Nocardia
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Bacteria - Gram Positive
- Staph aureus: Overview
- Staph aureus: Presentation
- Methicillin-Resistant Staph aureus (MRSA)
- Staph saprophyticus
- Strep pneumoniae: Overview
- Strep pneumoniae: Presentation
- Strep viridans
- Strep pyogenes: Overview
- Strep pyogenes: Presentation
- Strep agalactiae
- Strep bovis
- Enterococcus
- Bacillus anthracis
- Bacillus cereus
- Clostridium tetani
- Clostridium perfringens
- Clostridium botulinum
- Clostridium difficile
- Corynebacterium diphtheriae
- Listeria monocytogenes
- Nocardia
- Actinomyces
Nocardia spp.
- Characteristics
- Gram + rod with branching filaments
- Forms long, branching filaments resembling fungi
- Note: Actinomyces is also gram + filamentous rod
- Partially acid-fast
- Weakly pink with Ziehl-Neelsen stain, meaning that it resists the acid-mediated removal of stain (hence, acid-fast)
- Contrast vs. Actinomyces - not acid fast
- Aerobic
- Contrast vs. Actinomyces - anaerobic
- Catalase +
- Increased risk of infection in patients with chronic granulomatous disease
- Found in soil
- Urease +
- Gram + rod with branching filaments
- Risk factors
- Immunocompromised individuals
- Inhalation of bacteria causes pulmonary infection
- E.g. chronic steroid use, HIV infection
- Trauma
- Direct contact via skin break can infect immunocompetent individuals
- Immunocompromised individuals
- Presentation
- Pulmonary cavitary lesions
- Most common in immunocompromised patients
- Mimics tuberculosis but with negative PPD
- Contrast vs. Actinomyces, which presents with oral/facial abscesses
- Cutaneous infections
- Usually after trauma in immunocompetent individuals
- Presents as cellulitis or painful lymphadenopathy
- Pulmonary cavitary lesions
- Treatment
- Trimethoprim-sulfamethoxazole (TMP-SMX)
- First-line treatment
- Carbapenems used in patients with sulfa allergies
- Trimethoprim-sulfamethoxazole (TMP-SMX)