Education, judicious use necessary to combat escalating antibiotic resistance

A pattern of escalating antimicrobial resistance in the United States and other countries highlights the need to improve education about judicious antibiotic use, promote better infection control, improve systems used to determine susceptible organisms and create antibiotic regimens that will cover the broadest range of organisms, according to a speaker at the 2010 Annual Conference on Antimicrobial Resistance in Bethesda, Md.

“Combination chemotherapy will become the rule of practice as we wait for the development of new compounds and vaccines,” Ronald N. Jones, MD, of JMI Laboratories in North Liberty, Iowa, told a group of physicians at the meeting. “Maybe the future of infectious disease management is not new classes of drugs, but new classes of chemicals that attack the resistance mechanisms that are already in place.”

Jones reviewed data from two global resistance surveillance programs, SENTRY and MYSTIC, and noted a trend in both for increased resistance rates. Of particular interest is the spike in methicillin-resistant Staphylococcus aureus rates in the United States from 34% in 1997 to 1999, to 55% in recent years. In contrast, programs in Europe that emphasize infection control have actually held MRSA rates steady or even reduced them, Jones said.

Vancomycin resistance rates have increased from 17% to 20% in recent years, with Enterococcus faecium resistance rates as high as 77%. Jones said the available automated systems that detect vancomycin-resistant strains cannot accurately determine at-risk strains with minimum inhibitory concentrations ≥2 mgc/mL from those with MIC values of ≤1 mcg/mL.

“The varying flaws of even automated systems present a dangerous scenario that all clinical and microbiology support laboratories become ‘resource limited,’ and that simple and practical tests via disk diffusion methods can present the most logical approach for the guidance of treatment guidelines, formulary drug selection and the therapy of individual patients,” Jones said, added that these flaws highlight the need for more precise susceptibility tests.

Variability in resistance rates among different regions of the world is also increasing, according to Jones, who said this diversity emphasizes the need for routine use of combination regimens. In India, for example, multidrug resistant organisms, including pneumonia, Pseudomonas, Acinetobacter and Escherichia, have forced physicians to prescribe broad-reaching therapeutic regimens, including carbapenems, beta lactams, protein synthesis inhibitors and broad-spectrum MRSA agents. This should serve as a cautionary tale for physicians in the United States, Jones said. He advocates judicious antibiotic use and the need to remain flexible to adjust for widely varying pathogen prevalence patterns. – by Colleen Zacharyczuk

For more information:

Jones R. What’s hot in antimicrobial resistance and the challenges in resource-limited settings. Presented at: 2010 Conference on Antimicrobial Resistance; Feb. 1-3, 2010; Bethesda, Md.