Infectious Disease Alert Updates
By Carol A. Kemper, MD, FACP
Aussie Flesh-Eating Disease
SOURCE: Buruli ulcer – Australia: (VI) increasing incidence. ProMED-mail post, Feb. 24, 2021. www.promedmail.org
An increasing number of Australians and travelers to Australia are being diagnosed with Buruli ulcer, raising public health concerns and prompting more extensive spraying for mosquitoes in the suburbs of Melbourne and along coastal areas of Victoria. Buruli ulcer, sometimes called Bairnsdale ulcer in Australia, where it is a nationally reportable disease, is caused by Mycobacterium ulcerans. It starts as a painless papule or pimple and slowly ulcerates and expands over several months, causing local tissue destruction, and potentially involving muscle, nerve, and even bone. Notably, the lesions are painless and without fever — making them distinct from a local cellulitis. The organism requires low temperatures for growth (29-33°C), so it generally results in infection on the extremities; rarely, the face is involved.
Globally, Australia has the third highest number of cases of Buruli ulcer, after Ghana and Nigeria, although many cases around the world likely go unreported. The infection has been reported from 33 countries, including countries in sub-Saharan Africa and Southeast Asia, Mexico, Peru, and Papua New Guinea. The disease has been present in Australia for decades, although it is being reported from previously unaffected and more affluent areas, including the suburbs of Melbourne, the coastal areas just east of Melbourne in Frankston and the Mornington Peninsula, as well as (going the other direction from Melbourne) the Greater Geelong, and the shire of East Gippsland. A handful of cases also have been observed in northern Queensland and near Darwin. Although 65 cases were reported in Australia in 2013 and 106 cases were reported in 2015, a total of 340 cases were reported in 2018. That the infection is affecting individuals living in suburbs and more affluent areas has garnered attention in the press and by health officials. The increase in cases also prompted a re-evaluation of the case definition, which previously required the isolation of the organism in culture or polymerase chain reaction (PCR) confirmation, and likely was resulting in under-reporting. A group of Australian clinicians, laboratory experts, and public health officials gathered in 2019 and drafted a new case definition, which allows for an expert clinical diagnosis without bacteriological confirmation.1
Buruli ulcer generally is considered a tropical disease, and the reasons for the observed increase in cases in Australia and other countries, such as Benin and Liberia, are not clear. The ecological niche for the organism and the transmission pathway are not known. In most countries, stagnate or slowly moving bodies of water and coastal salt marshes are considered risk factors, with certain species of mosquito as the likely vector. Epidemiological surveys in Australia have found the organism in the pelleted feces of possums, although these animals are not considered to be the source of human infection. Transmission is only rarely human-to-human. Fortunately, if the infection is recognized early, it generally responds well to an eight-week course of rifampin and clarithromycin (or rifampin and streptomycin). More extensive lesions may require skin grafting or even amputation.
REFERENCE
- Betts JM, Tay EL, Johnson PDR, et al. Buruli ulcer: A new case definition for Victoria. Commun Dis Intell 2018;44:1-7. https://www1.health.gov.au/internet/main/publishing.nsf/Content/8FA6078276359430CA257BF0001A4C42/$File/buruli_ulcer_a_new_case_definition_for_victoria.pdf
Misleading Imaging in COVID
SOURCES: Nawwar AA, Searle J, Green C, Lyburn ID. Infection control of COVID-19. Surgical mask-related facial cutaneous artifact on FDG Pet/CT. Clin Nucl Med 2021;46:e221-e223.
Xu G, Lu Y. COVID-19 mRNA vaccination-induced lymphadenopathy mimics lymphoma progression on FDG PET/CT. Clin Nuc Med 2021;46:353-354.
These two articles highlight the challenges of diagnostic testing at a time when all of us are being tested by an entirely new disease, COVID-19. Fluorodeoxyglucose-positron emission tomography computed tomography (FDG PET/CT) imaging obtained for staging of mantle cell lymphoma in a 56-year-old man revealed avid uptake in sub-diaphragmatic lymph nodes and the face, raising concerns about possible facial skin involvement. Cutaneous involvement would be unusual, but possible, with mantle cell lymphoma. The avidity extended from the bridge of the nose to the mandible. And yet, there was no apparent abnormality on corresponding CT and nothing found clinically. It was concluded that the man’s facemask must have resulted in build-up of local blood flow or increased heat and humidity to the facial tissues under the mask, yielding falsely positive results on PET imaging.
