Antimicrobial Susceptibility of Bacteria Isolated from Goat Milk in Sergipe - Brazil

Abstract

Background: Bacterial resistance is a fundamental aspect of One Health, which is defined as the inseparable unity of animal, human, and environmental health. Epidemiological surveillance on the spread of bacterial resistance in animals and their derived products is essential given that meat, milk, and dairy products can carry resistant microorganisms that may reach humans through the food chain either by direct consumption or by handling the product. To eliminate the scarcity of information, it is necessary to characterize the epidemiological situation in terms of bacterial resistance in dairy production in northeastern Brazil. Thus, the objective of this study was to determine the frequency and antimicrobial susceptibility profile of bacteria isolated from goat milk samples from some municipalities in the Brazilian state of Sergipe.
Materials, Methods & Results: The study included 28 goat farms in 4 municipalities of the Semiarid region of the State of Sergipe in Northeastern Brazil, namely Canindé de São Francisco (n = 11), Nossa Senhora da Glória (n = 6), Poço Verde (n = 6), and Porto da Folha (n = 5). All lactating does of each herd (n = 263) aged >1 year were, sampled randomly by non-probabilistic convenience sampling. Milk samples were collected from both teats, resulting in 526 samples in total.
Bacterial culturing and isolation were performed, followed by antimicrobial susceptibility profile analysis to the following active principles: amoxicillin with and without clavulanic acid, amikacin, ampicillin with sulbactam, ciprofloxacin, cefalexin, cefalotin, ceftriaxone, chloramphenicol, doxycycline, enrofloxacin, gentamicin, levofloxacin, ofloxacin, penicillin G, and tetracycline. A survey form was used to obtain zootechnical information for each farm. Data are described as absolute and relative frequencies. The significance assessment of the differences between herd characteristics and bacterial isolation was performed using Pearson's chi-squared test. Bacterial isolation occurred in 15.4% (81/526) of the samples from 23.2% (61/263) of the goats. Escherichia coli (45.9% = 28/61), Staphylococcus caprae (16.4% = 10/61) and Enterococcus faecalis (11.5% = 7/61), were the most frequently isolated species. Bacterial isolations were predominant in dairy herds with up to 50 animals, production of 20 to 50 L/day and in the municipality of Porto da Folha. In terms of antimicrobial susceptibility, most isolates demonstrated resistance to penicillin and amoxicillin (88.5%), followed by ceftriaxone (23%), ofloxacin (23%), tetracycline (23%), doxycycline (19.7%), chloramphenicol (11.5%), levofloxacin (11.5%), ampicillin/sulbactam (8.2%), amikacin (6.6%), cephalothin (4.9%), cephalexin (3.3%) and gentamicin (3.3%). Approximately 20% of the isolates were multidrug resistant, especially E. coli (50%) and S. aureus (16.7%).
Discussion: E. coli was the most frequently isolated species from the samples. It is considered an environmental pathogen, and its high frequency in different herds indicates poor milking hygiene. E. coli also stood out as the species presenting the most multidrug-resistant (MDR) isolates (50%), with strains resistant to beta-lactams, aminoglycosides, quinolones, tetracycline, and chloramphenicol. Coagulase-negative staphylococci are recognized as a public health problem as they are
etiological agents of various diseases and can easily acquire antimicrobial resistance genes. Although it was not the most frequently isolated species, S. aureus was the species with the second-highest frequency of MDR strains. The presence of MDR species is relevant and indicates the need for urgent action to reduce the dissemination of antimicrobial resistance. Relevant steps must be taken jointly by professionals involved in human, animal, and environmental health.

Keywords: animal product, antimicrobial resistance, goats, one health, surveillance.

Título: Susceptibilidade a antimicrobianos de bactérias isoladas de leite caprino em Sergipe - Brasil

Descritores: produto de origem animal, resistência antimicrobiana, caprinos, saúde única, vigilância.