RESUMEN

This study aimed to assess the efficacy of a multi-hurdle process combining mild High Hydrostatic Pressure (HHP) treatments and Thyme Oil (TO) edible films as a non-thermal method to combat pathogenic E. coli (aEPEC and STEC) in raw cow's-milk cheese stored at 7 °C and packaged under modified atmosphere. Changes in headspace atmosphere of cheese packs and treatment effects on Lactic Acid Bacteria (LAB) counts and diarrheagenic E. coli strains (aEPEC and STEC) were evaluated over a 28 d storage period. The results demonstrated that the combined treatment exhibited the most significant antimicrobial effect against both strains compared to individual treatments, achieving reductions of 4.30 and 4.80 log cfu/g after 28 d of storage for aEPEC and STEC, respectively. Notably, the synergistic effect of the combination treatment resulted in the complete inactivation of intact cells for STEC and nearly completed inactivation for aEPEC by the end of the storage period. These findings suggest that the combination of HHP with selected hurdles could effectively enhance microbial inactivation capacity, offering promising alternatives for improving cheese safety without affecting the starter microbiota.

Asunto(s)

Queso , Thymus (Planta) , Queso/microbiología , Animales , Thymus (Planta)/química , Presión Hidrostática , Microbiología de Alimentos , Recuento de Colonia Microbiana , Conservación de Alimentos/métodos , Escherichia coli/efectos de los fármacos , Escherichia coli/crecimiento & desarrollo , Bovinos , Leche/microbiología

RESUMEN

This study describes an outbreak of Streptococcus equi subspecies zooepidemicus infections that caused meningoencephalitis and bacteremia related to unpasteurized milk consumption in northeastern Brazil. Epidemiological investigations and a brief literature review were conducted. Strains with possible neurotropism had not been identified in Brazil before these cases; however, in 2023, another case of meningoencephalitis caused by Streptococcus equi sp. zooepidemicus was described, revealing the need to maintain surveillance and highlighting that these neurotropic strains continue to circulate in the environment.

Asunto(s)

Brotes de Enfermedades , Meningoencefalitis , Infecciones Estreptocócicas , Streptococcus equi , Meningoencefalitis/microbiología , Brasil/epidemiología , Infecciones Estreptocócicas/microbiología , Humanos , Streptococcus equi/aislamiento & purificación , Streptococcus equi/clasificación , Masculino , Animales , Femenino , Adulto , Leche/microbiología , Persona de Mediana Edad , Streptococcus

RESUMEN

BACKGROUND: Throughout a three-year study period, 1,577 bovine clinical mastitis samples and 302 bulk tank samples were analyzed from ten Brazilian dairy herds. Enterococcus spp. was isolated and identified in 93 (5.9%) clinical mastitis samples. In addition, 258 Enterococcus spp. were isolated from the bulk tank samples of the same herds. The identification of Enterococcus spp. isolated from bulk tanks and milk samples of clinical mastitis were accomplished by phenotypic characteristics and confirmed by MALDI-TOF Mass Spectrometry (MS). Fisher test was performed to verify the difference between bulk tanks and mastitis samples. RESULTS: The following species were identified from clinical mastitis: E. saccharolyticus (62.4%), E. faecalis (19.4%), E. faecium (15.1%), E. hirae (1.1%), E. mundtii (1.1%), E. durans (1.1%). Furthermore, from 258 bulk tank milk samples, eight enterococci species were isolated: E. faecalis (67.8%), E. hirae (15.1%), E. faecium (4.6%), E. saccharolyticus (4.6%), E. mundtii (3.1%), E. caseliflavus ( 2.7%), E. durans (1.2%), E. galinarum (0.8%). CONCLUSIONS: The difference in species predominance in bulk tank samples (67.8% of E. faecalis) and clinical mastitis (62.4% of E. saccharolyticus) was unexpected and caught our attention. Although Enterococcus spp. are traditionally classified as an environmental mastitis agent, in the present study, E. saccharolyticus behaved as a contagious agent of mastitis, which consequently changed the control patterns to be implemented.

Asunto(s)

Enterococcus , Mastitis Bovina , Leche , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Mastitis Bovina/microbiología , Mastitis Bovina/diagnóstico , Animales , Leche/microbiología , Leche/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/veterinaria , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Femenino , Enterococcus/aislamiento & purificación , Bovinos , Brasil , Infecciones por Bacterias Grampositivas/veterinaria , Infecciones por Bacterias Grampositivas/microbiología , Infecciones por Bacterias Grampositivas/diagnóstico

RESUMEN

Staphylococcus aureus is a well-known pathogen capable of producing enterotoxins during bacterial growth in contaminated food, and the ingestion of such preformed toxins is one of the major causes of food poisoning around the world. Nowadays 33 staphylococcal enterotoxins (SEs) and SE-like toxins have been described, but nearly 95% of confirmed foodborne outbreaks are attributed to classical enterotoxins SEA, SEB, SEC, SED, and SEE. The natural habitat of S. aureus includes the skin and mucous membranes of both humans and animals, allowing the contamination of milk, its derivatives, and the processing facilities. S. aureus is well known for the ability to form biofilms in food processing environments, which contributes to its persistence and cross-contamination in food. The biocontrol of S. aureus in foods by lactic acid bacteria (LAB) and their bacteriocins has been studied for many years. Recently, LAB and their metabolites have also been explored for controlling S. aureus biofilms. LAB are used in fermented foods since in ancient times and nowadays characterized strains (or their purified bacteriocin) can be intentionally added to prolong food shelf-life and to control the growth of potentially pathogenic bacteria. Regarding the use of these microorganism and their metabolites (such as organic acids and bacteriocins) to prevent biofilm development or for biofilm removal, it is possible to conclude that a complex network behind the antagonistic activity remains poorly understood at the molecular level. The use of approaches that allow the characterization of these interactions is necessary to enhance our understanding of the mechanisms that govern the inhibitory activity of LAB against S. aureus biofilms in food processing environments.

