Investigation and Findings
\nIdentification of Patient<\/p>\n
On September 7, 2024, CDC and the Louisiana Department of Health (LDH) were contacted by a clinician regarding an otherwise healthy man aged 18 years from Louisiana, who was being admitted to an intensive care unit with severe pneumonia and respiratory failure that required endotracheal intubation and mechanical ventilation. The patient had developed a cough 1 week earlier. He had worked part-time as a welder for 6 months immediately preceding his illness and had no reported history of smoking, vaping, or excessive alcohol consumption. Blood cultures were positive for B. cereus group bacteria and, because of the patient\u2019s pneumonia, respiratory failure, occupation, and geographic proximity to previously reported cases, welder\u2019s anthrax was suspected (1,3,4) (Table<\/a>).<\/p>\n Treatment<\/p>\n The patient initially received empiric antibiotic treatment with vancomycin, meropenem, ciprofloxacin, and doxycycline. Obiltoxaximab, a monoclonal antibody anthrax antitoxin directed against the protective antigen of B. anthracis and indicated for treatment of inhalation anthrax, was available from the U.S. Strategic National Stockpile. CDC requested the antitoxin, which was administered to the patient 34 hours after welder\u2019s anthrax was suspected (approximately 1 week after symptom onset). The patient\u2019s condition improved rapidly, and intubation and mechanical ventilation was discontinued 72 hours later. He received continued intravenous antimicrobial therapy (2) and drainage of a pleural effusion. He was discharged with a tailored antibiotic regimen after a 26-day hospitalization. All pulmonary symptoms had resolved by his 3-month follow-up visit.<\/p>\n Clinical Laboratory Analysis<\/p>\n Laboratory Response Network (LRN) polymerase chain reaction (PCR) testing of an isolate obtained from the patient\u2019s blood performed by the Louisiana State Public Health Laboratory confirmed the presence of an anthrax toxin gene. CDC identified the isolate as Bacillus tropicus by LRN algorithm and whole genome sequencing (WGS). Gene comparisons using multilocus sequencing typing indicated sequence type 78 (ST-78) and B. anthracis\u2013associated toxin genes.<\/p>\n Epidemiologic Investigation<\/p>\n After consultation with CDC and CDC\u2019s National Institute for Occupational Safety and Health (NIOSH), LDH interviewed the patient and representatives from his worksite\u00b6 to better understand his exposure history and welding practices. For 6 months preceding his illness onset, the patient worked 4 hours per day, 4 days per week as a welding apprentice in the shipbuilding and repair industry. He conducted shielded metal arc welding** using carbon steel and low-hydrogen carbon steel electrodes both in open areas and confined spaces\u2020\u2020 with limited ventilation and minimal use of personal protective equipment (PPE). No fans or ventilation systems were present in the patient\u2019s work area, including within enclosed spaces. Interviews with worksite representatives revealed that employees work on-site for several hours each day, do not consistently wear respirators when welding, and often take breaks and eat lunch in their work area rather than using the designated break area.<\/p>\n Environmental Investigation and Laboratory Analysis<\/p>\n After the patient recovered, LDH requested CDC\u2019s assistance in investigating the environmental source of infection using previously described methods (6). A total of 245 samples were collected from the patient\u2019s worksite, including 95 bulk soil samples from work areas, as well as 98 sterile sponge-stick\u00a7\u00a7 and 52 macrofoam-swab surface samples from tools or items that he possibly used (6). Samples were also collected from outdoor areas, tools, clothing, buildings, and break areas near the patient\u2019s work area. All samples were stored and transported to CDC, where DNA was extracted and tested for anthrax toxin genes by LRN algorithm (6). A cycle threshold value <40 was considered positive. A second extraction was performed on positive samples. DNA was purified using Agencourt AMPure XP beads according to manufacturer instructions\u00b6\u00b6 for all samples with at least one negative result, and quantitative real-time PCR (qPCR) was repeated. An additional extraction was performed on positive samples and qPCR was repeated. Samples were considered qPCR-positive if two extractions were positive and inconclusive if only one extraction was positive. Culture was performed on all qPCR-positive and inconclusive samples. WGS and phylogenetic analyses were performed on culture isolates (6).<\/p>\n Among the 245 collected samples, 28 (11.4%) were positive by qPCR for anthrax toxin genes (cycle threshold range\u00a0=\u00a029.0\u201339.9), consisting of one swab sample from work gloves found on a vessel in an area where the patient worked (not conclusively identified as belonging to the patient), two sponge samples from a handrail and table where the patient worked, and 25 soil samples collected across the worksite, including areas where the patient worked. Five samples (2.0%, all soil) were inconclusive, and the remaining 212 (86.5%) were negative.<\/p>\n One isolate from a positive soil sample was successfully cultured. The genotype was ST-78; all other known ST-78 strains are Bacillus tropicus. WGS indicated 99.998% +\/\u2013 0.096% average nucleotide identity among genome sequences from the clinical and environmental isolates using Basic Local Alignment Search Tool (BLAST+),*** an application of the National Center for Biotechnology Information sequence similarity search program. The phylogeny further suggests their high relatedness by the short (horizontal) phylogenetic distances (Figure<\/a>) and demonstrates clustering with genome sequences derived from patients from Louisiana (GCF_000832805.1, GCA_043275215.1, GCF_002007005.1, and SRR19658610), a zoo animal from Louisiana (GCF_046718865.1), the Louisiana environment (SRR19658609), a patient from Florida (GCF_000688755.1), a patient from Texas (GCF_000789315.1), and a B. cereus group genome with unknown origins (GCF_016027575.1).<\/p>\n","protected":false},"excerpt":{"rendered":"Investigation and Findings Identification of Patient On September 7, 2024, CDC and the Louisiana Department of Health (LDH)…\n","protected":false},"author":2,"featured_media":382113,"comment_status":"","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[33],"tags":[64,63,137,490],"class_list":{"0":"post-383153","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-medication","8":"tag-au","9":"tag-australia","10":"tag-health","11":"tag-medication"},"_links":{"self":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/383153","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/comments?post=383153"}],"version-history":[{"count":0,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/posts\/383153\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media\/382113"}],"wp:attachment":[{"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/media?parent=383153"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/categories?post=383153"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.newsbeep.com\/au\/wp-json\/wp\/v2\/tags?post=383153"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}