In Vitro and In Vivo Establishment of Pasteurella Haemolytica A2 in the Lungs of Goats

Pneumonic pasteurellosis is an important respiratory disease of sheep and goats throughout the world. It is mainly caused by Pasteurella haemolytica even though Pasteurella multocida has occasionally been associated with the same disease. In vitro challenge of lung tissues with Pasteurella haemolytica A2 revealed an early colonization of the bacteria onto the lung tissue as early as 1 hour post-challenge. The severity of colonization increased with time of challenge and reached a maximum rate at 6 hours post-challenge . Similar in vitro challenge on the lung tissues derived from goats that were exposed earlier to intranasal sprays of formalin-killed Pasteurella haemolytica A2, however, revealed a less severe colonization by 6 hours postchallenge. Following intratracheal challenge of goats with 108/ml colony forming units of Pasteurella haemolytica A2, 20% of the goats succumbed to peracute infection in which they died within 12 hours post-challenge. Examinations of the lungs revealed classical toxaemic lesions consisted of severe pulmonary oedema, pulmonary congestion and haemorrhage, and thrombosis with a few neutrophils in the alveoli. The lesions were remarkably similar to those peracute infections caused by Pasteurella multocida types A and D. The only difference was the absence of Pasteurella haemolytica A2 organisms in the heart blood samples compared to the infections by Pasteurella multocida types A and D. Goats that survived the peracute episode developed pneumonic lesion. Phagocytic activity by the bronchoalveolar macrophages was obvious by 4 days postchallenge and by day 7 post-challenge, the goats which were unable to phagocytose most of the bacterial cells succumbed to severe pneumonia in which the bacteria proliferated and overloaded the lungs leading to the invasion of the bacteria into the pneumocytes and spreading the infection further. Goats with efficient phagocytosis were able to reduce the number of bacterial cells in the lungs leading to failure of bacterial establishment in the lungs. Infections by Pasteurella haemolytica A2 isolated from nasal mucosa produced an insignificantly (p>0.05) less extensive lung lesions compared to infections by Pasteurella haemolytica A2 isolated from pneumonic lungs. The pulmonary responses and pattern of lesion developrrient, however, remained similar for both isolates

Enhanced Virgin Coconut Oil (EVCO) as Natural Postmilking Teat Germicide to Control Environmental Mastitis Pathogens

The antimicrobial capability of oil containing medium-chain fatty acids and their corresponding monoglycerides, known as Enhanced Virgin Coconut Oil (EVCO) against microorganisms isolated from bovine mastitis milk was studied. EVCO contains an effective amount of medium-chain free fatty acids (caprylic, capric and lauric acid) and their corresponding derivatives (monocaprylin, monocaprin and monolaurin) can act as antimicrobial agent with broad spectrum of antimicrobial properties. An in vitro assessment of EVCO against bovine mastitis microorganisms isolated from locally collected mastitis milk samples was conducted to determine its minimum bactericidal concentration (MBC>99). In general, EVCO exhibited its great antimicrobial capability to kill all mastitis microorganisms isolated from the mastitis milk sample at different concentrations of MBC>99 value. In fact, EVCO was found more effective to kill Mycoplasma sp. and gram positive microbes rather than gram negative microbes, especially in Mycoplasma bovis, Acholeplasma oculi, Enterococcus sp., Streptococcus sp. and Staphylococcus aureus with lower MBC>99 values in comparison with the synthetic antibiotic, Mastivet. A further investigation of the antimicrobial activities of EVCO against Staphylococcus aureus and Mycoplasma bovis against time revealed that EVCO was more efficient in killing these two microorganisms in a shorter time at a lower concentration as opposed to Mastivet. These findings indicated that EVCO has great potential application in postmilking teat germicide, which can be used as a preventive measure to control mastitis cases, especially against environmental mastitis pathogens

Phylogenetic diversity of Burkholderia pseudomallei isolated from veterinary cases and the environments in Peninsular Malaysia

