A Query About Culturing

Question: When and/or if all new admissions are cultured, will treatment be rendered on all >(+) cultures? What method is utilized to differentiate between an actual infection vs. colonization? Is this cost effective? -- Ms. T, New York City


Answer: Thank you for your question.  I'm assuming you are referring to the practice of culturing patients for resistant organisms, such as MRSA and VRE, in order to identify the reservoir of colonized or infected patients and to isolate them appropriately through use of CDC-recommended Contact Precautions to prevent spread of disease. I would refer you to the SHEA Guideline for Preventing Nosocomial Transmission of Multi-Drug Resistant Strains of Staph aureus and Enterococcus (Infection Control and Hospital Epidemiology, Vol 24, No. 5, 2003). In this guidelines, surveillance cultures are recommended at time of admission to the hospital (or other healthcare facility) for patients at high risk of carriage of MRSA, VRE, or both organisms. In addition, periodic (weekly) cultures are recommended for patients remaining in the hospital at high risk for these organisms. Surveillance cultures for MRSA should always include samples of the anterior nares as well as any areas of skin breakdown. Surveillance cultures for VRE should include stool samples or swabs of the rectum or peri-rectal area. These cultures are not for the purpose of treating patients but rather identifying patient who may be colonized or infected for proper room placement and isolation to prevent spread. Of course, the physician may elect to treat an infection noted. However, the article cautions to avoid therapy of patients who are colonized unless suppression or eradication of colonization is being attempted. In fact, according to these guidelines, at least one-third of hospitalized patients receive antimicrobials during their stay and much of this use is unnecessary and inappropriate. This not only increases the cost of care but also leads to development of resistant organism spread. We may need to remind physicians that the colonized patient (one in which the organism is merely present and with no symptoms or deep tissue invasion) do not need treatment as do those who are infected (with presence and invasion of the organism and associated symptoms).