Clinical Briefs

By Louis Kuritzky, MD, Clinical Assistant Professor, University of Florida, Gainesville. Dr. Kuritzky is a consultant for GlaxoSmithKline and is on the speaker's bureau of GlaxoSmithKline, 3M, Wyeth-Ayerst, Pfizer, Novartis, Bristol-Myers Squibb, AstraZeneca, Jones Pharma, and Boehringer Ingelheim.

The Ohsaki Study: Does Green Tea Consumption Impact Mortality?

Other than water, tea is the most often consumed beverage in the world. Animal studies and in vitro data support the potential role of green tea consumption (GTC) for reducing cardiovascular disease and cancer.

The Ohsaki Study is the largest trial (n = 40,530) to prospectively study the relationship between GTC and the end points of CV disease, cancer, and overall mortality. Using a cohort study methodology, investigators analyzed the association between GTC (divided into quartiles) and end points observed over 11 years of followup.

GTC was inversely associated with all-cause mortality, such that for those in the top quartile of GTC men enjoyed a 12% reduction in hazard ratio for mortality, and women a 23% reduction. Since all-cause mortality is primarily driven by cardiovascular disease, it should come as no surprise that CVD was also inversely related to GTC. For instance, those women who consumed more than 5 cups/d of green tea (top quartile) had a 31% lower CVD mortality than women in the lowest quartile (< 1 cup/d). No relationship between GTC and cancer was discernible.

Although there are some conflicting studies, two prior trials have also seen a favorable relationship between GTC and cardiovascular end points. The mechanism of benefit is uncertain, although it is postulated that phenols from green tea might favorably impact development of atherosclerosis through antioxidant or free-radical scavenging. Black tea and oolong tea consumption, which were also included in the data analysis, did not show similar benefits.

Kuriyama S, et al. JAMA. 2006;296:1255-1265.

Do Ethnicities Differ in Response to Spironolactone?

Thanks to the favorable results from the RALES trial (Randomized Aldactone Evaluation Study), clinicians commonly employ spironolactone (SPIR) as part of a standard treatment regimen for CHF, in addition to ACE inhibitors and beta blockers. Indeed, the emerging enthusiasm for including SPIR as part of the therapeutic CHF regimen has resulted in a visible increase in hyperkalemia in some populations. Interestingly, retrospective data suggests that African Americans may respond differently to spironolactone than Caucasians: they may develop lesser increases in serum potassium (K+).

Patients (n = 51) with systolic CHF from heart failure clinics in Illinois were enrolled predicated on their receiving stable and appropriate doses of ACE inhibitors (and/or ARBs) and beta blockers, and being normokalemic at baseline. All patients then received spironolactone titrated to 25 mg/d.

The median increase in K+ differed dramatically between African Americans and Caucasians: 0.1 mEq vs 0.5 mEq; K+ concentrations greater than 5.0 mEq/L occurred in 8% of African Americans, but 41% of Caucasians.

These differences were present even though there were no demonstrable differences in renal function or diuretic therapy. Similarly, aldosterone levels did not show meaningful ethnic disparity.

The mechanisms responsible for differences in propensity for increases in K+ remain uncertain. It appears that Caucasians are more susceptible to spironolactone induced increases in K+ than African Americans.

Cavallari LH, et al. Congest Heart Fail. 2006;12:200-205.

MRSA: Once the Exception, Now the Rule

Mrsa is a relative newcomer to the bacterial pathogen scene, being first identified in the 1960s. A decade ago, clinicians thought of MRSA as a typically hospital-acquired pathogen, and rarely identified it from healthy persons in the ambulatory setting. Today, the epidemiologic presence of MRSA in both hospital settings and amongst ostensibly healthy patients without risk factors in the ambulatory setting calls for enhanced clinician awareness of this pathogen and its appropriate treatment.

Moran et al sought to characterize the prevalence of MRSA from diverse communities around the United States. They studied bacterial isolates from adult patients presenting to emergency rooms with skin or soft tissue infections in 11 different cities across the United States: Albuquerque, Atlanta, Charlotte, Kansas City, LA, Minneapolis, New Orleans, New York, Philadelphia, Phoenix, and Portland.

Of the 422 patients presenting with skin/soft-tissue infections at these sites, 76% were caused by Staphylococcus, over half of which (59%) were MRSA. In over half the cases, prescribed antibiotics would not have been successful based upon culture and sensitivity results. MRSA was sensitive to clindamycin, trimethoprim/sulfamethoxazole, or tetracycline more than 90% of the time.

Because of the high prevalence and evolving resistance pattern of MRSA, clinicians would be wise to routinely culture patients with skin and soft-tissue infections, and consider antibiotic choices based upon prevailing sensitivity data.

Moran GJ, et al. N Engl J Med. 2006;355:666-674.