Assessment of Antibiotic Resistance Patterns of Bacterial Pathogens Isolated from Blood Culture Specimens at Livingstone University Teaching Hospital in Zambia

Abstract

Background. Bloodstream infections (BSI) are of public health concern because they are usually associated with high fatality rate if therapy is delayed. A combination of these infections with antibiotic resistance increases healthcare costs. In this study, microorganisms identified from blood cultures at Livingstone University Teaching Hospital (LUTH) between 2019 and 2021 were evaluated for their antibiotic resistance patterns. 

Methods: This was a single-centre laboratory based retrospective study. Data on isolated organisms from electronic laboratory system generated reports at LUTH microbiology laboratory for a period of 3 years, was analysed with SPSS version 20.

Results: A total of 765 specimens were processed and only 331 (43.3%) met the inclusion criteria. Of the 331 specimens, 61.3% and 38.7% were collected from female and male patients, respectively whereas 65.9% came from out-patient departments and 34.1% from in-patient departments. The commonest bacteria isolate was Escherichia coli (27.2%) followed by Enterobacter agglomerans (22.7%), Klebsiella pneumoniae (13%), Klebsiella oxytoca (6.3%), Enterobacter aerogenes (5.4%), Enterobacter cloacae (5.4%), Citrobacter freundii (4.8%), Serratia marcescens (3.6%), Proteus mirabilis (3.3%), and Staphylococcus aureus (2.7%). Of the common utilized antibiotics, ampicillin (92.9%) was the least effective drug followed by co-trimoxazole (82.7%), nalidixic acid (68.3%), penicillin (66.7%), tetracycline (63.5%), and chloramphenicol (50.3%), while imipenem (15.4%), norfloxacin (35.3%), and nitrofurantoin (38.8%) were the most effective. The patient's gender and hospital location may have an impact on antibiotic resistance.

Conclusion: The most common bacterial pathogens were Gram-negative Enterobacteriaceae that showed increased resistance to various classes of commonly used antibiotics at LUTH but with low resistance to imipenem. Due to the observed multidrug resistant pathogens for BSI, it is cardinal for healthcare facilities to monitor bacteria resistance patterns regularly and encourage the prudent use of antibiotics. However, antibiotic selection for susceptibility testing should be based on the Clinical and Laboratory Standards Institute (CLSI) and Zambia National Formulary (ZNF) recommendations to only test antibiotics1r for BSI instead of those recommended for other infections like urinary tract infections (e.g., tetracyclines).