Identification of plasmids from Brazilian Chromobacterium violaceum strains

Chromobacterium violaceum is an opportunistic pathogen found in tropical and subtropical regions worldwide. Chromobacterium violaceum infections are difficult to treat, and many strains are resistant to antibiotics. Recently, a novel plasmid (pChV1) was discovered in the type strain ATCC 12472, suggesting that other C. violaceum strains may harbor extra-chromosomal DNA. The aim of the present study was to detect and compare new plasmids in Brazilian strains of C. violaceum using next-generation sequencing techniques. We obtained draft genomes of six plasmids from strains isolated from the Amazon region and aligned them with pChV1. At least three plasmids, CVAC05, CVACO2, and CVT8, were similar to pChV1. Phylogenetic analysis suggested that these new extra-chromosomal DNA sequences have a common origin with pChV1 but have diverged. Many of the ORFs detected were related to plasmid segregation/maintenance, viral structural proteins, and proteins with unknown functions. These findings may enable better genetic manipulation of C. violaceum, which will enhance our ability to exploit this valuable microorganism in industrial and clinical applications.

[Field trial for eradication of methicillin- resistant Staphylococcus aureus (MRSA) in a pig breeding farm by bacteriophages]

INTRODUCTION

In recent years, Livestock Associated Methicillin-Resistant Staphylococcus aureus (LA-MRSA) are found frequently in pigs. The colonization of the care staff with LA-MRSA is strongly associated with the intensity and duration of animal contact and LA-MRSA herd prevalence. In human medicine, staphylococcal infections have been controlled successfully by topical or systemic administration of Staphylococcus - associated bacteriophages. Therefore, the present study investigated the effect of a bacteriophage cocktail on skin and mucosal colonization of pigs with MRSA in a pig farm with high MRSA prevalence. In a first experiment, the sows were washed with a bacteriophage cocktail and nose, mouth and vagina were rinsed before the sows were admitted to the farrowing house. Then, 10 ml of the bacteriophage cocktail was administered daily to the sows over the feed until weaning. The suckling piglets were sprayed and sampled twice a week during the suckling period and treated with the bacteriophage cocktail over the feed during the weaning period. In further experiments, the weaning room was nebulized three times a day with a bacteriophage cocktail and different concentrations of bacteriophages were added to the drinking water via Dosatron®. None of the experiments, however, showed an eradication of MRSA neither in nose nor in feces.

In vitro transduction of antimicrobial resistance genes into Escherichia coli isolates from backyard poultry in Mexico

The transmission of multidrug-resistant pathogens and antimicrobial resistance genes is an emerging problem involving multiple factors (humans, domestic animals, wildlife). The aim of this study was to investigate the presence of Escherichia coli isolates with different antimicrobial resistance genes from backyard poultry and to demonstrate the in vitro transduction phenomenon of these genes between phages from migratory wild birds and poultry E. coli isolates. We collected 197 E. coli isolates from chickens, turkeys, and ducks in backyard production units (northern region of the State of Mexico). Isolates were resistant to ampicillin (80.7%), tetracycline (64.4%), carbenicillin (56.3%), and nalidixic acid and trimethoprim-sulfamethoxazole (both, 26.9%). Moreover, the genes bla_TEM (56.3%), tetB (20.8%), tetA (19.2%), sulI (7.6%), sulII (10.1%), qnrA (9.6%), and qnrB (5.5%) were found. In vitro transduction using phages from migratory wild birds sampled in the wetland Chimaliapan (State of Mexico) was successfully achieved. It was possible to transduce qnrA, tetB, bla_TEM, and sulII genes to E. coli isolates from poultry. This is the first report that describes the transduction of antimicrobial resistance genes from phages of migratory wild birds to poultry and suggests the possible transmission in backyard production units.

Bacteriophages: the possible solution to treat infections caused by pathogenic bacteria

Since their discovery in 1915, bacteriophages have been used to treat bacterial infections in animals and humans because of their unique ability to infect their specific bacterial hosts without affecting other bacterial populations. The research carried out in this field throughout the 20th century, largely in Georgia, part of USSR and Poland, led to the establishment of phage therapy protocols. However, the discovery of penicillin and sulfonamide antibiotics in the Western World during the 1930s was a setback in the advancement of phage therapy. The misuse of antibiotics has reduced their efficacy in controlling pathogens and has led to an increase in the number of antibiotic-resistant bacteria. As an alternative to antibiotics, bacteriophages have become a topic of interest with the emergence of multidrug-resistant bacteria, which are a threat to public health. Recent studies have indicated that bacteriophages can be used indirectly to detect pathogenic bacteria or directly as biocontrol agents. Moreover, they can be used to develop new molecules for clinical applications, vaccine production, drug design, and in the nanomedicine field via phage display.

Feces of feedlot cattle contain a diversity of bacteriophages that lyse non-O157 Shiga toxin-producing Escherichia coli

This study aimed to isolate and characterize bacteriophages that lyse non-O157 Shiga toxin-producing Escherichia coli (STEC) from cattle feces. Of 37 non-O157 STEC-infecting phages isolated, those targeting O26 (AXO26A, AYO26A, AYO26B), O103 (AXO103A, AYO103A), O111 (AXO111A, AYO111A), O121 (AXO121A, AXO121B), and O145 (AYO145A, AYO145B) were further characterized. Transmission electron microscopy showed that the 11 isolates belonged to 3 families and 6 genera: the families Myoviridae (types rV5, T4, ViI, O1), Siphoviridae (type T5), and Podoviridae (type T7). Genome size of the phages as determined by pulsed-field gel electrophoresis ranged from 38 to 177 kb. Excluding phages AXO26A, AYO103A, AYO145A, and AYO145B, all other phages were capable of lysing more than 1 clinically important strain from serogroups of O26, O91, O103, O111, O113, O121, and O128, but none exhibited infectivity across all serogroups. Moreover, phages AYO26A, AXO121A, and AXO121B were also able to lyse 4 common phage types of STEC O157:H7. Our findings show that a diversity of non-O157 STEC-infecting phages are harbored in bovine feces. Phages AYO26A, AYO26B, AXO103A, AXO111A, AYO111A, AXO121A, and AXO121B exhibited a broad host range against a number of serogroups of STEC and have potential for the biocontrol of STEC in the environment.