Detection of Biofilm Formation and Antibiotics Resistance for Streptococcus Spp. Isolated from Some Dairy Products in Diwanyah City of Iraq

Abstract

Multidrug resistance and biofilm formation have increasingly become a leading human threat in particular dairy products, which become the primary source of essential nutrients word-wide. Biofilm formation is responsible for economic losses in the dairy industry. Therefore, in current study, the multi-drugs resistance and biofilm formation were investigated for Streptococcus spp. isolated different dairy products (milk, cheese, and cream) collected from various markets in Diwanyah city, Iraq. Bacteria were isolated and identified by morphological and biochemical characteristics using selective agar plates. Antibiotic resistance was tested using disc diffusion method, whereas biofilm formation was investigated using Microtiter plate method (MTP). The results showed that Streptococcus spp. isolates in milk (7 isolates), cheese (17isolates), and cream (18 strains) showed high resistance against novobiocin, Nalidixic acid, streptomycin, and cephalothin. However, all isolates showed high sensitivity to vancomycin. Streptococcus isolates showed a variant level of biofilm formation with high percentages (71.43%) of strong biofilm formation in milk isolates, 29.4% in cheese, and 50% in cream. These results suggested that multidrug resistance Streptococcus spp. has been observed in some dairy products with a high ability for biofilm formation and could affect the quality of dairy products and probable human threats.