Use of Antimicrobials in the Treatment of Reproductive Diseases in Cattle and Horses

Isolation of lactic acid bacteria from the reproductive tract of mares as potentially beneficial strains to prevent equine endometritis

Endometritis, the inflammation of the endometrium, is the leading cause of subfertility in mares, and therefore responsible for major economic losses in the horse industry worldwide. It is generally treated with uterine lavages combined with ecbolic agents and local or systemic antibiotics. However, since antibiotic overuse has been associated with antimicrobial resistance in mares with persistent endometritis, new prevention and treatment alternatives are needed. One such alternative could be the use of probiotic lactic acid bacteria (LAB) isolated from the host. Thanks to their species specificity, resident microbiota may restore ecological equilibrium within the host, and therefore, help prevent infections and improve physiological functions. In the present study, 257 bacterial strains were isolated from 77 healthy mares, and 88.76% (n = 228) of them were phenotypically classified as LAB. Within this group, 65.79% were able to inhibit at least one strain from each of the genera that most commonly cause equine endometritis (Streptococcus equi subsp. zooepidemicus, Escherichia coli, and Staphylococcus spp.). Five strains (RCE11, RCE20, RCE91, RCE99, and RCE167) were selected on the basis of their beneficial properties: ability to autoaggregate and adhere to equine epithelial cells, high inhibition of and co-aggregation with all the bacteria isolated from clinical cases of endometritis evaluated, and negative co-inhibition between one another. All five were finally identified as Enterococcus spp., namely E. faecium (two strains), E. hirae (two strains), and E. gallinarum (one strain). Further studies will assess their safety and biotechnological potential for the design of a multi-strain probiotic formula to prevent equine endometritis.

Antimicrobial Resistance and Extended-Spectrum Beta-Lactamase Genes in Enterobacterales, Pseudomonas and Acinetobacter Isolates from the Uterus of Healthy Mares

Antibiotic-resistant bacteria are a growing concern for human and animal health. The objective of this study was to determine the antimicrobial resistance and extended-spectrum beta-lactamase genes in Enterobacterales, Pseudomonas spp. and Acinetobacter spp. isolates from the uterus of healthy mares. For this purpose, 21 mares were swabbed for samples, which were later seeded on blood agar and MacConkey agar. The isolates were identified using MALDI-TOF and the antimicrobial susceptibility test was performed using the Kirby-Bauer technique. To characterize the resistance genes, a polymerase chain reaction (PCR) scheme was performed. Of the isolates identified as Gram-negative, 68.8% were Enterobacterales, represented by E. coli, Enterobacter cloacae, Citrobacter spp., and Klebsiella pneumoniae; 28.1% belonged to the genus Acinetobacter spp.; and 3.1% to Pseudomonas aeruginosa. A 9.3% of the isolates were multidrug-resistant (MDR), presenting resistance to antibiotics from three different classes, while 18.8% presented resistance to two or more classes of different antibiotics. The diversity of three genes that code for ESBL (blaTEM, blaCTX-M and blaSHV) was detected in 12.5% of the strains. The most frequent was blaSHV, while blaTEM and blaCTX-M were present in Citrobacter spp. and Klebsiella pneumoniae. These results are an alarm call for veterinarians and their environment and suggest taking measures to prevent the spread of these microorganisms.

Clinical Aspects of Bacterial Distribution and Antibiotic Resistance in the Reproductive System of Equids

Antibiotic administration is a standard therapeutic practice for the treatment of reproductive disorders of equids. This might lead to undesirable microbial imbalance and could favour the acquisition of antibiotic resistance. Therefore, it is imperative for clinicians to understand patterns of antibiotic resistance when considering and developing treatment regimes. Continued engagement of clinicians with novel alternative approaches to treat reproductive infections would be essential in order to address this rising threat within the One Health perspective. The objectives of the present review were to present the bacterial infections in the reproductive system of equids (horses, donkeys), to upraise the literature related to the issue of antibiotic resistance of bacteria causing these infections and to discuss the topic from a clinical perspective. Initially, the review summarised the various infections of the reproductive system of equids (genital system of females, genital system of males, mammary glands) and the causal bacteria, providing relevant information about horses and donkeys. Subsequently, the clinical therapeutics of these infections were presented, taking into account the significance of antibiotic resistance of bacteria as a limiting factor in treating the infections. Finally, approaches to circumvent antibiotic resistance in clinical settings were summarized. It was concluded that awareness regarding antibiotic resistance in equine reproductive medicine would increase, as we would recognise the multifaceted problem of resistance. Actions and initiatives within the One Health approach, minimizing the potential dissemination of resistant strains to humans and to the environment, with specific applications in medicine of equids should be appropriately instituted internationally.

