Study of MazEF, sam, and phd-doc putative toxin–antitoxin systems in Staphylococcus epidermidis

Today, to replace the antibacterial targets to overcome antibiotic resistance, toxin–antitoxin (TA) system is noticeable, where the unstable antitoxin neutralizes the stable toxin and protects the bacteria against the toxic effects. The presence and expression of TA genes in clinical and non-clinical strains of Staphylococcus epidermidis were investigated in this study. After identification of three TA pairs (mazEF, sam, and phd-doc) via existing databases (earlier, there has been no information in the case of S. epidermidis isolates), the presence and expression of these pairs were investigated by PCR and q-PCR, respectively. We detected three TA modules in all antibiotic sensitive and resistant isolates. In addition, q-PCR analysis revealed that the transcripts were produced from the three TA modules. This study showed the significant prevalence of these systems in pathogenic bacteria and they were equally found in both oxacillin-resistant and oxacillin-susceptible bacteria. The high prevalence of three systems can make them suitable as potential targets for antibiotic therapy

The frequency of Listeria monocytogenes strains recovered from clinical and non-clinical samples using phenotypic methods and confirmed by PCR

Background: Listeria monocytogenes is a facultative intracellular pathogen that causes listeriosis which has extensive clinical manifestations. Infections with L. monocytogenes are a serious threat to immunocompromised persons. The aim of this study was to determine the frequency of L. monocytogenes strains recovered from clinical and non-clinical samples using phenotypic methods and confirmed by PCR. Materials and Methods: In this study, 617 specimens were analyzed. All specimens were cultured in the specific PALCAM agar. Colonies were initially identified by routine biochemical tests. Finally, PCR assays using primers specific for inlA gene were performed. Results: In all, 46 (8.2%) L. monocytogenes isolates were recovered from 617 specimens. Fourteen (8.2%) strains, including 4 (7.5%), 2 (5.7%), 5 (14.2%) and 3 (8.5%) isolates were obtained from placental tissue, urine, vaginal and rectal swabs, respectively. In addition, 9 (7.4%) strains of L. monocytogenes which were isolated from 107 different dairy products originated from cheese 5 (7.1%), cream 2 (10%) and kashk 2 (11.7%), respectively. Among 11 (5.2%) strains isolated from 210 different meat products, 5 (5.5%), 4 (7.2%) and 2 (3%) strains belonged to sausage, meat and poultry extracts, respectively. Finally, 12 (9.2%) Listeria strains were recovered from 130 animal specimens that included 6 (10%), 4 (8%) and 2 (10%) strains from goat, sheep and cattle, respectively. Furthermore, all Listeria isolates (100%) were found to be carriers of  inlA gene in PCR assay. Conclusion: The present study showed that the clinical and non-clinical specimens were contaminated with L. monocytogenes. So, it seems necessary to use a simple and standard technique such as PCR for rapid detection of this organism from various sources

Prevalence, and virulence determination of Listeria monocytogenes strains isolated from clinical and non-clinical samples by multiplex polymerase chain reaction

Abstract INTRODUCTION: This study aimed to determine the prevalence, and virulence factors of Listeria monocytogenes isolated from various samples by multiplex polymerase chain reaction (MPCR). METHODS: A total of 617 isolates were obtained and MPCR was employed for detection of the inlA, inlC, and inlJ genes. RESULTS: L. monocytogenes was detected in 46 (7.45%) of the 617 specimens. inlA, inlC, and inlJ were detected in 100%, 76.26%, and 71% isolates, respectively. CONCLUSIONS: This study validated MPCR in the analysis and rapid detection of L. monocytogenes. The role of the genes in pathogenesis of the strains can also be affirmed