Eleonor A. Tendencia

Antibiotic resistance of bacteria from shrimp ponds

Abstract The incidence of antibiotic resistance was compared in bacteria isolated from pond water, pond sediment, water and sediment from the receiving environment (area where water from pond drains, which is 0 and 50 m away from the exit gate, in this study) and cultured shrimp from ponds that have not used any antimicrobials, ponds that have previously used antimicrobials and ponds that are currently using oxolinic acid. Most of the bacteria isolated from all sample and pond type were Vibrios . Among the Vibrios , V. harveyi were most commonly isolated. Multiple antibiotic resistance (MAR) to at least two antimicrobials was highest in ponds currently using oxolinic acid (24% of bacteria isolated from such ponds), followed by those that have previously used antimicrobials (19%) and the least was those from ponds that have not used any antimicrobials (17%). The lowest incidence of antibiotic resistance was observed in ponds that have not used any antimicrobials (41% of the isolates from such ponds). Among the individual antibiotics, incidence of resistance to oxytetracycline was highest (4.3% of the total number of isolates) followed by furazolidone (1.6%), oxolinic acid (1%) and chloramphenicol (0.66%). Resistance to individual chemotherapeutants did not reflect the pattern of antimicrobial use with ponds that have previously used antimicrobials showing the highest incidence of resistance to one antimicrobial (12% of total isolates from such ponds). Resistance to both oxolinic acid and furazolidone (15% of total number of isolates) was highest compared to other antimicrobial resistance profiles (1–12%). Multiple antimicrobial resistance and intermediate reaction to at least one antimicrobial are associated with antimicrobial use.

Level and percentage recovery of resistance to oxytetracycline and oxolinic acid of bacteria from shrimp ponds

Abstract The bacterial level of the water, sediment and cultured shrimp ( Penaeus monodon ) from different ponds were determined using a general medium, a presumptive Vibrio medium and a presumptive Pseudomonas – Aeromonas medium. Samples were taken from ponds that had not used any antimicrobial, ponds that had previously used and also ponds that were currently using oxolinic acid (OXA). The bacterial level in the sediment was higher than in the water using all three media. More bacteria existed in the pond system than in the receiving environment. Shrimp hepatopancreas harbored more bacteria than the lymphoid organ. The Vibrio density of the pond and bacterial levels in the shrimp were correlated with the use of the antimicrobial. The Vibrio level of the pond samples and microbial density of shrimps were higher from ponds that had not used any antimicrobials. The percentage recoveries of resistance to oxytetracycline (OTC) and OXA in bacteria from shrimp ponds and cultured shrimps were also determined using Zobells marine agar, Pseudomonas – Aeromonas selective agar and thiosulfate citrate bile sucrose agar (TCBS) with the addition of either 25 μg/ml OTC or 25 μg/ml OXA. Presumptive Vibrio bacteria and other bacterial taxa recovered from the pond/receiving water/sediment from all three sites showed some degree of resistance to OTC and OXA. However, a higher percentage recovery of strains resistant to OTC than to OXA was observed among the presumptive vibrios and other bacterial taxa. Pseudomonas and Aeromonas bacteria were more resistant to OXA compared with the vibrios. All bacterial taxa resistant to OTC were more readily recovered from the water samples than from the sediment samples. In general, between the samples from the pond and from the receiving environment, a higher percentage of resistant strains was observed in the latter. Higher percentage recovery of bacteria resistant to OXA was observed in shrimp from ponds currently using OXA than those from ponds that had not used any or those that had previously used them. The results of the present study showed that the percentage recovery of resistance reflected the pattern of antimicrobial use.

Antibacterial activity of tilapia Tilapia hornorum against Vibrio harveyi

Abstract Disease due to luminous Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia ( Tilapia hornorum ) on luminous bacteria Vibrio harveyi . Results showed that stocking tilapia at a biomass not lower than 300 g/m 3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m 3 ) rearing water without the growth of microalgae.

Investigation of some components of the greenwater system which makes it effective in the initial control of luminous bacteria

Abstract Two components of the greenwater system, the tilapia water and Chlorella , were investigated separately for their effect on the population of luminous bacteria. For the investigation of tilapia water, Tilapia hornorum was stocked at different biomasses 0, 1 and 3 kg/10 m 3 . Vibrio harveyi was introduced to the tanks at a final concentration of 10 3 cfu/ml. Luminous bacteria could not be detected in tanks stocked at 3 kg/10 m 3 from day 4 to day 6, and on day 6 in tanks stocked at 1 kg/10 m 3 . The bacteria could still be recovered in tanks without tilapia on day 6. Investigation of the effect of chlorella alone on V. harveyi was undertaken using sterile flasks containing 500-ml autoclaved seawater provided with aeration. In treated flasks Chlorella was added, whereas no Chlorella was added to control flasks. No luminous bacteria were recovered on day 2 and day 3 in flasks with Chlorella , while those without the microalgae still harboured luminous bacteria at day 3.

Effects of Gusathion A on the survival and shell quality of juvenile Penaeus monodon

Abstract Juvenile Penaeus monodon (body weight=10–20 g) were exposed to a commonly used organophosphate pesticide, Gusathion A, in ponds for 96 h. Prawns exposed to 1.5–150 ppb Gusathion A had 27–53% shell softening, with a 96 h LC50 of 120 ppb. Histopathological changes in the gills and hepatopancreas included slight hyperplasia of the gill epithelium, delamination of the hepatopancreatocytes, and general necrosis and degeneration of these tissues.

Comparing Profits from Shrimp Aquaculture with and without Green-Water Technology in the Philippines

To reduce disease impact, Philippine farmers developed the green-water (GW) system, which has been spreading rapidly since 2008. In the most applied GW-system, the shrimp pond receives water from a reservoir stocked with tilapia. We collected financial data on GW and non-GW systems from farms having similar management and environmental context. All farms had more than one pond; the average pond area was < 1 ha, and total pond areas per farm ranged from 1.4 to 139 ha. The total variable and fixed costs per ha of shrimp pond were not different for GW and non-GW farms, but on GW farms the cost per kg of shrimp produced was lower. The latter was higher than the 2009 market price of 30 g shrimp for non-GW farms mainly. In GW farms the cost of seed was lower, and survival rates and individual shrimp weights at harvest were higher for an equally long culture period.

Enhancing disease monitoring in shrimp through a geographical information system (GIS) application

Abstracts for ISVEE XIs for ISVEE XI