Staphylococci, methicillin-resistant

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. 

Mesolimbic System/Reward System Metabolic Syndrome Metabotropic Glutamate Receptors Metabotropic Receptor Metalloprote(in)ases Methicillin-resistant Staphylococci iV-Methyl D-aspartate Receptors Methylating Agents... 

For methicillin-resistant staphylococci, use vancomycin 0.5-1 g every 6-12 hours (pediatric dosing 40 mg/kg/day in divided doses) with dosage adjustments made for renal dysfunction. 

Severe staphylococcal Infections - Severe staphylococcal infections (including methicillin-resistant staphylococci) in patients who cannot receive or who have failed to respond to penicillins and cephalosporins, or who have infections with resistant staphylococci. Infections may include endocarditis, bone infections, lower respiratory tract infections, septicemia, and skin and skin structure infections. 

Cephalosporins Active Against Methicillin-Resistant Staphylococci... 

Ceftobiprole1, ceftaroline1 Intravenous, active against methicillin-resistant staphylococci, broad gram-negative activity... 

Linezolid Prevents bacterial protein synthesis by binding to the 23S ribosomal RNA of 50S subunit Bacteriostatic activity against susceptible bacteria Infections caused by methicillin-resistant staphylococci and vancomycin-resistant enterococci Oral, IV hepatic clearance (half-life 6 h) dosed twice-daily Toxicity Duration-dependent bone marrow suppression, neuropathy, and optic neuritis serotonin-syndrome may occur when coadministered with other serotonergic drugs (eg, selective serotonin reuptake inhibitors)... 

Altered penicillin binding proteins Modified PBPs have a lower affinity for p-lactam antibiotics, requiring clinically unattainable concentrations of the drug to effect binding and inhibition of bacterial growth. This mechanism may explain methicillin-resistant staphylococci, although it does not explain its resistance to non-lactam antibiotics like erythromycin to which they are also refractory. 

Vancomycin [van koe MYE sin] is a tricyclic glycopeptide that has become increasingly important because of its effectiveness against multiple drug resistant organisms such as methicillin-resistant staphylococci. The medical community is presently concerned about reports of emergence of vancomycin resistance in these strains as well as the enterococci. 

Vancomycin is the drug of choice for methicillin-resistant staphylococci since most methicillin-resistant S. aureus and most CNST are susceptible. 

As this category of penicillins was used for treatment, S. aureus and S. epidermidis became resistant to them through the production of altered penicillin-binding proteins. These strains of staphylococci are called methicillin resistant, which denotes resistance not only to all penicillinase-resistant penicillins but to all penicillin drugs. Methicillin-resistant staphylococci have become a major problem in treatment because they are also resistant to the cephalosporins, aminoglycosides, and macrolides. For this reason vancomycin, a more toxic antibiotic, is the drug of choice for these organisms. 

Because of its potential toxicity, vancomycin is reserved for serious infections in which less toxic antibiotics are ineffective or not tolerated. Generally, vancomycin is administered intravenously because of poor intestinal absorption. It is the drug of choice for treating infections caused by methicillin-resistant staphylococci and penicillin-resistant Streptococcus pneumoniae. Vancomycin has been used to treat enterococcal infections because of their resistance to the P-lactam antibiotics, but most enterococci are now also resistant to vancomycin. Oral administration of rancomycin is important for treatment of some gastrointestinal infections such as pseudomembranous colitis caused by C. difficile. 

Cephamycins include p-lactam such as cefoxitin, cefotetan, cefmetazole and latamoxef (moxalactam). Cephamycins are active against anaerobic bacteria, are less active against gram-positive cocci and, have no activity against methicillin-resistant staphylococci and enterococci. Cephamycin antibiotics such as cefotetan and latamoxef have a side chain called the... 

Vancomycin is a glycopeptide that has bactericidal action against gram-positive bacteria and some gram-negative cocci. Vancomycin is used because of its activity against methicillin-resistant staphylococci and corynebacteria. It has thus become popular for treatment of endocarditis and sepsis caused by these organisms. 

Vancomycin hydrochloride -Methicillin-Resistant Staphylococci 30 mg/kg per 24 h IV in two equally divided doses, not to exceed 2g/24 h unless serum levels are monitored 4-6... 

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