Gram-positive rods 

Gram-positive bacteria include cocci (staphylococci and streptococci), bacilli/rods (clostridium, diphtheria, listeria, and bacillus) and filamentous bacteria (actinomyces and Nocardia). In this article, we will focus mainly on the gram-positive rods which are also known as gram-positive bacilli and gram-positive filamentous bacteria. 

Diagram 1. Gram-positive cocci, bacilli/rods, and filamentous (not included here) bacteria 

Clostridium 

• Number of bacteria that can 
  • Form spores
  • Are obligate anaerobes (cannot live in environments that have oxygen)
  • Synthesize toxins 
• Clostridium tetani 
  • Spores found in the soil 
  • Classically after a penetrating injury 
  • Presentation
    • Tetanospasmin travels to the spinal cord and creates overstimulation of the nerve cells = spasms, muscle contractions 
    • Trismus = lockjaw as shown below
    • 
  • Treatment 
    • Clean and debride the wound 
    • Metronidazole - not very helpful 
    • Tetanus immune globulin 
    • Benzodiazepines and neuromuscular blockers can stop the contractions 
    • Vaccine 
      • Preventative
      • Made from the tetanus toxoid 
• Clostridium difficile 
  • 
  • Commonly causes severe diarrhea after antibiotic use 
  • Spores in the soil and on plants 
  • Ingestion does not lead to infection 
  • Produces several toxins 
  • Presentation 
    • Severe diarrhea after antibiotics use 
    • Pseudomembrane sometimes seen on endoscopy 
  • Diagnosis 
    • Stool samples are analyzed for the toxins 
  • Treatment 
    • Metronidazole 
    • Oral Vancomycin 
    • Surgery rarely done  
    • Fecal microbiota transplantation
• Clostridium botulinum 
  • Found in soil and plants 
  • "Botox" is the toxin that is harvested from this bacteria and used for cosmetic purposes
  • 
  • Survive up to 100 C
  • Prevents acetylcholine release = flaccid paralysis 
  • Adults usually get it from undercooked food 
  • Infants can get sick from spores = don't give honey to infants 
  • Both adults and kids can get it in their wounds 
  • Presentation - muscles of had and neck affected - 3Ds
    • Diplopia 
    • Dysphagia 
    • Dysphonia 
  • Diagnosis 
    • Stool toxin detection, mostly a clinical diagnosis 
  • Treatment 
    • Immunoglobin to bind to circulating toxin 
    • Supportive care for the toxin in the nerves
• Clostridium perfringes
  • Lives naturally in soil 
  • Can lead to gas gangrene
  •  
    • When vascular supply is compromised = low oxygen environment = anaerobic bacterial conditions
  • Can lead to food poisoning resulting in diarrhea
  • Diagnosis 
    • Gas on imaging 
  • Treatment 
    • Cleaning and debridement of the wound 
    • Wounds often have other anaerobes and gram-positive bacteria, requiring broad antibiotics 

Corynebacterium diphtheria 

• Cause of diphtheria 
• Presentation 
  • Sore throat with fever 
  • The pharynx has a white layer on top as shown below 
  • Complications 
    • Myocarditis 
    • Nephropathy and neuropathy
  • 
• Treatment 
  • Penicillin 
  • Vaccines for prevention
    • Diphtheria antitoxin and toxoid types 

Listeria 

• Found in the soil 
• Moves between cells 
• Can hijack the cellular actin filaments for movement 
• Presentation 
  • Common in newborns (vaginal transmission), HIV patients 
  • Infection through undercooked foods 
  • Gastroenteritis 
    • Diarrhea and vomiting 
  • Meningitis 
  • Infection during pregnancy 
    • Fever and chills 
    • Known as granulomatosis infantiseptica 
    • Can affect the baby's liver, spleen lungs, and brain 
    • Most babies do not survive this

Bacillus 

• Bacillus anthracis 
  • 
  • Eradicated by vaccinations in humans 
  • Infects farm animals
  • Uses a polypeptide capsule (as opposed to a polysaccharide capsule for most other bacteria)
  • Presentation 
    • Skin infection 
      • Through cuts 
      • Painless black ulcer formation with surrounding edema 
      • 
    • Pulmonary disease
      • Flu-like symptoms worsening quickly and leading to pulmonary hemorrhage 
  • Treatment 
    • Ciprofloxacin 
    • Doxycycline 
    • Clindamycin 
• Bacillus cereus 
  • 
  • Causes food poisoning 
  • Classically in reheated rice or undercooked foods 
  • Can cause vomiting or diarrhea 

Actinomyces 

• Part of the healthy oral and vaginal flora
• 
• Filamentous bacteria
• Anaerobe 
• Presentation 
  • Can lead to abscesses in the head and neck 
  • Yellow center 
• Treatment 
  • Penicillin 
  • Surgical drainage 

Nocardia 

• Found in the soil
• Filamentous 
• 
• Obligate aerobe 
• Presentation 
  • Pneumonia in the immunocompromised patients after inhalation of the bacteria 
  • Skin infection in immunocompetent people - cellulitis, abscesses 
  • Bacteremia 
• Diagnosis 
  • Bacteria normally produces urease which can be used for diagnosis 
• Treatment 
  •  Bactrim = TMP-SMX used for antibiotic treatment 

Diagram 2. Various antibiotics and their coverage as discussed above