Methicillin-resistant .S , aureus

Inpatient treatment of methicillin-resistant S. aureus can consist of IV vancomycin or oral agents as described above, depending on the severity of infection and concomitant organisms. IV vancomycin may also be converted to oral step-down therapy upon discharge. 

Community-acquired methicillin-resistant S. aureus (CA-MRSA) is becoming an increasingly common pathogen in cellulitis. CA-MRSA can be distinguished from health care-associated MRSA (HA-MRSA) by its genetic dissimilarity, host population, drug susceptibility patterns, and toxin production. 

MSSA methicillin-sensitive S. aureus MRSA methicillin-resistant S. aureus NBTE nonbacterial thrombotic endocarditis... 

MRSA, methicillin-resistant S. aureus PVD, peripheral vascular disease IJTI, urinary tract infection. 

The majority of SSTIs are caused by gram-positive organisms and, less commonly, gram-negative bacteria present on the skin surface. Staphylococcus aureus and Streptococcus pyogenes account for the majority of SSTIs. Community-associated methicillin-resistant S. aureus (CA-MRSA) has recently emerged and it is often isolated in otherwise healthy patients. 

Boijesson S, Melin S, Matussek A et al (2009) A seasonal study of the mecA gene and Staphylococcus aureus including methicillin-resistant S. aureus in a municipal waste water treatment plant Water Res 43(4) 925-932... 

Treat patients with methicillin-resistant S. aureus infection with linezolid 600 mg per 12 hours. 

Mupirocin is not related to any of the sys-temically used antibiotics. It is an inhibitor of bacterial protein synthesis and is especially active against gram-positive aerobic bacteria, e.g. methicillin-resistant S. aureus and group A beta-hemolytic streptococci. Absorption through the skin is minimal. Intranasal application may be associated with irritation of mucous membranes. 

An additional mechanism of antibiotic resistance involves an alteration of PBPs. Resistant bacteria, usually gram-positive organisms, produce PBPs with low affinity for p-lactam antibiotics. The development of mutations of bacterial PBPs is involved in the mechanism for p-lactam resistance in Streptococcus pneumoniae. Enterococcus faecium, and methicillin-resistant S. aureus (MRS A). 

Figure 4.8 Patterns of smaldigested DNA of Staphylococcus aureus isolates on pulsed-field gel electrophoresis (PFGE). The isolates were obtained from four patients in diversely distant locations within the United States. Lane 1 = ATCC29213 (positive control), lane 2 = a methi-cillin-resistant S. aureus isolated from a patient in Georgia lane 3 = a gylcopeptide intermediate S. aureus isolated from a patient in Michigan, lane 4 = a methicillin-resistant S. aureus from the same patient in Michigan, and lane 5 = a glycopeptidet-intermediate S. aureus isolate from a patient in New Jersey. (From Smith et al., 1999b.)...

Clindamycin is indicated for the treatment of skin and soft-tissue infections caused by streptococci and staphylococci. It is often active against community-acquired strains of methicillin-resistant S aureus, an increasingly common cause of skin and soft tissue infections. Clindamycin is also indicated for treatment of anaerobic infection caused by bacteroides and other anaerobes that often participate in mixed infections. Clindamycin, sometimes in combination with an aminoglycoside or cephalosporin, is used to treat penetrating wounds of the abdomen and the gut infections originating in the female genital tract, eg, septic abortion and pelvic abscesses and aspiration pneumonia. Clindamycin is now recommended rather than erythromycin for prophylaxis of endocarditis in patients with valvular heart disease who are undergoing certain dental procedures. Clindamycin plus primaquine is an effective alternative to trimethoprim-sulfamethoxazole for moderate to moderately severe Pneumocystis jiroveci pneumonia in AIDS patients. It is also used in combination with pyrimethamine for AIDS-related toxoplasmosis of the brain. 

Moran GJ et al Methicillin-resistant S. aureus infections among patients in the emergency department. N Engl J Med 2006 355 666. [PMID 16914702]... 

Mupirocin (pseudomonic acid A) is structurally unrelated to other currently available topical antibacterial agents. Most gram-positive aerobic bacteria, including methicillin-resistant S aureus (MRSA), are sensitive to mupirocin (see Chapter 50). It is effective in the treatment of impetigo caused by S aureus and group A -hemolytic streptococci. 

The utility of Av-GEB platform was demonstrated for the determination of the mecA DNA sequence related with methicillin-resistant S. aureus (MRSA) [67] in a simpler and specific manner with respect to previous DNA biosensing devices [58,65,66]. 

Mupirocin is indicated for topical treatment of minor skin infections, such as impetigo. Topical application over large infected areas, such as decubitus ulcers or open surgical wounds, has been identified as an important factor leading to emergence of mupirocin-resistant strains and is not recommended. Mupirocin is also indicated for intranasal application for elimination of methicillin-resistant S aureus carriage by patients or health care workers. 

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