Asunto(s)

Biopelículas , Enterotoxinas , Microbiología de Alimentos , Staphylococcus aureus , Staphylococcus aureus/fisiología , Enterotoxinas/metabolismo , Humanos , Animales , Lactobacillales/fisiología , Lactobacillales/metabolismo , Industria Lechera , Bacteriocinas/metabolismo , Contaminación de Alimentos/prevención & control , Leche/microbiología

RESUMEN

The objective of the study was to evaluate the frequency and genetic characteristics of ESBL-producing Escherichia coli and Klebsiella spp. and the risk factors associated with a high total bacterial count in bulk tank milk samples of dairy farms in three municipalities of the Antioquia Department, Colombia. Fifteen samples were positive for E. coli and Klebsiella spp. Subsequent analysis of the 16 S rRNA gene sequences confirmed these isolates included E. coli (n = 3), K. oxytoca (n = 11), and K. pneumoniae (n = 1). None of the isolates was positive for ESBL identification by phenotypic methods, but the only the isolate of K. pneumoniae was positive for the blaSHV61 gene by sequence analysis. The antibiotic susceptibility evaluation for all Klebsiella spp. isolates identified resistance to fosfomycin (50%; 6/12) and ampicillin (100%; 12/12). While most of the herds maintain adequate hygienic quality, specific risk factors such as having more than 60 milking cows, frequent changes in milkers, milking in paddocks, and using a chlorinated product for pre-dipping have been identified as associated with a high total bacterial count > 100,000 CFU/mL in bulk tank milk. However, certain variables including the milker being the owner of the animals and the proper washing and disinfection of the milking machine contribute to maintain a high level of hygiene and quality in the raw milk stored in the tanks. In conclusion, the frequency of ESBL producers was relatively low, with only K. pneumoniae testing positive for the blaSHV ESBL type. The presence of these bacteria in milk tanks represents a potential risk to public health for consumers of raw milk and its derivatives.

Asunto(s)

Antibacterianos , Klebsiella pneumoniae , Leche , beta-Lactamasas , Animales , Leche/microbiología , Colombia , beta-Lactamasas/genética , beta-Lactamasas/metabolismo , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/aislamiento & purificación , Klebsiella pneumoniae/efectos de los fármacos , Klebsiella pneumoniae/enzimología , Factores de Riesgo , Bovinos , Antibacterianos/farmacología , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Escherichia coli/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Carga Bacteriana , Infecciones por Klebsiella/microbiología , Infecciones por Klebsiella/epidemiología , Infecciones por Klebsiella/veterinaria , Industria Lechera , Granjas , Femenino

RESUMEN

An actinobacteria strain was isolated from an olive waste mill and tested for protease production on skimmed milk media. The strain identification was achieved through both 16 S rDNA sequencing and phenotypic characterization. The enzyme was purified using the ammonium sulfate/t-butanol three-phase partitioning (TPP) method, followed by characterization to investigate the effect of pH, temperature, and various chemical agents. Subsequently, the enzyme was assessed for its milk coagulation activity. The strain belonging to the Streptomyces genera, exhibits significant phylogenetic and phenotypic differences from the aligned species, suggesting its novelty as a new strain. The enzyme was best separated in the TPP aqueous phase with a 5.35 fold and 56.25% yield. Optimal activity was observed at pH 9.0 and 60 °C, with more than half of the activity retained within the pH range of 7-10 over one hour. The protease demonstrated complete stability between 30 and 60 °C. While metallic ions enhanced enzyme activity, EDTA acted as an inhibitor. The enzyme displayed resistance to H2O2, SDS, Tween 80, and Triton X-100. Notably, it was activated in organic solvents (ethyl acetate, petroleum ether, and xylene), maintaining > 75% of its original activity in butanol, ethanol, and methanol. Additionally, the enzyme yielded high milk coagulant activity of 11,478 SU/mL. The new Streptomyces sp. protease revealed high activity and stability under a wide range of biochemical conditions. Its use in the dairy industry appears particularly promising. Further industrial process investigations will be valuable in determining potential uses for this enzyme.

Asunto(s)

Estabilidad de Enzimas , Leche , Péptido Hidrolasas , Filogenia , Streptomyces , Temperatura , Streptomyces/aislamiento & purificación , Streptomyces/enzimología , Streptomyces/genética , Streptomyces/clasificación , Leche/microbiología , Animales , Concentración de Iones de Hidrógeno , Péptido Hidrolasas/metabolismo , Péptido Hidrolasas/aislamiento & purificación , Péptido Hidrolasas/química , Péptido Hidrolasas/genética , Proteínas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Proteínas Bacterianas/química , Proteínas Bacterianas/aislamiento & purificación , ARN Ribosómico 16S/genética

RESUMEN

In the present study, the effect of xanthan gum was evaluated on the metabolic activity and survival of two probiotic strains, namely B. lactis and L. casei using in vitro assay and skim milk model system. In vitro assay was carried out identifying by pH, optical cell density (OD), and formation of postbiotics (lactic, acetic, propionic, and butyric acids) in different basal media including glucose, inulin, and xanthan gum as carbon source. The highest pH values were recorded for control (without carbon source) and media with xanthan gum, whereas the media with glucose and xanthan gum had the highest OD values. In comparison to strains, B. lactis had higher pH and lower OD values than L. casei. It was found that xanthan gum supported the formation of postbiotics as a result of bacterial fermentation. In the skim milk model system, xanthan gum did not negatively affect probiotic viability, and the counts of both strains were above the required level for health benefits (8 log cfu g-1) after 28-day storage. The use of xanthan gum in skim milk matrix positively affected techno-functional properties such as syneresis, color, and textural parameters of samples.

