Multidrug-resistant Escherichia coli and Tetracycline-resistant Enterococcus faecalis in wild raptors of Alabama and Georgia, USA

Wild birds inhabit in a wide variety of environments and can travel great distances. Thus, wild birds can possibly spread antimicrobial resistance along the way, and this may represent a potential public health concern. We characterized antimicrobial resistance in fecal Escherichia coli and Enterococcus faecalis in wild raptors in the southeastern US. Cloacal samples were collected from 118 wild raptors of 17 species from 18 counties in Alabama and 15 counties in Georgia. A total of 112 E. coli and 76 E. faecalis isolates were recovered, and we found significantly more antimicrobial-resistant E. coli (20/112, 18%) than E. faecalis (6/76, 8%; P = 0.05). Five antimicrobial-resistant genes: blaTEM-1, blaCTX-M-1, tet(M), cmlA, cat, and gyrA, were identified in antimicrobial-resistant E. coli isolates. Five of 13 (38%) ampicillin-resistant E. coli harbored both bla-TEM-1 and blaCTX-M-1 genes, indicating they are extended-spectrum beta-lactamase-carrying strains. Both of the tetracycline resistance genes, tet(M) and tet(L), were identified in E. faecalis isolates. Wild raptors seem to be a reservoir host of antimicrobial-resistant E. coli and E. faecalis and may represent a hazard to animal and human health by transmission of these isolates

Multidrug-resistant Escherichia coli, Klebsiella pneumoniae and Staphylococcus spp. in houseflies and blowflies from farms and their environmental settings

Background: Antimicrobial resistance is rising globally at an alarming rate. While multiple active surveillance programs have been established to monitor the antimicrobial resistance, studies on the environmental link to antimicrobial spread are lacking. Methods: A total of 493 flies were trapped from a dairy unit, a dog kennel, a poultry farm, a beef cattle unit, an urban trash facility and an urban downtown area to isolate Escherichia coli, Klebsiella pneumoniae and Staphylococcus spp. for antimicrobial susceptibility testing and molecular characterization. Results: E. coli, K. pneumoniae and coagulase-negative Staphylococcus were recovered from 43.9%, 15.5% and 66.2% of the houseflies, and 26.0%, 19.2%, 37.0% of the blowflies, respectively. In total, 35.3% of flies were found to harbor antimicrobial-resistant bacteria and 9.0% contained multidrug-resistant isolates. Three Staphylococcus aureus isolates were recovered from blowflies while three extended spectrum beta lactamase (ESBL)-carrying E. coli and one ESBL-carrying K. pneumoniae were isolated from houseflies. Whole genome sequencing identified the antimicrobial resistance genes bla(CMY-2) and bla(CTXM-1) as ESBLs. Conclusion: Taken together, our data indicate that flies can be used as indicators for environmental contamination of antimicrobial resistance. More extensive studies are warranted to explore the sentinel role of flies for antimicrobial resistance

Identification and characterization of mcr mediated colistin resistance in extraintestinal Escherichia coli from poultry and livestock in China

Antimicrobial resistance to colistin has emerged worldwide threatening the efficacy of one of the last-resort antimicrobials used for the treatment of multidrug-resistant Enterobacteriaceae infection in humans. In this study, we investigated the presence of colistin resistance genes (mcr-1, mcr-2, mcr-3) in Escherichia coli strains isolated from poultry and livestock collected between 2004 and 2012 in China. Furthermore, we studied the maintenance and transfer of the mcr-1 gene in E. coli after serial passages. Overall, 2.7% (17/624) of the E. coli isolates were positive for the mcr-1 gene while none were positive for the mcr-2 and mcr-3 genes. The prevalences of mcr-1 were similar in E. coli isolates from chickens (3.2%; 13/404), pigs (0.9%; 1/113) and ducks (6.8%; 3/44) but were absent in isolates from cattle (0/63). The mcr-1 gene was maintained in the E. coli after six passages (equivalent to 60 generations). In vitro transfer of mcr-1 was evident even without colistin selection. Our data indicate the presence of mcr-1 in extraintestinal E. coli from food-producing animals in China, and suggest that high numbers of the mcr-1-positive bacteria in poultry and livestock do not appear to be readily lost after withdrawal of colistin as a food additive

Development of a sustained-release voriconazole-containing thermogel for subconjunctival injection in horses

