Pathogenicity of Antibiotic Resistant/Sensitive Bacteria Vibrio spp. and Aeromonas spp. | Chapter 2 | Theory and Applications of Microbiology and Biotechnology Vol. 3

Bacterial and viral diseases constitute a major factor limiting the successes of shrimp farming industry. In this context, Identification of drug resistant pathogens and determination of the pathogenic processes of shrimp are fundamental for further progress in the disease management. They could be valuable in the evaluation of their epidemiology and control measures. Water samples from the aquaculture environment were contaminated with Vibrio anguillarum, V. damsela, V. furnissii, Aeromonas hydrophila and A. sobria. Both Vibrio spp and Aeromonas spp were shown to be pathogenic and to cause mortality to the infected post larval P. monodon. Vibrio spp. were shown to grow in TCBS agar, zobell’s marine agar and blood agar while Aeromonas spp. additionally exhibited growth in blood agar with selective supplement ampicillin (10 µg/ml) and showed a zone of clearance in DNase agar. LD50 values of V. anguillarim, V. damsela, V. funrissii, A. hydrophila and A. sobria to post larval P. monodon were determined as 1.1 x 105, 2.7 x 105, 6.0 x 105, 8.5 x 104, and 7.5 x 104 bacterial cells/ml respectively. Ciprofloxacin and streptomycin were found to be the most effective antibiotics in the reduction of the mortality of experimentally infected post larvae. The growth of Vibrio spp was inhibited by nifurpirinol (prefuran) at 25 µg/ml, oxytetracycline at 13 µg/ml, erythromycin phosphate at 4 µg/ml, chloramphenicol at 12 µg/ml, streptomycin at 2 µg/ml, and ciprofloxacin at 1 µg/ml. While the growth of Aeromonas spp was inhibited by nifurpirinol (prefuran) at 24 µg/ml, oxytetracycline at 14 µg/ml, erythromycin phosphate at 5 µg/ml, chloramphenicol at 12 µg/ml, streptomycin at 2 µg/ml, and ciprofloxacin at 1 µg/ml. Vibrio spp. was sensitive to o/129 vibriostatic agent (150 µg) whereasAeromonas spp. was resistant to it. The pathogenic bacteria viz. Vibrio spp and Aeromonas spp could be controlled to some extent with judicious use of effective antibiotics to improve the health status of shrimp in culture conditions and can have a positive impact in the areas of sustainable aquaculture environment and development. 

Author(s) Details
P. Ramasamy

Research and Development Wing, Sree Balaji Medical College and Hospital, India. 

D. R. Gunasekaran
Research and Development Wing, Sree Balaji Medical College and Hospital, India. 

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Thermophilic Bacteria: Novel Polymers for Biotechnological Applications | Chapter 01 | Advances and Trends in Biotechnology and Genetics Vol. 3

Aims: We analyzed thermotolerant bacterial isolates of thermophiles from various regions in South East coasts of India. They were analyzed for Fatty Acid Methyl Ester (FAME) for identification and classification.

Study Design: A total of forty three (9.6%) thermotolerant bacterial isolates of thermophiles were secluded out of 444 isolates obtained from water samples from the Adyar River, Marina coast, Muttu Kadu Backwaters, Kovalam coast (India) and a prawn hatchery. In addition, a novel thermotolerant Gram positive Bacillus type bacterium from the pelletized feed of fish was examined. A total of 18 thermotolerant bacteria were analyzed for Fatty Acid Methyl Ester (FAME).

