Staphylococci vancomycin

Vancomycin is an antibiotic produced by Streptococcus orientalis and Amycolatopsis orientalis. With the single exception of flavobacterium, it is active only against gram-positive bacteria, particularly staphylococci. Vancomycin is a glycopeptide of molecular weight 1500. It is water soluble and quite stable. 

Vancomycin is bactericidal. It acts at an early stage in cell wall synthesis and does not bind to PBPs. It is not absorbed following oral administration and is used by this route in the treatment of colitis caused by Clostridium difficile and staphylococci. Vancomycin is not susceptible to beta-lactamases since it is not a beta-lactam. Vancomycin continues to have useful activity against strains of methicillin-resistant staphylococci. The answer is (C). 

B. subtilis, S. aureus, methicillin-resistant coagulase-negative staphylococci, vancomycin-resistant Enterococcus faecium, ESBL-positive K. pneumonia, S. typhi. Vibrio choiera... 

Synthesized by transposition of the niciogen of 4-quinolines the mtxl ifications result in a new series of DNA gyrase inhibitory drugs that have outstanding in viiro activities against a broad range of bacteria, including methicillin-resistant staphylococci, vancomycin-resis tant enterococci, and ciprofloxacin-resistant bacteria. 

Teicoplanin is a naturally occurring complex of five closely related tetracyclic molecules. Its mode of action and spectrum of activity are essentially similar to vancomycin, although it might be less active a inst some strains of coagulase-negative staphylococci. Teicoplanin can be administered by intramuscular injection. 

It is important to determine (1) whether the isolate is methicillin-susceptible or methicillin-resistant and (2) whether the patient has a prosthetic valve. For patients with no prosthetic material, methicillin-susceptible staphylococci treatment should consist of a penicillinase-resistant penicillin (e.g., nafcillin or oxacillin) with or without gentamicin, and for methicillin-resistant strains, therapy should consist of vancomycin (see Table 71-4). Combination therapy with aminoglycosides, when used in these patients, typically is given only during the first 3 to 5 days of therapy. In the absence of prosthetic material, some treatment guidelines do not recommend combination therapy against MRSA. However, many clinicians may combine either gentamicin or rifampin with vancomycin if the patient is unresponsive to monotherapy. 

For penicillin-allergic (nonanaphylactoid type) patients cefazolin 6 g/24 hours IV in 3 equally divided doses 6 IB Consider skin testing for oxacillin-susceptible staphylococci and questionable history of immediate-type hypersensitivity to penicillin cephalosporins should be avoided in patients with anaphylactoid-type hypersensitivity to P-lactams vancomycin should be used in these cases ... 

The answer is c. (Hardman, pp 996-997r 1145—1146. Ka tzung, p 8455 Metronidazole is often used to treat antibiotic-associated enterocolitis, especially when caused by C difficile. Vancomycin is no longer preferred because it induces selection of resistant staphylococci. Clindamycin is also associated with C difficile colitis, but in another way a higher percentage of patients taking this over other antibiotics develop antibiotic-associated enterocolitis. 

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

PVE that occurs within 2 months of cardiac surgery is usually caused by staphylococci implanted at the time of surgery. MethiciUin-resistant organisms are common. Vancomycin is the cornerstone of therapy. 

For methidllin-resistant staphylococci (both methiciUin-resistant S. aureus and CNST), vancomycin is used with rifampin for 6 weeks or more (Table 37-7). An aminoglycoside is added for the first 2 weeks if the organism is susceptible. 

For methiciUin-susceptible staphylococci, a penicillinase-stable penicillin is used in place of vancomycin. If an organism is identified other than staphylococci, the treatment regimen should be guided by susceptibilities and should be at least 6 weeks in duration. 

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. 

Initial therapy with trimethoprim-sulfamethoxazole appears to be effective for CA-MRSA and should be considered in geographic areas in which CA-MRSA are commonly encountered. Alternative agents for documented infections with resistant gram-positive bacteria such as methicil-lin-resistant staphylococci and vancomycin-resistant enterococci include linezolid, quinupristin/dalfopristin, daptomycin, and tigecycline. 

For C. difficile colitis oral or i.v. metronidazole is advised for at least 14 days. Shorter duration will increase the relapse-rate. Oral vancomycin is equally effective but more expensive and the frequent use of vancomycin in some countries has been associated with an increase in vancomycin-resistant enterococci and staphylococci. 

Multiply resistant coagulase-negative staphylococci are frequently the cause of postoperative endophtalmitis and require the use of a glycopep-tide (e.g. vancomycin). For topical treatment fusidic acid eye gel, tetracycline or chloramphenicol ointment are available, and can be administered 2 t.d. for 7 days. Trachoma should be treated with an oral macrolide (e.g. a single oral dose of 20 mg/kg azithromycin) or doxycyclin for 3 weeks (for moderate to severe cases). Keratitis needs hourly administration of fortified antibiotic eye drops for 2 weeks. Endophtalmitis needs specialist treatment for 6 weeks. 

Vancomycin and teicoplanin display excellent activity against staphylococci and streptococci, but because of the wide availability of equally effective and less toxic drugs, they are second-line drugs in the treatment of most infections. As antistaphylococcal agents they are less effective than 3-lactam cephalosporin antibiotics, such as nafciUin and cefazoUn. They have attained much wider use in recent years as a consequence of the emergence of methicUlin-resistant S. aureus (MRSA) infections, in particular the growing importance of Staphylococcus epidermidis infections associated with the use of intravascular catheters and in patients with peritonitis who are on continuous ambulatory peritoneal dialysis. 

Srinivasan A, Dick JD, and Perl TM. Vancomycin resistance in staphylococci. Clin Microbiol Rev... 

Quinupristin-dalfopristin is approved for treatment of infections caused by staphylococci or by vancomycin-resistant strains of E faecium, but not E faecalis, which is intrinsically resistant probably because of an efflux-type resistance mechanism. The principal toxicities are infusion-related events, such as pain at the infusion site, and an arthralgia-myalgia syndrome. 

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)... 

The use of an antagonistic antimicrobial combination does not preclude other potential beneficial interactions. For example, rifampin may antagonize the action of anti-staphylococcal penicillins or vancomycin against staphylococci. However, the aforementioned antimicrobials may prevent the emergence of resistance to rifampin. 

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