Antimicrobial use and resistance in food-producing animals-How can we protect the efficacy of antibiotics for reproductive diseases?

The ongoing emergence of antibiotic resistance jeopardizes efficacy of antibiotics in curing animals from bacterial infections that threaten their health, welfare and productivity. This review gives an overview of antimicrobial use data in food-producing animals, a discussion on how antimicrobials are used for some infections in the reproductive system in cattle, the horse and pig in Europe where there are differences in treatment practices including options to refine the use of antibiotics, and finally, a presentation of the antibiotic resistance for some bacteria collected from the reproductive system. It is shown that there are differences in applied treatment regimens for, as well as prevention of, several reproductive diseases in Europe. Some of the treatments are not evidence-based, which should be considered by clinicians and other stakeholders. It is concluded that a more refined and restrictive use of antibiotics could be achieved by adhering to evidence-based guidelines by national and international expertise including the scientific literature when available. This may call for a re-think among the animal health stakeholders regarding the use of antibiotics and may demand new skill-sets in the animal health sphere.

Oxytetracycline Persistence in Uterine Secretion after Intrauterine Administration in Cows with Metritis

Simple Summary

Puerperal metritis in cows involves the acute inflammation of the uterus, which is often treated with antibacterial drugs. Restrictions on the use of antibiotics in veterinary medicine require the very precise selection of an antibiotic based on its pharmacokinetics and on sensitivity tests of pathogenic bacteria. This study aimed to evaluate the changes in oxytetracycline levels in uterine secretion over time after intrauterine administration in cows with metritis in relation to the sensitivity of pathogenic bacterial isolates. The concentrations of oxytetracycline in the uterine secretions were higher than the minimum inhibitory concentrations against pathogenic bacteria, provoking the infection of the uterus. Higher concentrations were measured in milk rather than in plasma. The intrauterine infusion of oxytetracycline for three consecutive days led to the alleviation of the inflammation and the restoration of the estrus cycle in cows. The local intrauterine administration of oxytetracycline requires the monitoring of the withdrawal time of milk to ensure consumer safety.

Abstract

Puerperal metritis in cows is often treated with antibacterial drugs. The prudent use of antibiotics in farm animals requires state-of-the-art knowledge of their pharmacokinetics and data from sensitivity tests of pathogenic bacteria. Changes in oxytetracycline levels in the uterine secretion over time after intrauterine administration in cows with metritis were evaluated in relation to the sensitivity of pathogenic bacterial isolates. Oxytetracycline levels in plasma, milk and uterine secretion were determined via LC–MS/MS analysis. Pathogenic bacteria were isolated and their sensitivity to oxytetracycline was determined. The concentrations of oxytetracycline in the uterine secretion were 433.79 (39.17–1668.76) µg·mL⁻¹ six hours after the third application at a dose of 8 mg/kg and 84.33 (1.58–467.55) µg·mL⁻¹ 96 h after the last treatment. These levels were higher than the minimum inhibitory concentrations—namely, between 4 and 64 µg·mL⁻¹—against pathogenic isolates Trueperella pyogenes, Streptococcus intermedius, Escherichia coli and Bacillus pumilis. Higher concentrations over time were measured in milk rather than in plasma, indicating the need to monitor the withdrawal time for milk. The intrauterine infusion of oxytetracycline for three consecutive days resulted in the successful treatment of metritis in terms alleviating inflammation and restoring the estrus cycle in cows.

Evaluación de la administración de medicamentos veterinarios en hatos lecheros de quince municipios de Cundinamarca, Colombia

Objetivo Evaluar el conocimiento en el uso de Medicamentos de Uso Veterinario (MUV) de los productores ganaderos y personal involucrado en Bogotá y municipios aledaños. Métodos Se realizó un estudio de corte transversal a través de entrevistas a operarios y productores ganaderos de una muestra de 30 hatos lecheros localizados en 15 municipios cerca de Bogotá, Cundinamarca. Resultados Se identificó la implementación de prácticas para la administración de MUV, incluyendo parámetros que influencian su administración y conocimientos en las personas que los prescriben y administran. Se encontró que los medicamentos de mayor frecuencia fueron los antimicrobianos con 60,7%, entre los cuales se destaca el uso de penicilina y oxitetraciclina. Los MUV inyectables (parenterales) fueron las formas más frecuentes de aplicación con un 64,7%. Se identificaron 251 MUV en los hatos lecheros, de los cuales el 81,3% están compuestos por principios activos que requieren tiempo de retiro en leche y carne. Se destaca el rol del mayordomo en el cuidado animal a nivel diagnóstico y administración del tratamiento. Conclusión El presente estudio sugiere que el uso de MUV es implementado empíricamente en producciones lecheras y podría contribuir a mediano y largo plazo a la emergencia de cepas con resistencia a MUV.

