Antimicrobial therapy macrolides

Giguere S, Macrolides, azalides and ketolides, in Giguere S, Prescott JE, Baggot JD, Walker RD, Dowling PM, eds.. Antimicrobial Therapy in Veterinary Medicine, 4th ed., Blackwell, Ames, lA, 2006, pp. 191-205. 

Therefore, despite the 18% and 25% resistance to penicillin and macrolides, the clinical failure rate is less than this. Owing to the empirical treatment of CAP in the outpatient setting, establishing a meaningful clinical failure rate with any therapy is difficult to do. No studies have been performed that established a correlation between clinical failure rates with a particular antimicrobial agent and the percentage of resistant bacterial pathogens. 

Erythromycin estolate in conjunction with rifampin (both drugs administered orally) can be recommended for the treatment of Rhodococcus equi pneumonia in foals. Early diagnosis of the infection and prompt initiation of therapy considerably increase the effectiveness of treatment. Apart from this specific indication, macrolide antibiotics (including erythromycin) and lincosamides (lincomycin and clindamycin) are contra-indicated in horses. Antimicrobial agents in these classes can cause severe disturbance of the balance between commensal bacterial flora in the colon of the horse. 

Therapy with antibiotics generally should be continued for at least 7 to 10 days. Studies evaluating shorter treatment courses (usually 5 days) with the fluoroquinolones, second- and third-generation cephalosporins, and macrolide antimicrobials have demonstrated comparable efficacy with the longer treatment regimens. If the patient deteriorates or does not improve as anticipated, hospitalization may be necessary, and more aggressive attempts should be made to identify potential pathogens responsible for the exacerbation. 

Finally, the same approach has also been effective in malaria therapy (data not shown) indicative of the broad therapeutic potential of this macrolide conjugation strategy. Various anti-malarial drugs can be conjugated to the macrolide desosamine ring that in turn mediates their uptake into the parasite vacuole leading to improved overall efficacy in vivo. Examples using this approach include certain kinase inhibitors, and antimicrobial compounds as the small molecule payloads. 

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