FDG PET/CT scanning was obtained in a 72-year-old man, also with mantle cell lymphoma, who had achieved complete remission in response to chemotherapy. Serial follow-up PET/CTs had been unremarkable for recurrent lymphoma — until 10 months post-treatment, when a PET/CT revealed a cluster of highly avid left axillary lymph nodes, concerning for recurrent cancer. But the images also revealed less explicable uptake in the left deltoid muscle and surrounding soft tissues, until it was determined the patient had undergone COVID mRNA vaccination two days earlier. Vaccine-induced soft tissue inflammation, myositis, lymphadenopathy, and even bone edema have been misinterpreted previously on magnetic resonance imaging and PET/CT.
Abstruse 2021 CLABSI Case Definition
SOURCE: National Healthcare Safety Network (NHSM) Patient Safety Component Manual. January 2021. https://www.cdc.gov/nhsn/pdfs/pscmanual/pcsmanual_current.pdf
The reduction of hospital-acquired infection (HAI)is a priority for us all. Our facility has spent a decade successfully working to reduce our rates of catheter-associated bloodstream infections (CLABSI), hospital-acquired Clostridioides difficile infection (HO-CDI), and catheter-associated urinary tract infections (CAUTI). Series of tiered best-practice interventions to prevent HAI have been implemented thoughtfully, with welcome results for HO-CDI and CAUTI. However, despite our best efforts, the number of reported CLABSI has increased — not improved. After in-depth clinical investigation and root cause analysis of each case, I believe most of these CLABSI events are an artifact of the National Healthcare Safety Network (NHSN) case definition.
The NHSN Patient Safety Component Manual definition of CLABSI is presented in an increasingly complex and abstruse 42-page document called the “Device-associated Module.” Hospitals are required to abide by this document, but I cannot imagine how the usual hospital infection prevention staff could begin to implement this document, and the statistical section requires an advanced degree. I have read it through several times, and I do not get it. The module goes to great lengths to define bloodstream infections, with a sub-definition of mucosal barrier injury laboratory-confirmed bloodstream infection (MBI-LCBI), which in turn describes three subcategories of MBI-LCBI with a series of tiered requirements. Presumably, this complexity is an attempt to prevent hospitals from omitting some bloodstream infections as CLABSI.
However, in the process of attempting to create a series of requirements that are appropriately inclusive, the case definition has become so complex as to be specious — and appears to be artifactually creating more device-related infections than it correctly identifies. For example, as an infectious disease (ID) specialist with years of experience, I would regard perhaps at most one of our NHSN-defined CLABSI events as a “true” CLABSI, even when viewed in a critical light. The other so-called CLABSIs are either artifacts of contaminated blood draws obtained from peripherally inserted central catheter (PICC) lines, or bacteremias in cancer patients with existing Medi-ports. The most illegitimate “CLABSI events” occurred in three cancer patients with existing Medi-ports, each of whom developed gram-negative bacteremia. The first of these developed chemotherapy-induced febrile neutropenia, and blood cultures yielded Klebsiella spp. Urine cultures yielded the same organism, with a colony count of 30,000 CFU/mL to 50,000 CFU/mL. This inexplicably failed to meet criteria as a “secondary source,” although in the setting of frank neutropenia, this presents an obvious risk. However, because no “secondary source” could be confirmed, this case was classified as a CLABSI. Two other patients had severe malignant bowel obstruction, confirmed both clinically and radiographically, but again no “secondary source” for infection, with a documented paired culture, could be confirmed (simply because a “source” culture could not be reasonably obtained without an invasive procedure). All three gram-negative bacteremias were treated successfully with 10- to 14-day courses of antibiotics, and the ports were not removed and showed no further evidence of infection. The ID consultants involved in the care of these patients did not define or code these cases as device-related infections, and the devices were not removed, as certainly would be indicated for a true gram-negative device-related infection. If you wish to identify a device-related bloodstream infection, why not look at the ID consultant’s notes and treatment?
The government has the responsibility to create and apply regulations that naturally achieve important objectives without causing undue harm.
Aussie Flesh-Eating Disease; Misleading Imaging in COVID; Abstruse 2021 CLABSI Case Definition
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