Methicillin-resistant Staphylococcus aureus strain

LJ Frank, D Wisniewski, GG Hammond, J Hermes, A Marcy, PM Cameron. High-yield expression, refolding, and purification of penicillin-binding protein 2a from methicillin-resistant Staphylococcus aureus strain 27R. Prot Expr Purif 6 671-678, 1995. 

Arakere, G, Nadig, S., Swedberg, G., Macaden, R., Amarnath, S.K., Raghunath, D. (2005) Genotyping of methicillin-resistant Staphylococcus aureus strains from two hospitals in Bangalore,South India./. Clin. Microbiol, 43(7), 3198-3202. 

N. M. Amiali, M. R. Mulvey, J. Sedman, A. E. Simor and A. A. Ismail, Epidemiological typing of methicillin-resistant Staphylococcus aureus strains by Fourier Transform infrared spectroscopy, J. Microbiol. Methods, 2007, 69, 146-153. 

An additional disadvantage with many penicillin and cephalosporin antibiotics is that bacteria have developed resistance to the drugs by producing enzymes capable of hydrolysing the P-lactam ring these enzymes are called P-lactamases. This type of resistance still poses serious problems. Indeed, methicillin is no longer used, and antibiotic-resistant strains of the most common infective bacterium Staphylococcus aureus are commonly referred to as MRSA (methicillin-resistant Staphylococcus aureus). The action of P-lactamase enzymes resembles simple base hydrolysis of an amide. 

Hiramatsu et al Methicillin resistant Staphylococcus aureus clinical strain with reduced vancomycin susceptibility. J Antimicrob Chemother 1997 40 135. [PMID 9249217]... 

The prototypical lantibiotic, nisin, was discovered in 1928 for its antibacterial properties and has been used as a preservative in dairy products since the 1950s (1). Nisin and other lantibiotics exhibit nanomolar efficacy against many Gram-positive strains of bacteria (2), which include methicillin resistant Staphylococcus aureus, vancomycin resistant enterococci, and oxacillin resistant bacteria. On the other hand, some lantibiotics function as morphogenetic peptides rather than antibiotics and are important for spore formation in streptomycetes (3). Since the structural elucidation of nisin in the early 1970s, extensive research efforts have been directed at understanding the biosynthesis and mode of action of various lantibiotics. 

Chang SC, Hsieh SM, Chen ML, Sheng WH, Chen YC. Oral fusidic acid fails to eradicate methicillin-resistant Staphylococcus aureus colonization and results in emergence of fusidic acid-resistant strains. Diagn Microbiol Infect Dis 2000 36(2) 131-6. 

While many natural products have been tested against hundreds of different strains of bacteria, the most common bacteria used in susceptibility tests include Bacillus cereus, Bacillus subtillis, Chlamydia pneumonia, Enterococcus faecalis, Escherichia coli, Staphylococcus aureus, methicillin-resistant Staphylococcus aureus (MRSA), Streptococcus pneumoniae, Klebsiella pneumoniae, vancomycin-resistant Enterococcus (VRE), Pseudomonas aeruginosa and Helicobacter pylori [18, 19], As the amount of published data describing the in vitro, in vivo and clinical antibacterial activities of natural products is so vast it could easily fill a book (or two), this review focuses only on natural products for which there is in vitro, in vivo and some clinical antibacterial data, as well as a plausible mechanism of action. 

Another worrisome trend is the increased in vitro resistance reported for many gram-positive bacteria. Of greatest concern is the increasing incidence of methicillin-resistant Staphylococcus aureus (MRSA). Treatment choices for SSTIs have been further complicated by the increased incidence of macrolide-resistant strains of S. aureus and S. pyogenes ... 

Richardson JF, Reith S (1993) Characterization of a strain of methicillin-resistant Staphylococcus aureus (EMRSA-15) by conventional and molecular methods. J Hosp Infect 25 45-52 Robinson DA, Enright MC (2003) Evolutionary models of the emergence of methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 47 3926-3934 Robinson DA, Enright MC (2004a) Evolution of Staphylococcus aureus by large chromosomal replacements. J Bacteriol 186 1060-1064... 

Zhang K, McClure JA, Elsayed S, Conly JM (2009) Novel staphylococcal cassette chromosome mec type, tentatively designated type VIII, harboring class A tnec and type 4 ccr gene complexes in a Canadian epidemic strain of methicillin-resistant Staphylococcus aureus. Antimicrob Agents Chemother 53 531-540... 

The aminoglycoside, arbekacin (6), is a derivative of dibekacin and is effective against most resistant strains. It showed remarkable antimicrobial effects on methicillin-resistant Staphylococcus aureus (MRSA), a leading cause of nosocomial infections. Since its introduction, arbekacin (6)has been clinically used as one of the most effective antibiotics in the treatment of MRSA infections (11). 

The development of a DNA piezoelectric biosensor for the detection of the mecA gene, present in methicillin resistant Staphylococcus aureus (MRSA) strain, was described [6]. Methicillin resistant Staphylococcus aureus is the... 

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