MRSA

Staphylococcus (MRSA) = methicillin-resistant Staphylococcus aureus. 

As recently as 1970, only about 30 naturally occurring organohalogen compounds were known. It was simply assumed that chloroform, halogenated phenols, chlorinated aromatic compounds called PCBs, and other such substances found in the environment were industrial pollutants. Now, only a third of a century later, the situation js quite different. More than 5000 organohalogen compounds have been found to occur naturally, and tens of thousands more surely exist. From a simple compound like chloromethane to an extremely complex one like vancomycin, a remarkably diverse range of organohalogen compounds exists in plants, bacteria, and animals. Many even have valuable physiological activity. Vancomycin, for instance, is a powerful antibiotic produced by the bacterium Amycolatopsis orientalis and used clinically to treat methicillin-resistant Staphylococcus aureus (MRSA). 

Methicillin-resistent staphylococci are strains of staphylococci, which show resistance to a wide variety of antibiotics. They are named for their resistance to methicillin, a (3 -lactamase-resistant penicillin. Methicil-lin-resistante Staphylococcus aureus (MRSA) has become a serious problem particularly in hospitals. 

Problems of recent years involving listeriosis, salmonellosis, giardiasis and Legionnaire s disease have received attention, as have the re-emergence of tuberculosis and the importance of methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). 

Early cephalosporins were spelt with ph, more recently with T. t Methicillin-resistant Staph, aureus (MRSA) strains are resistant to cephalosporins. t Enterococci are resistant to cephalosporins. 

MRSA strains are a frequent problem in hospital infechon, such strains often showing multiple antibiotic resistance. Furthermore, increased resistance to some... 

To prevent development of resistance and promote synergy, inhaled tobramycin or colistin is usually added to an oral fluoroquinolone for P. aeruginosa coverage.1,3 Methicillin-sensitive S. aureus (MSSA) may be treated with oral amoxiciUin-clavulanic acid, dicloxacillin, first- or second-generation cephalosporins, trimethoprim-sulfamethoxazole, or clindamycin, depending on sensitivity. Likewise, methiciUin-resistant S. aureus (MRSA) may be treated with oral trimethoprim-sulfamethoxazole, clindamycin, minocycline, or linezolid. H. influenzae often produces... 

MRSA methiciUin-resistant Staphylococcus aureus MSSA methiciUin-sensitive Staphylococcus aureus... 

Infections acquired from an external source are referred to as exogenous infections. These infections may occur as a result of human-to-human transmission, contact with exogenous bacterial populations in the environment, and animal contact. Resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. 

MRSA, methici 11in-resistant Staphylococcus aureus MRSE, methici llin-resistant Staphylococcus epidermidis. Adapted, with permission. 

Health care MRSA, extended-spectrum P-lactamase-producing K. pneumoniae, P. aeruginosa, Acinetobacter spp. 

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. 

CA-MRSA is susceptible to more antibiotics than HA-MRSA. Like HA-MRSA, CA-MRSA typically is sensitive to vancomycin, linezolid, daptomycin, tigecycline, and quinupristin/ dalfopristin, but it also may be sensitive to clindamycin, doxy-cycline, minocycline, and/or trimethoprim-sulfamethoxazole (TMP-SMX).14... 

Of the latter four agents, clindamycin has the most data supporting its use. However, the clinician must be aware of inducible clindamycin resistance. For CA-MRSA isolates determined to be resistant to erythromycin but sensitive to clindamycin, an additional laboratory analysis, known as the erythromycin-clindamycin D-zone test, is conducted to assess for inducible clindamycin resistance.15 Isolates for which the D-zone test indicates inducible resistance should not be treated with clindamycin. 

With regard to the clinical effectiveness of TMP-SMX and the tetracyclines, anecdotal evidence and small trials support their use in the treatment of CA-MRSA cellulitis. However, large randomized, controlled trials are needed to confirm their place in therapy.16,17... 

Finally, CA-MRSA produces the virulent Panton-Valentine leukcocidin toxin. It destroys leukocytes, causes severe tissue damage and necrosis, and has been associated with both necrotizing skin infections and pneumonia.14... 

Limited clinical data exist for the treatment of MRSA infections. 

CCA-MRSA isolates resistant to erythromycin should be evaluated for inducible clindamycin resistance. 

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