Antimicrobial resistance in bacteria isolated from pigs with respiratory clinical signs in Brazil

Abstract

Antimicrobial resistance is a current and important issue to public health, and it is usually associated with the indiscriminate use of antimicrobials in animal production. This study aimed to evaluate the antimicrobial susceptibility profile in bacterial isolates from pigs with clinical respiratory signs in Brazil. One hundred sixty bacterial strains isolated from pigs from 51 pig farms in Brazil were studied. In vitro disk-diffusion method was employed using 14 antimicrobial agents: amoxicillin, penicillin, ceftiofur, ciprofloxacin, enrofloxacin, chlortetracycline, doxycycline, oxytetracycline, tetracycline, erythromycin, tilmicosin, florfenicol, lincomycin, and sulfadiazine/trimethoprim. The majority of isolates were resistant to at least one antimicrobial agent (98.75%; 158/160), while 31.25% (50/160) of the strains were multidrug resistant. Streptococcus suis and Bordetella bronchiseptica were the pathogens that showed higher resistance levels. Haemophilus parasuis showed high resistance levels to sulfadiazine/trimethoprim (9/18=50%). We observed that isolates from the midwestern and southern regions exhibited four times greater chance of being multidrug resistant than the isolates from the southeastern region studied. Overall, the results of the present study showed a great level of resistance to lincomycin, erythromycin, sulfadiazine/trimethoprim, and tetracycline among bacterial respiratory pathogens isolated from pigs in Brazil. The high levels of antimicrobial resistance in swine respiratory bacterial pathogens highlight the need for the proper use of antimicrobials in Brazilian pig farms.

Assessment of animal diseases caused by bacteria resistant to antimicrobials: Swine

“…For tetracycline, one Chinese study reported only 3.6% resistance (Zhou et al, 2010). Figure 27 indicates that even lower levels of resistance to tetracycline were detected in a Brazilian study (Serpa et al, 2020) and in a study on isolates from several European countries (El Garch et al, 2016). Importantly, the latter two studies would have had proportions of 57.1% and 47.7% if %R+I had been reported instead of %R.…”

“…For sulfonamides‐trimethoprim , the highest continent‐specific proportion of resistance (40.5%) was observed in South America, although based on only 42 isolates in one study from Brazil (Serpa et al., 2020 ). The lowest level of resistance was observed in Oceania represented by Australia (0.7% of 148 isolates).…”

“…Also for fluoroquinolones, it is not completely fair to compare studies reporting %R with studies reporting %R + I. This is exemplified by Serpa et al (2020) who found 11.8% resistance to enrofloxacin, but by adding the intermediate category, this percentage would increase to 18.9%.…”