Isolation of aerobic bacteria from ticks infested sheep in Iraq

Objective: To highlight the presence of aerobic bacteria in live ticks infested sheep, in Diyala Governorate, Iraq. Methods: One hundred and thirty adult alive ticks were picked up from sheep which were reared in different farms in Diyala Governorate, Iraq, during the period from November 2012 to May 2013. Ticks were classified in the Natural History Museum in Baghdad. They were dissected aseptically for extraction of the salivary gland and mid-gut. The removed tissue from each organ was inoculated in buffer peptone water (1%) and incubated for 2 h at 37 °C, to maintain weak and/or injured bacterial cells, then transmitted to nutrient broth incubated at 37 °C for 18 h. Culturing was done on three solid bacteriological media (nutrient, blood and McConkey agars), and then incubated at 37 °C for 24 h. Bacterial identification was performed by using multiple biochemical tests and API-20 strips. Data were analyzed by using Statistical Analysis System version 9.1, 2010. Chi-square test was used for comparison at significant level of P ≤ 0.05. Results: Two species of ticks were identified [Rhipicephalus (Boophilus) annulatus and Hyalomma turanicum]. High bacterial isolation rate was observed (483 isolates). A significant high isolation rate was recorded from Rhipicephalus annulatus (63.14%). Six bacterial species were identified [Escherichia coli (28.36%), Pseudomonas aeruginosa (18.01%), Bacillus cereus (14.69%), Staphylococcus aureus (13.66%), Citrobacter freundii (13.04%), and Enterobacter species (12.21%)]. Also the high bacterial isolation rates were recorded in the temperate months (November, March and April); these coincided with high reproductive performance of ticks. Conclusions: The high isolation rate of aerobic pathogens from ticks might reflect the active contribution of this arthropod in environmental contamination and increase the probability of transmitting bacterial pathogens to their hosts.