Treatment of bacterial respiratory infections in lambs

Comparative genomic analysis of Brazilian Mesomycoplasma ovipneumoniae strains revealed genomic differences associated with the geographic origin and health status and mutations in the gyrA

Sheep respiratory disease (SRD) is a multifactorial illness commonly affecting sheep. Mesomycoplasma (Mycoplasma) ovipneumoniae is one of the most important etiological agents of SRD and should be better understood, especially in countries where it was recently detected, such as Brazil. Also, the intensive use of quinolones in mycoplasmal infections increases the selective pressure for resistance to this drug class, and no data about antimicrobial resistance in Brazil is available. Therefore, this study aimed to perform a comparative genomic analysis of newly isolated Brazilian M. ovipneumoniae strains, identify point mutations in target genes that may be associated with antibiotic resistance, and perform a phylogenomic analysis of these strains with available genome representatives of M. ovipneumoniae. Glucose-fermenting fried egg-like colonies identified as M. ovipneumoniae were obtained after a culture of tracheobronchial lavage from infected sheep. The genomes were sequenced, de novo assembled and comparatively evaluated. Important putative virulence factors were detected in all isolates: the analysis of the average nucleotide homology of all these genes with the M. ovipneumoniae ATCC 29419 revealed associations between clpB, lgt, tuf, and dnaJ genes and geographic location. In addition, nucleotide substitutions in a few positions of the Quinolone-Resistant Determinant Region of the gyrA gene, including the Ser83Ala, were detected. The phylogenomic analysis showed that the Brazilian isolates belonged to two different clades corresponding to geographic location, and the isolates from São Paulo showed high similarity, which differs from isolates from Rio de Janeiro. This first genomic analysis of the Brazilian M. ovipneumoniae genomes demonstrates strain segregation according to location and health status, reinforcing the importance of continuous surveillance and diagnostics of this bacteria causing sheep respiratory disease in the Brazilian flocks.

Clearance of Mycoplasma ovipneumoniae in Captive Bighorn Sheep (Ovis canadensis) Following Extended Oral Doxycycline Treatment

Respiratory disease is a significant barrier for bighorn sheep (Ovis canadensis) conservation, and a need remains for management options in both captive and free-ranging populations. We treated Mycoplasma ovipneumoniae infection in six bighorn lambs and five bighorn yearlings at two captive research facilities with twice daily oral doxycycline for 8 wk or longer. Doses of 5 mg/kg twice daily mixed in formula for lambs and 10 mg/kg twice daily mixed in moistened pellets for older lambs and yearlings were tolerated well with minimal side effects. All animals in this case report remain Mycoplasma ovipneumoniae free over 2 yr later. Further evaluation is warranted to confirm efficacy of this therapeutic approach.

Use of Antibiotics Against Bacterial Infections on Dairy Sheep and Goat Farms: Patterns of Usage and Associations with Health Management and Human Resources

The objectives of the study were (a) to describe the patterns of antibiotic usage against four major clinical problems and (b) to evaluate factors that were associated with their use on small ruminant farms. Sheep and goat farmers mostly administered the antibiotics to animals at the dose prescribed (80.4%) and observed the necessary withdrawal period (98.7%), but fewer farmers (22.3%) weighed the animals to calculate their bodyweight before antibiotic administration. For the treatment of clinical mastitis, oxytetracycline, penicillin and streptomycin were the antibiotics used more frequently; 2.03 different antibiotics were used per sheep flock and 2.06 per goat herd, most frequently administered in injectable forms (88.8% of farms). In cases of abortion, oxytetracycline was administered more frequently; 1.12 different antibiotics were used per sheep flock and 1.03 per goat herd. In 94 farms (21.2%), routine administration of antibiotics was performed to newborns; oxytetracycline and ampicillin were administered more often. For the treatment of pneumonia in newborns, oxytetracycline, penicillin and tulathromycin were used more frequently; 1.33 antibiotics were used per sheep flock and 1.29 per goat herd. For the treatment of diarrhoea in lambs and kids, oxytetracycline, amoxicillin and penicillin were the antibiotics used more frequently; 1.34 antibiotics were used per sheep flock and 1.59 per goat herd. Results of multivariable analyses indicated 16 variables associated with the various outcomes for usage of antibiotics for the treatment of the above clinical problems. Of these, 11 variables were associated with the farmers: education of farmers was significant for three outcomes; the age, the experience, the professional involvement and farming family tradition of farmers and the daily period spent at the farm were each significant for one outcome.

