Antimicrobial activity of 1,3 dihydroxyj–2–methylimidazolium bis (Trifluoromethylsulfonyl) imde and selected antibiotics against streptococcus species isolated from groundwater in the Northwest Province, South Africa

Abstract

In developing countries, access to unsafe water and inadequate sanitation continue to be a danger to human health and untreated groundwater constitutes one of the main sources of drinking water supply. The consumption of untreated contaminated groundwater has frequently been identified as a potential source for the transfer and spread of both antibiotic resistant bacteria strains and waterborne infections among humans. Antibiotics are used for the treatment of bacterial infections and therefore the emergence of drug resistant bacterial strains has huge clinical implications. Faced with the rapid growth of bacterial resistance to a number of commonly used antibiotics, ionic liquids are attracting increasing attention as agents that could serve as antimicrobial agents. The aim of this study was to isolate, identify and determine the antimicrobial activity of an ionic liquid and selected antibiotics against Streptococcus species isolated from groundwater samples. A total of 22 samples were collected from borehole taps in some villages in the Northwest Province and analysed for the presence of streptococci. Gram-staining, catalase test, oxidase test and Prolex Streptococcal Grouping Latex assays were used for bacteria identification. The growth inhibitory effect of the ionic liquid 1,3 dihydroxy-2-methylimidazolium bis (trifluoromethylsulfonyl) imide and selected antibiotics was determined. One hundred and seventy six presumptive isolates were obtained and screened for characters of streptococci and 165 isolates were obtained. All the isolates were Gram positive cocci; a large proportion (92.7%) was oxidase negative and only 51.5% were catalase negative. Based on serotyping, 86.7% of the isolates were positively identified as streptococci. All the isolates from Motlhabeng, Stella and Taung were resistant to penicillin G. Moreover, large proportions (75.0% to 95.8%) of these isolates were resistant to vancomycin. All the isolates except a large proportion of those from Stella (88%) and Taung (83%) were found to be more susceptible (22.5% to 50%) to chloramphenicol. Generally, the growth inhibition zone diameter for 1,3 dihydroxy-2-methylimidazolium bis (trifluoromethylsulfonyl) imide against the isolates ranged from 6 to 9 mm and 9 to 22mm for 1% and 10% solutions respectively. In conclusion multi-drug resistant streptococci were isolated from groundwater intended for human consumption. Isolates were however susceptible to the IL tested and the antimicrobial effect increased with increase in concentration of the IL.