Asunto(s)

Leche , Polisacáridos Bacterianos , Probióticos , Polisacáridos Bacterianos/farmacología , Animales , Leche/química , Leche/microbiología , Lacticaseibacillus casei/efectos de los fármacos , Bifidobacterium animalis , Concentración de Iones de Hidrógeno , Fermentación

RESUMEN

Staphylococcus aureus is one of the primary pathogenic agents found in cheeses produced with raw milk. Some strains of S. aureus are enterotoxigenic, possessing the ability to produce toxins responsible for staphylococcal food poisoning when present in contaminated foods. This study aimed to genotypically characterize, assess the antimicrobial resistance profile, and examine the enterotoxigenic potential of strains of S. aureus isolated from artisanal colonial cheese. Additionally, a bacterial diversity assessment in the cheeses was conducted by sequencing the 16S rRNA gene. The metataxomic profile revealed the presence of 68 distinct species in the cheese samples. Fifty-seven isolates of S. aureus were identified, with highlighted resistance to penicillin in 33% of the isolates, followed by clindamycin (28%), erythromycin (26%), and tetracycline (23%). The evaluated strains also exhibited inducible resistance to clindamycin, with nine isolates considered multidrug-resistant (MDR). The agr type I was the most prevalent (62%) among the isolates, followed by agr type II (24%). Additionally, ten spa types were identified. Although no enterotoxins and their associated genes were detected in the samples and isolates, respectively, the Panton-Valentine leukocidin gene (lukS-lukF) was found in 39% of the isolates. The presence of MDR pathogens in the artisanal raw milk cheese production chain underscores the need for quality management to prevent the contamination and dissemination of S. aureus strains.

Asunto(s)

Antibacterianos , Queso , Leche , Staphylococcus aureus , Queso/microbiología , Brasil , Leche/microbiología , Animales , Staphylococcus aureus/efectos de los fármacos , Antibacterianos/farmacología , Pruebas de Sensibilidad Microbiana , Virulencia , Microbiología de Alimentos , Humanos , Farmacorresistencia Bacteriana , Contaminación de Alimentos/análisis , Enterotoxinas/genética

RESUMEN

In herds of dairy goats, mastitis represents a major health and economic problem due to the multiresistance of some microorganisms. In this context, the study aimed to determine the potential of antimicrobial action and antibiofilm of the crude ethanolic extract (CEE) of Hymenaea martiana (jatobá) leaves, as well its fractions, on Staphylococcus sp isolated from bacterial cultures of goat milk. In vitro assays were performed to determine the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC), as well as tests of the effect of CEE on biofilm formation and quantification and the consolidated biofilm. The experimental infection was performed in two groups, each consisting of five goat. Experimental Group 1 (G1) consisted of five females treated with an intramammary ointment based on the CEE, at a concentration of 5%. Experimental Group 2 (G2) consisted of five females treated with a commercial intramammary ointment based on gentamicin, once a day, for six consecutive days. The diagnosis of mastitis was performed using a bacterial culture. The dichloromethane fraction of CEE was the one with the lowest concentrations of MBC, ranging from 195.3 to 781 µg / ml. Concerning to the biofilm, interference of the tested extract was observed for two isolates. In the present study, the ointment prepared from H. martiana extract (jatobá) was able to reduce bacterial infection in mammary glands experimentally infected with S. aureus. Antibacterial activity may be related to the classes of secondary metabolites found.

Asunto(s)

Antibacterianos , Biopelículas , Enfermedades de las Cabras , Cabras , Mastitis , Pruebas de Sensibilidad Microbiana , Extractos Vegetales , Infecciones Estafilocócicas , Staphylococcus aureus , Animales , Femenino , Enfermedades de las Cabras/tratamiento farmacológico , Enfermedades de las Cabras/microbiología , Infecciones Estafilocócicas/veterinaria , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/fisiología , Mastitis/veterinaria , Mastitis/tratamiento farmacológico , Mastitis/microbiología , Pruebas de Sensibilidad Microbiana/veterinaria , Antibacterianos/farmacología , Antibacterianos/administración & dosificación , Extractos Vegetales/farmacología , Extractos Vegetales/administración & dosificación , Biopelículas/efectos de los fármacos , Leche/microbiología , Hojas de la Planta/química

RESUMEN

Paratuberculosis (PTBC) is a chronic intestinal disease of animals caused by Mycobacterium avium paratuberculosis (MAP). MAP infection is diagnosed through indirect tests based on the immune response. The aims of this study were to compare the performance of two milk ELISA for the diagnosis of PTBC and to assess the bulk tank milk (BTM) MAP exposure in dairy cattle in Argentina. A total of 357 fecal, serum, and milk samples were collected. The fecal samples were processed by culture for MAP isolation, while both, serum and milk samples were used for the detection of antibodies by two different ELISA tests, "in-house" and commercial kit. MAP was isolated in 3.9% of fecal samples. For milk ELISA, poor concordances were obtained. Optimized cut-off points were calculated. The highest sensitivity and specificity values (64% and 80% respectively) were obtained with the combination of MAP isolation and commercial milk ELISA. The results indicate that the combination of different techniques to identify of dairy cattle infected with MAP increases the efficiency of diagnosis. In addition, BTM  samples (n=98) were evaluated to determine herd status using the commercial kit during two seasons, identifying 33.3% of positive samples in autumn and 35.4% in spring.

