In vitro antimicrobial susceptibility of Mycoplasma mycoides mycoides large colony and Arcanobacterium pyogenes isolated from clinical cases of ulcerative balanitis and vulvitis in Dorper sheep in South Africa

Lesions of the prepuce and penis in rams: A retrospective study

In the ovine reproductive management, a thorough breeding soundness evaluation including specific inspection of the male genital tract represents a valuable tool for assessing the reproductive potential of a selected subject and for diagnosing genital disorders. During examination, accurate inspection on penis and prepuce is necessary, since conditions affecting these structures may hamper regular coitus. Records from 1270 males undergoing breeding soundness evaluation (n = 1232) or admitted for genital disorders to the Section of Obstetrics and Gynaecology (n = 38) of the Department of Veterinary Medicine, were collected, and lesions of penis and prepuce were therefore classified. The data collected revealed that 47/1270 rams examined presented lesions of the penis and prepuce. The most frequent condition was urolithiasis accounting for over 2% of the cases, followed by lack of the urethral process (0.39% incidence), lack of the glans penis and hypospadias (0.23% cases). Moreover, most of the conditions (40%) were observed in animals less than 2 years old, suggesting the importance of a careful breeding soundness evaluation in animals at young age.

Antimicrobial Resistance in Corynebacterium spp., Arcanobacterium spp., and Trueperella pyogenes

There is currently only limited information on the antimicrobial susceptibility and resistance of Corynebacterium spp., Arcanobacterium spp., and Trueperella pyogenes from animals. The comparability of the data is hampered by the use of different antimicrobial susceptibility testing methods and interpretive criteria. To date, standard broth microdilution methods and clinical breakpoints that are approved by the Clinical and Laboratory Standards Institute and are applicable to Corynebacterium spp., Arcanobacterium spp., and T. pyogenes are available. The lack of species-specific clinical breakpoints for the different animal species reduces the explanatory power of the data. Among the isolates of the three genera, elevated MICs for different classes of antimicrobial agents (e.g., β-lactams, macrolides, lincosamides, tetracyclines, aminoglycosides, phenicols, sulfonamides/diaminopyrimidines, and fluoroquinolones) have been described. The most comprehensive data set is available for T. pyogenes, which also includes information about genes and mutations involved in antimicrobial resistance. In T. pyogenes isolates, the macrolide-lincosamide-streptogramin B resistance genes erm(B) and erm(X) were identified. Tetracycline resistance in T. pyogenes was based on the resistance genes tet(W), tet(Z), and tet(33), whereas the aminoglycoside resistance genes aacC, aadA1, aadA2, aadA5, aadA24, and aadB have been described in T. pyogenes. So far, only single genes conferring either phenicol resistance (cmlA6), trimethoprim resistance (dfrB2a), or β-lactam resistance (blaP1) are known to occur in T. pyogenes isolates. Various 23S rRNA mutations, including A2058T, A2058G, and G2137C, were identified in macrolide/lincosamide-resistant T. pyogenes.

Florfenicol concentrations in ovine tear fluid following intramuscular and subcutaneous administration and comparison with the minimum inhibitory concentrations against mycoplasmal strains potentially involved in infectious keratoconjunctivitis

OBJECTIVE

To measure florfenicol concentrations in ovine tear fluid after IM and SC administration and determine minimum inhibitory concentrations (MICs) of florfenicol against field isolates of Mycoplasma organisms potentially involved in infectious keratoconjunctivitis.

ANIMALS

9 healthy adult Lacaune ewes.

PROCEDURES

Animals received an IM and SC administration of florfenicol (20 mg/kg) in a 2-way crossover design. Samples of blood and tear fluid were collected before and for 24 hours after administration. Concentrations of florfenicol in plasma and tear fluid were measured via high-performance liquid chromatography. The MIC of florfenicol for various Mycoplasma strains cultured from sheep and goats was determined via an agar dilution method.

RESULTS

Mean florfenicol concentration in tear fluid for the 24-hour period was significantly higher after IM administration (0.70 μg/mL) than after SC administration (0.22 μg/mL) and was maintained for a longer duration. The lacrimal fluid-to-plasma concentration ratio was not different between the 2 routes of administration, with mean values of 40.2% and 32.5% after IM and SC administration, respectively. The MIC for Mycoplasma agalactiae, Mycoplasma conjunctivae, and Mycoplasma mycoides isolates ranged from 0.5 to 8 μg of florfenicol/mL. Two strains of M agalactiae could be considered resistant to florfenicol.

CONCLUSIONS AND CLINICAL RELEVANCE

Florfenicol readily penetrated the preocular tear fluid of sheep after IM and SC administration. For both routes of administration, doses > 20 mg/kg would be necessary to achieve tear fluid concentrations of florfenicol greater than the MICs for most strains of Mycoplasma organisms.

Contagious agalactia due to Mycoplasma spp. in small dairy ruminants: epidemiology and prospects for diagnosis and control

Contagious agalactia (CA) is a serious disease of small dairy ruminants that has a substantial economic impact on the goat and sheep milk industries. The main aetiological agent of the disease is Mycoplasma agalactiae, although other species, such as Mycoplasma mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum and Mycoplasma putrefaciens, are pathogenic in goats. There are two clinical-epidemiological states of CA in sheep and goats; herds and flocks may exhibit outbreaks of CA or may be chronically infected, the latter with a high incidence of subclinical mastitis and only occasional clinical cases. The complex epidemiology of CA is related to the genetic characteristics and mechanisms of molecular variation of the Mycoplasma spp. involved, along with presence of CA-mycoplasmas in wild ruminant species. In goats, the situation is particularly complex and asymptomatic carriers have been detected in chronically infected herds. The coexistence of other non-pathogenic mycoplasmas in the herd further complicates the diagnosis of CA and the design of efficient strategies to control the disease. Routes of infection, such as the venereal route, may be involved in the establishment of chronic infection in herds. Current challenges include the need for improved diagnostic methods for detection of chronic and subclinical infections and for the design of more efficient vaccines.

In vitro susceptibilities of field isolates of Mycoplasma mycoides subsp. mycoides large colony type to 15 antimicrobials

In vitro susceptibilities of 16 Mycoplasma mycoides subsp. mycoides large colony type field isolates to 15 antimicrobial agents were determined using a broth microdilution method. The most effective antimicrobials were fluoroquinolones, tetracyclines and macrolides, with MIC values under 2 microg/ml. Resistance to nalidixic acid, gentamicin, streptomycin and spectinomycin was observed.