Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis

Pathology of systemic multiple bacterial infections and peritonitis in hatchery-produced African catfish Clarias gariepinus (Burchell, 1822) larvae

Diseases are the major problems that have a significant impact on African catfish Clarias gariepinus seed production. This study reports the necropsy, microscopy, bacteriology and histopathology of diseased catfish larvae that experienced mass mortalities (>80%). The gill filaments of diseased larvae revealed no ectoparasites. The intestines had no parasitic association. About 35 – 40% of the dead larvae had ruptured abdomen. The affected larvae had abdominal haemorrhages and disintegrated intestine with marked degenerative and inflammatory changes, which indicated peritonitis. Bacteria including Aeromonas veronii, Edwardsiella tarda and Pseudomonas putida were isolated from the haemorrhagic exudates of diseased catfish larvae. Histopathology demonstrated dense melanomacrophage aggregates in the spleen. The intestine had extensive degeneration, basophilic margination and disintegration of the mucosal layer. The kidney section suggested a suppurative infection with necrosis of haematopoietic tissue, inflammation of the epithelial tissue, vacuolar degenerations and hypoplastic haematopoietic tissue. Aeromonas veronii and E. tarda immersion challenge at 5×106 cells mL–1 yielded no mortalities under laboratory conditions. Nevertheless, the hatchery management measures and the laboratory analyses supported peritonitis with systemic multiple bacterial infections in the observed large-scale motilities of excessively fed larvae

Water and sediment quality characteristics of medium saline traditional shrimp culture system (bheri)

Quality of water in shrimp culture ponds depends on several physical, chemical and biological processes. In this study, the physico-chemical characteristics of water and sediment samples from inlet, pond and outlet of a traditional shrimp culture pond, locally called as bheri, were examined for nine months from March to November 2011. Majority of the physicochemical parameters of bheri were well within the optimum levels. The average BOD values in pond water and outlet water were 2.03 ppm and 2.33 ppm, respectively. In pond water, the levels of ammonia were from 0.012 to 0.033 ppm, which was well within the safe level (<0.1 ppm). The present study recorded low levels of nitrite (0.0037 to 0.0043 ppm) and nitrate (0.056 - 0.091 ppm) in pond water, which was within the safe levels recommended for shrimp farming. These physicochemical parameters did not affect the cultured shrimp as there was no incidence of diseases or growth retardation during the culture period. The effluent water characteristics also did not vary much and well within the recommended levels for protecting the coastal ecosystem. It is unlikely that the traditional shrimp culture pose any adverse environmental effect when effluents are discharged into the open coastal ecosystem

Oxytetracycline resistant bacteria in Clarias gariepinus and Clarias batrachus larvae and the environment

Antibiotics and several other chemicals are used in catfish aquaculture as a remedy for various diseases. Reports on the distribution of different groups of bacteria especially the antibiotic resistant bacteria in catfish nursery system are scanty. The present study quantified motile aeromonads, pseudomonads and antibiotic (oxytetracycline) resistant bacteria in Clarias gariepinus and C. batrachus larvae and the rearing water from five catfish nurseries of West Bengal, India between March 2007 and July 2007. The C. gariepinus and C. batrachus larvae recorded mean counts of log 7.26±0.18/g and log 6.24±0.64/g, log 6.37±0.41/g and log 4.93±0.51/g, log 5.46±0.22/g and log 4.38±0.53/g and, log 6.27±0.64/g and log 5.57±0.12/g, respectively for total viable bacteria (TVCs), motile aeromonads (MACs), presumptive pseudomonads (PPCs) and oxytetracycline resistant bacteria (ARBCs). The levels of TVCs, MACs, PPCs and ARBCs were significantly high in C. gariepinus than in C. batrachus larvae. The rearing water recorded comparatively low bacterial counts than in larvae. The difference between the TVCs of larvae and larval rearing water of C. gariepinus was statistically significant, where as it was insignificant for C. batrachus. The mean proportion of motile aeromonads of C. gariepinus larvae and rearing water was about 4-5 fold higher than in C. batrachus

Prevalence of white spot virus and monodon baculovirus in shrimp culture systems of West Bengal, India

The global shrimp aquaculture is impacted by episodes of viral diseases resulting in huge income losses. This communication presents the results of the polymerase chain reaction (PCR) based surveillance of white spot virus (WSV) and monodon baculovirus (MBV) in shrimp culture systems of West Bengal, India. The WSV was detected in 14.87% of the total samples (N = 121) by first PCR and 16.53% of samples by nested PCR. The WSV infection was noticed in 12 of 65 Penaeus monodon, 6 of 39 Litopenaeus vannamei and 2 of 11 Macrobrachium rosenbergii samples. The MBV was detected in 8 of 65 P. monodon samples by non-nested PCR and all were also positive for WSV, thus indicating concurrent infection of shrimp. The results emphasized the need to observe strict quarantine measures during the seed selection to prevent the introduction of viral pathogens in grow-out systems

POKRETNE VRSTE AEROMONAS OTPORNE NA ANTIBIOTIKE UZROKUJU SEPTIKEMIJU KOD MLAĐI FILIPINSKOG SOMA Clarias batrachus (Linnaeus, 1758)