Asunto(s)

Enfermedades de los Bovinos , Mycobacterium avium subsp. paratuberculosis , Paratuberculosis , Bovinos , Animales , Paratuberculosis/diagnóstico , Paratuberculosis/microbiología , Leche/microbiología , Enfermedades de los Bovinos/diagnóstico , Enfermedades de los Bovinos/microbiología , Ensayo de Inmunoadsorción Enzimática/veterinaria , Sensibilidad y Especificidad , Heces/microbiología

RESUMEN

The present study aimed to assess the occurrence and counts of Staphylococcus aureus in Brazilian artisanal cheeses (BAC) produced in five regions of Brazil: Coalho and Manteiga (Northeast region); Colonial and Serrano (South); Caipira (Central-West); Marajó (North); and Minas Artisanal cheeses, from Araxá, Campos das Vertentes, Cerrado, Serro and Canastra microregions (Southeast). The resistance to chlorine-based sanitizers, ability to attach to stainless steel surfaces, and antibiogram profile of a large set of S. aureus strains (n = 585) were assessed. Further, a total of 42 isolates were evaluated for the presence of enterotoxigenic genes (sea, seb, sec, sed, see, seg, sei, sej, and ser) and submitted to typing using pulsed-field gel electrophoresis (PFGE). BAC presented high counts of S. aureus (3.4-6.4 log CFU/g), varying from 25 to 62.5%. From the S. aureus strains (n = 585) assessed, 16% could resist 200 ppm of sodium hypochlorite, whereas 87.6% produced strong ability to attach to stainless steel surfaces, corroborating with S. aureus ability to persist and spread in the environment. Furthermore, the relatively high frequency (80.5%) of multidrug-resistant S. aureus and the presence of enterotoxin genes in 92.6% of the strains is of utmost attention. It reveals the lurking threat of SFP that can survive when conditions are favorable. The presence of enterotoxigenic and antimicrobial-resistant strains of S. aureus in cheese constitutes a potential risk to public health. This result calls for better control of cheese contamination sources, and taking hygienic measures is necessary for food safety. More attention should be paid to animal welfare and hygiene practices in some dairy farms during manufacturing to enhance the microbiological quality of traditional cheese products.

Asunto(s)

Queso , Staphylococcus aureus Resistente a Meticilina , Infecciones Estafilocócicas , Animales , Staphylococcus aureus/genética , Queso/microbiología , Brasil , Microbiología de Alimentos , Acero Inoxidable/análisis , Enterotoxinas/genética , Leche/microbiología

RESUMEN

Mastitis is the most common disease of dairy cattle and can be manifested in clinical and subclinical forms. The overuse of antimicrobials in the treatment and prevention of mastitis favours antimicrobial resistance and milk can be a potential route of dissemination. This study aimed to evaluate the biological quality of bulk tank milk (BTM) and the microbiological quality and signs of mastitis of freshly milked raw milk. In addition, to evaluate antimicrobial resistance in Enterobacteriaceae and Staphylococcus spp. isolated from freshly milked raw milk. None of the farms were within the official Brazilian biological quality limits for BTM. Freshly milked raw milk with signs of clinical (CMM), subclinical (SCMM) and no signs (MFM) of mastitis were detected in 6.67%, 27.62% and 65.71% samples, respectively. Most samples of freshly milked raw milk showed acceptable microbiological quality, when evaluating the indicators total coliforms (78.10%), Escherichia coli (88.57%) and Staphylococcus aureus (100%). Klebsiella oxytoca and S. aureus were the most prevalent microorganisms in SCMM and MFM samples. Antimicrobial resistance and multidrug resistance (MDR) were observed in 65.12% and 13.95% of Enterobacteriaceae and 84.31% and 5.88% of Staphylococcus spp., respectively, isolated from both SCMM and MFM samples. Enterobacteriaceae resistant to third-generation cephalosporin (3GCR) (6.98%) and carbapenems (CRE) (6.98%) and methicillin-resistant S. aureus (MRSA) (4.88%) were observed. Antimicrobial-resistant bacteria can spread resistance genes to previously susceptible bacteria. This is a problem that affects animal, human and environmental health and should be evaluated within the one-health concept.