A pilot study on bacterial isolates associated with purulent vaginal discharge in dairy cows in the south-west region of Western Australia

This study aimed to determine the bacterial isolates associated with postpartum endometritis among dairy cows in Western Australia and their antimicrobial susceptibility profiles. A cross‐sectional study was conducted between June–October 2020. Endometritis was defined as evidence of mucopurulent to purulent vaginal discharge 60–100 days postpartum. Vaginal discharge samples were obtained, cultured, identified and tested for antimicrobial susceptibility. A total of 118 bacterial isolates were grown from 46 animals, representing 36 species. The bacteria isolated from both aerobic and anaerobic cultures included Bacillus (60.2%), Streptococcus (12.7%), Trueperella (10.1%), Escherichia (6.7%) and Staphylococcus (5.9%). The remaining genera <5% were Histophilus, Aeroccocus, Enterococcus and Moraxella. Resistance was variable between isolates, but the highest resistance levels were observed in Streptococcal and Bacillus isolates to enrofloxacin, clindamycin and erythromycin, respectively. All Streptococcal isolates exhibited 100% resistance to enrofloxacin, and the greatest resistance levels were found in Streptococcus luteinises to trimethoprim‐sulfamethoxazole 83%, clindamycin 66% and 33% quinupristin‐dalfopristin. There was 84.5% resistance to clindamycin and 35.2% to erythromycin in the Bacillus isolates, with the highest resistance found in Bacillus licheniformis and Bacillus subtilis. Escherichia coli exhibited 12.5% resistance to gentamycin, ceftiofur, whereas amoxicillin‐clavulanic acid exhibited 37.5%. Within the Staphylococcal isolates, 28.5%, 28.5%, 42.8% and 14.2% resistance to ceftiofur, erythromycin, cefoxitin, penicillin and tetracycline were observed, respectively. The presence of resistance to important antimicrobials for human use, such as cephalosporins, macrolides and fluoroquinolones, highlights the need for judicious use of antimicrobials in dairy cattle.

Characterisation of the rumen resistome in Spanish dairy cattle

BACKGROUND

Rumen microorganisms carry antimicrobial resistance genes which pose a threaten to animals and humans in a One Health context. In order to tackle the emergence of antimicrobial resistance it is vital to understand how they appear, their relationship with the host, how they behave as a whole in the ruminal ecosystem or how they spread to the environment or humans. We sequenced ruminal samples from 416 Holstein dairy cows in 14 Spanish farms using nanopore technology, to uncover the presence of resistance genes and their potential effect on human, animal and environmental health.

RESULTS

We found 998 antimicrobial resistance genes (ARGs) in the cow rumen and studied the 25 most prevalent genes in the 14 dairy cattle farms. The most abundant ARGs were related to the use of antibiotics to treat mastitis, metritis and lameness, the most common diseases in dairy cattle. The relative abundance (RA) of bacteriophages was positively correlated to the ARGs RA. The heritability of the RA of the more abundant ARGs ranged between 0.10 (mupA) and 0.49 (tetW), similar to the heritability of the RA of microbes that carried those ARGs. Even though these genes are carried by the microorganisms, the host is partially controlling their RA by having a more suitable rumen pH, folds, or other physiological traits that promote the growth of those microorganisms.

CONCLUSIONS

We were able to determine the most prevalent ARGs (macB, msbA, parY, rpoB2, tetQ and TaeA) in the ruminal bacteria ecosystem. The rumen is a reservoir of ARGs, and strategies to reduce the ARG load from livestock must be pursued.

