Honey bees (Apis mellifera L.) as mechanical vectors of Gram-negative bacteria: a field and laboratory study in different environments in Iraq

Abstract

This study aimed to isolate and diagnose Gram-negative bacteria from the wings and hind legs of honeybee workers (Apis mellifera L.)  collected from different environments in the provinces of Kirkuk and Salah al-Din in Iraq, where 70 isolates were isolated from 76 samples, in addition to evaluating their susceptibility to certain antibiotics. Honeybee samples were collected from apiaries, farms, and home gardens, then cultured on selective and differential media. Isolates were performed on selective and differential media (MacConkey, EMB, Nutrient agar). The isolates were identified by morphological methods and biochemical tests (Gram, Oxidase, Catalase, TSI, Indole, MR-VP, Citrate, Urease, H2S, carbohydrate fermentation) and confirmatory diagnostic methods. Antibiotic sensitivity testing (Kirby–Bauer) was also performed on Mueller-Hinton agar medium.

The results showed the isolation of several Gram-negative bacteria, including E. coli, Acinetobacter spp., and Citrobacter koseri. and Klebsiella oxytoca, with variation in distribution depending on the collection sites. Antibiotic susceptibility tests also showed that many isolates exhibited variation in test results between resistance and sensitivity to a group of commonly used antibiotics. These results suggest that honeybees may act as mechanical vectors for environmental bacteria and some potential pathogens, which is influenced by their foraging behavior and contact with the surrounding environment. The study highlights the importance of monitoring the spread of antibiotic resistance in microbial communities associated with pollinators.