Asunto(s)

Antibacterianos , Farmacorresistencia Bacteriana , Enterobacteriaceae , Mastitis Bovina , Leche , Staphylococcus , Animales , Bovinos , Leche/microbiología , Mastitis Bovina/microbiología , Enterobacteriaceae/efectos de los fármacos , Enterobacteriaceae/aislamiento & purificación , Femenino , Staphylococcus/efectos de los fármacos , Brasil , Antibacterianos/farmacología , Infecciones por Enterobacteriaceae/veterinaria , Infecciones por Enterobacteriaceae/microbiología , Infecciones por Enterobacteriaceae/tratamiento farmacológico , Infecciones Estafilocócicas/veterinaria , Infecciones Estafilocócicas/microbiología , Infecciones Estafilocócicas/tratamiento farmacológico , Infecciones Asintomáticas , Pruebas de Sensibilidad Microbiana/veterinaria

RESUMEN

Due to specific bacterial microbiota, raw milk cheeses have appreciated sensory properties. However, they may pose a threat to consumer safety due to potential pathogens presence. This study evaluated the microbiological contamination of 98 raw milk cheeses from Beira Baixa, Portugal. Presence and enumeration of Coagulase Positive Staphylococci (CPS), Listeria monocytogenes, Salmonella spp., pathogenic Escherichia coli, and indicator microorganisms (non-pathogenic E. coli and Listeria spp.) was attained. E. coli antimicrobial resistance (AMR) was also evaluated. PCR and/or Whole genome sequencing (WGS) was used to characterize E. coli, Salmonella spp. and L. monocytogenes isolates. Sixteen cheeses (16.3%) were classified as Satisfactory, 59 (60.2%) as Borderline and 23 (23.5%) as Unsatisfactory/Potential Injurious to Health. L. monocytogenes, CPS > 104 cfu g-1, Extraintestinal pathogenic E. coli (ExPEC) and Salmonella spp. were detected in 4.1%, 6.1%, 3.1% and 1.0% of the samples, respectively. Listeria innocua (4.1%) and E. coli > 104 cfu g-1 (16.3%) were also detected. AMR E. coli was detected in 23/98 (23.5%) of the cheese samples, of which two were multidrug resistant. WGS identified genotypes already associated to human disease and Listeria spp. cluster analysis indicated that cheese contamination might be related with noncompliance with Good Hygiene Practices during cheese production.

Asunto(s)

Queso , Microbiología de Alimentos , Leche , Queso/microbiología , Portugal , Animales , Leche/microbiología , Inocuidad de los Alimentos , Listeria monocytogenes/genética , Listeria monocytogenes/aislamiento & purificación , Listeria monocytogenes/clasificación , Bacterias/aislamiento & purificación , Bacterias/clasificación , Bacterias/genética , Higiene , Escherichia coli/genética , Escherichia coli/aislamiento & purificación , Contaminación de Alimentos/análisis , Farmacorresistencia Bacteriana , Humanos

RESUMEN

The aim of this study was to compare the effects of feeding pasteurized waste milk or saleable milk to calves on weight, health and emergence of antimicrobial resistance in Escherichia coli strains isolated from those calves. An experimental study under field conditions on a commercial pasture-based Argentinian dairy farm was carried out. Forty Holstein calves were assigned randomly to either pasteurized waste milk (PWM) or non-pasteurized saleable milk (SM). The antimicrobial agents (AM) used on the farm, both to treat or prevent diseases, were recorded. The passive immunity level, calf live weight, AM presence in milk, clinical examination of calves, and E. coli isolation and identification, were performed. A total of 258 E. coli strains were isolated from fecal samples (132 isolates from SM calves and 126 from PWM calves at six sampling times). All E. coli isolated were used to perform AM susceptibility tests (disc diffusion and agar dilution). No differences were observed between groups in health parameters, average daily gain or prevalence of resistant E. coli strains to any AM evaluated throughout the study. Peaks of trimethoprim, sulfamethoxazole and enrofloxacin minimum inhibitory concentration (MIC) were observed at 30 d in E. coli from both groups of calves, whilst additional peaks to tetracyclin and ampicillin were observed only in SM calves. All MIC apart from gentamicin decreased at 75 and 90 d of age (during the weaning period). Gentamicin MIC behaved differently, having no peaks and increasing at 90 d only in PWM group. In conclusion, we found no evidence that emergence of antibiotic resistance is related to the consumption of pasteurized waste milk.

Asunto(s)

Antibacterianos , Farmacorresistencia Bacteriana , Infecciones por Escherichia coli , Escherichia coli , Heces , Leche , Pasteurización , Animales , Bovinos , Escherichia coli/efectos de los fármacos , Heces/microbiología , Leche/microbiología , Infecciones por Escherichia coli/veterinaria , Infecciones por Escherichia coli/microbiología , Antibacterianos/farmacología , Alimentación Animal , Enfermedades de los Bovinos/microbiología , Enfermedades de los Bovinos/prevención & control , Pruebas de Sensibilidad Microbiana , Peso Corporal/efectos de los fármacos , Femenino , Dieta/veterinaria

RESUMEN

Non-aureus staphylococci (NAS) are gaining importance in mastitis and public health, and some NAS have been reclassified as mammaliicocci (NASM). Bovine milk production has a major influence on the world economy, being an essential source of income for small, medium and large producers, and bovine mastitis caused by NASM can cause an economic impact. Mastitis generates financial losses due to reduced revenue, increased veterinary costs and expenses associated with animal slaughter. However, it is also a public health issue involving animal health and welfare, human health and the ecosystem. Furthermore, it is an increasingly common infection caused by NASM, including antimicrobial-resistant strains. Despite all these adverse effects that NASM can cause, some studies also point to its protective role against mastitis. Therefore, this review article addresses the negative and positive aspects that NASM can cause in bovine mastitis, the virulence of the disease and resistance factors that make it difficult to treat and, through the One Health approach, presents a holistic view of how mastitis caused by NASM can affect both animal and human health at one and the same time.

