RESUMO
Objectives: To determine the antimicrobial activity of silver nano-particles(AgNPs) with tetracycline and ampicillin against multi-drug resistance (MDR) and extensively-drug resistance (XDR) Salmonella typhi. Methods: Cross sectional non-probability purposive study was conducted from September, 2021 to May, 2022 at Microbiology department PNS Shifa, Hospital Karachi. Blood cultures of patients suspicious of typhoid fever were collected and incubated in automated Bact/Alert system. Positive cultures were identified on blood and MacConkey and processed by API-10S, confirmed by serotyping (O9 antisera) (SSI Diagnostica's Salmonella). Antibiotic resistance was done by Kirby-Bauer disk diffusion (Sigma and Rich). MDR and XDR isolates were preserved in Brain Heart Infusion in a volume of 2ml in screw capped bottles at -70°C. Antimicrobial powders (ampicillin and tetracycline (Alfa Aesar) weighed by an electrical weighing balance (OHAUS) to take 1mg of antimicrobial drug. Absorbance spectra of serial concentrations of antibiotics (UV-Vis spectrophotometer (Mole-Qule-) AgNPs (10nm) (nanocomposix) + Antibiotic in (1:1 volume ratio). Conjugation of silver nanoparticles with tetracycline and ampicillin was done by FTIR (thermos scientificThermos ScientificNicolet 50). Results: Out of 77 isolates, 54 were resistant to ceftriaxone (XDR) and 23 sensitive to ceftriaxone (MDR). All isolates were susceptible to azithromycin and meropenem. Comparison of zone of inhibitions of ampicillin and Amp-AgNPsas and tetracycline with Tet-AgNPs was done. Minimal inhibitory concentration was also done to determine antimicrobial activity. Conclusion: Significant synergistic inhibitory effects against Salmonella Typhi isolates were obtained by combination of tetracycline with silver nano-particles even at low concentration.
RESUMO
OBJECTIVE: To determine blaCTX-M-15(Cefotaxime-Munich) gene amongst the extensively drug resistant (XDR) Salmonella typhi (S. typhi) isolates by quantitative Polymerase Chain Reaction (qPCR). STUDY DESIGN: Observational, cross-sectional study. Place and Duration of the Study: PNS Shifa Hospital and Bahria University of Health Sciences (BUHS), from January to June 2022. METHODOLOGY: All the patients clinically suspected of enteric fever, whose blood culture specimens yielded growth of S. typhi were included in this study. These samples were confirmed by serotyping and biochemical reactions. The ceftriaxone resistance was evaluated by antibiotic susceptibility test according to CLSI 2020 guidelines, whereas blaCTX-M-15 gene was detected by (PCR) using gene-specific primers. RESULTS: Out of 149 S. typhi isolates, 87.2% were confirmed XDR S. typhi resistant to ceftriaxone (CRO). Among these, 83.9% harboured blaCTX-M-15 gene. CONCLUSION: There was a very high frequency of XDR S. typhi harbouring blaCTX-M-15 in Karachi, Pakistan. KEY WORDS: blaCTX-M-15, Salmonella typhi, Third generation cephalosporin, Typhoid fever, Extensively drug resistant.