Antibiotic susceptibility patterns of pathogens isolated from laboratory specimens at Livingstone Central Hospital in Zambia

Abstract

BackgroundAntibiotics are essential commodities in managing bacterial infections in humans, animals and plants but are hampered by the development of antibiotic resistance which is one of the most serious public health threats of the twenty-first century. Moreover, the rate at which novel antibiotics are discovered is slower that the rate of emerging antibiotic resistance. Therefore, the few remaining potent antibiotics in clinical setting should be safeguarded by closer monitoring of their effectiveness via periodic antibiogram studies. This study aimed to evaluate the antibiotic susceptibility patterns of routinely isolated bacteria at Livingstone Central Hospital (LCH).MethodsA cohort retrospective study with secondary information collected from electronic laboratory system generated reports on all isolated organisms at LCH microbiology laboratory for three years (January 2019 to December 2021) was used. Study variables such as age, gender, patient’s location, name of the organism and the antibiotic susceptibility were considered. Descriptive statistics was used to describe our data and a chi-square test was used for categorical variables where a p-value of ≤0.05 was considered as statistically significant.ResultsA total of 765 specimens were processed from January 2019 to December 2021 and only 500 (65.4%) met the inclusion criteria for this study. Of the 500, 291(58.2%) specimens were received from female and from the age-group 17-39 years (253, 50.6%) and 40-80 years (145, 29%) in form of blood (331, 66.2%), urine (165, 33%) and sputum (4, 0.8%). The out-patient department (323, 64.6%) had a higher number of specimen culture requests that reduced from 175 (35%) for the year 2019 and 2020 to 150 (30%) for year 2021. Amongst the common bacterial isolates identified, Staphylococcus aureus (142, 28.4%) was the commonest isolate followed by Escherichia coli (91, 18.2%), Enterobacter agglomerans (76, 15.2%), and Klebsiella pneumoniae (43, 8.6%). The resistance pattern indicated that ampicillin (93%) was the least effective drug followed by oxacillin (88%), penicillin (85.6%), co-trimoxazole (81.5%), erythromycin (71.9%), nalidixic acid (68%), ceftazidime (60%), tetracycline (55.1%), and ciprofloxacin (45.9%) whereas the most effective antibiotics were imipenem (14.5%), piperacillin/tazobactam (16.7%) and clindamycin (34.5%). The resistance levels were affected by patient gender, location, and specimen type.However, the screening of methicillin resistant Staphylococcus aureus (MRSA) with cefoxitin showed 76.3% (29/38) susceptibility and 23.7% (9/38) resistance.ConclusionThe commonest bacterial isolates were Staphylococcus aureus, Escherichia coli, Enterobacter agglomerans, Klebsiella pneumoniae and Klebsiella oxytoca. The least effective antibiotics were ampicillin, penicillin, oxacillin, cotrimoxazole, and erythromycin whereas the most effective antibiotics were imipenem, piperacillin/tazobactam, and clindamycin. Therefore, re-establishing of the empiric therapy is needed for proper patient management, studies to determine the levels of extended spectrum beta lactamase- and carbapenemase-producing bacteria are warranted.