Infections caused by multidrug-resistant Klebsiella species that produce Extended-Spectrum β-lactamase (ESBL) enzymes have been reported with increasing frequency in intensive-care units and are associated with significant morbidity and mortality. Because of the high resistance to numerous antimicrobial agents, treatment can be problematic. Moreover formation of microbial biofilms has imposed a serious problem in treatment of microbial infections using conventional antibiotics. This has prompted researchers to identify alternatives such as plant products as antimicrobial agents. Researches on plant derived natural antimicrobials agents, has exclusively focused more on their effects against planktonic micro-organisms, however, the biofilm forms are more resistant to antimicrobial agents and therefore more difficult to control.
In this study we investigated the prevalence of (ESBLs) among Klebsiella isolates, the prevalence of biofilm formation among these isolates and the effect of five natural essential oils on inhibition of biofilm formation. Out of the 102 Klebsiella isolates, 52 isolates were (ESBL), and 44 isolates were strong and moderate biofilm producer. ESBL production was more common among strong and moderate biofilm producers; this probably is due to high rate of conjugation inside the biofilm, which facilitates transfer of drug resistant genes. Out of the five commercial essential oils investigated for their effect on inhibition of biofilm formation the Eucalyptus oil showed the maximum inhibition of biofilm formation followed by garlic oil, clove oil, ginger oil and black seed oil.