MRSA, Staph, Staff, Mersa, Methicillin Resistant Staphylococcus Aureus Symptoms & Treatment

Drugs before surgery ward off MRSA

Link: HighWire Press -- Medline Abstract.

The use of prophylactic antibiotics in orthopaedic surgery is effective in reducing surgical site infections in hip and knee arthroplasty, spine surgery, and open reduction and internal fixation of fractures. To maximize the beneficial effect of prophylactic antibiotics while minimizing adverse effects, the correct antimicrobial agent must be selected, the drug must be administered just before incision, and the duration of administration should not exceed 24 hours.

1 in 3 get inadequate MRSA response in rural hospitals

Link: HighWire Press -- Medline Abstract.

Data regarding the epidemiology, treatment, and outcomes of methicillin-resistant Staphylococcus aureus (MRSA) infections in rural and community hospitals are limited. METHODS: This cohort study was conducted at 1 tertiary care hospital and 8 community hospitals in the southeastern United States. Patients with a surgical site infection (SSI) and/or bacteremia due to MRSA were prospectively identified at each study hospital during the period 1994-2003. RESULTS: A total of 129 patients with SSI and 564 patients with bacteremia due to MRSA were identified. Only 57 patients with SSI (44.2%) received antibiotics active against MRSA on the initial date of diagnosis; only 95 (73.6%) received an agent active against MRSA by day 7 after diagnosis of SSI due to MRSA. Ninety-five patients with SSI due to MRSA (73.6%) were readmitted to the hospital within 90 days after their original surgery. The 1-year mortality rate among patients with SSI due to MRSA was 22%. Inadequate therapy was also commonly given to patients with bacteremia: only 216 (38.3%) received antibiotics active against MRSA on the initial day of infection, and only 383 (67.9%) received an agent active against MRSA by day 7 after diagnosis. Approximately one-third of patients with bloodstream infection died during their initial hospitalization. Patients hospitalized in community hospitals were less likely to receive effective antimicrobial therapy on both the day of infection and within 7 days after infection, compared with patients in the tertiary care hospital. CONCLUSION: Inadequate therapy is commonly administered after diagnosis of SSI and bacteremia due to MRSA in patients in community hospitals.

Daptomycin effective for MRSA heart problems

Link: HighWire Press -- Medline Abstract.

Daptomycin is a lipopeptide antibiotic with potent in vitro activity against gram-positive cocci, including S. aureus. This study evaluated in vitro and in vivo efficacy of daptomycin against 2 methicillin-resistant clinical S. aureus (MRSA) isolates: MRSA 277 (vancomycin MIC 2 microg/ml) and GISA ATCC 700788 (vancomycin MIC 8 microg/ml). Time-kill experiments demonstrated that daptomycin was bactericidal in vitro against these 2 strains. The in vivo activity of daptomycin (6 mg/kg q 24 h) was evaluated using a rabbit model of infective endocarditis and compared with high-dose (HD, 1 g i.v. q 6 h) and recommended-dose (RD, 1 g i.v. q 12 h) vancomycin regimens for 48 hours and an untreated control group. Daptomycin was significantly more effective than vancomycin-RD in reducing the density of bacteria in the vegetations for the MRSA (0 [0-1.5] vs. 2 [0-5.6] log CFU/g veg; P = 0.02) and GISA (2 ([0-2]) vs. 6.6 [2.0-6.9] log CFU/g veg; P < 0.01) strains studied. In addition, daptomycin sterilized more vegetations than vancomycin-RD against MRSA (13/18 [72%] vs. 7/20 [35%]; P = 0.02) and both vancomycin regimens against GISA (12/19 [63%] vs. 4/20 [20%]; P < 0.01). No statistical difference between vancomycin-HD and vancomycin-RD for MRSA treatment was noted. These results support the use of daptomycin for treatment of aortic valve endocarditis caused by GISA and MRSA.

Telavancin results show promise

Link: Comparative Surveillance Study of Telavancin Activity Against Recent Gram-Positive Clinical Isolates From Across the United States -- Draghi et al., 10.1128/AAC.01641-07 -- Antimicrobial Agents and Chemotherapy.

Telavancin is an investigational, rapidly bactericidal, lipoglycopeptide antibiotic that is being developed to treat serious infections caused by gram-positive bacteria. A baseline prospective surveillance study was conducted to assess telavancin activity, in comparison with other agents, against contemporary clinical isolates collected in 2004 to 2005 from across the United States. Nearly 4000 isolates were collected including staphylococci, enterococci, and streptococci (pneumococci, {beta}-hemolytic, and viridans). Telavancin had potent activity against Staphylococcus aureus and coagulase-negative staphylococci (MIC range, 0.03–1.0 µg/ml), independent of resistance to methicillin or to multiple agents. Telavancin activity was particularly potent against all streptococcal groups (MIC90s, 0.03–0.12 µg/ml). Telavancin had excellent activity against vancomycin-susceptible enterococci (MIC90, 1 µg/ml), and was active against VanB strains of vancomycin-resistant enterococci (MIC90, 2 µg/ml) but less active against VanA strains (MIC90, 8–16 µg/ml). Telavancin also demonstrated activity against vancomycin-intermediate S. aureus and vancomycin-resistant S. aureus strains (MICs, 0.5 µg/ml–1.0 µg/ml and 1.0 µg/ml–4.0 µg/ml, respectively). These data may support the efficacy of telavancin for treatment of serious infections with a wide range of gram-positive organisms.

Rifampin shows some promise but results inconclusive

Link: Arch Intern Med -- Abstract: Adjunctive Use of Rifampin for the Treatment of Staphylococcus aureus Infections: A Systematic Review of the Literature, April 28, 2008, Perlroth et al. 168 (8): 805.

Results  The methods of in vitro studies varied substantially among investigations. The effect of rifampin therapy was often inconsistent, it did not necessarily correlate with in vivo investigations, and findings seemed heavily dependent on the method used. In addition, the quality of data reporting in these investigations was often suboptimal. Animal studies tended to show a microbiologic benefit of adjunctive rifampin use, particularly in osteomyelitis and infected foreign body infection models; however, many studies failed to show a benefit of adjunctive therapy. Few human studies have addressed the role of adjunctive rifampin therapy. Adjunctive therapy seems most promising for the treatment of osteomyelitis and prosthetic device–related infections, although studies were typically underpowered and benefits were not always seen. Conclusions  In vitro results of interactions between rifampin and other antibiotics are method dependent and often do not correlate with in vivo findings. Adjunctive rifampin use seems promising in the treatment of clinical hardware infections or osteomyelitis, but more definitive data are lacking. Given the increasing incidence of S aureus infections, further adequately powered investigations are needed.

Daptomycin approved for Scotland

Link: Pioneering new drug to fight MRSA is given go-ahead in Scotland - Scotsman.com News.

A NEW drug to help treat patients struck down by MRSA has been approved for use on the NHS in Scotland. The Scottish Medicines Consortium recommended Cubicin (daptomycin) to treat severe infections caused by the superbug. The decision was welcomed by microbiologists, who said there was still a need for treatments for MRSA, which is resistant to most antibiotics. Cubicin is one of only two new classes of antibiotics to be developed in the past 20 years.

Tigecycline an MRSA antidote?

Link: Tigecycline for the treatment of patients with severe sepsis or septic shock: a drug use evaluation in a surgical intensive care unit -- Swoboda et al. 61 (3): 729 -- Journal of Antimicrobial Chemotherapy.

Results: The majority of patients had co-morbidities such as cancer (51%) or renal replacement therapy (57%). The mean Acute Physiology and Chronic Health Evaluation (APACHE) II score of patients at admission was 27. Intra-abdominal infection was most frequently diagnosed (50% of patients); intra-abdominal infection and pneumonia were diagnosed in 14%. Methicillin-resistant Staphylococcus aureus was found in 16% of patients (colonization; infection: 6%) and vancomycin-resistant enterococci in 27% (colonization; infection: 21%). The mean duration of tigecycline therapy was 9 ± 4 days; 76% of patients received tigecycline in combination, with 64% being treated second line. APACHE score and renal replacement were identified as predictive factors for mortality. SICU mortality was 30%. Conclusions: Tigecycline treatment of critically ill SICU patients with severe sepsis or septic shock appeared to result in remarkably low mortality. Tigecycline may be an important treatment option for septic patients with infections resistant to other available agents.

