ABSTRACT
Background: staphylococcus aureus can cause nosocomial and community acquired infections and deaths worldwide. S. aureus produces many virulence factors including toxin production and difSerer7t resistance mechanisms. Consequently, staphylococcal strains are important candidates for molecular epidemiology and monitoring pathogenesis and antibiotic resistance patterns
Aim: Design simple and rapid method for screening of S. aureus isolates carrying toxic and resistance genes which is an important step in controlling the dissemination of this potentially virulent pathogen
Method: in this study multiplex PCR assay was evaluated on 61 different clinical S. aureus isolates and the PCR results was correlated with the phenotypic antibiotic resistance data obtained by the broth microdilution assay. Also toxic genes detection by PCR was correlated well with phenotypic toxin test obtained by reversed passive latex agglutination test. We described a multiplex PCR assay for the defection of genes, for toxic shock syndrome toxin [tst], exfoliative toxins A and B [eta and etb], genes encoding methicillin resistance [mecA], and macrolide-lincosamide-streptogramin B resistance genes [ermA and ermC]. Detection of femA gene was also used as an internal positive control
Result: in comparison with antibiotic susceptibility test, the multiplex PCR had high sensitivity and specificity. A total of 39 oxacillin resistant strains were found carried a ermA gene. The ermA gene was present in 19 isolates [31.2%]; while ermC gene was detected in eleven isolates [18%] of the studied S. aureus. Seven isolate [11.5%] carried both ermA and ermC. A total of 37 strains were resistant to erythromycin and / or clindamycin. For these isolates, we found a perfect correlation between the results of the multiplex PCR and those of classical phenotypic resistance and toxin detection testing
Conclusion: concerning its high sensitivity and specificity, the multiplex PCR assay offers a rapid, simple, inexpensive and accurate identification of antibiotic resistance profiles together with the identification of medically important staphylococcal toxigenic strains and could be used in clinical diagnosis as well as in epidemiological studies
ABSTRACT
Difference in the composition of microbiota in different periodontal diseases has been observed. There are several microbial methods used to identify the periodontopathic bacteria which harbor the periodontally affected sites. The present study compared molecular detection of bacterial periodontitis to conventional microbiological method as well as identifying prominent isolated species. This study also describes clinical parameters as well as evaluating the effect of non-surgical treatment modalities [SRP] among different periodontal diseases on total viable bacterial count. Clinical parameters include: probing depth [PD], clinical attachment level [CAL], bleeding on probing percent [BOP%] at baseline and three months after. Gingival crevicular fluid samples from 45 patients were collected and analyzed at day 0, 1, 30 and 90 days after SRP' treatment. The microbiologic assessment was done using universal primers for PCR detection of bacterial periodontal infection. The ability to detect bacterial infection from 45 gingival crevicular fluid samples by PCR using universal primers encoding for the 16 S rDNA was compared with bacterial culture. Bacteria were detected by PCR with 100% specificity and 77.5% sensitivity compared to culture. Detection of 16 S rDNA proved to be effective in preventing PCR inhibition and was applied to detect the occurrence of non-cultural bacteria in the tested samples. The occurrence of bacteria was decreased by non-surgical mechanical debridement [SRP] which was evaluated by total viable count technique. Frequently isolated bacteria species were identified as Porpheromonas gingivitis, Fusobacterium nucleatum, Tenner Ella forsythia, Aggregibacter actinomyctemecommitans and Prevotella intermedia. The results indicated that using universal bacterial primers is a rapid and simple method for detection of bacterial periodontitis. A favorable clinical response to these therapeutic measures can be obtained. Moreover, the bacterial count is affected significantly by non- surgical treatment modality