4.2M-bacili

Bacilli Classification

• All bacilli are Gram negative except for:

  • Bacillus

  • Mycobacterium

  • Clostridium

  • Listeria

  • Corynebacterium

  • Lactobacillus

  • Actinomyces

  • Nocardia

  • Gardnerella

  • Erysipelothrix

  • Arcanobacterium

Corynebacterium diphtheriae

General Information

• Always a pathogen

• Classification:

  • GS: Gram (+)

  • MR: Club-shaped bacilli organized in V or L configurations (mimics Chinese characters)

  • MT: Nonmotile

  • AR: Facultative anaerobe

  • O: Pili presence

Reservoir and Transmission

• Reservoir: Human upper respiratory tract (URT)

• Transmission:

  • Respiratory droplets

  • Indirect contact via fomites

Virulence Factors

• Exotoxin production

• Catalase enzyme presence

Diphtheria Disease

Symptoms

• Mild sore throat with fever

• Pseudomembrane formation in the pharynx

• Characteristic "Bull's Neck" appearance

• Bacteria produce toxins within the pseudomembrane, causing further tissue damage

Management & Prevention

• Appropriate antibiotic therapy

• Diphtheria antitoxin

• Supportive therapy (soft diet, ice collar, adequate hydration)

• DPT vaccine

Clostridium botulinum

General Information

• Classification:

  • GS: Gram (+)

  • MR: Bacilli

  • MT: Motile

  • AR: Anaerobe

  • O: Flagella and subterminal spores

Reservoir and Transmission

• Natural habitat: Soil

• Transmission:

  • Ingestion of heat-resistant spores (found in wild/raw honey and bulging canned goods)

Virulence Factors

• Botulinum toxin is one of the most potent toxins known, inhibiting the release of Acetylcholine from peripheral nerves, leading to impaired neuromuscular transmission

Botulism Disease

Symptoms

• Fatal food poisoning characterized by:

  • Flaccid paralysis due to potent neurotoxin

  • Trouble swallowing and slurred speech

  • Weak muscles and breathing issues

  • Droopy eyelids and blurry vision

Management & Prevention

• Appropriate antibiotic therapy

• Botulism Intravenous Immunoglobulin (IG)

• Aggressive supportive care

• Avoid giving honey to infants, and educate on proper food preparation

Clostridium tetani

General Information

• Classification:

  • GS: Gram (+)

  • MR: Bacilli with drumstick or tennis racket appearance

  • MT: Motile

  • AR: Anaerobe

  • O: Terminal spores with peritrichous flagella

Reservoir and Transmission

• Reservoir: Soil, unsterilized metals, and rusty materials

• Transmission: Entry through punctured wounds, also affects umbilical stump of the newborn

Virulence Factors

• Spores and toxin (tetanospasmin) inhibit release of GABA and glycine, both inhibitory neurotransmitters, causing excessive stimulation

Tetanus Disease

Symptoms

• Acute onset of hypertonia or painful muscular contractions

• Characteristic muscle spasms:

  • Trismus (lockjaw)

  • Respiratory muscle paralysis

  • Opisthotonos (spinal arching)

Management & Prevention

• Tetanus Immunoglobulin (TIG)

• Wound debridement

• Appropriate antibiotic therapy

• Tetanus Toxoid vaccine and DPT vaccine

• Support with airway maintenance and wound care

Vibrio cholerae

General Information

• Always a pathogen

• Classification:

  • GS: Gram (-)

  • MR: Comma-shaped colon bacilli

  • MT: Motile

  • AR: Aerobic

  • O: Presence of pili with a single polar flagellum

Reservoir and Transmission

• Reservoir: Human and salt water

• Transmission: Fecal-oral route via contaminated water or indirect contact through soiled hands

Virulence Factors

• Choleragen toxin stimulates mucosal cells to increase chloride secretion, leading to outpouring of intestinal fluids

Cholera Disease

Symptoms

• Acute bacterial disease characterized by:

  • Severe diarrhea with "rice water stools"

  • Massive loss of fluid and electrolytes

Management & Prevention

• Appropriate antibiotic therapy

• Fluid and electrolyte replacement

• Proper record keeping of vital signs and intake/output

• Sewage disposal and environmental sanitation

Salmonella typhi

General Information

• Classification:

  • GS: Gram (-)

  • MR: Bacilli

  • MT: Motile

  • AR: Facultative anaerobes

  • O: Encapsulated with pili and peritrichous flagella

Reservoir and Transmission

• Reservoir: Human colon

• Transmission: Fecal-oral via contaminated shellfish and oysters

Virulence Factors

• Presence of peritrichous flagella, capsule, and pili

Typhoid Fever Disease

Symptoms

• Infection affecting the GIT, specifically the lymphoid tissues of Peyer's Patches in the ileum, resulting in:

  • Fever, diarrhea, and rose spots

  • Potentially leading to bowel perforation and toxin absorption into the bloodstream

Management & Prevention

• Appropriate antibiotic therapy

• Fluid and electrolyte replacement

• Hygiene, sanitation, and proper sewage disposal

Shigella species

General Information

• Always a pathogen

• Classification:

  • GS: Gram (-)

  • MR: Bacilli

  • MT: Nonmotile

  • AR: Facultative anaerobes

Reservoir and Transmission

• Reservoir: Human

• Transmission: Fecal-oral route

Virulence Factors

• Produces Shiga toxin along with enterotoxin and neurotoxin

Bacillary Dysentery Disease

Symptoms

• Initially presents as watery diarrhea, progressing to bloody diarrhea

• Invasion of the submucosa of the intestinal tract by Shiga toxin causes inflammation and ulceration

Management & Prevention

• Appropriate antibiotic therapy

• Fluid and electrolyte replacement

• Hygiene, sanitation, and proper sewage disposal

Escherichia coli

General Information

• Opportunistic pathogen and indigenous microbiota of the colon

• Classification:

  • GS: Gram (-)

  • MR: Bacilli

  • MT: Motile

  • AR: Facultative anaerobes

  • O: Presence of peritrichous flagella, some encapsulated and with pili

Reservoir and Transmission

• Reservoir: Human colon

• Transmission: Fecal-oral

Virulence Factors

• Presence of capsules, flagella, and toxins (endotoxin and enterotoxin)

E. coli Diseases

Types

1. Urinary Tract Infection

2. Healthcare-associated infections

3. Diarrhea, including Traveler's diarrhea (variously known as Montezuma's Revenge, Dehli's belly, etc.)

Management & Prevention

• Appropriate antibiotic therapy

• Fluid and electrolyte replacement

• Hygiene, sanitation, and proper sewage disposal

Traveler's Diarrhea Prevention

• Avoid ice

• Wash hands with soap and water frequently, especially after using the bathroom

• Consume freshly prepared food served hot

• Wash or peel raw produce

• Drink boiled water or beverages from sealed containers

Pseudomonas aeruginosa

General Information

• Opportunistic pathogen and indigenous microbiota of the skin & upper respiratory tract

• Classification:

  • GS: Gram (-)

  • MR: Bacilli

  • MT: Motile

  • AR: Obligate aerobe

  • O: Encapsulated with a single polar flagellum; produces characteristic blue (pyoverdin) and green (pyocyanin) pigments

  • