Locally Acquired Melioidosis Linked to Environment - Mississippi, 2020-2023.

Melioidosis, caused by Burkholderia pseudomallei, is a rare but potentially fatal bacterial disease endemic to tropical and subtropical regions worldwide. It is typically acquired through contact with contaminated soil or fresh water. Before this investigation, B. pseudomallei was not known to have been isolated from the environment in the continental United States. Here, we report on three patients living in the same Mississippi Gulf Coast county who presented with melioidosis within a 3-year period. They were infected by the same Western Hemisphere B. pseudomallei strain that was discovered in three environmental samples collected from the property of one of the patients. These findings indicate local acquisition of melioidosis from the environment in the Mississippi Gulf Coast region.

Contact investigation of melioidosis cases reveals regional endemicity in Puerto Rico.

BACKGROUND: Melioidosis results from infection with Burkholderia pseudomallei and is associated with case-fatality rates up to 40%. Early diagnosis and treatment with appropriate antimicrobials can improve survival rates. Fatal and nonfatal melioidosis cases were identified in Puerto Rico in 2010 and 2012, respectively, which prompted contact investigations to identify risk factors for infection and evaluate endemicity. METHODS: Questionnaires were administered and serum specimens were collected from coworkers, neighborhood contacts within 250 m of both patients' residences, and injection drug user (IDU) contacts of the 2012 patient. Serum specimens were tested for evidence of prior exposure to B. pseudomallei by indirect hemagglutination assay. Neighborhood seropositivity results guided soil sampling to isolate B. pseudomallei. RESULTS: Serum specimens were collected from contacts of the 2010 (n = 51) and 2012 (n = 60) patients, respectively. No coworkers had detectable anti-B. pseudomallei antibody, whereas seropositive results among neighborhood contacts was 5% (n = 2) for the 2010 patient and 23% (n = 12) for the 2012 patient, as well as 2 of 3 IDU contacts for the 2012 case. Factors significantly associated with seropositivity were having skin wounds, sores, or ulcers (odds ratio [OR], 4.6; 95% confidence interval [CI], 1.2-17.8) and IDU (OR, 18.0; 95% CI, 1.6-194.0). Burkholderia pseudomallei was isolated from soil collected in the neighborhood of the 2012 patient. CONCLUSIONS: Taken together, isolation of B. pseudomallei from a soil sample and high seropositivity among patient contacts suggest at least regional endemicity of melioidosis in Puerto Rico. Increased awareness of melioidosis is needed to enable early case identification and early initiation of appropriate antimicrobial therapy.

Burkholderia pseudomallei isolates in 2 pet iguanas, California, USA.

Burkholderia pseudomallei, the causative agent of melioidosis, was isolated from abscesses of 2 pet green iguanas in California, USA. The international trade in iguanas may contribute to importation of this pathogen into countries where it is not endemic and put persons exposed to these animals at risk for infection.

Lethal factor toxemia and anti-protective antigen antibody activity in naturally acquired cutaneous anthrax.

Cutaneous anthrax outbreaks occurred in Bangladesh from August to October 2009. As part of the epidemiological response and to confirm anthrax diagnoses, serum samples were collected from suspected case patients with observed cutaneous lesions. Anthrax lethal factor (LF), anti-protective antigen (anti-PA) immunoglobulin G (IgG), and anthrax lethal toxin neutralization activity (TNA) levels were determined in acute and convalescent serum of 26 case patients with suspected cutaneous anthrax from the first and largest of these outbreaks. LF (0.005-1.264 ng/mL) was detected in acute serum from 18 of 26 individuals. Anti-PA IgG and TNA were detected in sera from the same 18 individuals and ranged from 10.0 to 679.5 µg/mL and 27 to 593 units, respectively. Seroconversion to serum anti-PA and TNA was found only in case patients with measurable toxemia. This is the first report of quantitative analysis of serum LF in cutaneous anthrax and the first to associate acute stage toxemia with subsequent antitoxin antibody responses.

Serologic surveillance of anthrax in the Serengeti ecosystem, Tanzania, 1996-2009.

