Bacterial drug resistance

The answer is c. (Hardman, pp 1161-1162.) An important problem in the chemotherapy of TB is bacterial drug resistance For this reason, concurrent administration of two or more drugs should be employed to delay the development of drug resistance. Isoniazid is often combined with ethambutol for this purpose. Streptomycin or rifampin may also be added to the regimen to delay even further the development of drug resistance. 

Parish JH, Bentley J. Relationships between bacterial drug-resistance pumps and other transport proteins. J Mol Evol 1996 42 281—293. 

Because the natural penicillins have been used for many years, drug-resistant strains of microorganisms have developed, making the natural penicillins less effective than some of the newer antibiotics in treating a broad range of infections. Bacterial resistance has occurred within tire penicillins. Bacterial resistance is the ability of bacteria to produce substances that inactivate or destroy the penicillin. One example of bacterial resistance is tiie ability of certain bacteria to produce penicillinase, an enzyme that inactivates penicillin. The penicillinase-resistant penicillins were developed to combat this problem. 

Streptococcus pneumoniae is the most common bacterial cause of community-acquired respiratory tract infections. S. pneumoniae causes approximately 3000 cases of meningitis, 50,000 cases of bacteremia, 500,000 cases of pneumonia, and over 1 million cases of otitis media each year. The increasing prevalence of drug-resistant S. pneumoniae has highlighted the need to prevent infection through vaccination. Both licensed pneumococcal vaccines are highly effective in preventing disease from the common S. pneumoniae serotypes that cause human disease. 

Epothilones A, B and E (4,5 and 6) (Fig. 2) are representative members of a new class of bacterially derived natural products which exhibit potent biological activity. Isolated by Hofle and coworkers [6] from a soil sample collected near the Zambesi river, the compounds have provided a great deal of excitement in the scientific community due to their potent cytotoxicity against a number of multiple drug-resistant tumor cell lines and because of the mechanism by which they exert this effect. Like Taxol [7], the epothilones promote the combination of a- and 3-tubulin subunits and stabilize the resulting microtubule structures. This mode of action inhibits the cell division process and is, therefore, an attractive strategy for cancer chemotherapy [7,8]. 

Analogues of the umuDC genes can be found in locations other than the bacterial chromosome, for example, plasmid pKMIOl (Walker and Dobson, 1979), a derivative of the drug resistance plasmid R46 (Mortelmans and Stocker, 1979), which carried mucAB genes (Shanabruch and Walker, 1980) (see pp. 879-880). 

Resistance Prescribing tigecycline in the absence of a proven or strongly suspected bacterial infection is unlikely to provide benefit to the patient and increases the risk of the development of drug-resistant bacteria. 

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