PURPOSE. To determine in vitro release profiles, transcorneal permeation, and ocular injection characteristics of a voriconazole-containing thermogel suitable for injection into the subconjunctival space (SCS). METHODS. In vitro release rate of voriconazole (0.3% and 1.5%) from poly (DL-lactide-coglycolide-b-ethylene glycol-b-DL-lactide-co-glycolide) (PLGA-PEG-PLGA) thermogel was determined for 28 days. A Franz cell diffusion chamber was used to evaluate equine transcorneal and transscleral permeation of voriconazole (1.5% topical solution, 0.3% and 1.5% voriconazole-thermogel) for 24 hours. Antifungal activity of voriconazole released from the 1.5% voriconazole-thermogel was determined via the agar disk diffusion method. Ex vivo equine eyes were injected with liquid voriconazole-thermogel (4°C). Distension of the SCS was assessed ultrasonographically and macroscopically. SCS voriconazole-thermogel injections were performed in a horse 1 week and 2 hours before euthanasia and histopathologic analysis of ocular tissues performed. RESULTS. Voriconazole was released from the PLGA-PEG-PLGA thermogel for more than 21 days in all groups. Release followed first-order kinetics. Voriconazole diffused through the cornea and sclera in all groups. Permeation was greater through the sclerae than corneas. Voriconazole released from the 1.5% voriconazole-thermogel showed antifungal activity in vitro. Voriconazole-thermogel was easily able to be injected into the dorsal SCS where it formed a discrete gel deposit. Voriconazole-thermogel was easily injected in vivo and did not induce any adverse reactions. CONCLUSIONS. Voriconazole-containing thermogels have potential application in treatment of keratomycosis. Further research is required to evaluate their performance in vivo

Passive protection against anthrax in mice with plasma derived from horses hyper-immunized against Bacillus anthracis Sterne strain

In this study, equine source polyclonal anti-Bacillus anthracis immunoglobulins were generated and utilized to demonstrate passive protection of mice in a lethal challenge assay. Four horses were hyper-immunized with B. anthracis Sterne strain for approximately one year. The geometric mean anti-PA titer in the horses at maximal response following immunization was 1:77,936 (Log2 mean titer 16.25, SEM ± 0.25 95% CI [15.5 –17.0]). The geometric mean neutralizing titer at maximal response was 1:128 (Log2 mean titer 7, SEM ± 0.0, 95% CI 7). Treatment with hyper-immune plasma or purified immunoglobulins was successful in passively protecting A/J mice from a lethal B. anthracis Sterne strain challenge. The treatment of mice with hyper-immune plasma at time 0 h and 24 h post-infection had no effect on survival, but did significantly increase mean time to death (p < 0.0001). Mice treated with purified immunoglobulins at time 0 h and 24 h post-infection in showed significant increase in survival rate (p < 0.001). Bacterial loads in lung, liver and spleen tissue were also assessed and were not significantly different in mice treated with hyper-immune plasma from placebo treated control mice. Mice treated with purified antibodies demonstrated mean colony forming units/gram tissue fourfold less than mice receiving placebo treatment (p < 0.0001). Immunotherapeutics harvested from horses immunized against B. anthracis Sterne strain represent a rapidly induced, inexpensive and effective expansion to the arsenal of treatments against anthrax

Experimental inoculation of house flies Musca domestica with Corynebacterium pseudotuberculosis biovar equi

Corynebacterium pseudotuberculosis (Actinomycetales Corynebacteriaceae) infection in horses causes three different disease syndromes: external abscesses, infection of internal organs and ulcerative lymphangitis. The exact mechanism of infection in horses remains undetermined, but transmission by insect vectors is suspected. The present study first determined the optimal culture media for inoculation of house flies (Musca domestica L.) (Diptera Muscidae), with C. pseudotuberculosis biovar equi and the time required for fly inoculation. A second experiment determined the duration of bacterial survival on flies. Exposure of house flies to 3 different preparations of blood agar supplemented with dextrose and colonized with C. pseudotuberculosis determined that a 10 minute exposure to the bacteria was enough to inoculate the flies. C. pseudotuberculosis could be recovered for up to 24 hours after house flies were exposed for 30 minutes to a blood agar plate colonized with the bacteria and moistened with 10% dextrose. These findings support the hypothesis that the house fly is a potential vector of pigeon fever and aid in establishing a protocol for a future experimental model to demonstrate the role of house flies as mechanical vectors in C. Pseudotuberculosis infection