|The Good News in Infectious Diseases
Many times in the world of Infectious Diseases (ID), we hear solely about the bad news that is out there in terms of infections, and there is tons of it, including progressive gram negative antibiotic resistanceon the local and national levels (i.e. superbugs like E coli or Klebsiella KPC’s), Clostidium difficile, flu outbreaks, etc. There is significant good news appearing in the world of ID as well. Examples of important infections where actual reductions in incidence are occurring include hospital-acquired MRSA and global tuberculosis. There are also significant advances in cutting edge technology available for rapid diagnosis of infections.
In terms of reduced incidence of important infections, consider the case of Hospital-Acquired MRSA, (HA-MRSA as opposed to Community-Acquired MRSA). Nationally, the fraction of Staph aureus isolates that are MRSA is about 58%, which is rising, but the absolute number of HA-MRSA infections leveled off in 2007 and then has declined since. Why? The change is generally credited to improved central line insertion practices and “bundles” as advocated by Peter Pronovost, M.D., from Johns Hopkins University School of Medicine. In fact, in a longitudinal study of Michigan ICU’s, the participants were able to eliminate central line-related infections using the bundle approach during the study period….completely! Other efforts nationally at preventing ventilator-associated pneumonia (VAP) have also played a role in HA-MRSA reduction.
On the global front, there is good news regarding tuberculosis. Although still a major threat to human health with 1.4 million TB deaths in 2010 (many in HIV+ persons) there was a reduction in global tuberculosis cases reported by WHO between 2006 and 2010. This was the first decline since records had been kept. In China, there was an 80% decline in TB mortality between 1990 and 2010. In the US, TB cases declined 3.8% between 2009 and 2010 to around 11,000 cases. This was the lowest prevalence since 1953 (MMWR).
At the same time some of our worst scourges are yielding, rapid molecular diagnostics of infectious diseases are now clinically available and can help dramatically reduce the time to detection of these and other infections. The traditional culture-based methods are gradually being replaced by faster technologies. Important examples of this include the TB Gene-Xpert system that SB County Public Health has recently purchased. This will virtually eliminate the 6 week waiting period for TB cultures on sputum samples. It is a PCR-based method that is sensitive for detection of TB DNA in AFB smear-negative and AFB smear-positive samples. In a recent clinical trial published in the New England Journal of Medicine, this technology was found to be >90% sensitive and >90% specific on respiratory samples. Rapid fluorescent hybridization techniques (FISH) are available and highly sensitive for detection of Candida in blood, with same-day results. This offers dramatically decreased door-to-antifungal time for some of our most critically ill patients, as is often the case in those with Candidemia (chemotherapy patients, post-op patients, TPN patients, dialysis patients, etc.) At Cottage Hospital, Clostridium difficile PCR is now in use, and data presented at the recent IDSA meeting by Lena Kang-Birken from the antibiotic stewardship team shows the time to diagnosis of patients at Cottage has dropped, as has the time patients spend in isolation awaiting test results. MRSA PCR’s are available that can be used on blood samples that accurately detect MRSA presence within hours of the blood being drawn. In the future, microarrays will give a complete picture of a person’s pathogen burden in a matter of minutes. Many of the organisms harming people are getting stronger but so are our tools for detecting them.
Posted by DrSugar on 03/08/2012 at 7:22 AM