Potential aquatic bacterial pathogens in the Philippines and Thailand

Strains of Aeromonas spp., `non–cholera vibrios´(NCVs) and Plesiomonas shigelloides isolated from aquatic environments and fish and human diarrhoeal cases in the Philippines and Thailand were characterised for potential virulence markers, such as the production of cytotoxin, cell-associated and cell-free haemolysin and their capacity to adhere to human intestinal (Henle 407) cells in vitro. In addition, the occurrence of tlh and tdh haemolysin genes and urease activity among Vibrio parahaemolyticus strains were also investigated. The antimicrobial susceptibility profile of these strains was identified with selected antibiotics used in human medicine and aquaculture. The minimum inhibitory concentration of ampicillin, ceftiofur, gentamicin, neomycin,streptomycin, enrofloxacin, florfenicol, oxytetracycline and trimethoprimsulphamethoxazole was determined using broth microdilution method. Susceptibility to imipenem and detection of extended-spectrum β-lactamases (ESBLs) in ampicillin resistant strains was achieved by the combination disc diffusion method. The results showed that strains recovered from clinical sources (human and fish)produced the investigated potential virulence determinants, while these are absent in environmental strains. Such virulence factors may be involved in the pathogenesis of disease caused by these bacterial pathogens in both humans and animals. Moreover, antimicrobial resistance among environmental strains was rare. Acquired resistance to tetracycline and fluoroquinolone was demonstrated in Aeromonas strains of clinical origin and it could be possible that acquired resistance is associated with the use of antimicrobials in therapy

What has changed in canine pyoderma? A narrative review

Canine pyoderma is a common presentation in small animal practice and frequently leads to prescription of systemic antimicrobial agents. A good foundation of knowledge on pyoderma was established during the 1970s and 1980s, when treatment of infection provided relatively few challenges. However, the ability to treat canine pyoderma effectively is now limited substantially by the emergence of multidrug-resistant, methicillin-resistant staphylococci (MRS) and, in some countries, by restrictions on antimicrobial prescribing for pets. The threat from rising antimicrobial resistance and the zoonotic potential of MRS add a new dimension of public health implications to the management of canine pyoderma and necessitate a revisit and the search for new best management strategies. This narrative review focusses on the impact of MRS on how canine pyoderma is managed and how traditional treatment recommendations need to be updated in the interest of good antimicrobial stewardship. Background information on clinical characteristics, pathogens, and appropriate clinical and microbiological diagnostic techniques, are reviewed in so far as they can support early identification of multidrug-resistant pathogens. The potential of new approaches for the control and treatment of bacterial skin infections is examined and the role of owner education and hygiene is highlighted. Dogs with pyoderma offer opportunities for good antimicrobial stewardship by making use of the unique accessibility of the skin through cytology, bacterial culture and topical therapy. In order to achieve long term success and to limit the spread of multidrug resistance, there is a need to focus on identification and correction of underlying diseases that trigger pyoderma in order to avoid repeated treatment

Understanding the use of sex pilus specific bacteriophages to reduce conjugative dissemination of antibiotic resistance

Antimicrobial resistance (AMR) is considered as one of the greatest threats to human public health and in agriculture and food security. To address this threat, a Global Action Plan encourages development of alternatives to antibiotics, including the use of bacteriophage to control infections. A large proportion of transmissible antibiotic resistance is encoded on conjugative plasmids. Transmission requires sex pili and a sex pilus targeting (SPS) phage could provide a selection against plasmid carriage. The aim of this research is to isolate novel SPS phage to tackle AMR bacteria. Fifteen SPS phages were isolated, eleven were ssDNA phages in the Inoviridae family and four were ssRNA phages of the Leviviridae family. All phages were able to infect strains with the F plasmid but there was some phage plasmid specificity observed on different F like plasmid field isolates. Phylogenetic analysis of the 11 ssDNA phages genomes and protein pIII confirmed that they belong to genus Inovirus and are highly similar to filamentous (Ff) phages (M13, fd, f1). Three of the ssRNA phages were highly similar to genus Levivirus and the remaining ssRNA phage was similar to Allolevivirus. Two ssDNA phages R4 and R7, and ssRNA phage R13 represent a new species of Inovirus and Allolevivirus, respectively under ICVCN guidelines. All the phages demonstrated good stability under various conditions of temperature, pH and detergent. One step growth analysis and plasmid loss kinetics of selected ssDNA and ssRNA phages were tested against strains containing derepressed and repressed plasmids. Phage growth on derepressed plasmid hosts had a short latent period and large burst size compared to a longer latent period with shorter rise period and burst size observed on repressed plasmid hosts. Selected phages demonstrated ca. 60% plasmid loss on derepressed hosts. Selection was limited on more repressed plasmid hosts, with a minimum loss of 0% and a maximum loss of 14%. These results suggest that treatment with phage will have variable efficacy in reducing plasmid borne AMR and that repression may pose a limit on the effectiveness of this approach to treat or reduce infections by targeting the plasmids. However, further investigations are required to fully understand SPS phage impact under additional environmental selective conditions

Understanding the use of sex pilus specific bacteriophages to reduce conjugative dissemination of antibiotic resistance

