Clinico-microbiological study of Citrobacter isolates from various clinical specimens and detection of β-lactamase production.

Citrobacter species have been reported to cause a wide spectrum of infections in humans and invasive infections are associated with a high mortality rate, with 33 to 48% of patients succumbing to Citrobacter bacteraemia. The high mortality rate associated with Citrobacter infections may be due in part to ineffective empirical antibiotic therapy. Citrobacter has been found to produce SHV and TEM derived Extended spectrum beta lactamases in addition to chromosomal inducible AmpC beta - lactamases which could be contributing to increasing drug resistance. The aims of the study were to detect the prevalence of Citrobacter infections with its associated risk factors, antibiotic susceptibility patterns and determination of beta-lactamase activity- both extended spectrum beta - lactamase and AmpC beta-lactamase activity among Citrobacter isolates. The isolates were identified by standard microbiological procedures. ESBL detection was by double disc diffusion method and AmpC beta-lactamase detection was done using Cefotaxime and Cefoxitin discs. C. braakii (33.3%) was the commonest genomospecies identified followed by C. freundii (21.3%) and C. amalonaticus (16.66 %) among 150 Citrobacter isolates. Diabetes mellitus was the major risk factor. Imipenem (100%)was most effective whereas 98% showed resistance to Ampicillin; carbapenems and fourth generation Cefipime showed better sensitivity than third generation cephalosporins. The study highlights the need for informed antibiotic treatment guided by routine antimicrobial susceptibility and knowledge of the ESBL status of the isolate, the outcome of which undoubtedly will be better patient care.

Clinico-microbiological study of infections in the intensive care unit and study of antimicrobial resistance in bacterial isolates.

Infectious disease specialists have long recognized that the risk of ICU patients acquiring nosocomial infections is 5-10 times greater than those in general wards. Several factors such as severe underlying disease, multiple illnesses, malnutrition, extremes of age, immunosuppression, use of invasive medical devices, ICU crowding and animate reservoirs increase the risk of acquiring infections in the ICU. Out of 113 isolates obtained in our study, 32.7% were from ventilator-associated pneumonia patients and 17.7% from urinary tract infection patients. The major isolates were Staphylococcus aureus (21.2%) and Klebsiella spp. (20.4%). Methicillin resistant Staphylococcus aureus (MRSA) and ESBL producing Klebsiella and E. coli were the major drug resistant bacteria isolated and associated with significant mortality. Control of these infections poses a major problem in treating the patients because of the rising trend of drug resistance among these bacteria.