Updates

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

Are You "Coated" with Bacteria?

Source: Burden M, et al. Newly cleaned physician uniforms and infrequently washed white coats have similar rates of bacterial contamination after an 8-hour workday. J Hosp Med 2011;6:177-182.

The National Health Service in Britain in 2007 elected to ban traditional white coats and other long-sleeved garments for physicians in the workplace (including long-sleeved blouses and shirts). Subsequently, Scotland adopted similar policies. This decision was based on limited data suggesting that the cuffs and lower pockets of long-sleeved garments are more heavily colonized with bacteria than shorter garments.

These authors have succeeded in debunking this notion. One hundred residents and hospitalists working on the internal medicine service in hospital (in Colorado) were randomly assigned either to start the day fresh with a newly laundered standard short-sleeved uniform or to wear their own (presumably not recently laundered) white coats. The latter group was not informed of their randomization assignment till the day they showed up for work, giving them no chance to switch to an unused coat. Cultures were obtained throughout the workday, beginning before the coat was put on to 2.5, 5, and 8 hours later. Cultures were obtained from the breast pocket, sleeve cuff (of either the short uniform sleeve or the long sleeve), and the skin of the volar surface of the wrist area. Cultures were incubated for 18-22 hours, and colony counts (up to 200) were determined. In addition, colonies of Staphylococcus were tested for coagulase production and methicillin resistance.

At the end of the day, no differences were found between the colony counts cultured from the clean uniforms and that of the white coats (respectively, mean colony counts, 142 [range 83-213] vs. 104 [range 80-127]; P = 0.61). No significant differences were found between the colony counts cultured from the sleeve cuffs of the short-sleeved uniforms vs. the longer sleeve cuffs of the white coats (mean colony counts, 37 vs. 58), or between the pockets of either garment (mean colony counts, 75 vs. 46). Colony counts were generally greater for the sleeve cuffs compared with the breast pocket of the long-sleeved coat (although the difference was small), whereas no difference in colony counts was observed between the short sleeve cuffs and breast pockets of the uniforms. No differences were found between the degree of bacterial colonization of the wrists for either those wearing a white coat or a short-sleeved uniform.

In addition, colonization with MRSA was similar for those wearing their own long white coats compared with the group assigned to wear clean uniforms (16% vs. 20%).

Serial cultures obtained throughout the workday demonstrated that a freshly laundered uniform starts out nearly sterile. But within 2.5-3 hours, the uniform is colonized with 50% of the bacterial colonies found at 8 hours of wear.

These data demonstrate that, when worn by a resident or hospitalist on the hospital wards, bacterial colonization of a freshly laundered garment is remarkably fast, and within 1 workday is similar to that of an unwashed days-old long-sleeved white coat. There is no evidence that long sleeves vs. short sleeves is less likely to result in bacterial colonization of either the garment or the wearer's wrists.

Bacteria Wired on Caffeine

Source: Harmon K. Newly discovered bacteria lives on caffeine. Scientific American. Available at: http://www.scientificamerican.com/blog/.

A novel strain of bacteria, Pseudomonas putida CBB5, has been found to enzymatically "digest" caffeine. Researchers at the 111th General Meeting of the ASM in New Orleans recently reported the discovery of this bacterium in the flowerbeds at the University of Iowa. Using N-demethylase enzymes called NdmA and NdmB, the organism is capable of breaking down the components of caffeine (which is nothing more than a complex blend of roasted carbon, hydrogen, nitrogen, and oxygen) into carbon dioxide and ammonia. These are then used as substrates for bacterial growth and reproduction.

Following isolation of the genes responsible for these enzymes, they were inserted into E. coli, which then was capable of similar enzymatic caffeine "consumption." It is uncertain whether these bacteria are naturally capable of breaking down caffeine, or whether this capability has evolved because of the ubiquitous presence of caffeine in the environment. Finding this organism on a college campus, where the organism was clearly pulling an all-nighter, might be a clue.

Leishmaniasis and Human Trafficking

Source: Cannella AP, et al. A cluster of cutaneous Leishmaniasis associated with human smuggling. Am J Trop Med Hyg 2011;84:847-850.