Asunto(s)

Mastitis Bovina , Staphylococcus , Bovinos , Animales , Mastitis Bovina/microbiología , Femenino , Humanos , Staphylococcus/efectos de los fármacos , Virulencia , Leche/microbiología , Farmacorresistencia Bacteriana , Antibacterianos/farmacología

RESUMEN

Pathogenic bacterial biofilms present significant challenges, particularly in food safety and material deterioration. Therefore, using Enterococcus mundtii A2, known for its antagonistic activity against pathogen adhesion, could serve as a novel strategy to reduce pathogenic colonization within the food sector. This study aimed to investigate the biofilm-forming ability of E. mundtii A2, isolated from camel milk, on two widely used stainless steels within the agri-food domain and to assess its anti-adhesive properties against various pathogens, especially on stainless steel 316L. Additionally, investigations into auto-aggregation and co-aggregation were also conducted. Plate count methodologies revealed increased biofilm formation by E. mundtii A2 on 316L, followed by 304L. Scanning electron microscopy (SEM) analysis revealed a dense yet thin biofilm layer, playing a critical role in reducing the adhesion of L. monocytogenes CECT 4032 and Staphylococcus aureus CECT 976, with a significant reduction of ≈ 2 Log CFU/cm2. However, Gram-negative strains, P. aeruginosa ATCC 27853 and E. coli ATCC 25922, exhibit modest adhesion reduction (~ 0.7 Log CFU/cm2). The findings demonstrate the potential of applying E. mundtii A2 biofilms as an effective strategy to reduce the adhesion and propagation of potentially pathogenic bacterial species on stainless steel 316L.

Asunto(s)

Adhesión Bacteriana , Biopelículas , Enterococcus , Acero Inoxidable , Biopelículas/efectos de los fármacos , Biopelículas/crecimiento & desarrollo , Adhesión Bacteriana/efectos de los fármacos , Enterococcus/fisiología , Enterococcus/efectos de los fármacos , Animales , Microbiología de Alimentos , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/fisiología , Antibiosis , Listeria monocytogenes/efectos de los fármacos , Listeria monocytogenes/fisiología , Listeria monocytogenes/crecimiento & desarrollo , Leche/microbiología

RESUMEN

Artisanal cheese from Serra Geral, Minas Gerais, Brazil, stands out for its cultural asset and socio-economic relevance. However, standards of identity and quality and the peculiar terroir associated with the edaphoclimatic conditions have not been established. Therefore, the production flow diagram and the physico-chemical and microbiological quality of the raw milk, pingo (natural starter culture), production benches, water and fresh cheese were investigated for the first time. In addition, lactic acid bacteria (LAB) from cheese and its production environment were identified by MALDI-TOF. For that, 12 cheese making facilities were selected. The raw milk and pingo showed adequate physico-chemical characteristics for cheesemaking; however, high microbial counts were found. In the water, total and thermotolerant coliforms were also identified. The fresh cheeses were classified as 'high moisture and fat' and 'soft mass'. Most physico-chemical parameters were satisfactory; however, there were high counts of total coliforms, Staphylococcus spp. and coagulase-positive staphylococci. There were high counts of LAB in the raw milk, pingo, bench surface and fresh cheese. A total of 84 microbial biotypes from MRS agar were isolated. Lactococcus lactis was the predominant LAB, followed by Lactococcus garvieae. Leuconostoc mesenteroides (benches), Leuconostoc pseudomesenteroides (fresh cheese), and Enterococcus faecium (pingo) were identified sporadically. These results indicate the risks to public health associated with the consumption of the fresh cheese, and measures to improve its safety are needed.

Asunto(s)

Queso , Lactobacillales , Lactococcus lactis , Animales , Queso/análisis , Leche/microbiología , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción , Brasil , Microbiología de Alimentos , Agua

RESUMEN

Using on-farm microbiological culture (OFC), based on chromogenic culture media, enables the identification of mastitis causing pathogens in about 24 h, allows rapid decision making on selective treatment and control management measures of cows with clinical mastitis (CM). However, accurate interpretation of OFC results requires trained and experienced operators, which could be a limitation for the use of OFC in dairy farms. Our hypothesis was that AI-based automated plate reading mobile application can analyze images of microorganisms' colonies in chromogenic culture media with similar diagnostic performance as a trained specialist evaluator. Therefore, the aim of the present study was to evaluate the diagnostic accuracy of an AI-based application (Rumi; OnFarm, Piracicaba, São Paulo, Brazil) for interpreting images of mastitis causing microorganism colonies grown in chromogenic culture media. For this study two trials were organized to compare the results obtained using an AI-based application Rumi with the interpretation of: (1) a trained specialist, using MALDI-TOF MS as the gold standard; (2) farm personnel users (FPU). In trial 1, a total of 476 CM milk samples, from 11 farms located in São Paulo (n = 7) and Minas Gerais (n = 4), southeast Brazil, were inoculated in chromogenic culture media plates (Smartcolor 2, OnFarm, Piracicaba, São Paulo, Brazil) by specialists under lab conditions, and digital images were recorded 24 h after incubation at 37 °C. After that, all the 476 digital images were analyzed by the Rumi and by another specialist (who only had access to the digital images) and the diagnostic accuracy indicators sensitivity (Se) and specificity (Sp) were calculated using MALDI-TOF MS microbiological identification of the isolates as the reference. In Trial 2, a total of 208 CM milk samples, from 150 farms from Brazil, were inoculated in chromogenic culture media plates by FPU, and the results of microbiological growth were visually interpreted by FPU under on-farm conditions. After visual interpretation, results were recorded using an OnFarmApp application (herd manage application for mastitis by OnFarm, Piracicaba, São Paulo, Brazil), and the images of the chromogenic culture plates were captured by the OnFarmApp to be evaluated by Rumi and Bayesian Latent Class Models were performed to compare Rumi and the FPU. In Trial 1, Rumi presented high and intermediate accuracy results, with the only exception of the low Enterococcus spp.'s Se. In comparison with the specialist, Rumi performed similarly in Se and Sp for most groups of pathogens, with the only exception of non-aureus staphylococci where Se results were lower. Both Rumi and the specialist achieved Sp results > 0.96. In Trial 2, Rumi had similar results as the FPU in the Bayesian Latent Class Model analysis. In conclusion, the use of the AI-based automated plate reading mobile application can be an alternative for visual interpretation of OFC results, simplifying the procedures for selective treatment decisions for CM based on OFC.

