Drug-resistant strains

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. 

In the recently released book on worldwide compliance issues (Adherence to Long-term Therapies, Evidence for Action),7 published by the World Health Organization, researchers indicate that the problem of noncompliance is worse in countries in the developing world than in countries in the industrialized world. Many parts of the United States have similar morbidity and mortality rates as countries in the Third World.8 Specific disease states may have significant additional noncompliance ramifications due to the development of drug-resistant strains of bacteria.9 Many times what is necessary is referral to specific clinicians for individualized treatment and monitoring to enhance compliance. The case histories provided in this text will allow you to follow what others have done in similar situations to optimally help patients succeed in improving compliance rates and subsequent positive health outcomes. 

The 23-valent pneumococcal polysaccharide vaccine contains 23 serotypes that are responsible for causing more than 80% of invasive S. pneumoniae infections in adults. The vaccine includes those serotypes that are associated with drug resistance. Use of the vaccine will not prevent the development of antibiotic-resistant S. pneumoniae, but is likely to prevent infection from drug-resistant strains. The 23-valent pneumococcal polysaccharide vaccine has demonstrated good immunogenicity in adults, but an individual will not develop immunity to all 23 serotypes following vaccination.10... 

Five new compounds with unique furan skeleta, named psoracorylifols A-E (Fig. 12) were isolated from the seeds of Psoralea corylifolia L. (Fabaceae), a well-known traditional Chinese medicine (TCM). The psoracorylifols A-E showed significant inhibitory activity against two strains of HP (SSI and ATCC 43504) with an MIC range of 12.5-25/rg/mL, and against HP ATCC 43504, a drug-resistant strain with an MIC of 128 figlroL ... 

Streptomycin Prevents bacterial protein synthesis by binding to the S12 ribosomal subunit (see also Chapter 45) Bactericidal activity against susceptible mycobacteria Used in tuberculosis when an injectable drug is needed or desirable and in treatment of drug-resistant strains IM, IV renal clearance (half-life 2.5 h) administered daily initially, then 2 x week Toxicity Nephrotoxicity, ototoxicity... 

Chapman et al. 1985 Yarlett et al. 1987 Rasoloson et al. 2002) (Fig. 3). Involvement of reductive activation in the antitrichomonad action of metronidazole was further confirmed by studies on laboratory-developed drug-resistant strains that lack the electron generating enzymes and are thus incapable of activating the drug (see below). 

Fig. 10 Ultrastructure of hydrogenosomes of the T. foetus strain KV1-MR100 with fully developed metronidazole resistance (a,b) and of its drug-susceptible parent clone KV1 (c,d). Note the irregular shape, enlarged electron-dense core, and presence of tubular extensions (arrows) in hydrogenosomes of the drug-resistant strain. Bars 0.2 xm in a,b,c and 0.4 im in d. Original electron micrographs from the author (JK)...

Lloyd D, Pedersen JZ (1985) Metronidazole anion radical anion generation in vivo in Trichomonas vaginalis oxygen quenching is enhanced in a drug-resistant strain. J Gen Microbiol 131 87-92... 

The phenomenon of antibiotic resistance gives the public a significant stake in whether an individual completes or complies with therapy. For example, in the case of tuberculosis, an individual s failure to comply with the lengthy therapeutic regime can give rise to the development of multi-drug resistant strains (MDR-TB) of the disease, which are difficult and expensive to treat (Kim 2003). MDR-TB can spread... 

Komura, I., and K. Izaki. 1971. Mechanism of mercuric chloride resistance in microorganisms. I. Vaporization of a mercury compound from mercuric chloride by multiple drug resistance strains of Escherichia coli. J. Biochem. (Tokyo) 70 885-893. 

Following the development of synthetic antimalarial agents, such as chloroquine and mefloquine, the use of Cinchona alkaloid quinine declined. However, with the emergence of chloroquine-resistant and multiple-drug-resistant strains of malarial parasites, its use has become firmly reestablished. Quinine is the drug of choice for severe chloroquine-resistant malaria due to Plasmodium falciparum. In the U.S., the related alkaloid quinidine is recommended because of its wide availability and use as an antiarrhythmic agent. In many clinics in the tropics, quinine is the only effective treatment for severe malaria unfortunately, decreasing sensitivity of P. falciparum to quinine has already been reported from Southeast Asia. 

---