Microbial Prevalence and Antimicrobial Sensitivity in Equine Endometritis in Field Conditions

Endometritis is one of the main causes of infertility in mares. In the present study, 363 mares with a history of repetitive infertility, and positive endometrial cytology and/or vaginal discharge were included. An endometrial swab for microbiological purposes plus sensitivity test was obtained from each mare. A positive culture was obtained in 89% of mares. The main isolated genera were Staphylococcus (25.1%), Streptococcus (18.2%), Escherichia (17.3%) and Pseudomonas (12.1%). With regard to species, the most isolated microorganism was Escherichia coli (17.3%), Staphylococcus spp. (15.6%) and Streptococcus spp. (13.5%). Sensitivity tests showed that the most efficient antimicrobial was amikacin (57.3% of cultures), followed by cefoxitin (48.6%) and gentamicin (48.3%). When sensitivity test was analyzed in terms of Gram+ and Gram- bacteria, Gram+ were highly resistant to cephaloridine (77.3% of cultures), apramycin (70.8%) and penicillin (62.3%), whereas Gram- were highly resistant to penicillin (85.8%), followed by cephaloridine (78.9%). In conclusion, the present study shows the most prevalent microorganisms isolated from equine endometritis, which were found to be resistant to β-lactam antimicrobials. Likewise, these results highlight the significance of performing microbiological analyses as well as sensitivity tests prior to applying an antimicrobial therapy.

Treatment protocols and management of retained fetal membranes in cattle by rural practitioners in Belgium

Retained fetal membranes (RFM) is a frequent postpartum disorder in cattle causing considerable economic losses, and a common indication for antibiotic (AB) administration. There is controversy with regard to the treatment of RFM, and scientific recommendations are often in conflict with current legislation on AB use and practical routines in the field. The aim of this study was to assess the therapeutic approaches of RFM by Belgian rural veterinarians. A digital survey was sent to 468 Belgian veterinarians; 149 complete questionnaires (Wallonia: 78; Flanders: 71) were obtained. Survey questions captured socio-demographic characteristics, case definition, therapeutic approaches and treatment options for RFM. Questions on treatment were duplicated for dairy and beef cattle. When confronted with dairy cows suffering from RFM without fever, 35.6 % of vets do not treat with AB, while the majority administers AB, either intrauterine (47.6 %), systemically (10.7 %) or both (6.1 %). Dairy cows with RFM and fever receive a systemic (33.5 %), intrauterine (2.7 %) or combined (61.8 %) AB treatment. For a beef cow with RFM without fever, 21.5 % of vets prefer no AB treatment, while others prefer an intrauterine (24.2 %), systemic (24.8 %), combined (29.5 %) AB treatment. Beef cows with RFM and fever receive AB from the large majority of vets, by systemic (34.9 %) or combined (56.3 %) administration. In case of a parenteral treatment, benzylpenicillin, amoxicillin and ampicillin are by far the most frequently used molecules; only a minority of vets use cephalosporins. Manual placental removal is attempted by 93.9 % of the respondents. These results demonstrate that there is room for improvement when considering the treatment protocols of RFM. Many veterinarians use AB in RFM cows not presenting symptoms of general illness, or administer intrauterine AB in cows with or without clinical signs of illness. Concerning the molecules of choice, practical routines are largely in line with national AB recommendations. Beef cows suffering from RFM are treated more rigorously than dairy cows, regardless of their rectal temperature.

Reproductive Tract Infections in Dairy Cows: Can Probiotics Curb Down the Incidence Rate?

Postpartum uterine diseases are common in dairy cows and are a great concern for the dairy industry as they are associated with various consequences, including lower fertility, lower milk yield, and an overall negative impact on the host health. An infected uterus is a source of bacterial compounds and cytokines that spill into the systemic circulation, spreading inflammation to other organs. In this review article, we discuss a short overview of the anatomy of the reproductive tract of dairy cows and several infectious diseases of the uterus including metritis, endometritis, and pyometra. Additionally, we discuss the microbiome of the reproductive tract in health and during uterine diseases. As well, diagnostic criteria for metritis and endometritis and contributing factors for increased susceptibility to metritis infection are important topics of this review. To better understand how the uterus and reproductive tract respond to bacterial pathogens, a section of this review is dedicated to immunity of the reproductive tract. Both the innate and adaptive immunity systems are also discussed. We conclude the review with a factual discussion about the current treatments of uterine diseases and the new developments in the area of application of probiotics for uterine health. Mechanisms of actions of probiotics are discussed in detail and also some applications to prevent uterine infections in dairy cows are discussed.

