IN VITRO EVALUATION OF THE ANTIMICROBIAL EFFECT OF Nepeta cataria AND Basella alba AGAINST CLINICALLY RESISTANT Acinetobacter baumannii IN NAIROBI, KENYA A

Abstract

Acinetobacter baumannii once considered a low-category pathogen, has emerged as an obstinate infectious agent. It has displayed stubbornness to last resort antimicrobials, high prevalence of infections in the hospital setting and significantly increased rate of community-acquired infections over the past decade. To overcome this problem, knowledge of the antibiotic resistance mechanisms, and prospective treatment options of A. baumannii is important. The purpose of this study was to determine the potential antimicrobial activity of Nepeta cataria and Basella alba against Acinetobacter baumannii isolates. Nepeta cataria and Basella alba leaves were collected from Ol Donyo Sabuk National Park and Botanical garden JKUAT respectively. The leaves were dried under shade at room temperature for 30 days. Methanolic and aqueous plant extraction was done at PAUSTI Molecular Biology and Biotechnology Laboratory. Extracts were subjected to toxicity testing using brine shrimp and preliminary phytochemical screening. 30 anonymous stocked Acinetobacter baumannii isolates from different clinical sources were obtained from Aga Khan University Hospital in Nairobi. They were inoculated into appropriate media and identified according to standardized protocols. The antimicrobial activity of the plants extracts was determined by well diffusion method described by (CLSI, 2017). The antibiotic susceptibility testing was done for all bacterial isolates using the Kirby-Bauer disc diffusion technique. Molecular investigation involved the DNA extraction and the PCR amplification was performed using OXA-23, OXA-24 and NDM primers. From the phytochemical screening, the methanolic plant extracts revealed more phytochemicals as compared to aqueous extracts and most of them were detected from Nepeta cataria compared to Basella alba plant extracts. xv The methanolic plant extracts had MIC values 60 mg/ml when tested against Acinetobacter baumannii. The results recorded from this study demonstrated that methanolic extract of Nepeta cataria and Basella alba had greater antimicrobial effect against Acinetobacter baumannii than aqueous extracts. Nepeta cataria extracts showed greater antimicrobial effect than Basella alba extracts. The antibiotic susceptibility analyses of the 30 isolates revealed that 100% were resistant to cefotaxime followed by the resistance to ampicillin (93.3%), piperacillin (80%), amikacin (60%), ciprofloxacin (67%), gentamicin (50%), imipenem (56.6 %) and minocycline (37%). Molecular analysis revealed that all the 30 Acinetobacter baumannii isolates were 100 % positive for OXA-23, 17 % for NDM-1 and only 10% for the OXA-24. The detected antimicrobial activity of the two plants justify their potential use as an alternative treatment to Acinetobacter infections. Further studies on animal models are required to authenticate its use. Further tests on the potential activity of these plants on other microbes is important to curb the rising antimicrobial resistance.