MRSA testing Methicillin- Resistant Staphylococcus Aureus MRSA

when selecting an empirical regimen is to choose an agent that has adequate activity against the infecting organisms. Empirical antibiotic choices should be individualized based on institutional antibiograms, which tend to be quite different from hospital to hospital, from city to city, and from country to country. Pitout J.D., et al. 2008 The next issue surrounding the therapy of ESBL-producing infections is that even if an agent is selected that has activity against the bacteria in vitro, clinical efficacy in patients is not always guaranteed. Although in vitro tests ESBLs are inhibited by ß-lactamase inhibitors such as clavulanic acid, other study has shown the activity of ß-lactamß- lactamase inhibitor combination agent e.g. piperacillin-tazobactam is influenced by the bacterial inoculums, dose administration regimen and specific type of ESBL present. The other consideration treatment of ESBL-producing bacteria are cephamycins e.g. cefoxitin, cefotetan and Cefepime. This is widely believe to occur as a result of the so-called inoculums effect that occurs when the minimum inhibitory concentration of the antibiotic rises i.e. the antibiotic looses activity with the increasing size of the inoculums or number of bacteria tested. This effect has been described for cephalosporins, β-lactam-β lactamase inhibitor combinations piperacillin, tazobactam and to a lesser extent with the quinolones. Tigecycline is also one of the drugs in the pipeline which can be considered for treatment. Pitout J.D., et al. 2008; Perez et al. 2007 The carbapenems imipenem, meropenem, ertapenem, doripenem are still the first choice of treatment for serious infections with ESBL-producing E coli and K pneumonia. It has been reported that 98 of the ESBL-producing E coli, K pneumonia and P. mirabilis are still susceptible to these drugs. This agents are highly stable to hydrolysis by ESBLs, are distributed into body tissues in high concentration and there is no inoculums effect. Perez et al, 2007; Pitout J.D., et al. 2008. But with the emergence of the carbapenem – resistant Enterobateriaceae, the “magic bullet” is actually difficult to find. There are some older drugs which can be used to treat the ESBL-producing E. coli or K. pneumonia infections. Fosfomycin was reported of having admirable in vitro activity against the ESBL- producing E. coli or K. pneumonia. In HongKong, most of the ESBL-producing E coli isolates were reported to be sensitive to fosfomycin. Ho et al., 2010. Colistin is another choice which we can consider for the treatment of these organisms. Although once considered as quite a toxic antibiotic, it is a last resort that we can consider at the present moment as there is no new anti gram negative antibiotics available for the treatment of these multidrug resistant organisms. Perz et al. 2007 To reduced the problem of antimicrobial resistance, action should be taken along to tracks; promotion of prudent use of antibiotics and prevention of the spread of resistant bacteria. Improving antibiotic use can be achieved by changing the prescribing behavior of doctors, education, guideline and clinical pathway, antimicrobial cycling, antimicrobial order form, combination therapy streamlining or de-escalation, dose optimization, intravenous or oral therapy.