Optimizing antimicrobial use by improving medication adherence among pig producers.

In Japan, many pig producers buy antimicrobials using veterinarians' prescriptions. Even if veterinarians prescribe antimicrobials for treatments and metaphylaxis, producers may be using them for prophylaxis on farms with a high incidence of chronic diseases. To reduce the frequency of antimicrobial use, we applied the concept of medication adherence and launched an intervention in eight farrow-to-finish farms. For the intervention farms, we attempted to implement measures for preventing the repeated onset of chronic infections that interfered with adherence, confirmed the need to continue medications, and discontinued medications if possible. For each farm, these interventions began at different time points after 2017 and continued until 2020. We evaluated the effectiveness of this intervention based on the amount of active ingredients/population correction unit and the total number of defined daily doses for the weight group/slaughter pig. The ratio of antimicrobial use for both indicators in the year 2020 compared with the start of the intervention decreased on all farms. Among the eight non-intervention farms, six showed an increase in both indicators. These results suggest that interventions for chronic diseases administered by producers and veterinarians lead to high adherence to prescriptions and responsible and prudent use of antimicrobials on pig farms.

Indications and patterns of antimicrobial use in pig farms in the southern Kyushu, Japan: large amounts of tetracyclines used to treat respiratory disease in post-weaning and fattening pigs.

In Japan, reducing the use of antimicrobials in pig production is a significant issue. However, there are no published reports concerning porcine disease treatment, as related to the age of the pigs and the indications (e.g., organ system) in Japan. In this study, we analyzed the prescription records of 17 farrow-to-finish farms from 2014 to 2018 in southern Kyushu, Japan. The farms' antimicrobial usage was calculated as the active ingredient per population correction unit (PCU) or the number of treated pigs per PCU using the defined daily dose. All data were analyzed according to the indications and production stages (sows, suckling pigs, post-weaning pigs, and fattening pigs). In terms of active ingredients/PCU, tetracyclines were the most commonly used (43.2-59.3%), and the largest amounts of antimicrobials administered through feeds were for treating the respiratory organs of fattening pigs. In terms of the number of treated pigs/PCU, tetracyclines were most frequently used (16.3-31.1%), and a high frequency of antimicrobials administered through feeds was used for the treatment of respiratory organs in post-weaning pigs. In this study, it was confirmed that tetracyclines were used frequently as a herd treatment for respiratory diseases in post-weaning and fattening pigs in southern Kyushu, Japan. The findings suggest that it is necessary to improve the treatment and prevention of respiratory diseases in post-weaning and fattening pigs in order to reduce the frequencies of antimicrobial treatments.

Assessment of reproductive and growth performance of pigs on commercial swine farms in southern Kyushu, Japan.

The objective of the present study was to assess the productivity of pigs to investigate the time-dependent change in productivity and compare productivity according to breeding company group and porcine reproductive and respiratory syndrome (PRRS) status on commercial swine farms in southern Kyushu, Japan. Data used in the present study were 245 annual productivity records from 2014 to 2018 obtained from 72 farms. Average sow inventory was 481.2 sows. Mean numbers of pigs weaned per sow per year and market pigs sold per sow per year were 23.7 and 21.6, respectively. Pigs born alive per litter increased from 11.1 to 11.9 pigs from 2014 to 2018 (p < .05). Farms using domestic breeding companies had similar numbers in 2016 to those using international breeding companies, but fewer pigs in 2014, 2015, 2017, and 2018 (p < .05). Farms with an unknown or unstable PRRS status had fewer pigs born alive per litter and pigs weaned per sow per year than those with stable or negative PRRS statuses (11.2 ± 0.06 vs. 11.8 ± 0.08 pigs and 22.6 ± 0.38 vs. 25.0 ± 0.22 pigs, respectively; p < .05). These results can be used to establish feasible targets and standards of performance to identify problem areas and improve production.

Antimicrobial resistance profiles and phylogenetic groups of Escherichia coli isolated from healthy Thoroughbred racehorses in Japan.

In this study, we investigated the occurrence of antimicrobial resistance in commensal Escherichia coli isolated from healthy Thoroughbred (TB) racehorses in Japan. A total of 212 fecal samples were individually collected from TB racehorses from March 2017 to August 2018 at Japan Racing Association training centers. E. coli was isolated by using selective agar media, deoxycholate-hydrogen sulfide-lactose (DHL) and eosin methylene blue (EMB). A total of 417 E. coli isolates were examined against 10 antimicrobial agents by using the broth microdilution method. The 417 E. coli isolates were phylogenetically grouped using a multiplex polymerase chain reaction. The highest proportion of resistance was observed for streptomycin (30.9%, 129/417) followed by ampicillin (19.4%, 81/417), trimethoprim (15.8%, 66/417), tetracycline (8.4%, 35/417), chloramphenicol (2.6%, 11/417), kanamycin (1.2%, 5/417), nalidixic acid (0.5%, 2/417), cefazolin (0.2%, 1/417), colistin (0.2%, 1/417), and gentamycin (0%). Multidrug-resistant (MDR) E. coli was detected in 7.9% (33/417) of isolates. The proportions of resistance against ampicillin, streptomycin, kanamycin, and chloramphenicol and of multidrug-resistant phenotypes in E. coli belonging to phylogenetic group B2 were significantly higher than those of other groups. This study clarified the distribution of antimicrobial-resistant (AMR) E. coli in Japanese racehorses. A continuous monitoring program for antimicrobial resistance is required to control the spread of AMR bacteria in racehorses.

Antimicrobial-Resistant Enterococcus faecium and Enterococcus faecalis Isolated From Healthy Thoroughbred Racehorses in Japan.

In this study, the occurrence of antimicrobial-resistant (AMR) enterococci was evaluated in Thoroughbred (TB) racehorses in Japan. Fecal samples were collected from 212 healthy TB racehorses at the Miho and Ritto Training Centers of the Japan Racing Association from March 2017 to August 2018. Isolation and identification were performed by enterococcus selective medium and confirmed to the species using MALDI-TOF MS. Enterococcus faecium and E. faecalis isolates were subjected to antimicrobial susceptibility test against 11 antimicrobials by minimum inhibitory concentration based on recommendation from Clinical and Laboratory Standards Institute guidelines. Among 583 enterococcus isolates, E. faecium and E. faecalis were identified for 48.2% (281/583) and 7.4% (43/583), respectively. One isolate that was representing E. faecium (153 isolates) and E. faecalis (31 isolates) from each sample was selected for antimicrobial susceptibility test. The highest rate of resistance for E. faecium isolates was observed against enrofloxacin (57.5%; 88/153), followed by streptomycin (32.0%; 49/153), kanamycin (18.3%; 28/153), gentamycin (5.9%; 9/153), erythromycin (5.9%; 9/153), and oxytetracycline (4.6%; 7/153). For E. faecium isolates, the highest resistance was observed against streptomycin (90.3%; 28/31), followed by kanamycin (41.9%; 13/31), gentamycin (29.0%; 9/31), lincomycin (9.7%; 3/31), oxytetracycline (6.5%; 2/31), erythromycin (6.5%; 2/31), tylosin (6.5%; 2/31), enrofloxacin (6.5%; 2/31), and chloramphenicol (3.2%; 1/31). The results indicated that enrofloxacin and aminoglycosides were highly resistant among tested antimicrobials. Continuous monitoring studies are useful to increase the awareness of the potential for AMR bacteria to arise from imprudent use of antimicrobials in TB racehorses in Japan.