Bacteremia associated with central venous catheterization and their antibiogram among patients on hemodialysis therapy at Muhimbili National Hospital – Dar Es Salaam, Tanzania

Abstract

ABSTRACT Background: For patients on maintenance hemodialysis therapy, vascular-associated infections contribute significantly to frequent morbidity and related mortality. To date, there is paucity of data in Tanzania on the magnitude of bacteremia associated with central venous catheterization, isolation of underlying bacterial etiologic agents and determining their respective antimicrobial susceptibility pattern. Objective: To determine the prevalence of bacteremia associated with central venous catheterization, bacterial etiologic agents and antimicrobial susceptibility pattern among patients on hemodialysis at Muhimbili National Hospital – Dar es Salaam. Methodology: A cross-sectional descriptive hospital based study was conducted for a period of 6 months involving patients receiving hemodialysis therapy via central venous catheters at Muhimbili National Hospital. A structured questionnaire was used to collect socio-demographic data, clinical characteristics and laboratory parameters of the participants. Two sets of blood samples (8mls each) for aerobic culture were collected aseptically from a central venous catheter and peripheral venopuncture (opposite to the central line), inoculated in the blood culture bottle broth and incubated in automated blood culture machine (BD- BACTEC FX 40). Time difference to positivity was noted and bacteria identification and susceptibility testing were performed according to standard guidelines. Data was analyzed using SPSS version 23.0; continuous variables were summarized as means and standard deviation, categorical variables as frequencies and proportions. Multivariate analysis for teasing out independent risk factors was determined using logistic regression model. Results: Out of 109 patients, 39 patients (35.7%) had significant positive blood cultures. Staphylococcus albus was the commonest isolate (35.9%), followed by E.coli(25.6%), S.aureus(15.4%), P. aeruginosa(12.8%) and K. oxytoca(10.3%). Proportion of resistant isolates for Staphylococcus aureus and Staphylococcus albus to various tested antibiotics wereas follows; penicillin (66.7% & 78.6%), trimethoprim-sulfamethoxazole (100% & 85.7 %), gentamicin (0% & 28.6%), ciprofloxacin (14.3% & 16.7%), clindamycin (0% & 7%) and cefoxitin (0% & 0%) respectively. For Escherichia coli and Klebsiella oxytoca, respective resistant isolates patterns were to; amoxillin/clavulanic acid (100% & 100%), trimethoprim-sulfamethoxazole (100% & 100%), meropenem (0% & 0%), ceftriaxone (10% & 50%) and ceftazidime (20% & 25%) respectively. All pseudomonas isolates were resistant to aztreonam and amoxillin/clavulanic acid and 20% resistant to piperacillin and meropenem. No pseudomonas isolates were susceptible to piperacillin/tazobactam. Independent predictors for bacteremia associated with central venous catheterization were; catheter duration of 30 days or more [OR 10.2, 95% CI (2.6-40.6), p=0.001], catheterization at femoral site [OR 6.7(3.2-10.8), p=0.042] and both fever within the last 48 hrs; [OR 6.1(1.7-21.6), p=0.005] and fever within the last 1 month; [OR 9.6 (2.6-34.9), p=0.001]. Conclusion and recommendations: Bacteremia associated with central venous catheterization is common among patients undergoing hemodialysis at MNH and both gram negative and gram positive bacteria are responsible etiological agents. The isolated underlying bacteriologic agents show rampant resistance to commonly prescribed antibiotics including drug combinations which have proven potency to other types of infections. Further, temporary catheters that are in use 30 days after insertion, femoral venous catheterization and fever are independent predictors for bacteremia among these patients. We strongly recommend that due to multi-drug resistant isolates, blood cultures should be taken promptly from all patients suspected to have bacteremia associated with central venous catheterization. Further, we recommend that practitioners avoid femoral site catheterization, limit temporary catheter use for hemodialysis to less than 30 days since insertion and to aggressively investigate and treat fever in these patients