This study was designed to determine the genotype and the phylogeny of Burkholderia pseudomallei isolated from veterinary cases and from the animal environments in Peninsular Malaysia. The Malaysian B. pseudomallei population were then compared to those found elsewhere. A total of 113 isolates from veterinary cases (35) and the environment (56 from soil and 22 from water) were characterized using multilocus sequence typing (MLST). Two novel alleles, allele 97 and 69 of the gene locus ace and lepA respectively were recovered. Isolates were resolved into 12 distinct sequence types (STs) out of which five were novel, namely ST1130, ST1131, ST1338, ST1339 and ST1367. The isolates from veterinary cases co-clustered with those from the environment. B. pseudomallei isolates in this study were highly clonal and have descended from a common ancestor clonal complex (CC) 48 found in Southeast Asia. This study shows that veterinary case isolates are often caused by similar STs, with similar populations found in the direct animal environment and those previously reported to cause human infections in Malaysia and elsewhere. Isolates of B. pseudomallei from human infections have been given more attention, with a comparatively lower focus on isolates from animals and the farm environment. This study highlighted the genotype and phylogeny of B. pseudomallei isolated from animals and the environment and their relations to the isolates from human cases reported in Malaysia and elsewhere. Most STs reported in this study, from veterinary cases and animal environment are similar to those previously reported as causing human infections in Malaysia and elsewhere. Therefore, even though direct zoonosis is uncommon, monitoring melioidosis occurrences in animals can provide insights on the bacterial strains infecting humans

Stimulation of the bronchus-associated lymphoid tissue of goats and its effect on in vitro colonization by Pasteurella haemolytica

Twenty goats of about 7 months of age were divided into five groups. The goats in groups 1 and 2 were exposed once, using an intranasal spray to 2 ml of an inoculum containing 106 colony-forming units/ml of living or dead Pasteurella haemolytica A2, respectively. The goats in groups 3 and 4 were similarly exposed twice at a 2-week interval. Group 5 was the untreated control. The number and size of the bronchus-associated lymphoid tissue (BALT) in goats exposed twice to either living or dead organisms were significantly (p>0.05) increased compared with those exposed once and with the unexposed control. In vitro colonization by living P. haemolytica A2 onto the lung tissue in which the BALT had been stimulated by two exposures of either living or dead organisms was significantly (p>0.05) reduced. The study indicates that stimulation of the respiratory mucosal immunity may prevent P. haemolytica A2 infection

The relationship between bacterial sources and genotype to the antimicrobial resistance pattern of Burkholderia pseudomallei

Background: Melioidosis is a fatal emerging infectious disease of both man and animal caused by bacteria Burkholderia pseudomallei. Variations were suggested to have existed among the different B. pseudomallei clinical strains/genotypes which may implicate bacterial susceptibility and resistance toward antibiotics.Aim: This study was designed to determine whether the phenotypic antibiotic resistance pattern of B. pseudomallei is associated with the source of isolates and the genotype.Materials and Methods: A collection of 111 B. pseudomallei isolates from veterinary cases of melioidosis and the environments (soil and water) were obtained from stock cultures of previous studies and were phylogenetically characterized by multilocus sequence typing (ST). The susceptibility to five antibiotics, namely meropenem (MEM), imipenem, ceftazidime (CAZ), cotrimoxazole (SXT), and co-amoxiclav (AMC), recommended in both acute and eradication phases of melioidosis treatment were tested using minimum inhibitory concentration antibiotics susceptibility test.Results: Majority of isolates were susceptible to all antibiotics tested while few resistant strains to MEM, SXT, CAZ, and AMC were observed. Statistically significant association was found between resistance to MEM and the veterinary clinical isolates (p<0.05). The likelihood of resistance to MEM was significantly higher among the novel ST 1130 isolates found in veterinary cases as compared to others.Conclusion: The resistance to MEM and SXT appeared to be higher among veterinary isolates, and the novel ST 1130 was more likely to be resistant to MEM as compared to others

The Goat as a Model for studies of pneumonic pasteurellosis caused by Pasteurella Multocida

A model of pneumonic pasteurellosis has been established in goats using Pasteurella multocida harvested from pneumonic lungs of goats (types A and D), rabbits (type A) and sheep (type D). The resultant infections were acute, subacute or chronic. The gross and histological lesions of the subacute and chronic infections were typical of pneumonic pasteurellosis. P. multocida type D produced significantly (P<0.01) more severe lesions when compared with other isolates. There were strong correlations between the clinical signs and the severity of lesions