Disease relevance of MRSA

• Recently, we demonstrated rapid dissemination of different methicillin-resistant Staphylococcus aureus (MRSA) clones at the Institute for Microbiology at the University of Magdeburg (B. Ghebremedhin, W. König, and B. König, Eur. J. Clin. Microbiol. Infect. Dis. 24:388-398, 2005) [1].
• The in vitro activity of cefepime combined with vancomycin was assessed by the chequerboard method against 35 clinical isolates of methicillin-susceptible (MSSA, n = 8) or -resistant (MRSA, n = 10) Staphylococcus aureus and methicillin-susceptible (MSSE, n = 9) or -resistant (MRSE, n = 8) Staphylococcus epidermidis and S. aureus ATCC 25923 (MSSA) [2].
• METHODS: The study compared the antibiotic susceptibility (Etest) patterns of Escherichia coli, Staphylococcus aureus/methicillin-resistant S. aureus (MRSA) and Salmonella spp. after broth culture for 72 h in the presence or absence of sub-lethal concentrations of TTO (0.25%, 0.25% and 0.1%) [3].
• The tested bacteria included methicillin-resistant Staphylococcus aureus (MRSA), methicillin-susceptible S. aureus (MSSA), methicillin-resistant Staphylococcus epidermidis (MRSE), methicillin-susceptible S. epidermidis (MSSE), Streptococcus pyogenes, Streptococcus pneumoniae, and Enterococcus faecalis [4].
• Contrastly, the culture supernatant of strain L 22, identified as Lactobacillus reuteri, significantly inhibited all of the clinical isolates of methicillin-resistant S. aureus (MRSA) [5].

Psychiatry related information on MRSA

• OBJECTIVE: To determine the median response time to therapy with vancomycin alone or with vancomycin plus rifampin in patients with methicillin-resistant Staphylococcus aureus (MRSA) endocarditis [6].
• Our experience may be valuable in the future decision-making process for control of new and more challenging multiresistant bacteria, eg, vancomycin-resistant strains of MRSA [7].
• We describe the investigation and control of a community-acquired outbreak of MRSA skin infections in a closed community of institutionalized adults with developmental disabilities [8].
• Substance abuse and prior outpatient antibiotic use were not identified as major risks for community-acquired MRSA bacteremia [9].
• Conjunctival MRSA carriers were more likely to have anemia, malignant tumor, liver dysfunction, and dementia, and to be postoperation and chronically bedridden [10].

High impact information on MRSA

• The clinical syndromes associated with MRSA in children without identified risk were similar to those associated with community-acquired methicillin-susceptible S aureus [11].
• DESIGN--Restriction endonuclease analysis of plasmid DNA (REAP) was used in the analysis of 45 MRSA isolates [12].
• We recently discovered an emerging neonatal infectious disease, neonatal toxic shock syndrome-like (TSS-like) exanthematous disease (NTED), which is induced by a superantigen, TSS toxin-1 (TSST-1), produced by methicillin-resistant Staphylococcus aureus (MRSA) [13].
• Here, we analyzed the activation and the response of TSST-1-reactive Vss2(+) T cells in NTED patients during the acute and recovery phases and in asymptomatic infants exposed to MRSA [13].
• Genome and virulence determinants of high virulence community-acquired MRSA [14].

Chemical compound and disease context of MRSA

• We have characterised an MRSA isolate resistant to linezolid that was recovered from a patient treated with this agent for dialysis-associated peritonitis [15].
• The new oxazolidinone antimicrobial, linezolid, has been approved for the treatment of infections caused by various gram-positive bacteria, including meticillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) [15].
• PURPOSE: To assess the impact of the use of mupirocin ointment on colonization, transmission, and infection with methicillin-resistant Staphylococcus aureus (MRSA) in a long-term-care facility [16].
• Ciprofloxacin (750 mg orally twice a day) was used to treat 22 episodes of methicillin-resistant Staphylococcus aureus (MRSA) colonization among 20 patients [17].
• Postantibiotic effect with temafloxacin against Legionella pneumophila showed a considerable delay in regrowth, and temafloxacin delayed regrowth of MRSA and MSSA to a greater extent than did ciprofloxacin or ofloxacin [18].