Oxytetracycline Pharmacokinetics After Intramuscular Administration in Cows with Clinical Metritis Associated with Trueperella Pyogenes Infection

Systemic therapy with oxytetracycline is often used for treatment of clinical metritis although data about its penetration into the uterus and uterine secretion are lacking. Uterine secretions and milk from six cows with clinical metritis were collected for microbiological assay. The animals were treated intramuscularly with long-acting oxytetracycline (20 mg/kg) and samples of plasma, milk and uterine secretions were collected for determination of the antibiotic concentrations by HPLC-PDA analysis. Pharmacokinetics of the antibiotic and in silico prediction of its penetration into the uterus were described. Trueperella pyogenes with MIC values of 16-64 µg mL^-1 was isolated (n of cows = 4) from uterine secretions. Oxytetracycline showed fast absorption and penetration in the uterine secretions and milk. No change of withdrawal time for milk was necessitated in cows with clinical metritis. Maximum levels in uterine secretions and predicted concentrations of oxytetracycline in the uterus were lower than MIC values. Systemic administration of long-acting oxytetracycline did not guarantee clinical cure and was not a suitable choice for treatment of clinical metritis associated with Trueperella pyogenes. The appropriate approach to antibiotic treatment of uterine infections of cows requires knowledge on penetration of the antibiotics at the site of infection and sensitivity of pathogens.

Genital bovine leptospirosis: A new look for an old disease

Bovine leptospirosis is often associated with host-adapted leptospires infections, such as strains belonging to the Sejroe serogroup. Although bovine leptospirosis by adapted strains may result in abortions, fetal death, premature births and the birth of weak and/or low-weight calves, this infection is more closely associated with subtler syndromes, such as subfertility and early embryonic death. In this way, this silent disease can go unnoticed and undiagnosed, compromising reproductive efficiency with a consequent decrease in the productivity of herds over long periods. For many years, genital tract infection has been considered a secondary effect of renal infection with the assumption being that leptospires are found in the genital tract due to bacteremia caused by renal colonization. In contrast to this hypothesis, there is some evidence in the literature that suggests that genital leptospirosis should be considered a specific syndrome dissociated from renal/systemic disease. Therefore, this paper aims to gather and critically analyze information about genital leptospirosis in cattle, considering the disease a distinct syndrome, herein denominated bovine genital leptospirosis (BGL), that requires a unique approach to diagnosis and treatment.

Short communication: Pegbovigrastim treatment in vivo does not affect granulocyte ability to migrate to endometrial cells and kill bacteria in vitro in healthy cows

In periparturient dairy cows, immune suppression, resulting in decreased neutrophil numbers and function, leads to increased susceptibility to postpartum conditions such as mastitis, retained placenta, and metritis. Administration of polyethylene glycol-conjugated bovine granulocyte colony stimulating factor (pegbovigrastim, Imrestor; Elanco Animal Health, Greenfield, IN) 7 d before and within 24 h of calving, effectively improves granulocyte production and function in vivo as well as in milk. A recently developed coculture assay was adapted for use with endometrial epithelial cells to assess the effects of pegbovigrastim application on directed granulocyte migration and bactericidal activity in vitro on a per-cell basis in endometrial cell cultures. Granulocytes from treated and untreated periparturient cows (6 and 5 per group, respectively) were evaluated for their ability to migrate to and kill bacteria after treatment, in context of the infected endometrium. We hypothesized that in addition to increasing the absolute concentration of circulating neutrophil granulocytes, pegbovigrastim treatment in vivo alters the ability of granulocytes to migrate to endometrial cells in vitro. The results clearly show a marked increase in the total concentration of granulocytes and monocytes between the 2 treatment groups as early as 2 d after the first injection, and this increased between the samples taken 2 d after calving. No migratory or killing differences were identified between granulocytes of both groups, suggesting that pegbovigrastim-induced granulocytes were as effective as non-induced cells. This may also be due to the absence of negative energy balance in the study animals and leads us to conclude that the positive effects seen in vivo are most likely based on the larger number of granulocytes present rather than a direct effect of pegbovigrastim treatment on the functionality of cells for the parameters tested in this study.