Comparative Therapy of Animal and Bird Diseases Caused by Mycoplasmas

Mycoplasmas are the cause of many pathologies, both of various species of animals and birds. The minimum inhibitory concentrations (MICs) of enrofloxacin, difloxacin, oxytetracycline, chlortetracycline, doxycycline, tylosin, tilmycosin, tilvalosin, tiamulin, florfenicol, lincomycin, spectinomycin and 2 combinations (spectinomycin and lincomycin) with the isolates of Myecoplasma sympathy were significantly different. Elevated MICs of tilmicosin were observed in both M. synoviae and M. gallisepticum isolates (MIC values> = 64 μg/ml), and this was observed in all isolates with high MICs of tylosin. The increase in the MIC of lincomycin was mainly associated with the increase in the MIC of tilmicosin. In vitro susceptibility testing of 50 M. gallisepticum strains isolated in Israel in the period of 1997-2010 carried out by a group of scientists led by Gerchman I. showed that acquired resistance to tylosin, as well as to tilmicosin, is present in 50 % of them. Moreover, 72 % (13/18) of the strains isolated from clinical specimens since 2006 showed acquired resistance to enrofloxacin, tylosin and tilmicosin. All isolates with MIC> = 0.63 μg/ml for tylosin and MIC> = 1.25 μg/ml for tilmycosin have one of these mutations, which indicates a significant role in reducing the sensitivity of M. gallisepticum to 16-membered macrolides. Fluoroquinolones, tilmicosin, tulathromycin, chlortetracycline, doxycycline and oxytetracycline are effective against Mannheimia haemolytica and Mycoplasma, which are the main causative agents of respiratory infections in lambs. Antimicrobial resistance of Mycoplasma bovis isolates to antibacterial drugs is not high. With the exception of tilmicosin, all isolates were highly susceptible to the tested antimicrobials (oxytetracycline and florfenicol). Tilmicosin and oxytetracycline are effective in treating respiratory diseases in young calves, even if they are affected by Mycoplasma spp. Tilmicosin is more effective in eliminating the clinical signs of mycoplasmosis. Treatment of mycoplasma respiratory syndrome with tulathromycin resulted in slightly higher (P = 0.009) therapeutic success (87.9 % and 80 %, respectively) than initial treatment with enrofloxacin (70.2 % and 62.5 %, respectively). Animals treated with tulathromycin also received fewer follow-up treatments and increased weight gain compared to animals treated with enrofloxacin. Tulatromycin was evaluated in the treatment of pneumonia in weaning pigs intranasally inoculated with Mycoplasma hyopneumoniae. Tulatromycin was also quite effective. Use of broad-spectrum drugs, which include tilmicosin, is also promising. Therefore, the therapeutic efficacy of the analyzed drugs used for the treatment of mycoplasmosis, both in birds and animals (cattle, small ruminants, and pigs), depends both on the drugs used and on etiological agents. A significant role in the effectiveness of treatment with certain drugs is played by the infections accompanying mycoplasmosis.

Antibiotic Resistance of Staphylococci from Bulk-Tank Milk of Sheep Flocks: Prevalence, Patterns, Association with Biofilm Formation, Effects on Milk Quality, and Risk Factors

Simple Summary

This work investigated the presence of staphylococci resistant to antibiotics in the raw milk produced in sheep farms, which is intended for human consumption, in an extensive study performed throughout Greece. In 31% of flocks, staphylococci resistant to at least one antibiotic were recovered; in 12% of flocks, staphylococci resistant to at least three different antibiotic classes were found. Factors potentially associated with recovery of resistant isolates were the lack of experience by farmers (<5 years), the period immediately post lambing, and the intensive management system applied in the flocks.

Abstract

The objectives of this work were to study prevalence and characteristics of resistance to antibiotics of staphylococcal isolates from the bulk-tank milk of sheep flocks across Greece, to assess possible associations of the presence of antibiotic resistance with the quality of milk in these flocks and to evaluate flock-related factors potentially associated with antibiotic resistance among these isolates. A cross-sectional study was performed in 325 sheep flocks in Greece. Bulk-tank milk samples were collected for bacteriological examination; staphylococcal isolates were evaluated for resistance to 20 antibiotics. Oxacillin-resistant staphylococcal isolates, isolates resistant to any antibiotic, and multi-resistant isolates were recovered from 8.0%, 30.5%, and 12.0% of flocks, respectively. Of 232 isolates, 11.6% were resistant to oxacillin, 46.1% were resistant to at least one antibiotic, and 16.4% were multi-resistant. Resistance was seen more frequently among coagulase-negative (50.6%) than among Staphylococcus aureus (31.5%) isolates. Resistance was more frequent against penicillin and ampicillin (34.1% of isolates), clindamycin (17.7%), and fosfomycin (14.2%). An association was found between biofilm formation by staphylococci and resistance to fosfomycin. For recovery of oxacillin-resistant isolates, the lack of experience by farmers emerged as a significant factor; respective factors for the isolation of staphylococci resistant to any antibiotic or multi-resistant isolates were the early stage of the lactation period (0th–1st month) and the intensive management system applied in the flocks, respectively.