Resistant 'Superbugs' Create Need for Novel Antibiotics

Teri Capriotti, DO, MSN, CRNP

Disclosures

Dermatology Nursing. 2007;19(1):65-70. 

In This Article

Antibiotics Developed to Combat MRSA, VRSA, and VRE

Glycopeptides

Recent worldwide emergence of CA-MRSA has prompted the development of several new antibiotics (see Table 2 ). In the past, as vancomycin became less effective against MRSA, clinicians turned to another glycopeptide, teico planin (Targ ocidAE). Glyco pepti des exert their bactericidal action by interfering with synthesis of the bacterial cell wall and RNA. However, due to the similarity of the glycopeptides, bacteria quickly developed resistance to teicoplanin. The short-lived success of teicoplanin as an alternative to vancomycin motivated pharmacologic investigators to develop different antibiotic approaches.

Streptogramins

The failure of glycopeptide antibiotics led to the creation of a new class of drug, the streptogramins, a combination of quini pristin and dalfopristin. Quinupristin/ dalfopristin (SynercidAE) became the drug of choice for MRSA nosocomial infections by the year 2000. It exerts bactericidal activity by interfering with protein synthesis at the bacterial ribosome, which differs from the glycopeptide strategy. The dalfopristin component interferes with early phases of bacterial protein synthesis and quinipristin interferes with the late phase of protein synthesis. The two act synergistically to hinder the synthesis of bacterial proteins (Medical Eco nomics, 2005).

However, Synercid has a major drawback. It is an intravenous medication requiring slow infusion within a large volume of fluid, and this administration method makes it impractical for the outpatient setting (Shah, 2005). Its limitation to parenteral administration was a particular disadvantage in light of the increasing incidence of community-acquired MRSA infections. It also has caused disabling myopathy as a side effect in some treated individuals. These drawbracks heightened the need for an oral form of the drug and further antibiotic development for resistant bacteria.

The oral streptogramin pristinamycin has been used in Europe in combination with doxycycline to combat MRSA infections. In a small trial of 53 patients, 74% (39 patients) were effectively cured of MRSA infection. More extensive clinical investigations with larger population groups are needed to evaluate this drug combination further (Dancer, Robb, Crawford, & Morrison, 2003). It is not available presently in the United States.

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