Trends in the Antibiotic Resistance Patterns of Enteric Fever Isolates – a Three Year Report from a Tertiary Care Centre

Objectives: The incidence of multidrug resistant enteric fever is increasing alarmingly. This study was planned to determine the rate of isolation of Salmonella spp. and to compare the isolates for their epidemiological parameters and antimicrobial susceptibility patterns at our center. Methods: The study was conducted over a span of three years with a total of 8142, 8134, and 8114 blood culture samples processed for the years 2008, 2009, and 2010 respectively. The minimum inhibitory concentration (MIC) for ciprofloxacin and chloramphenicol was determined using an agar dilution method. The MIC for ciprofloxacin was also confirmed by Epsilon-test (E -test) strips. Results: Of the total 302 Salmonella spp. isolated, 257 were Salmonella enterica serotype Typhi (85.1%) and 45 (14.9%) were S. enterica serotype Paratyphi A. The majority of the isolates recovered were from the pediatric age group (54.6%) and males (60.6%). Complete susceptibility was observed to chloramphenicol, cefotaxime, ceftriaxone, and azithromycin over the last two years (2009 and 2010), with an increase in resistance to nalidixic acid (100%) and ciprofloxacin (13.6%). Conclusions: In our study, we found augmentation of resistance to nalidixic acid and fluoroquinolones and complete sensitivity to ceftriaxone along with reemergence of chloramphenicol sensitivity for Salmonella isolates. This report emphasises the necessity of continuous surveillance of antibiograms of enteric fever isolates in an area.

Outbreak of Salmonella Typhi enteric fever in sub-urban area of North India: a public health perspective

Outbreaks of enteric fever are a major health concern not only due to significant human morbidity and mortality but also fear of spread of multidrug resistant strains. We report an outbreak of enteric fever caused by Salmonella enterica serotype Typhi in a suburban area, in city Chandigarh of North India. Twenty-seven strains of S. typhi were isolated from blood cultures over a period of two weeks with 18 of these 27 patients residing in the same area. Maximum cases were in the age group 5-14 years (10 patients, 55.5%) while 4 (22.2%) cases were children under 5 years. All the strains showed similar resistogram being resistant to ampicillin and nalidixic acid, intermediate to ciprofloxacin and sensitive to chloramphenicol, ceftriaxone, cefotaxime, cotrimoxazole and azithromycin on disc diffusion testing. Minimum inhibitory concentration of ciprofloxacin was determined by agar dilution method and was found to be raised (≥ 2 μ g/mL). This nalidixic acid resistant S. typhi outbreak report warrants the necessity of implementing stringent sanitation practices in public health interest.

Inducible clindamycin resistance in Staphylococcus aureus: a study from a tertiary care hospital of north India

Clindamycin is a preferred therapeutic option in erythromycin resistant Staphylococcus aureus skin and soft tissue infections. However, a major concern regarding its use for staphylococcal infections is the possible presence of inducible resistance to clindamycin. The present study was aimed to determine the incidence of constitutive and inducible clindamycin resistance in S.aureus isolates in our hospital. Retrospective study. Pt. BDS University of health Sciences, Rohtak, Haryana, India. A total of 250 consecutive, non-duplicate S. aureus strains were isolated from various clinical specimens, both from inpatients and outpatients. Antibiotic susceptibility tests were performed using Kirby-Bauer disc diffusion method. Methicillin resistance was detected by oxacillin disc on Mueller-Hinton Agar [MHA] plate supplemented with 2% NaCl. D-test was performed on all erythromycin-resistant and clindamycin-sensitive isolates to detect inducible clindamycin resistance. Observed and counted were methicillin resistance in S.aureus, constitutive and inducible resistance of the isolates to clindamycin, origin of the MLSBi isolates that is "community" or "hospital" and resistance of MLSBi isolates to other drugs. Among 250 S.aureus strains, 112 [44.8%] were found to be Methicillin-resistant Staphylococcus aureus [MRSA] and 20% had MLSBi phenotype. MRSA isolates showed higher inducible as well as constitutive resistance [p <0.0001] to clindamycin as compared to methicillin-sensitive S.aureus [MSSA]. All S.aureus isolates having MLSBi phenotype were sensitive to vancomycin and linezolid. The study strongly recommends the routine testing of in vitro inducible clindamycin resistance in S.aureus isolates as it will help in guiding therapy