Methicillin resistance, detection

Along this line Matsue et al. [37,45,78,79] have developed a number of biochips. Among them are multi-analyte assays for human placental lactogen (HPL) and human chorionic gonadotropin (HCG) [45] and leukocidin, a toxic protein produced by methicillin-resistant Staphylococcus aureus [79]. Figure 37.8 shows an example of a dual immunoassay with SECM detection. The analyte is defined by the position on the chip and the amount of analyte is quantified via the collection current at the UME. The current originates from the reduction of ferrocinium methanol (Fc+) at the UME. Fc+ is produced locally at the chip surface by the enzyme HRP under consumption of H202. 

Staphylococcus aureus MRSA ATCC BAA-44. The initial concentration of methicillin-resistant Staphylococcus aureus (MRSA) was 6.0xl06 cfu/ml. After contact with the silver composition, there were 500,000 cfu/ml detected after 10 minutes contact (91.6% killed), 70,000 cfu/ml after 30 minutes contact (98.8% killed), 30,000 cfu/ml after 1 hour contact (99.5% killed), and fewer than 10 cfu/ml after one day contact (virtually total kill). 

Vancomycin/glycopeptide intermediately resistant and methicillin-resistant S. aureus have been described in Japan, Europe, the Far East, and the USA. Some vancomycin-susceptible strains of S. aureus contain subpopulations with intermediate resistance to vancomycin (heterogeneous strains), and these may escape laboratory detection (93,94,97-99). 

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... 

Coudron PE, Jones DL, Dalton HP, Archer GL. Evaluation of laboratory testing for detection of methicillin-resistant Staphylococcus aureus and Staphylococcus epidemhdis. J Clin Microbiol. 1986 24 764-9. 

J. M. Boyce, Methicillin-resistant Staphylococcus aureus detection, epidemiology, and control measures. Infect. Dis. Clin. North Am., 1989, 3, 901-913. 

Vancomycin intermediate 5. aureus, first isolated in Japan in May 1996, then subsequently in the eastern United States (2,3), may be an example of transfer of exogenous genetic material. Transfer of vancomycin resistance from vancomycin-resistant enterococci (VRE) to S. aureus has been demonstrated in the laboratory (4,5). Because S. aureus is a leading cause of nosocomial pneumonia, 37.5% of which have become methicillin resistant (6), the threat of an increasing prevalence of VISA and the eventual appearance of vancomycin-resistant 5. aureus (VRSA) have sobering implications. Detection of VISA will ensure proper isolation to prevent nosocomial spread and initiate appropriate, albeit less than optimal, therapy. 

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. 

Shore AC, Rossney AS, O Connell B, Herra CM, Sullivan DJ, Humphreys H, Coleman DC (2008) Detection of staphylococcal cassette chromosome mec-associated DNA segments in multire-sistant methicillin-susceptible Staphylococcus aureus (MSSA) and identification of Staphylococcus epidermidis ccrAB4 in both methicilhn-resistant S. aureus and MSSA. Antimicrob Agents Chemother 52 4407-4419... 

---