Fish play a crucial role in the Bangladeshi diet, providing more than 60% of animal source food, representing a crucial source of micro-nutrients and possessing an extremely strong cultural attachment. In this study isolation and identification of Aeromionas hydrophila was done by studying cultural properties, Gram's staining and biochemical properties of isolates of diseased indigenous Koi fish (Anabas testudineus) of different upazillas of Mymensingh district. Antibiogram profile of the isolated bacteria was studied by using wide range of commercially available antibiotics. Quantitative study of bacteria isolated from diseased indigenous Koi fish showed variation of number in different organ. Total bacterial load was found to be 1.90 × 105, 1.19 × 105, 3.21 × 105, 2.18 × 106 and 3.14 × 105 cfu/g in lesions; 2.52 × 107, 2.34 × 108, 5.41 × 108, 2.54 × 109 and 5.21 × 109 cfu/g in liver; 2.54 × 108, 2.41 × 108, 1.90 × 107, 3.65 × 107 and 3.45 × 108 cfu/g in spleen; 3.51 × 107, 5.28 × 107, 3.14 × 106, 1.85 × 107 and 4.52× 107 cfu/g in kidney in diseased Koi of Mymensingh sadar, Muktagacha, Tarakanda, Gouripur and Fulpur upazillas, respectively under Mymensingh districts. Aeromonas hydrophila was initially identified by their specific morphological, physiological and biochemical characteristics. Then molecular detection of A. hydrophila was done by PCR. PCR products of desired 760 bp were obtained for A. hydrophila. The results of the antibiotic sensitivity test is exhibited that most of the bacterial samples were sensitive against ciprofloxacin (92%) and levofloxacin (84%), intermediate resistant against gentamicin (40%) and resistant against novobiocin (84%), ampicillin (100%) and penicillin (92%).

The study was carried out from November, 2014 to February, 2015 with the objective of isolating Aeromonas hydrophila an important fish pathogen from infected air-breathing catfish Magur (Clarias batrachus) in Mymensingh district. Quantitative study of the isolated bacteria from infected C. batrachus was found variation of number in different organs. Total bacterial load was found to be 1.16 x 105 to 3.15 x 106 cfu/g in lesions, 2.14 x 108 to 4.17 x 109 cfu/g in liver, 1.90 x 107 to 5.12 x 108 cfu/g in spleen and 2.32 x 106 to 5.24 x 108 cfu/g in kidney of infected C. batrachus in Mymensingh district. The isolates were found to produce acid from arabinose, whereas acid and gas from different sugar media such as maltose, sucrose, and dextrose. Morover, they were capable to ferment glucose but resistant to vibriostatic agent 0129 test. Further identification of A. hydrophila was accomplished using PCR. The PCR products of desired 760 bp were obtained for A. hydrophila. The isolated A. hydrophila were 96% sensitive to Enrofloxacin followed by 88% to Ciprofloxacin and 76% to Levofloxacin. On the other way, 100% were resistant to the Ampicillin followed by 96% to Penicillin and 92% to Novobiocin. So far, this is the first molecular identification of A. hydrophila from farmed C. batrachus in Bangladesh. The present study will provide future research scopes on identification of pathogenicity island in chromosome and serotyping of all A. hydrophila isolates. Asian Australas. J. Food Saf. Secur. 2017, 1 (1), 17-24

This study was carried out for the evaluation of causative agents of dental plaques which leads to dental caries. A total of 76 samples collected from the dental caries patients of various age and sex were processed on different bacterial isolation media like Tryptose Soya Agar, Nutrient Agar, and MacConkey Agar. Total viable count of bacteria was ranged from 0.8×10 5 to 2.9×10 5 . Out of total 184 isolates bacterial species were Streptococcus mutans (28.80%), Streptococcus mitis (23.91%), Staphylococcus aureus (28.26%) and Streptococcus salivarius (19.02%). The biochemical properties of the isolates were tested according to Bergey's Manual of Systematic Bacteriology and UK Standards for Microbiology Investigation. Antibiotic Susceptibility testing of different species of bacteria were performed according to Kirby Bauer disc diffusion method on Muller Hinton Agar by using commercial antibiotic discs. Effect of the bacterial isolates on different age groups was studied where the age group of 26 to 35 years was found to have highest prevalence (32.60%) of infection while the lowest prevalence (10.86%) of infection was seen in the group of below 15 years of age. A relative study was also performed on caries patients according to their economic status and gender where Higher Middle Economic Class was in highest percentage (35.32%) of infection. Different species of bacteria showed various sensitivity patterns to several kinds of antibiotics. Regular use of tooth paste containing triclosan and fluoride may be beneficial for prevention of dental caries instead of using antibiotics presented in this study.

Abstract:The research work was conducted on 105 layer chicks with a view to determine the rate of distribution of neurotropic virulent Newcastle disease virus (NVNDV) in various organs following infection through natural (intranasal, intraocular and oral) and parenteral (intravenous, intramuscular and subcutaneous) routes of inoculation at different ages (7, 15 and 28 days of old). Each bird received a dose of 0.2 ml contained 300 ELD 50 of reference NVNDV. The highest body temperature (≥108 0 F) was recorded in the birds of almost all the experimental groups within 48 to 72 hours of PI. Appearance of clinical signs was observed earlier (48 to 72 hours of PI) in parenterally infected birds than those of inoculated through natural routes. The shortest duration (24-48 hours of PI) and longest duration (74-138 hours of PI) of death time were recorded in birds those inoculated through IV and oral routes of infection respectively. Isolation of NDV was positive from day 2 of PI and onward in all the groups with some minor variations in some cases. The CEF system was found more sensitive for the isolation of viruses compare to that of avian embryo. The highest HA titre of NDV was found in the brain tissue followed by lungs and kidney. Significantly (p<0.01) higher HA titre of NDV isolate was recorded in the birds of all the experimental groups inoculated through IV route. Following infection, the MDA titre decreased day by day in the birds with the increase of HA titres of NDV.

The present study was carried out to evaluate the comparative capability of producing infections and causing mortality of the experimental Magur (Clarias batrachus) with motile Aeromonas species. A total of 200 apparently healthy C. batrachus were acclimatized to the laboratory conditions for experimental study. Nine different groups (each group consisting of 20 fish) of healthy C. batrachus was injected with nine motile Aeromonas isolates (A. hydrophila-3, A. sobria-3 and A. caviae-3). Experimental C. batrachus were infected with motile A. hydrophila, A. sobria and A. caviae to groups 1-3, 4-6 and 7-9, respectively while group 10 was injected with sterile physiological saline (0.85% NaCl) and served as the control. The selected motile bacterial species via intramuscularly were injected at the rate of 4.5 × 105 cfu/fish for pathogenicity study on C. batrachus and monitored up to two weeks. The highest clinical infections were noticed 90% in group-3 whereas only 35% in group-8 within the experimental period. After two weeks of the experiment, the cumulative mortality rate was also found highest (60%) in group-3 but lowest (15%) in group-9 while no infection or mortality showed in group-10 (control group). The development of infection and mortality to the injected C. batrachus was associated more severely by Aeromonas hydrophila than A. sobria and A. caviae used in this study. However, the isolates motile Aeromonas species could serve as the primary cause of skin lesions as well as mortality in cultured C. batrachus. Asian Australas. J. Food Saf. Secur. 2017, 1 (1), 45-50