Bacillus anthracis, the bacterium that causes anthrax, is responsible for varying death rates among animal species. Difficulties in case detection, hazardous or inaccessible carcasses, and misdiagnosis hinder surveillance. Using case reports and a new serologic assay that enables multispecies comparisons, we examined exposure to and illness caused by B. anthracis in different species in the Serengeti ecosystem in Tanzania during 1996-2009 and the utility of serosurveillance. High seroprevalence among carnivores suggested regular nonfatal exposure. Seropositive wildebeest and buffalo showed that infection was not invariably fatal among herbivores, whereas absence of seropositivity in zebras and frequent detection of fatal cases indicated high susceptibility. Exposure patterns in dogs reflected known patterns of endemicity and provided new information about anthrax in the ecosystem, which indicated the potential of dogs as indicator species. Serosurveillance is a valuable tool for monitoring and detecting anthrax and may shed light on mechanisms responsible for species-specific variability in exposure, susceptibility, and mortality rates.

Predictability of anthrax infection in the Serengeti, Tanzania.

Anthrax is endemic throughout Africa, causing considerable livestock and wildlife losses and severe, sometimes fatal, infection in humans. Predicting the risk of infection is therefore important for public health, wildlife conservation and livestock economies. However, because of the intermittent and variable nature of anthrax outbreaks, associated environmental and climatic conditions, and diversity of species affected, the ecology of this multihost pathogen is poorly understood.We explored records of anthrax from the Serengeti ecosystem in north-west Tanzania where the disease has been documented in humans, domestic animals and a range of wildlife. Using spatial and temporal case-detection and seroprevalence data from wild and domestic animals, we investigated spatial, environmental, climatic and species-specific associations in exposure and disease.Anthrax was detected annually in numerous species, but large outbreaks were spatially localized, mostly affecting a few focal herbivores.Soil alkalinity and cumulative weather extremes were identified as useful spatial and temporal predictors of exposure and infection risk, and for triggering the onset of large outbreaks.Interacting ecological and behavioural factors, specifically functional groups and spatiotemporal overlap, helped to explain the variable patterns of infection and exposure among species.Synthesis and applications. Our results shed light on ecological drivers of anthrax infection and suggest that soil alkalinity and prolonged droughts or rains are useful predictors of disease occurrence that could guide risk-based surveillance. These insights should inform strategies for managing anthrax including prophylactic livestock vaccination, timing of public health warnings and antibiotic provision in high-risk areas. However, this research highlights the need for greater surveillance (environmental, serological and case-detection-orientated) to determine the mechanisms underlying anthrax dynamics.

Identification and characterization of clinical Bacillus spp. isolates phenotypically similar to Bacillus anthracis.

Bacillus anthracis, the etiological agent of anthrax, is a gram-positive, spore-forming rod, with colonies exhibiting a unique ground-glass appearance, and lacking hemolysis and motility. In addition to these phenotypes, several others traits are characteristic of B. anthracis such as susceptibility to gamma phage, the presence of two virulence plasmids (pX01 and pX02), and specific cell wall and capsular antigens that are commonly detected by direct fluorescent-antibody assays. We report on the identification and characterization of 14 Bacillus megaterium and four Bacillus sp. clinical isolates that are nonhemolytic, nonmotile, and produce a capsule antigenically similar to B. anthracis. This work furthers our understanding of Bacillus diversity and the limitations of the assays and phenotypes that are used to differentiate species in this genus. Further work is necessary to understand whether these strains are opportunistic pathogens or just contaminates.

Comparison of four selective media for the isolation of Burkholderia mallei and Burkholderia pseudomallei.

Currently there are no commercially available selective media indicated for the isolation of Burkholderia mallei and Burkholderia pseudomallei. Ashdown's agar, a custom selective medium for isolation of B. pseudomallei, is well described in the literature but unavailable commercially. Three commercially available media, Burkholderia cepacia selective agar (BCSA), oxidative-fermentative-polymyxin B-bacitracin-lactose (OFPBL) agar, and Pseudomonas cepacia (PC) agar are recommended for isolation of B. cepacia from respiratory secretions of cystic fibrosis patients. We evaluated the sensitivity and selectivity of these four media using 20 B. mallei, 20 B. pseudomallei, 20 Burkholderia spp., and 15 diagnostically challenging organisms. Ashdown's agar was the most sensitive medium for the isolation of B. pseudomallei, but it was unable to support growth of B. mallei. Pseudomonas cepacia agar was highly sensitive and selective for both organisms. In non-endemic areas, we suggest the use of the commercially available PC agar for the isolation of B. mallei and B. pseudomallei.