seudomonas aeruginosa is the most common cause of bacterial infection in the hospital environment. P. aeruginosa is a Gram-negative bacterium that is often the source of infection. P. aeruginosa has potential as pathogens in the hospital environment. The bacteria are commonly found as bacteria causing nosocomial infections for example P. aeruginosa as one of the gram-negative bacteria that most commonly infects the amount of 25.8%. The ability of P. aeruginosa bacteria to survive in extreme environmental conditions and can survive in the long term on the surface of the body often leads to infection. Besides, transmission of infection through contact patient to another often occur in the hospital [1,2]. In the treatment of multidrug-resistant…show more content… The results were read after 18–24 h of incubation at 37°C. The MIC was interpreted as the value at which the inhibition zone intersected the scale on the Etest strip. For testing of antimicrobial combinations, an antibiotic strip was placed onto an agar plate at room temperature and removed after 1 h. Afterwards, a second antibiotic strip was placed on top of the gradient of the first agent. To evaluate the effect of an antibiotic combination, the fractional inhibitory concentration (FIC) index was calculated as follows:
FIC index = (FIC of drug meropenem)+(FIC of drug gentamicin), where FIC of drug meropenem = (MIC of drug meropenem in combination)÷(MIC of meropenem alone), and FIC of gentamicin = (MIC of gentamicin in combination) ÷(MIC of gentamicin alone). Synergism was defined as an FIC index of ≤0.5, additivity as an FIC index of >0.5≤1, indifference as an FIC index of >1≤2, and antagonism as an FIC index of >2 .
In vitro activity of each combination was determined by placing Etest strips of the two antimicrobials on the agar at a 90° angle with the intersection at the respective MICs for the organism (Fig.