Abstract

Background: Urinary tract infection (UTI) is a significant public health concern due to the increasing multidrug resistance exhibited by both Gram-negative and Gram-positive bacterial pathogens. This challenge necessitates the search for effective alternative antimicrobial agents, including plant-based therapeutics such as Ocimum gratissimum.
Objectives: This study aimed to determine the antibacterial efficacy of Ocimum gratissimum extracts against bacterial isolates obtained from UTI patients attending the Federal University Teaching Hospital, Lafia. It also sought to characterize the bioactive compounds present in the extracts and to detect antibiotic-resistance genes in the isolated bacteria.
Methods: Gas Chromatography–Mass Spectrometry (GC-MS) was used to identify organic compounds present in ethanol, water and methanol extracts of Ocimum gratissimum. Bacterial isolates were identified using polymerase chain reaction (PCR). Antibacterial susceptibility testing was conducted using agar well diffusion, while minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the micro-broth dilution method.
Results: The bacteria isolated included Escherichia coli, Proteus mirabilis, and Klebsiella spp. GC-MS analysis showed that the most abundant compound in the ethanol extract was 3-methyl-4-isopropylphenol (59.451%), while the methanol extract contained 3-methyl-4-isopropylphenol as well (52.281%). PCR analysis revealed that Klebsiella, Proteus, and E. coli (E3) expressed the blaTEM gene; P. mirabilis and E. coli (E3) expressed blaCTX-M-4; while E. coli (E1 and E2) expressed blaSHV. Antibacterial testing showed that E. coli (E2) exhibited intermediate susceptibility to water and ethanol extracts at 250 mg/mL with zones of inhibition of 13.5 ± 0.6 mm and 13.0 ± 0.5 mm, respectively. Proteus mirabilis and Klebsiella spp. were resistant at all tested concentrations. MIC values ranged between 62.5–31.3 mg/mL.
Conclusion: Water and ethanol extracts of Ocimum gratissimum contain potent bioactive compounds and demonstrated antimicrobial activity against selected UTI pathogens, suggesting their potential as alternative therapeutic agents for managing urinary tract infections.

Key words: Antibacterial activity, urinary tract infections, Ocimum gratissimum, Escherichia coli, Proteus mirabilis, and Klebsiella