MRSA Infections:

- Discussion: (see MSSA)
    - true methicillin resistance involves the production of enzymes which are able to maintain cell-wall integrity during growth and division even when beta lactams have inactivated penicillin-binding proteins (ie resistant to penicillins and cephalosporins);  
    - MSRA of are now present in both large and small non-teaching hospitals and in community nursing homes;
           - approximately 15% of all nosocomial staph aureus isolates are methicillin resistant;
           - approximately 75 % of staph. epidermidis strains are resitant and 80% staph haemolyticus strains are resistant; 
    - osteomyelitis:
           - Comparative Severity of Pediatric Osteomyelitis Attributable to Methicillin-Resistant Versus Methicillin-Sensitive Staphylococcus aureus 

    - Panton-Valentine leucocidin: 
           - pore-forming toxin secreted by community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) and with the often-lethal necrotizing pneumonia;
           - genes encoding for Panton-Valentine leucocidin may be a primary reason for aggressive prevalance in the community;
           - references:
                   - Necrotizing fasciitis caused by community-associated methicillin-resistant Staphylococcus aureus in Los Angeles. 
                   - Community-acquired methicillin-resistant Staphylococcus aureus carrying Panton-Valentine leukocidin genes: worldwide emergence.
                   - Association between Staphyloccocus aureus strains carrying gene for Panton-Valentine leukocidin and lethal necrotising pneumonia in immunocompetent patients.
                   - Is Panton-Valentine leukocidin the major virulence determinant in community-associated methicillin-resistant Staphylococcus aureus disease?
                   - Staphylococcus aureus Panton-Valentine Leukocidin Causes Necrotizing Pneumonia

    - treatment:
           - prevention:
                   - the best treatment is prevention:
                   - hospital personel should wash hands after every patient contact; 
                   - ref: The role of MRSA screening in joint-replacement surgery.
           - antibiotic choices:
                   - vancomycin
                   - zyvox 
                   - septra and rifampin (for chronic suppression) 
                          - The bactericidal effects of anti-MRSA agents with rifampicin and sulfamethoxazole-trimethoprim against intracellular phagocytized MRSA

                   - clindamycin
                          - inducible resistance (appears sensitive on petri dish but is not)
                          - D-test: an erythromycin disk is placed near a clindamycin disk on a Kirby-Bauer plate;
                                 - w/ inducible resistance, zone of inhibition around clinda will be flattened in direction of erythromycin disc and will resemble letter D;
                   - minocycline
                   - rifampin
                          - Rifampicin as an adjunct to vancomycin therapy in MRSA septicaemia in burns
                   - teicoplanin
                   - daptomycin
                   - bacitracin (topical)
                          - Eradication of colonization by methicillin-resistant Staphylococcus aureus by using oral minocycline-rifampin and topical mupirocin
                          - Contemporary antimicrobial activity of triple antibiotic ointment: a multiphased study of recent clinical isolates in the United States and Australia.

    - references: 
           - Intramedullary Fixation of Long Bones--Basic Science and Pathology: Orthopedic Experience with methicillin-resistant Staphylococcus aureus during a Hospital Epidemic.
           - Comparison of levofloxacin, alatrofloxacin, and vancomycin for prophylaxis and treatment of experimental foreign-body-associated infection by methicillin-resistant Staphylococcus aureus.
           - Teicoplanin alone or combined with rifampin compared with vancomycin for prophylaxis and treatment of experimental foreign body infection by methicillin-resistant Staphylococcus aureaus. 
           - Necrotizing Fasciitis Caused by methicillin-resistant Staphylococcus aureus Resulting in Death. A report of three cases.
           - Natural history of community-acquired methicillin-resistant Staphylococcus aureus colonization and infection in soldiers.
           - Bactericidal activity of orally available agents against methicillin-resistant Staphylococcus aureus.

No mercy for MRSA: treatment alternatives to vancomycin and linezolid

MRSA colonisation and subsequent risk of infection despite effective eradication in orthopaedic elective surgery

Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Friday, January 18, 2013 4:04 pm