Antimicrobial resistance (AMR) is considered as one of the greatest threats to human public health and in agriculture and food security. To address this threat, a Global Action Plan encourages development of alternatives to antibiotics, including the use of bacteriophage to control infections. A large proportion of transmissible antibiotic resistance is encoded on conjugative plasmids. Transmission requires sex pili and a sex pilus targeting (SPS) phage could provide a selection against plasmid carriage. The aim of this research is to isolate novel SPS phage to tackle AMR bacteria. Fifteen SPS phages were isolated, eleven were ssDNA phages in the Inoviridae family and four were ssRNA phages of the Leviviridae family. All phages were able to infect strains with the F plasmid but there was some phage plasmid specificity observed on different F like plasmid field isolates. Phylogenetic analysis of the 11 ssDNA phages genomes and protein pIII confirmed that they belong to genus Inovirus and are highly similar to filamentous (Ff) phages (M13, fd, f1). Three of the ssRNA phages were highly similar to genus Levivirus and the remaining ssRNA phage was similar to Allolevivirus. Two ssDNA phages R4 and R7, and ssRNA phage R13 represent a new species of Inovirus and Allolevivirus, respectively under ICVCN guidelines. All the phages demonstrated good stability under various conditions of temperature, pH and detergent. One step growth analysis and plasmid loss kinetics of selected ssDNA and ssRNA phages were tested against strains containing derepressed and repressed plasmids. Phage growth on derepressed plasmid hosts had a short latent period and large burst size compared to a longer latent period with shorter rise period and burst size observed on repressed plasmid hosts. Selected phages demonstrated ca. 60% plasmid loss on derepressed hosts. Selection was limited on more repressed plasmid hosts, with a minimum loss of 0% and a maximum loss of 14%. These results suggest that treatment with phage will have variable efficacy in reducing plasmid borne AMR and that repression may pose a limit on the effectiveness of this approach to treat or reduce infections by targeting the plasmids. However, further investigations are required to fully understand SPS phage impact under additional environmental selective conditions

Detection of Chlamydophila psittaci antibodies from captive birds at the Ninoy Aquino Parks and Wildlife Nature Center, Quezon city, Philippines

The present study was undertaken to detect the presence of Chlamydophila psittaci antibodies in captive birds at the Wildlife Rescue Center, Ninoy Aquino Parks and Wildlife Nature Center, Quezon City, Philippines. Blood was collected from 36 birds of different species and the presence of antibodies against C. psittaci was detected using an ELISA-based test kit. 25% of the samples demonstrated antibodies against C. psittaci. The results of this study confi rmed the presence of C. psittaci antibodies among the captive birds examined

Molecular typing and antimicrobial susceptibility of Vibrio parahaemolyticus strains

The aim of the present study was to use three PCR-based techniques for the analysis of genetic variability among Vibrio parahaemolyticus strains isolated from the Philippines. Seventeen strains of V. parahaemolyticus isolated from shrimps and from the environments where these shrimps are being cultivated were analyzed by RAPD, ERIC and REP-PCR. Antimicrobial susceptibility of these strains to selected compounds was investigated using broth microdilution method. Results of this work and analysis of similarity among strains using Dice coefficient and unweighted average pair group method have demonstrated genetic variability within the V. parahaemolyticus strains. The RAPD, ERIC and REP-PCR were found to be suitable typing methods for V. parahaemolyticus. They have good discriminative ability and can be used as rapid means of comparing these strains for epidemiological investigation. However, the REP-PCR analysis yielded a relatively small number of products suggesting that the REP sequences may not be widely distributed in the V. parahaemolyticus genome. Results of antimicrobial susceptibility revealed that resistance among the strains was rare. In conclusion, RAPD, ERIC and REP-PCR techniques are useful methods for molecular typing of V. parahaemolyticus strains. To our knowledge this is the first study of this kind carried out on V. parahaemolyticus strains isolated from the Philippines

Occurrence, characterisation and detection of potential virulence determinants of emerging aquatic bacterial pathogens from the Philippines and Thailand

Strains of Aeromonas spp., 'non-cholera vibrios' (NCVs) and Plesiomonas shigelloides isolated from aquatic environments, fish and human diarrhoeal cases in the Philippines and Thailand were characterised for potential virulence markers. Thus, the production of cytotoxin, cell-associated and cell-free haemolysin and their capacity to adhere to human intestinal (Henle 407) cells in vitro was investigated. In addition, the occurrence of tlh and tdh haemolysin genes and urease activity among V. parahaemolyticus strains was investigated. The results showed that strains recovered from clinical sources (human and fish) produced these virulence factors, whereas these are absent in environmental strains

Antimicrobial susceptibility of Aeromonas spp., Vibrio spp. and Plesiomonas shigelloides isolated in the Philippines and Thailand

Aeromonas spp., non-cholera vibrios (NCVs) and Plesiomonas shigelloides belong to the expanding group of water and food-borne pathogens. They are widely distributed in aquatic environments and are increasingly regarded as important pathogens of aquatic animals, causing significant economic losses in the aquaculture industry worldwide. In addition, these bacteria have been implicated as opportunistic pathogens, mainly causing gastroenteritis in humans. The occurrence and isolation of these bacteria from different sources has been reported in Asia, including the Philippines and Thailand. However, information on antimicrobial susceptibility of these isolates, especially those recovered from aquaculture and aquatic environments is scarce. The aim of this study was to acquire data on the occurrence of antimicrobial resistance among 38 strains of Aeromonas spp., NCVs and P. shigelloides isolated from different sources in the Philippines and Thailand. In addition, the production of extended-spectrum ß-lactamases (ESBLs) by selected strains was determined