Philippine catfish, Clarias batrachus farming is receiving much attention in recent years so also the diseases in catfish aquaculture. During the disease surveillance in catfish farms, mortalities were observed in C. batrachus fingerlings in a nursery and this report describes the bacteriological and histopathological observations made on the diseased catfish. The gross and clinical signs observed were lethargy, anorexia, vertical movement, skin erosion, operculum erosion, pale gills, reddening of mouth, fin haemorrhage, red lateral line and distended abdomen. The bacteria isolated from the kidney were identified phenotypically as species belonging to classical motile aeromonad group (Aeromonas caviae, A. hydrophila, A. jandaei and A. sobria) and newly described aeromonad group (A. aquariorum, A. fluvialis and A. rivuli). Multiple antibiotic resistance (MAR) index was in the range of 0.3-0.8. These antibiotic resistant motile aeromonads caused septicaemia and 100% mortality. Histologically, haemocyte infiltration, necrosis, inflammation of epidermal tissue, rough epidermal layer and fibrosis in muscle tissue, and loss of typical tubular epithelial lining, necrosis of tubular tissue, inflammation of epithelial layer, cellular and nuclear hypertrophy, pycnotic nuclei, karyolysis and hypoplastic haematopoietic tissue in the kidney of diseased catfish were noted. The inflammatory responses observed in the kidney of C. batrachus were indicative of suppurative infection.Uzgoj filipinskog soma, Clarias batrachus, izaziva veliku pozornost posljednjih godina, kao i bolesti kod uzgoja soma. Tijekom nadzora bolesti na farmama somova uočena je smrtnost kod mlađi C. batrachus u mrjestilištu, a ovaj rad opisuje bakteriološka i histopatološka opažanja uočena kod zaraženih somova. Opaženi općeniti i klinički znakovi su letargija, anoreksija, vertikalno gibanje, erozija kože, erozija operkuluma, blijede škrge, crvenilo usta, krvarenje peraja, crvena bočna linija i napuhani trbuh. Bakterije izolirane iz bubrega su fenotipski identificirane kao vrste koje spadaju u klasičnu pokretnu skupinu Aeromonas (Aeromonas caviae, A. hydrophila, A. jandaei i A. sobria)i nedavno opisanu skupinu Aeromonas (A. aquariorum, A. fluvialis i A. rivuli). Indeks višestruke rezistencije na antibiotike je u rasponu od 0,3-0,8. Ove pokretne vrste Aeromonas otporne na antibiotike uzrokovale su septikemiju i stopostotnu smrtnost. Histološki, zabilježena je infiltracija hemocita, nekroza, upala epidermalnog tkiva, grubi epidermalni sloj i fibroza u mišićnom tkivu te gubitak tipične cjevaste epitelne unutarnje stjenke, nekroza cjevastog tkiva, upala epitelnog sloja, stanična i nuklearna hipertrofija, piknoza jezgre, karioliza i hipoplastično hematopoetsko tkivo u bubrezima oboljelih somova. Upalne reakcije uočene u bubregu C. batrachus upućuju na gnojne infekcije

Prevalence of diseases caused by Flavobacterium spp. and other opportunistic bacteria in carps of sewage-fed farms in West Bengal, India

India is the second largest fish producing nation after China, contributing about 5.68% of the global fish production. The state West Bengal is occupying the second position in freshwater fish production after Andhra Pradesh. Although a number of constraints have been put forth, diseases and poor farm management are some of the most noticeable reasons for the reduced fish production in West Bengal. This study reports the prevalence of diseases caused by Flavobacterium spp. and other opportunistic bacteria in carps of sewage-fed farms in West Bengal. The bacteriological examination of the diseased carps revealed infections with different bacterial species and most of them were opportunistic pathogens. Flavobacteriosis, aeromoniasis, pseudomoniasis and other mixed bacterial infections, as confirmed by conventional biochemical tests and by VITEK 2 Compact system, were noted frequently. Antibiotic sensitivity of the opportunistic bacterial pathogens from the diseased carps indicated that some of these bacterial strains are resistant to potential human medicines like erythromycin, cotrimoxazole, oxytetracycline, nitrofurantoin, etc., which is a serious cause for concern. These results further present the fact that sewage-fed fish farms and the food fish from such systems may pose a serious public health risk from the antibiotic-resistant bacteria, if not handled properly

African catfish Clarias gariepinus farming practices in North and South 24 Parganas districts of West Bengal, India

Clarias gariepinus is widely cultured due to its tolerance to environmental extremes, high production and good feed conversion rate. This communication describes the farming practices of C. gariepinus in North and South 24 Parganas districts of West Bengal. Clarias gariepinus is cultured in ponds of 0.1–0.75 ha, where fingerlings were stocked at a density of 860–1150 cubic.m–1. The current practices of seed transportation were stressful to fish as the majority of the farmers noticed 5–10% mortalities, despite the use of antibiotics. Acclimatization of seeds was practiced by the majority of farmers before stocking. Different feeds including slaughter-house wastes and dead poultry were supplied. Multiple stocking and harvesting were a common practice. Major problems identified were insufficient feed, disease, transport, poor seed quality and lack of financial support. The survival percentage was poor, as 88% of the farmers recorded <40–50% survival at harvest. Dropsy was the most common disease and had a significant impact on economy. Antibiotics or other aquadrugs were frequently used for treatment, although the success varied. In general, the C. gariepinus farming has helped to recycle the wastes generated in and around metropolitan Kolkata and adjacent municipalities into wealth, but it suffers from management issues and economic losses

Transferable chloramphenicol resistance determinant in luminous Vibrio harveyi from penaeid shrimp Penaeus monodon larvae

Antibiotic-resistant luminous Vibrio harveyi strains isolated from Penaeus monodon larvae were screened for the possession of transferable resistance determinants. All the strains were resistant to chloramphenicol and the determinant coding for chloramphenicol resistance was transferred to Escherichia coli at frequencies of 9.50x10-4 to 4.20x10-4. The results probably suggest the excessive use of chloramphenicol in shrimp hatcheries to combat luminous vibriosis