Enterococci resistance

After 5 days administration of quinupristin + dalfopristin 7.5 mg/kg infused over 1 hour bd, the fecal microflora in 20 healthy volunteers increased significantly during treatment and returned within 12 weeks to baseUne concentrations after the end of treatment. There were anerobes and enterococci resistant to erythromycin or to quinupristin - - dalfopristin, but glycopeptide-resistant enterococci did not emerge (22). 

Morris JG, Shay DK, Hebden JN. Enterococci resistant to multiple antimicrobial agents, including vancomycin. Establisment of endemicity in a university medical center. Ann Int Med 1995 123 250-259. 

Centers for Disease Control and Prevention. Nosocomial enterococci Resistant to vancomycin—United States, 1989-1993. Morb Mortal Wkly Rep 1993 42 597-599-Gin AS, Zhanel GG. Vancomycin-resistant enterococci. Ann Pharmacol 1996 30 615-624. Travis J. Reviving the antibiotic miraclef Science 1994 264 360-362. 

Resistance to streptogramin type B antibiotics can be mediated in staphylococci and enterococci by plasmids carrying a vgb gene [2]. The Vgb enzyme is a lyase that linearizes the cyclic hexadepsipeptide by cleavage of the ester bond via an elimination reaction. 

Nucleotidylation - the addition of adenylate-residues by Lnu enzymes - can also be the cause of resistance to lincosamide antibiotics in staphylococci and enterococci. A plasmid encoded ADP-ribosylating transferase (Arr-2) that leads to rifampicin resistance has been detected in various Enterobacteriaceae as well as in Pseudomonas aeruginosa. 

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. 

In recent years multi-drug resistance has increased among certain pathogens. These include aureus, enterococci andM. tuberculosis. Staphylococcus aureus... 

Arthur M., Reynolds P. Courvalin P. (1996) Glycopeptide resistance in enterococci. Trends Microbiol, 4,401-407. 

Acquired resistance to the glycopeptides is transposon-mediated and has so far been largely confined to the enterococci. This has been a problem clinically because many of these strains have been resistant to all other antibiotics and were thus effectively untreatable. Fortunately, the enterococci are not particularly pathogenic and infections have been confined largely to seriously ill, long-term hospital patients. Two types of acquired glycopeptide resistance have been described (Woodford et al. 1995). The VanA phenotype is resistant to vancomycin and teicoplanin, whereas VanB is resistant... 

For enterococci, it is imperative to determine species and antibiotic susceptibilities. If the organism is susceptible to penicillin and vancomycin, treatment may consist of high-dose penicillin G, ampicillin, or vancomycin plus gentamicin (see Table 71-6). Treatment length is usually 4 to 6 weeks, with the aminoglycoside used over the entire course. As resistance develops to penicillin, ampicillin and vancomycin remain treatment options. Once the isolate becomes resistant to ampicillin, vancomycin is considered the treatment of choice. 

If the isolate is determined to be vancomycin-resistant, it is most important to know the exact species because some of the treatment options, such as quinupristin/dalfopristin, are not active against E. faecalis. Currently, the treatment options for vancomycin-resistant enterococci (VRE) are not well established by clinical studies or patient experience. The treatment recommendations for vancomycin-resistant E. faecium include linezolid or quinupristin/dalfopristin for a minimum of 8 weeks. However, newer agents, such as daptomycin, may provide another option for treatment for either enterococci species (E. faecium and E. faecalis). Additionally, guidelines suggest the use of imipenem-cilistatin plus ampicillin or ceftriaxone plus ampicillin for the treatment of E. faecalis with a minimum of 8 weeks of therapy. Consultation with an infectious diseases specialist is recommended. 

Ampicillin is the standard penicillin that has broad-spectrum activity, and is the drug of choice for enterococci sensitive to penicillin. Amoxicillin is frequently used as well. Increasing E. coli resistance has limited amoxicillin use in acute cystitis. Amoxicillin-clavulanate is empirically preferred due to resistance. 

There are no major advantages of these agents over others in the treatment of UTIs, and they are more expensive. They may be useful in cases of resistance to amoxicillin and trimethoprim-sulfamethoxazole. These agents are not active against enterococci. 

Collignon P.J. (1999). Vancomycin-resistant enterococci and use of avoparcin in animal feed is there a link Med J Austral, 21, 144-146. 

The two most frequently used antibiotics are metronidazole and vancomycin. Metronidazole is recommended as first-line therapy because of the risk of development of vancomycin-resistant enterococci with vancomycin use, as well as its much higher cost. Metronidazole and vancomycin have similar efficacy, though in one study, symptoms resolved sooner with vancomycin [61]. Metronidazole is given orally for 10 days, at a dose of 1 g per day. Vancomycin is given orally for 10 days doses vary from 500 mg/day to 2 g/day. For mild to moderately severe CDAD, low-dose vancomycin is as effective as high-dose vancomycin. Vancomycin use is generally restricted to... 

In addition to isolates with high-level aminoglycoside resistance, /3-lacta-mase-producing enterococci (especially Enterococcus faecium) are increasingly reported. If these organisms are discovered, use of vancomycin or ampicillin-sulbactam in combination with gentamicin should be considered. 

Vancomycin-resistant enterococci, particularly E. faecium, are becoming more common. 

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. 

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