Updates

by Carol A. Kemper

Bed Bugs Are Back

ProMED-mail Post, April 15, 2004; www.promedmail.org

Since the mid-1990s, public health officials have been noticing a steady resurgence in the United States, the United Kingdom, and in Europe of an age-old pest—bed bugs, all countries where bed bugs had been more or less non-existent for the past 20-30 years. Bed bugs, which are fairly ubiquitous in developing countries, enjoy cozy warm surroundings, such as the seams of your mattress. They can survive for up to 1 year without feeding, which means they can survive even in stored furniture. The reason for their resurgence in the United States and the United Kingdom is not clear, but with the increase in international travel to developing countries, the bugs may simply be hitching a ride home in your luggage. It is also suspected that broad resistance to insecticides may be occurring, especially to permethrin, which is widely used in mosquito netting.

The predominate species, Cimex lectularis, and its tropical cousin, Cimex hemipterus, are night feeders, and actively suck blood from small vessels in the skin. Mature adults measure about 5 mm in length and are readily visible to the naked eye—if you know where to look for them. They require ~10-20 minutes to become fully engorged, and multiple bites are common. Although, for the most part, they are considered more pests than potential vectors of disease, the bites can cause erythema and itching, sleeplessness, and even anemia, especially in babies or small children. While there is some evidence that hepatitis B surface antigen may be present for up to 6 weeks in a bed bug (and HIV can survive in the mouthparts for 1 hour), there is thus far, no good evidence that bed bugs play a role in the transmission of these organisms.

Can You Guess the Pathogen?

I recently saw a 38-year old, otherwise healthy woman, referred to my office with a 2.5 cm necrotic anterior shin wound. The problem started about 3 months earlier, when she noticed a small non-tender papule, initially thought to be a small focus of folliculitis from shaving. She was a frequent flier at her local nail salon, where she received a pedicure every 3 weeks, using one of those new-fangled spa chairs with the whirlpool foot bath. The lesion gradually enlarged, began draining serous fluid, and eventually ulcerated. She failed to respond to several attempts at debridement and treatment with cephalexin. An initial biopsy revealed only chronic inflammation, and routine cultures were unremarkable. About 2 months after the initial papule had appeared, she developed a second, smaller (~0.5 cm) satellite lesion, just medial to the primary lesion. A repeat biopsy, again, showed chronic inflammation, and cultures grew Mycobacterium chelonae vs abscessus. She was initially treated with clarithromycin, doxycycline, and ethambutol pending identification of the organism, followed by a combination of clarithromycin and doxycycline, with a good response, but modest residual scarring.

Skin and soft tissue infections due to the atypical mycobacteria M. fortuitum, M. chelonae, and M. abscessus are popping up with increasing frequency in nail salons, beauty parlors, and following cosmetic surgery. These rapid growers are ubiquitous in soil and water. Winthrop and colleagues documented the first large-scale outbreak of M. fortuitum furunculosis in ~115 persons from a single nail salon, which used a whirlpool foot bath.1,2 Since then, nail salon whirlpool foot baths are being increasingly recognized as a cause of both sporadic and community outbreaks of atypical mycobacterial skin and soft tissue infections. Most of the reported cases of salon-related infection have been due to M. fortuitum, although any of the atypical mycobacterium, including M. avium, can happily survive in warm spa water and cause localized skin infection. In the larger outbreak above1, lesions due to M. fortuitum typically first presented as a small papule, with progression to large fluctuant boils, with frequent ulceration. Multiple lesions were common, but only 1 apparently healthy individual developed lymphatic spread. Histopathology variously showed chronic inflammation and necrosis, with more acute lesions occasionally showing granulomata. AFB were visualized in only 1 of 15 specimens (7%). Most of the M. fortuitum isolates were susceptible to amikacin (100%), ciprofloxacin (100%), minocycline (100%), cefoxitin (91%), doxycycline (89%), and septra (61%); only a minority were sensitive to the macrolides. Patients received a mean duration of 4 months of therapy, and scarring was common.