Asunto(s)

Mastitis , Aplicaciones Móviles , Animales , Bovinos , Femenino , Teorema de Bayes , Brasil , Medios de Cultivo , Leche/microbiología

RESUMEN

Este estudo objetivou avaliar aspectos que exercem influência sobre a contagem bacteriana total (CBT) e a contagem de células somáticas (CCS) do leite e avaliar a adequação das amostras do produto à Instrução Normativa nº 76, de 26 de novembro de 2018, do Ministério da Agricultura e Pecuária do Brasil (IN 76). A pesquisa foi realizada em propriedades rurais da microrregião de Birigui, São Paulo, Brasil, e se baseou em coleta de dados, por entrevista estruturada, e coletas de leite nas propriedades. Foi realizada amostragem por conveniência, sendo escolhidos 15 produtores de cada estrato (de acordo com a produção diária de leite: pequeno - até 100 L; médio - 101 a 300 L; grande - mais de 300 L), totalizando 45 produtores de leite. Participaram da pesquisa somente propriedades com base da alimentação volumosa em sistema de pastejo ou em semiconfinamento. Para avaliar a influência de diferentes fatores sobre a contagem bacteriana total (CBT) e a contagem de células somáticas (CCS), separadamente, realizou-se regressão multivariada. Ainda, foi determinado o coeficiente de correlação entre variáveis desta pesquisa. As variáveis resposta foram transformadas em logaritmo para normalização dos dados. Foi feita comparação entre os resultados da pesquisa e os parâmetros da IN 76 para verificar o cumprimento das normas pelos produtores. Foram encontrados valores médios de 6.986.977,818.961.790,7 UFC/mL para CBT e de 608.911,1 ± 414.802,9 CS/mL para CCS. A utilização de tanque de resfriamento individual mostrou-se favorável à baixa CBT, em comparação com não uso de tanque ou uso de tanque comunitário, conforme o esperado, pois quanto mais tempo leva para resfriar o leite, maior é a proliferação de bactérias no produto. Foi verificado que o leite de produtores que realizam o California Mastitis Test (CMT) com maior frequência apresentou CCS mais elevada, o que não era esperado. As análises físico-químicas médias foram densidade 1,031 g/mL a 15°C, índice crioscópico -0,538 °H, teor de proteína 3,58%, teor de gordura 4,06%, extrato seco total 12,75%, extrato seco desengordurado 8,69%, acidez titulável 16,2 °D e estabilidade ao álcool (Alizarol 72%) 100%. Em 13,3% (6/45) das amostras foi detectada presença de antibióticos. Considerando a IN 76, o leite de somente 8,9% (4/45) dos produtores apresentou-se adequado simultaneamente para todos os parâmetros analisados (CBT, CCS, densidade, índice crioscópico, proteína, gordura, extrato seco total, extrato seco desengordurado, acidez titulável, estabilidade ao alizarol e pesquisa de antibióticos). A utilização de tanque de resfriamento individual e a realização de CMT favoreceram menor CBT e maior CCS, respectivamente.

---

This study aimed to evaluate aspects that exerts influence on the total bacterial count (TBC) and somatic cell count (SCC) of milk and evaluate the conformity of the samples to the Normative Instruction no. 76, from November 26, 2018, of the Brazilian Agriculture and Livestock Ministry (NI 76). The research was done in farms around Birigui micro-region, São Paulo State, Brazil, and was based on data collection obtained by structured interviews and milk collection in the farms. Convenience sampling was carried out from 15 producers of each stratum (according to daily milk production: small - up to 100 L; medium - 101 to 300 L; large - more than 300 L), totalizing 45 milk producers. Only farms with grazing or semi-feedlot system for roughage feeding base were included. To evaluate the influence of different factors on Total Bacterial Count (TBC) and Somatic Cell Count (SCC), separately, a multivariate regression was done. Moreover, the correlation coefficient among variables was determined. The response variables were transformed into logarithms for the normalization of the data. A comparison between results and NI 76 parameters was done to verify the standard compliance by producers. Mean TBC was 6.986.977,8 ± 18.961.790,7 CFU/mL and mean SCC was 608.911,1414.802,9 cells/mL. The use of individual cooler tank was favorable to lower TBC, compared with the non-use of the tank or with the use of the communitarian tank, as expected, since the longer it takes to cool the milk, the higher the proliferation of bacteria in the product. It was verified that milk from farmers that more frequently perform California Mastitis Test (CMT) showed higher SCC, which was not expected. The average physicochemical analyzes were density 1.031 g/mL at 15°C, cryoscopic index -0.538 °H, protein content 3.58%, fat content 4.06%, total dry extract 12.75%, dry extract defatted 8.69%, titratable acidity 16.2 °D and alcohol stability (Alizarol 72%) 100%. The presence of antibiotics was detected in 13.3% (6/45) of the samples. Considering NI 76, milk from only 8.9% (4/45) farmers were proper simultaneously for all the parameters analyzed (TBC, SCC, density, cryoscopic index, protein, fat, total dry extract, defatted dry extract, titratable acidity, alizarol stability and antibiotics). The use of individual cooling tank and the CMT performance support lower TBC and higher SCC respectively.