Ceftobiprole effective against MRSA

Link: In vitro activity profile of ceftobiprole, an anti-MRSA cephalosporin, against recent Gram-positive and Gram-negative isolates of European origin -- Pillar et al. 61 (3): 595 -- Journal of Antimicrobial Chemotherapy.

Ceftobiprole activity against MRSA (MIC90 2 mg/L) was 4-fold less than the activity against methicillin-susceptible S. aureus (MIC90 0.5 mg/L) and a similar trend was observed for methicillin-resistant CoNS (MIC90 2 mg/L) and methicillin-susceptible CoNS (MIC90 0.25 mg/L). Activity against S. pneumoniae (MIC90s: penicillin-susceptible, 0.015 mg/L; -intermediate, 0.25 mg/L; -resistant, 0.5 mg/L) was comparable to that of ceftriaxone. Ceftobiprole activity against Enterobacteriaceae (MIC90s: ceftazidime-susceptible, 0.12 mg/L; non-susceptible, >32 mg/L), P. aeruginosa (MIC90s: ceftazidime-susceptible, 8 mg/L, non-susceptible, >32 mg/L) and Acinetobacter spp. (MIC90: >32 mg/L for imipenem-susceptible and non-susceptible) was comparable to that of cefepime. As with cefepime, ceftobiprole activity was decreased among cephalosporin-resistant isolates of Gram-negative bacilli [extended-spectrum β-lactamase (ESBL) or non-ESBL mediated]. Conclusions: Ceftobiprole demonstrated potent in vitro activity against MRSA and showed activity against key Gram-negative bacilli comparable to that of cefepime. Given this broad spectrum of activity, ceftobiprole appears well suited for development and use in the treatment of a variety of healthcare-associated infections.

Antimicrobial Activity of Ceftaroline and ME1036

Link: Antimicrobial Activity of Ceftaroline and ME1036 Tested against Clinical Strains of Community-Acquired Methicillin-Resistant Staphylococcus aureus (CA-MRSA) -- Sader et al., 10.1128/AAC.01351-07 -- Antimicrobial Agents and Chemotherapy.

Two investigational anti-methicillin-resistant Staphylococcus aureus (MRSA) {beta}-lactams, ceftaroline (cephalosporin) and ME1036 (carbapenem) were susceptibility tested by reference broth microdilution methods against 152 strains of community-acquired MRSA (CA-MRSA) from the United States (47 medical centers). Ceftaroline and ME1036 were 64- and >128-fold more potent that ceftriaxone, respectively. All isolates had the PVL genes and SCCmec type IV, while 67.8% of isolates showed PFGE clonal type USA300-0114.

One dozen drugs work against MRSA

Link: HighWire Press -- Medline Abstract.

The prevalence of methicillin-resistant Staphylococcus aureus (MRSA) is characterized by variations (sometimes extreme) by country and geographic region. The conventional association of MRSA with healthcare settings has been upset by the emergence of community-associated MRSA infections in many areas. With this surge in MRSA comes a renewed interest in alternative agents to vancomycin for treatment of MRSA infections, including older drugs, such as clindamycin, doxycycline and trimethoprim- sulfamethoxazole. Newer agents, such as linezolid and daptomycin, are aiming to improve on the poor cure rates found with vancomycin in serious MRSA infections, but definitive studies showing superiority of these drugs are not yet available. Finally, the drug-development pipeline contains a number of agents for the treatment of MRSA infections, including enhanced glycopeptides (dalbavancin, oritavancin and telavancin) and anti-MRSA cephalosporins (ceftobiprole). As MRSA becomes the 'new normal' in many areas, clinicians will have to sort out the proper role of a dozen or more anti-MRSA drugs.