A 26 year old patients presents with suspected pneumococcal meningitis.CSF culture is sent for antibiotic sensitivity. Which empirical antibiotic should be given till culture sensitivity result come?
To achieve synergism Every AMA has a specific effect on selected microorganisms. Depending on the drug pair as well as the organism involved, either synergism (supra-additive effect), additive action, indifference or antagonism may be observed when two AMAs belonging to different classes are used together. Antibiotics are the mainstay of treatment in S pneumoniae infections. Until the 1970s, essentially all pneumococcal isolates were sensitive to easily achievable levels of most commonly used antibiotics, including penicillins, macrolides, clindamycin, cephalosporins, rifampin, vancomycin, and trimethoprim-sulfamethoxazole The mechanism of pneumococcal resistance to penicillin and cephalosporins is through alteration in the molecular cell wall targets, penicillin-binding proteins (PBPs). Mutations that alter the PBPs result in decreased affinity for binding to these agents, rendering them less effective. This type of resistance can be overcome if the antibiotic concentration at the site of infection exceeds the MIC of the organism for 40%-50% of the dosing interval. Penicillin-resistant pneumococci are often resistant to multiple additional classes of antibiotics, including other penicillin derivatives, cephalosporins, sulfonamides, trimethoprim-sulfamethoxazole (through amino acid changes), macrolides (through methylation or an efflux pump), quinolones (through decreased permeability, efflux pumps, and alteration of enzymes), and chloramphenicol (through inactivating enzymes). Resistance is obtained as pa of a cassette of genetic information, or a transposon, that encodes resistance to multiple antibiotics. Resistance rates of pneumococcal isolates in the United States to trimethoprim-sulfamethoxazole, tetracycline, and the macrolides are relatively high. Some isolates (< 10% in the United States) that are resistant to macrolides are also resistant to clindamycin. Vancomycin-resistant pneumococcal isolates have not been repoed in the United States. The phenomenon of tolerance (survival but not growth in the presence of a given antibiotic) has been observed, but its clinical relevance is unknown. Any strain with an in vitro MIC greater than 1 ug/mL to vancomycin should be immediately repoed to the state health depament and arrangements made for confirmatory testing at the CDC. In the United States, most pneumococcal isolates remain susceptible to fluoroquinolones. In ceain countries and specific populations in whom the use of "respiratory fluoroquinolones" is more prevalent (eg, nursing homes), an increase in resistance to these agents has been seen. REFERENCE: emedicine.medscape.com , ESSENTIALS OF MEDICAL PHARMACOLOGY(K.D.TRIPATHI,SIXTH EDITION,PAGE NO:677)
Penicillin G
Ceftriaxone + metronidazole
Doxycycline
Cefotaxime + vancomycin
Chemotherapy