Cost of retained fetal membranes for dairy herds in the United States

OBJECTIVE To estimate the cost of a case of retained fetal membranes (RFM) for dairy herds in the United States. DESIGN Deterministic computer-based spreadsheet analysis. SAMPLE Inputs from published studies and reports. PROCEDURES Economic losses attributable to RFM were direct (reduction in milk yield and longer interval until pregnancy) and indirect (increased risk of developing clinical disease and increased culling risk). Cost attributable to milk loss was calculated as the mean marginal loss of milk production for cows with RFM and cows with RFM complicated by metritis. Cost of the increased risk of developing clinical disease because of RFM was a product of the cost of each clinical disease and the risk of each clinical disease attributable to RFM. Cost attributable to reduced reproductive performance was a function of a longer interval until pregnancy, whereas cost for increased culling attributable to RFM was associated with the market value of cull cows and replacement heifers as well as herd turnover rate. RESULTS Cost of a case of RFM determined by use of default inputs was $386 (reduction in milk yield, $287; increased time until pregnancy, $73; increased disease risk, $25; and increased culling risk, $1). Sensitivity analysis revealed that milk and feed prices were the most influential inputs. CONCLUSIONS AND CLINICAL RELEVANCE Cost of a case of RFM, including uncomplicated cases, was substantial and comparable to that for other common clinical diseases during the transition period. Preventive measures during the nonlactating period should be considered to minimize the incidence of RFM.

Minimum inhibitory concentrations of frequently used antibiotics against Escherichia coli and Trueperella pyogenes isolated from uteri of postpartum dairy cows

The objective of this study was to determine minimum inhibitory concentrations (MIC) of frequently used antimicrobials for Escherichia coli and Trueperella pyogenes isolated from postpartum bovine uteri of cows with acute puerperal metritis (APM, n = 67), cows suspected to have APM (n = 37), and healthy cows (n = 37) and to evaluate possible differences in MIC according to clinical signs. Cows with APM had reddish-brown, fetid vaginal discharge and rectal temperature (RT) ≥39.5°C within 21 d in milk; cows suspected to have APM had either reddish-brown, fetid vaginal discharge or RT ≥39.5°C within 21 d in milk; and healthy cows had neither fetid discharge nor RT ≥39.5°C. Samples were collected from cows on commercial dairy herds (n = 7) using the cytobrush technique. A total of 37 T. pyogenes isolates and 85 E. coli isolates were tested. Ceftiofur, a third-generation cephalosporin that is often used to treat APM, was the focus of analysis. Trueperella pyogenes and E. coli were isolated more often from samples of cows with APM (46 and 90%, respectively) compared with samples from healthy cows (19 and 54%, respectively). Regarding cows suspected to have APM, T. pyogenes and E. coli were numerically more often isolated (30 and 70%, respectively) than in healthy cows (19 and 54%, respectively). Minimum inhibitory concentrations of ceftiofur were low. For T. pyogenes and E. coli, MIC₅₀ (concentration that inhibited growth of 50% of isolates) were 0.25 and 0.5 µg/mL and MIC₉₀ (concentration that inhibited growth of 90% of isolates) were 0.5 and 1 µg/mL, respectively. Although ceftiofur inhibited all T. pyogenes at the highest concentration tested (64 µg/mL), the growth of 5.9% of E. coli was not impaired. Recently, ampicillin has been suggested as an alternative treatment for APM. Although the T. pyogenes isolates exhibited low MIC in general (MIC₅₀ ≤0.015 µg/mL and MIC₉₀ = 0.06 µg/mL) and 81.1% of all T. pyogenes could be inhibited at the lowest ampicillin concentration tested, 11.8% of the E. coli isolates were not impaired at the highest concentration (64 µg/mL) tested in this study. The MIC₅₀ and MIC₉₀ of E. coli were 4 and ≥128 µg/mL, respectively. We detected no difference in the MIC distributions of ceftiofur or ampicillin among isolates from the 3 APM groups. In summary, E. coli with high MIC against ceftiofur as well as against ampicillin were found in this study.

Characterization of Staphylococcus spp. strains in milk from buffaloes with mastitis in Brazil: the need to identify to species level to avoid misidentification

ABSTRACT Mastitis is an inflammation of the mammary gland that affects dairy cattle worldwide causing economic losses. Coagulase-negative staphylococci (CNS) are the predominant cause of this type of infection. We have recently showed that coagulase-positive staphylococci could be misidentified. So, the aim of this study was to characterize the Staphylococcus spp. strains initially classified as coagulase-negative Staphylococci, isolated from buffalo with subclinical mastitis. Milk of buffaloes with mastitis in herds was collected and 9 strains were identified as CNS by phenotypic tests. Molecular methodologies latter identified the strains as coagulase-negative Staphylococcus chromogenes (5), coagulase-positive Staphylococcus hyicus (2) and coagulase-positive Staphylococcus aureus (2). Our results strongly support the need to identify the isolates to a species level in order to avoid misidentification and to be aware of the classification using the coagulase test alone.