The Year in Infectious Disease

ATLANTA, Dec. 26 -- Tuberculosis remained at relatively low rates in the U.S., despite more reported cases of multi-drug resistant TB (MDR TB). But a new alarm was sounded in 2006 ? extensively drug resistant TB (XTR TB).

Extensively drug resistant TB and avian flu topped the last of ominous developments in infectious disease during the year. The following summary reviews some of the highlights of the year in infectious disease. For fuller accounts, links to the individual articles published in MedPage Today have been provided.

TB
The CDC defines tuberculosis as extensively drug resistant if isolates are resistant to isoniazid and rifampin as well as to any fluoroquinolone and at least one of three injectable second-line drugs (such as amikacin, kanamycin, or capreomycin.)

The new strains are rarer than MDR TB, but they appear to be more deadly. Patients with XDR TB are 64% more likely to die during treatment than patients with MDR TB, the CDC reported in March.
Multidrug TB Evolving into Extensively Drug Resistant Organism

When patients with XDR TB also have HIV, however, the picture is yet grimmer. South African researchers reported in July at the World AIDS Conference on 53 patients co-infected with HIV and XDR TB. Despite the use of antiretroviral drugs, most of the patients died within a few days of diagnosis and the outbreak eventually killed all but one.
IAC: Resistant TB Strain Kills South African HIV-Patients Within Days

Treatment and diagnosis of TB, however, made some progress in 2006.

Researchers at Harvard proposed a shorter treatment regimen ? two months instead of the standard six ? that they said could dramatically reduce the burden of the disease in developing countries. But the idea, based on a mathematical model, depends on rapid expansion of therapy with existing drugs and new medications.
Shorter TB Therapy Could Reduce Cases and Deaths

And several researchers reported that three new tests for the TB microbe ? predicated on blood samples in two cases and on rapid culture methods in the other ? hold the promise of faster, more accurate diagnosis. The current Lwenstein-Jensen culture method is highly accurate but takes up to six weeks to deliver a result.
TB Blood Tests Yield Impressive Results and
Rapid TB Test Outperforms Gold Standard

Avian Flu
The avian flu dominated the early part of the year, as the disease spread from Asia into Europe and Africa> But there was still no indication that the H5N1 virus has acquired the ability to spread easily among humans. Indeed, research at the University of Wisconsin showed that the virus prefers to infect cells that are deep in the human airway, unlike the seasonal flu, which prefers cells in the nose and throat.
Human Lungs Resist Avian Flu Infection

Two vaccines against the current strain of avian flu were tested and found to be immunogenic, but only at extremely high doses. That drew rapt attention to findings from the University of Rochester, where researchers showed that a prime-boost strategy sharply improved the response to the vaccine.
IDSA: 'Priming' Strategy Might Eke Out Avian Flu Vaccine

Meanwhile, scientists at Boston Children?s Hospital ? using the sudden drop in air travel during the weeks after the 9/11 attacks ? showed that the seasonal flu can hitch a ride on airliners, increasing the speed with which it spreads. The study was the first solid evidence to back suspicion that air travel contributes to the spread of influenza.
Flu Viruses Hitch Rides on Jetliners

MRSA
While methicillin-resistant Staphylococcus aureus (MRSA) has been a concern for some time, pediatric clinics and hospitals are seeing more and more children with acute bacterial infections of skeletal muscle caused by the bug. Houston researchers said that although the absolute number of cases remained low, it had tripled between 2000 and 2005.
MRSA Strains Muscle In on Kids

That report was paralleled by one from the University of California at Los Angeles that chronicled an increase in MRSA skin infections and noted that doctors were increasingly resorting to the techniques used before penicillin ? lancing and draining.
MRSA Skin Infections Flooding Emergency Department

And the CDC reported in June that six unrelated clusters of MRSA had been tied to unlicensed fly-by-night tattooists. Some of the tattoos were performed with needles made of old guitar strings, using inks intended for an ink-jet printer, the researchers said.
Community-Acquired MRSA Outbreaks Tied to Fly-by-Night Tattooists

Leprosy
Leprosy, that scourge of Biblical times, is relatively easily treated today with antibiotics. But the checkered flag goes to Avelox (moxifloxacin), according to a pilot study in California. The drug cleared lesions rapidly without serious side effects or toxicity.
ICAAC: Avelox Takes the Checkered Flag for Leprosy

C. difficile
The nosocomial infection Clostridium difficile is an increasing problem in hospitals, as new and more virulent strains of the bacterium make themselves felt. Researchers at the University of Illinois gave physicians some guidance in how to treat severe cases of diarrhea associated with C.difficile: Use vancomycin as the first line of treatment. The finding comes from a randomized, prospective, double-blind trial of vancomycin against Flagyl (metronidazole), the usual first-line treatment.
IDSA: Vancomycin Outdoes Flagyl in Severe C. difficile Diarrhea

Interestingly, while many antibiotics increase the likelihood of C. difficile colitis, tetracycline appears to have a protective effect. The research, a case-control study presented at the Interscience Conference on Antimicrobial Agents and Chemotherapy, showed that patients getting tetracycline had a lower odds ratio for getting C. difficile colitis, while other antibiotics had odds ratios as high as 3.31.
ICAAC: Tetracycline May Protect Against C. difficile Colitis

HPV
The success of the Gardasil vaccine against human papillomavirus (HPV) -- the sexually transmitted organism that causes most cervical cancers ? promoted the CDC to urge in mid-summer that it should be part of routine care for girls as young as 11. The decision was based on the understanding that many young women acquire HPV infections soon after the onset of sexual activity, so that targeting girls 11 and 12 would prevent most such infections. Also, younger people have more active immune systems, so that the vaccine is likely to be most effective in girls.
CDC Panel Urges Routine Cervical Cancer Vaccination for Girls 11 And 12

Duct Tape
And finally, duct tape ? that staple of the home handyman ? is nonetheless useless as a wart treatment. There had been some evidence that the substance might work, but a randomized, placebo-controlled trials in The Netherlands proved to be a sticky wicket for duct tape. It was no better than placebo in getting rid of verruca vulgaris.
Sticky Duct Tape Fails as Wart Treatment in School Children