Although M. chelonae has also been implicated in whirlpool bath infections, it has more frequently been associated with skin and soft tissue infection due to cosmetic procedures.3-5 In New York City, in 2002, 25 cases of infection due to M. chelonae occurred in persons receiving various cosmetic injections, such as silicone and collagen.4 Following this outbreak, officials cracked-down on unlicensed cosmetologists in NYC. Most recently, 12 cases of M. chelonae infection were reported following various plastics procedures (including breast implants, breast lifts, and tummy tucks) in the Dominican Republic.5

The diagnosis of these infections can easily be delayed or missed unless the clinical suspicion is high. While the rapid growers can grow on routine media if held long enough, they are often missed in routine cultures. Swab cultures are also low yield, and AFB smears are seldom positive. Thus, tissue biopsy with mycobacterial culture is key to the diagnosis of these infections.

References

1. Winthrop KL, et al. The Clinical Management and Outcome of Nail Salon-Acquired Mycobacterium fortuitum skin infection. Clin Infect Dis. 2004;38:38-44.

2. Winthrop KL, et al. An Outbreak of Mycobacterial furunculosis Associated with Footbaths at a Nail Salon. N Engl J Med. 2002; 346:1366-71.

3. Centers for Disease Control and Prevention. Mycobacterium chelonae Infections Associated with Face Lifts—New Jersey, 2202-2003. MMWR. 2204; 53:192-194.

4. Mycobacterium abscessus—USA (New York). ProMED-mail post, January 14, 2003; NYC Dept. of Health and Mental Hygiene Alert #2, 2003.

5. Nontuberculous mycobacterial Infections After Cosmetic Surgery—Santo Domingo, Dominican Republic, 2003-2004. ProMED-Mail Post, June 18, 2004.

If It Was a Bear, It Would Have . . .

Kunimoto D, et al. J Clin Micro. 2004; 42:3374-3376.

I remember as a kid, standing in awe, in front of a nearby lake home in northern Minnesota, from which the siding had been literally ripped off, right down to the plywood, by a hungry bear trying to get at the garbage left inside. The claw marks left on the fragments of siding left a strong impression. Fortunately, brown bears seldom attack people (or, you hope they read the same book about bears as we do), but they will rip the door off your car trying to get to the make-up bag or cooler left inside.

Grizzlies are another thing—for example, in Alberta, Canada, 69% of serious and fatal bear attacks are by grizzlies, although they make up only 2.5% of the bear population. The unfortunate hunter in this report was out hunting elk east of Banff National Park when he was attacked by a grizzly bear. He sustained deep wounds to his scalp and shoulders, with teeth marks evident on the cranium. The wounds were debrided, and intraoperative cultures grew a variety of aerobic Gram-positive and Gram-negative organisms, including Serratia fonticola, Serratia marcescens, Aeromonas hydrophila, Bacillus cereus, and Enterococcus durans. The Gram-negative organisms were resistant to ampicillin, cephazolin, and cefuroxime. Interestingly, no anaerobes were isolated. He responded well to 1 week of piperacillin-tazobactam, followed by 3 weeks of ciprofloxacin.

Other investigators have also noted a lack of anaerobes in cultures taken from bear mouths and bear wounds. Most surveys, of which there are few, have demonstrated Staphycoccus areus, S. epidermidis, and Gram-negatives. Whether this is due to the difficulty in isolating anaerobes, possibly in more remote locations, is unknown. But it is interesting to speculate that diet may play a role. While bears are omnivores, 90% of their diet is derived from vegetable matter, berries and roots, punctuated by the occasional squirrel, beetle, or deer. In contrast, anaerobes appear to be more common in more preditory meat-eaters, such as humans, felines, and dogs—where anaerobes may play an important role in the pathogenicity of bite wounds.

More Bites . . .

ProMED-mail post, July 15, 2004; www.promedmail.org.

Feline immunodeficiency virus is spreading rapidly through the lion population in Kruger National Park in South Africa. The Harare Herald recently reported in mid-July that up to 60-80% of the lions in the southern portion of the park are now infected with the AIDS-like virus, although lions in adjoining areas in Zimbabwe and Mozambique thus far show no evidence of disease. Nonetheless there is considerable concern that infection will quickly spread to other parts of the park, as male lions have quite a wide migratory range. Lions are especially vulnerable because of their social structure in prides, with close physical contact, in contrast to cheetahs and leopards, which are more solitary. The disease is very similar to HIV: It is spread through bites and sexual contact. Affected animals eventually succumb to wasting, neurologic disease and infection.

Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, Section Editor, Updates, Section Editor, HIV.