Biological context of MRSA

• From our results, one may conclude that the pool of circulating MSSA strains is an important parameter with regard to the epidemiology of hospital- and community-acquired MRSA clones and their potential virulence [1].
• The MRSA strains that were sequence type 8 (ST8), staphylococcal cassette chromosome mec (SCCmec) type IV, and Panton-Valentine leukocidin-positive clustered separately from those that were ST5 and SCCmec type II [19].
• We performed a blinded study to compare repetitive-sequence PCR and multilocus sequence typing for genotyping hospital- and community-acquired methicillin-resistant Staphylococcus aureus (MRSA) [19].
• In contrast, simultaneously circulating MRSA strains (n = 24) harbored in general two or three genes of the enterotoxin gene cluster, and the tst-positive MRSA isolates belonged to the well-known epidemic types ST22, ST45, and ST228 and were classified as spa types t001, t028, and t032 [1].
• Emergence of MRSA infections in horses in a veterinary hospital: strain characterisation and comparison with MRSA from humans [20].

Anatomical context of MRSA

• DESIGN: Monthly surveillance for MRSA colonization of nares, perineum, rectum, and wounds [21].
• In summary, the susceptibility of S. aureus strains, including MRSA strains, to components of the innate immune system varies, with the MRSA strains showing more resistance to both innate immune factors and chemotherapeutic agents [22].
• Methicillin- and cephem-resistant Staphylococcus aureus (MRSA) strains were found to be unable to grow in sputum from patients treated with a beta-lactam antibiotic [23].
• In an attempt to control the spread of methicillin-resistant Staphylococcus aureus (MRSA) within a spinal cord injury unit, we investigated the mode of transmission and implemented a multidisciplinary approach for control that consisted of grouping of patients into cohorts, contact isolation, and antibiotics [24].
• In this study, we compared the efficacy of daptomycin with that of vancomycin, each with or without rifampin, in a model of experimental aortic valve endocarditis due to MRSA [25].

Associations of MRSA with chemical compounds

• Except for one MRSA isolate, synergic killing was demonstrated with clinically achievable concentrations of vancomycin (0.5-1 mg/L) and cefepime (methicillin-susceptible isolates: 0.5-1 mg/L; methicillin-resistant isolates: 2-64 mg/L) [2].
• The multiplex PCR correctly distinguished between isolates of S. aureus, which were sensitive to methicillin (MSSA) and those resistant to it (MRSA) [26].
• Minimum inhibitory concentrations (MIC90) and geometric mean MICs for sparfloxacin were as follows (mg/l): P. aeruginosa 128-23.7, E. cloacae 1-0.13, A. anitratus 2-0.14, K. pneumoniae 1-0.08, MRSA 16-0.98, MSSA 0.12-0.03, MRSE 0.25-0.12 and MSSE 0.12-0.05 [27].
• Gentamicin is active against more than 95% of MRSA strains cultured in our hospital and against 87% of MRSA strains cultured in the neurosurgery unit [28].
• A number-needed-to-treat (NNT) analysis showed that, with MRSA prevalence at 15%, cefuroxime plus gentamicin at induction could prevent one MRSA infection per 421 treated patients compared with cefuroxime alone [28].

Other interactions of MRSA

• For 10 of the clinical isolates (two MSSA, three MRSA, two MSSE, three MRSE) and the reference strain, the interaction of cefepime and vancomycin was also determined by the time-kill method [2].
• However, all MRSA isolates with a type 8 capsule showed identical PFGE patterns using the 2 restriction-endonuclease enzymes Sma I and SST II [29].
• Vancomycin can be reserved for patients known to be colonized with MRSA (NNT: 51) [28].
• All MRSA isolates were screened for Panton-Valentine leukocidin (PVL) genes by use of polymerase chain reaction, and isolate relatedness was determined by use of pulsed-field gel electrophoresis (PFGE) [30].
• These data suggest and confirm the clonality of type 5 and type 8 MRSA isolates [29].

Analytical, diagnostic and therapeutic context of MRSA

• The concentration-effect relationship was bimodal for MSSA and MRSA [two successive sharp drops in bacterial counts (0.3-1x MIC and 100-1000x MIC) separated by a zone of low concentration dependency] [31].
• Investigation of prevalence of MRSA in referrals to neurosurgery: implications for antibiotic prophylaxis [28].
• Of the 52 MRSA patients, 40 had 101 sessions of skin grafting and 33 of them survived [32].
• MAIN OUTCOME MEASURES: Intensive care unit costs attributable to MRSA infection, computed from excess therapeutic intensity in cases using estimates from a cost model derived in the same ICU, were compared with costs of the control program, derived from time-motion study of nurses and physicians [33].
• OBJECTIVE--To evaluate two molecular epidemiologic methods used in the analysis of a nosocomial methicillin-resistant Staphylococcus aureus (MRSA) outbreak [12].

References