Staphylococcus aureus, methicillin-resistant

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. 

Let us work out an example (Example 8.2). In a drug stability evaluation, an antimicrobial product was held at ambient temperature ( 68°F) for 12 months. The potency (%) through HPLC was measured, 10 colony-forming units (CPU) of Staphylococcus aureus (methicillin-resistant) were exposed to the product for 2 min, and the microbial reductions (logio scale) were measured. Table 8.2 provides the data. 

Staphylococcus (MRSA) = methicillin-resistant Staphylococcus aureus. 

Streptococcus pneumoniae Penicillin susceptible Penicillin intermediate Penicillin resistant Group B Streptococcus Staphylococcus aureus Methicillin susceptible Methicillin resistant Staphylococcus epidermidis Listeria monocytogenes... 

Nosocomial pneumonia caused by Staphylococcus aureus (methicillin-susceptible and -resistant strains), or Streptococcus pneumoniae (penicillin-susceptible strains only). 

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. 

Recently, a water-based polymer synthesised from N-chloro-2,2,6,6-tetramethyl-4-pipridinyl methacrylate (Cl-TMPM) was prepared via emulsion polymerisation (Figure 10.3). Furthermore, the addition of this antimicrobial material to commercial water-based latex paints led to antimicrobial activity against methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococcus, Escherichia coli, Candida tropicalis, bacteriophage MS2 virus and Staphylococcus chartarum [53]. 

C. beijerinckii is also a producer of clostrubin, an exceptional polyphenolic polyketide antibiotic [26]. Small doses (0.12-0.97 pM minimal inhibitory concentration (MIC)) of clostrubin inhibit growth ofvarious pathogenic bacteria, such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and mycobacteria [26]. 

Pereira, E.M., Shuenck, R.R, Malvar, K.L., et al. (2010) Staphylococcus aureus, SUqthylococcus epidermidis and Staphylococcus haemolyticus methicillin-resistant isolates are detected directly in blood cultures by multiplex PCR. Microbiol Res 165, 243—249. 

As recently as 1970, only about 30 naturally occurring organohalogen compounds were known. It was simply assumed that chloroform, halogenated phenols, chlorinated aromatic compounds called PCBs, and other such substances found in the environment were industrial pollutants. Now, only a third of a century later, the situation js quite different. More than 5000 organohalogen compounds have been found to occur naturally, and tens of thousands more surely exist. From a simple compound like chloromethane to an extremely complex one like vancomycin, a remarkably diverse range of organohalogen compounds exists in plants, bacteria, and animals. Many even have valuable physiological activity. Vancomycin, for instance, is a powerful antibiotic produced by the bacterium Amycolatopsis orientalis and used clinically to treat methicillin-resistant Staphylococcus aureus (MRSA). 

Methicillin-resistent staphylococci are strains of staphylococci, which show resistance to a wide variety of antibiotics. They are named for their resistance to methicillin, a (3 -lactamase-resistant penicillin. Methicil-lin-resistante Staphylococcus aureus (MRSA) has become a serious problem particularly in hospitals. 

Oxazolidinones are a new class of synthetic antimicrobial agents, which have activity against many important pathogens, including methicillin-resistant Staphylococcus aureus and others. Oxazolidinones (e.g. linezolid or eperezolid) inhibit bacterial protein synthesis by inhibiting the formation of the 70S initiation complex by binding to the 50S ribosomal subunit close to the interface with the 3OS subunit. 

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). 

HAMILTON-MILLER J M T aud SHAH s (1999) Disorganization of cell division of methicillin-resistant Staphylococcus aureus by a component of tea Camellia sinensis) a study by electron microscopy , FEMS Microbiology Letters, 176, 463-9. 

YAM T s, HAMILTON-MILLER J M T and SHAH s (1998) The effect of a component of tea Camellia sinensis) on methicillin resistance, PBP2 synthesis, and (J-lactamase production in Staphylococcus aureus, J Antimicrobial Chemtherapy, 42, 211-16. 

Infections acquired from an external source are referred to as exogenous infections. These infections may occur as a result of human-to-human transmission, contact with exogenous bacterial populations in the environment, and animal contact. Resistant pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus spp. 

Rybak JM, LaPlante KL. Community-associated methicillin-resistant Staphylococcus aureus A review. Pharmacotherapy 2005 25(1) 74-85. 

Clinical Dilemma about Methicillin-Resistant Staphylococcus aureus ... 

Methicillin-resistant Staphylococcus aureus (MRSA) is a common hospital-acquired pathogen and is also increasing in the community. MRSA has presented a problem in the past because it required treatment with vancomycin. Community-acquired MRSA presents a major therapeutic challenge. MRSA can cause pneumonia, cellulitis, and other infections. Clinicians should be aware of the rate of hospital and community MRSA in your geographic area. New treatment options are available for MRSA. They include linezolid, tigecycline, and daptomycin. Prospective clinical trials have not demonstrated benefits of these agents over vancomycin.36-37... 

Colonization with resistant gram-positive organisms (e.g., methicillin-resistant Staphylococcus aureus)... 

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