Hot Topics in Infectious Disease By Kim erlich, MD “It is time to close the book on infectious diseases, and declare the war against pestilence won.” --William Stewart MD, Surgeon General of the United States, in a speech given in 1967. “The global HIV/AIDS epidemic is an unprecedented crisis…… We have 30 million orphans already.” --Kofi Annan, Secretary General of the United Nations 1997-2006, and 2001 Nobel Peace Prize Recipient “Increasing global populations and environmental selection pressure is a recipe for disaster; in time we will see spread of a highly transmissible agent that carries a high mortality, and both our scientists and our governments will be powerless to stop it.” --Anonymous 2011 Since the infamous words in 1967 attributed to Surgeon General William Stewart, we have seen a steady increase in the numbers and magnitude of infectious agents resulting in global disease, suffering and death. Although we have made great progress in the management, prevention, and control of numerous infectious diseases, the books (and the cyber-files) are larger and more voluminous than ever, with no evidence that we will ever be able to “close the book” on infectious diseases. Numerous Infectious Diseases made headlines in 2011, and at least one Hollywood movie, Contagion, made millions in the box office and gained public attention. Let’s look at a few of the “Hot Topics in Infectious Diseases” that will likely remain in the headline news in 2012. Multi-drug Resistant Bacteria Increased antibiotic selection pressure, routine use of antibiotics in animal feed,
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and the ability of bacteria to share genetic information between species has resulted in a steady increase in bacterial clones with acquired resistance to commonly prescribed antibiotics. While this phenomenon was historically a problem confined to intensive care units and large tertiary care centers, multi-drug resistant bacteria are now common in local communities and throughout the world. The most well known example of this phenomenon is the global spread of methicillin-resistant Staphylococcus aureus (further discussed in this article) , but other examples include vancomycin resistant enterococcus, extended spectrum beta-lactamase (ESBL) producing gram negative rods, carbapenemaseproducing Enterobacteraciae (CRE), and multi-drug resistant gonorrhea. Many of the newer antibiotic resistant gram negative rods are resistant to nearly all antibiotics, with the exception of some older compounds such as polymixin and colistin. Strategies to combat the spread of these organisms throughout the population include preventing routine addition of antibiotics to animal feed, and limiting injudicious use of antibiotics in humans through strategies such as the Centers for Disease Control’s “Get Smart About Antibiotics” campaign. Clinicians need to be aware of the bacterial resistant patterns in their community, and to resist the impulse to over-prescribe antibiotics when they are not needed. Methicillin Resistant Staphylococcus aureus Of all the multidrug resistant organisms, methicillin resistant Staphylococcus aureus (MRSA) has been the most widespread and problematic. Initially seen only in intensive care units and tertiary care centers, clones of MRSA have now
spread throughout the community and are found in all corners of the world. The most prevalent community acquired MRSA strain, USA-300, carries genes for resistance to all beta-lactam antibiotics and produces the PantonValentine leukocidin enzyme with increased virulence and propensity for skin and soft tissue infections. In our community, up to 45 percent of all S. aureus isolates are MRSA. Fortunately, several antibiotics, such as vancomycin, linezolid, daptomycin, TMP/SMX and clindamycin, are still effective in treating most of these infections, but there is growing concern that resistance to other antibiotics may be only a matter of time. The global spread of community acquired strains of MRSA has changed the paradigm for clinicians who deal with patients who are suspected or confirmed to have S. aureus infection. In many instances, patients who present with suspected S. aureus infection, such as boils or abscesses, should be placed initially on antibiotic regimens which provide coverage against MRSA while awaiting definitive culture results. Since S. aureus is the most common pathogen resulting in post-op infections, and since antibiotics are frequently used pre-operatively to prevent post-op wound infections in certain procedures, important unanswered questions include: 1) when should routine pre-operative antibiotic prophylaxis provide coverage against MRSA? And, 2) how important is pre-op screening for MRSA and pre-op decolonization? These questions require rigorous studies to help guide clinicians. Clostridium difficile Clostridium difficile, an anaerobic spore-forming bacillus, causes pseudomembranous colitis, manifesting as diarrhea that often recurs and can progress to toxic megacolon, sepsis, and death. The numbers of cases of C.