently not very well investigated. Methods:    In this study, 16S rRNA gene sequence of 16 type strains of the Bordetella species were analyzed. Also, phylogenies conducted on the same gene of 247 isolates of Bordetella species, comprising a wide physiological as well as ecological diversity and encompassing ex-type representatives of the 16 Bordetella species, were analyzed.   Results:   It was found that the phylogenetic diversity of the genus may be very different from that is currently assumed. Interestingly, the 16S rRNA gene signals could not resolve some species with promising bootstrap and posterior probability values as our phylogenies, using maximum likelihood and Bayesian inference methods, showed. Conclusion:   Our results indicate a probable need for additional phylogenetic signals which can be provided by coding genes. Therefore, sequence data of ompA gene of Bordetella species, a critically significant genomic region in pathogenesis, was here analyzed, phylogenetically. This gene confirmed the tree topology and the phylogenetic species boundaries already revealed by the 16S rRNA gene, but showed a better discriminatory power which resolved Bordetella species with higher statistically significant values