Occurrence of antibiotic-resistant enterococci in some insects from stored food products in Botswana

Abstract

The occurrence of antibiotic-resistant enterococci in some insects from stored food products from fourteen geographical areas in Botswana was investigated in the present study. Eleven insect species were identified from a total of 737 stored food products. Oryzaephilus surinamensis was the most predominant. It comprised 65% and 51.1% of the species in food products from households and the selected warehouse respectively; followed by Tribolium castaneum, which comprised 17.1% of the species in stored foods from households and 32.3% of the species in stored food products from the warehouse. There was no significant difference (p<0.05) in the distribution of the insect species from the geographical areas sampled. Sixty-eight per cent (68%) of the total insect numbers harboured Enterococcus species. Enterococcus species were isolated from Prostephanus truncates and Cryptolestes ferrugeneus, obtained from laboratory stored maize cultures. The isolation rate of enterococci was significantly higher (p<0.05) in laboratory stored product insects as compared with insects collected from stored foods sampled from the selected geographical areas. Enterococci showed total resistance to erythromycin, fusidic acid, oxacillin, novobiocin, and penicillin G but were all sensitive to chloramphenicol. This shows the capacity of some stored product insects to carry antibiotic-resistant and potentially pathogenic Enterococcus species. The latter is of public health importance and therefore there is need to monitor the occurrence of Enterococcus species in insects infesting stored products. These insects can act as vectors of pathogenic microorganisms & cause health hazards to consumers if proper pest management strategies are not applied to stored products.