Physicians at the University of California-San Diego (UCSD) report a cluster of 5 cases of cutaneous Leishmaniasis in illegal immigrants from East Africa, which surprisingly turned out to be consistent with New World Leishmaniasis, although all 5 had come from an area endemic for Old World Leishmaniasis. How did this occur?

Four Somali and 1 Ethiopian were brought to the Emergency Room at UCSD by Immigration and Custom Enforcement Agents. They had all been found being smuggled across the U.S.-Mexico border about 20 miles south of the city, and had been held in custody for up to 60 days. They each presented with one small cutaneous ulcer, either nodular or pustular, in different locations on the body (thumb, ear, foot, etc.) and in different stages of development. Initially thought to be MRSA folliculitis, prison officials had attempted administration of trimethoprim-sulfamethoxazole and doxycycline without response. The patients were then referred to UCSD for further care.

Skin biopsies were obtained, and the histology was consistent with leishmaniasis, although the presence of a number of features, such as large vacuoles, was more consistent with New World Leishmaniasis. Cultures yielded a Leishmania spp. and isoenzyme analysis confirmed L. panamensis, which is a member of the Viannia group of Leishmania. Confirmatory PCR was performed at the Centers for Disease Control and Prevention. All of the patients responded to liposomal amphotericin, although one patient relapsed, requiring a second course of therapy.

The story of how they had arrived at the Mexican border from East Africa was not readily forthcoming, but eventually it was learned that all 5 individuals had been smuggled at different times along an identical route from Djibouti to Dubai to Moscow to Havana, Cuba, and then to Quito, Ecuador, through Colombia, and then by ground via Panama to the U.S.-Mexico border. The trip through Panama required foot travel, and the individuals slept outdoors on the ground at night in sleeping bags. They described many insect bites.

New World Leishmaniasis occurs throughout Central and South America and is caused by the bite of a sand fly. Only a small number of the 76 sand fly species in Ecuador, Colombia, and Panama can transmit Leishmaniasis, and recent data suggest that up to 1% of female Lutzomyia sand flies are infected. Within 2-8 weeks of a sand fly bite, a small pustule develops, which progresses to a painless ulcer. Fourteen different species of Leishmania exist in the New World, a number of which can cause mucocutaneous involvement, including L. panamensis. More aggressive therapy with amphotericin is therefore warranted.

Subsequent to this event, 3 individuals from East Africa presented to the physicians in Tacoma, WA, with a similar story. They had been smuggled along the identical route, and skin biopsies yielded the same organism. The discovery of two clusters of Leishmaniasis, in San Diego and in Tacoma, suggest that human trafficking from East Africa through this route must be fairly common with important public health implications for U.S. residents.

Space Suits in the OR?

Source: Hooper GJ, et al. Does the use of laminar flow and space suits reduce early deep infection after total hip and knee replacement? The ten-year results of the New Zealand Joint Registry. J Bone Joint Surg (Br) 2011;93-B:85-89.

Ten years of data from the New Zealand Registry of Surgical Cases were examined to assess the risk of early postoperative infection in total hip replacement (THR) and total knee replacement (TKR), with regard to the use of a laminar flow room or wearing a space suit during the procedure. Surprising, the results were quite the opposite of what one might imagine.

A total of 51,485 primary THR and 36,826 TKR procedures were examined. Laminar flow operating suites were used in 35.5% of these procedures, and space suits were worn by the orthopedic surgeon during 23.5% of cases. The risk of infection was actually greater for those procedures performed with a space suit compared to those without. For example, 46 (0.089%) of THR procedures required revision for early infection within 6 months of the original procedure. The risk of early infection for cases involving the use of a space suit was 0.186% compared to without 0.064% (P < 0.0001). Similarly, the risk of infection was significantly greater for procedures performed in a laminar flow operating suite (0.148%) compared to the usual OR (0.061%), as well as for those procedures where both a space suit and laminar flow room were used compared with the usual OR without a suit. These results were independent of the age of the patient or underlying diagnosis.