Results: Amongst 134 isolates that grew on E. coli FAGI agar, 23 (17%) were thermotolerant when tested at 15 psi for 30 min. Of the 72 isolates that grew on Staphylococcus Baird Parker agar 10 (13%) were thermotolerant, whilst among the 128 isolates that grew on Salmonella agar ÖNÖZ 10 (8%) were thermotolerant. In contrast, none of the 110 isolates that grew on TCBS agar (Vibrio sp.) exhibited thermotolerance, although they were isolated from the same regions as the other bacteria. The optimal temperature for the growth of most thermophiles was 45°C, except for 9 isolates. Of the latter, 7 grew at 50°C, one at 52°C and one at 55ºC, respectively.There were some extremely thermotolerant bacterial isolates that exhibited consistency in profuse growth at 15 psi (121°C) for 30 min. Other isolates showed inconsistency in growth after autoclaving the cultures at 15 psi (121°C) for 30 min, and these bacteria showed development of endospores. Isolates of thermotolerant bacteria that grew on Staphylococcus Baird Parker agar and Salmonella agar ÖNÖZ were predominantly antibiotic resistant when compared with those bacterial isolates that grew on E. coli FAGI agar. A major 43 kDa toxin-protein as well as 15 other minor protein subunits was detected in the thermotolerant Bacillus sp. isolate. The proteins were toxic and caused mortality to goldfish Cyprin macrophthalmus. The thermotolerant bacteria were identified as B. cereus, Bacillus subtilis, B. pumilus, B. laevolacticus), B. alcalophilus, Kurthiasibirica, Geobacillus stearothermophilus, Staphylococcus schleiferi and S. gallinarum,

Conclusions: This study documents 43 thermotolerant bacterial isolates from water samples and a Bacillus-type bacterium from fish feed in Chennai region, India and these bacterial isolates offer the potential for exploitation in biotechnological applications.

Author(s) Details

Palaniappan Ramasamy
Research and Development Wing, Sree Balaji Medical College and Hospital, BIHER (Bharath University), Chromepet, Tamil Nadu, Chennai-600044, India.

Aruna Sharmili
Department of Biotechnology, Stella Mary’s College, Tamil Nadu, Chennai-600032, India.

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Linezolid and Methicillin Resistances in S. Aureus Isolated from the Anterior Nares of Apparently Healthy Undergraduates of the Niger Delta University, Nigeria | Chapter 03 | Theory and Applications of Microbiology and Biotechnology Vol. 2

Background: The carriage of Staphylococcus aureus in the anterior nares of subjects in the study environment has not been carried out before and this study is thus a reference study against which future studies can be compared. The isolates obtained were also tested against frequently used antibiotics as well as linezolid, an antibiotic which is of considerable importance in the treatment of Methicillin Resistant Staphylococcus aureus (MRSA).

Methods: A total of 400 nasal swabs were collected from anterior nares of apparently healthy subjects aseptically using a sterile swab sticks. The antibiotic susceptibilities of isolates of S. aureus obtained against eight different antibiotics including Linezolid were determined using the disc-plate method.

Results: The results showed that 91 (22.8%) of the subjects tested are nasal carriers of S. aureus. The incidences of resistance observed with each of the antibiotics tested were as follow: Erythromycin 83(91.2%), Tetracycline 79(86.8%), Co-trimoxazole 78(86.8%), Cefoxitin 77(84.6%), Linezolid 72(79.1%), Ciprofloxacin 70(76.9%), Augmentin 49(53.8%) and Gentamycin 39 (42.9%).

Conclusion: Treatment of S. aureus infections within the study environment should be based on the results of in vitro susceptibility testing of the isolates. Gentamicin promises to be the best antibiotic for the treatment of disorders associated with Staphylococci in the study area. This is of special importance in an environment within which a very substantial proportion of the isolates are resistant to methicillin and linezolid.

Author(s) Details

Abdulrasheed Abdu
Department of Medical Microbiology and Parasitology, Faculty of Basic Medical Sciences, College of Health Sciences, Niger Delta University, Wilberforce Island, Amassoma, Bayelsa-State, Nigeria.

Prof. Adebayo Lamikanra
Department of Pharmaceutics, Faculty of Pharmacy, Niger Delta University, Wilberforce Island, Nigeria and Faculty of Pharmacy, Obafemi Awolowo University, Ile-Ife, Osun-State, Nigeria.

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