Abstract
Aim: To evaluate the antimicrobial activities of some aromatic essential oils against a new pathogenic Escherichia coli strain with extended-spectrum beta-lactamase (ESBL) activity.
Methodology: A total of 66 enteric bacteria were isolated from 250 urine samples that had been collected from human patients at different hospitals in Cairo, Egypt. Virulence factors of pathogenic isolates were determined, and the antibacterial activities of cinnamon bark oil and clove oil against E. coli EMH-542017 were estimated using the VITEK 2 system; this strain was confirmed as E. coli based on its 16S rRNA gene sequence, which was deposited in NCBI GenBank. Finally, modification of the bacterial cell wall following treatment with essential oil was observed with transmission electron microscopy (TEM).
Results: The results confirmed that E. coli EMH-542017 was capable of producing hydroxamate siderophores and was resistant to 11 antibiotics, which were significantly observed with different grades. Nevertheless, screening by the combination disc method showed that 20 isolates were ESBL producers. Polymerase chain reaction analysis confirmed that the selected isolate EMH-542017 was positive for both ESBL blaCTX-M-9 genes. The addition of cinnamon and clove oils at levels of 12.5, 25, and 50 mg ml(-1) was revealed to have high bactericidal effects on bacterial growth, and a change in bacterial cell morphology was detected by TEM, in which the cell wall seemed to be damaged and the flagella were lost following essential oil treatments, demonstrating that essential oil treatments are an effective means of suppressing multidrug-resistant E. coli.
Interpretation: Despite these results, there is an urgent need to identify effective, safe, and economical treatments to reduce and protect against urinary tract infections in Egyptian patients.