---

Este estudio tuvo como objetivo evaluar los aspectos que influyen en el contaje bacteriano total (CBT) y el contaje de células somáticas (CCS) de la leche y evaluar la adecuación de las muestras del producto a la Instrucción Normativa nº 76, de 26 de noviembre de 2018, del Ministerio de Agricultura y Ganadería en Brasil (IN 76). La investigación se llevó a cabo en propiedades rurales en la microrregión de Birigui, São Paulo, Brasil, y se basó en la recolección de datos, a través de entrevistas estructuradas, y colectas de leche en las propiedades. Se realizó un muestreo por conveniencia, escogiendo 15 productores de cada estrato (de acuerdo con la producción diaria de leche: pequeño - hasta 100 L; medio - 101 hasta 300 L; grande ­ más de 300 L), totalizando 45 productores de leche. Participaron de la investigación únicamente propiedades basadas en alimentación voluminosa en sistema de pastoreo o, a lo sumo, en semiconfinamiento. Para evaluar la influencia de diferentes factores sobre el contaje bacteriano total (CBT) y el contaje de células somáticas (CCS), por separado, se realizó una regresión multivariada. Asimismo, se determinó el coeficiente de correlación entre las variables de esta investigación. Las variables de respuesta se transformaron en logaritmos para la normalización de datos. Se realizó una comparación entre los resultados de la investigación y los parámetros de la IN 76 para verificar el cumplimiento de las normas por parte de los productores. Se encontraron valores medios de 6.986.977,818.961.790,7 UFC/mL para CBT y de 608.911,1 +414.802,9 CS/mL para CCS. El uso de un tanque de enfriamiento individual se ha mostrado favorable a la baja CBT, en comparación con no usar un tanque o usar un tanque comunitario, conforme lo esperado, ya que cuanto más se tarda en enfriar la leche, mayor es la proliferación de bacterias en el producto. Se verificó que la leche de los productores que realizan el California Mastitis Test (CMT) con mayor frecuencia presentó CCS más alto, lo cual no se esperaba. Los análisis fisicoquímicos promedio fueron densidad 1,031 g/mL a 15°C, índice crioscópico -0,538 °H, contenido de proteína 3,58%, contenido de grasa 4,06%, extracto seco total 12,75%, extracto seco desgrasado 8,69%, acidez titulable 16,2°D y estabilidad del alcohol (Alizarol 72%) 100%. En el 13,3% (6/45) de las muestras se detectó la presencia de antibióticos. Considerando la IN 76, la leche de solo el 8,9% (4/45) de los productores se presentó adecuado simultáneamente para todos los parámetros analizados (CBT, CCS, densidad, índice crioscópico, proteína, grasa, extracto seco total, extracto seco desgrasado, acidez titulable, estabilidad al alizarol e investigación de antibióticos). El uso de un tanque de enfriamiento individual y la realización de CMT favorecieron un CBT más bajo y un CCS más alto respectivamente.

Asunto(s)

Animales , Bovinos , Calidad de los Alimentos , Análisis Multivariante , Leche/microbiología , Carga Bacteriana/veterinaria , Medio Rural

RESUMEN

This study aimed to investigate the probiotic properties of Lactic Acid Bacteria (LAB) isolates derived from various milk sources. These isolates identified based on their morphological characteristics and 16S rRNA gene sequencing. Four strains of Lactococcus lactis and two strains of Weissella confusa were identified with over 96% 16S rRNA gene similarity according to the NCBI-BLAST results. The survival of the isolates was determined in low pH, pepsin, bile salts, and pancreatin, and their adhesion ability was assessed by in vitro cell adhesion assay, hydrophobicity, auto- and co-aggregation, and safety criteria were determined by hemolytic, gelatinase activities, and DNAse production ability tests. The results showed that the LAB isolates had different levels of resistance to various stress factors. L. lactis subsp. cremoris MH31 showed the highest resistance to bile salt, while the highest pH resistance was observed in L. lactis MH31 at pH 3.0. All the isolates survived in pepsin exposure at pH 3.0 for 3 h. The auto-aggregation test results showed that all strains exhibited auto-aggregation ranging from 84.9 to 91.4%. Co-aggregation percentage ranged from 19 - 54% and 17 - 57% against Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 29213, respectively. The hydrophobicity capacity of the LAB isolated ranged from 35-61%. These isolates showed different adhesion abilities to Caco-2 cells (81.5% to 92.6%). None of the isolates exhibited DNase, gelatinase and hemolytic activity (γ-hemolysis). All results indicate that these LAB strains have the potential to be used as probiotics.

Asunto(s)

Lactobacillales , Lactococcus lactis , Probióticos , Weissella , Humanos , Animales , Lactococcus lactis/genética , ARN Ribosómico 16S/genética , Células CACO-2 , Leche/microbiología , Pepsina A , Desoxirribonucleasas , Gelatinasas