TOPIC: HEMOLYTIC ACTIVITY AND STREPTOMYCIN SUSCEPTIBILITY PROFILE OF BACTERIA ISOLATES ASSOCIATED WITH NASAL SECRETION
This study was carried out on hemolytic activity and streptomycin susceptibility profile of bacteria isolates associated with nasal secretion. To date, very little work has been done on the respiratory system flora of apparently healthy cattle. The objective of this study was to identify bacterial species found in the upper respiratory system and lungs of apparently healthy cattle; the isolates from nasal cavity were tested for susceptibility to selected antimicrobials. A total of 255 nasal swabs were collected from apparently healthy cattle in Maiduguri, Kaduna and Kano states, Nigeria, from which four hundred and four (404) bacterial isolates were identified, following the identification criteria given by Shears et al., (1993) and Quinn et al., (1994). They included: Bacillus 160/404 (39.60%), coagulase negative Staphylococcus 121/404(29.95%), Streptococcus species other than Streptococcus agalactiae 104/404 (25.74%), coagulase positive Staphylococcus 16/404 (3.96%) and Streptococcus agalactiae 3/404 (0.74%). Additionally, coagulase negative Staphylococcus (37.04%), coagulase positive Staphylococcus (37.04%), Streptococcus species (14.81%) and E. coli (11.11%), were also isolated from cattle lungs obtained from Athi river cattle slaughterhouse, some of which were showing pathological lesions. When the nasal isolates were tested for antimicrobial susceptibility, they were found to be most susceptible to Gentamycin (95.8%), followed by Tetracycline (90.5%), Kanamycin and Chloramphenicol (each at 85.3%), Sulphamethoxazole (84.2%), Co-Trimoxazole (82.1%), Ampicillin (78.9%) and finally Streptomycin (76.8%). Antimicrobial resistance was reported in ascending order in Gentamycin (4.21%), followed by Tetracycline (9.47%), Kanamycin and Chloramphenicol (14.74%), Sulphamethoxazole (15.79%), Co-Trimoxazole (17.89%), Ampicillin (21.05%) and finally Streptomycin (23.16%). Multidrug resistance was reported in 30.5% of all isolates subjected to the test antimicrobials. Most of the resistant organisms showed resistance to a combination of two antimicrobials which was 20% of the total number resistant. This study indicated presence of similar bacteria in both nasal cavity and lungs, thus strongly suggesting the involvement of the otherwise harmless nasal commensals in pulmonary disease causation in cattle. These nasal bacteria may find their way to the lungs in cases when the animals are stressed, as a result of the harsh conditions that the animals live in and also in the way they are used for transport and are burdened by humans. The levels of antimicrobial resistance to the antimicrobials used, as demonstrated in this study, indicate that the antimicrobial resistant normal flora (bacteria) harbor resistance genes which are transferable to pathogenic bacteria in the animal, not to mention transfer of resistant bacteria to other animals and humans; compounding the antimicrobial resistance situation. This study identified Gentamycin, Tetracycline, Kanamycin and Chloramphenicol as the most effective antimicrobials that can currently be used for treating respiratory or other infections in cattle.