First report of Tabanus (Tabanus) rubidus Wiedemann, 1821 (Diptera, Tabanidae) from Assam, India, with detection of multidrug-resistant Mammaliicoccus sciuri and Staphylococcus kloosii

Abstract

A survey of Staphylococcus and Mammaliicoccus bacteria in Tabanus (Tabanus) rubidus Wiedemann, 1821 (Diptera, Tabanidae) was conducted in three habitats in Assam, India — Lokhrah, Ghar Chuk, and the Royal Global University campus — during peak fly activity in 2024. This constitutes the first record of T. rubidus from Assam. A total of 120 adult flies were collected and their morphological identity confirmed under a stereomicroscope using established taxonomic keys. Bacterial identification using the VITEK® 2 Compact system confirmed 168 staphylococcal isolates across six species. Mammaliicoccus sciuri was the most prevalent (82 isolates, 48.8%), followed by Staphylococcus kloosii (44 isolates, 26.2%). Antimicrobial susceptibility testing against 13 drugs revealed that 51.2 per cent of M. sciuri isolates were multidrug-resistant (MDR), with high resistance to methicillin (47.8%), erythromycin (65.4%), and tetracycline (40.5%). Among S. kloosii, 31.8 per cent were MDR, with notable resistance to penicillin (72.7%) and clindamycin (38.2%). All isolates remained susceptible to vancomycin and linezolid. These findings document the carriage of multidrug-resistant staphylococci in T. rubidus in Assam, suggesting that horse flies may serve as environmental reservoirs of antimicrobial resistance.