14. Bacillus: Anthracis and Cereus

Aerobic gram-positive bacilli, specifically the *Bacillus* genus, present distinct clinical challenges ranging from common foodborne illness to life-threatening systemic infections. *Bacillus cereus* typically causes self-limiting emetic or diarrheal food poisoning, often associated with contaminated rice. Conversely, *Bacillus anthracis* is a highly virulent pathogen requiring specialized laboratory handling due to its spore-forming nature and potential for severe disease. Clinical manifestations of anthrax include cutaneous lesions, gastrointestinal distress, and high-mortality inhalational pneumonia or meningitis. Laboratory diagnosis relies on identifying non-hemolytic colonies and specific morphological features, often requiring PCR confirmation. Treatment strategies prioritize fluoroquinolones or doxycycline, sometimes supplemented with clindamycin or linezolid to mitigate toxin production, alongside post-exposure prophylaxis and vaccination for high-risk occupations. These organisms underscore the necessity of rigorous infection control and precise diagnostic differentiation in both clinical and laboratory settings.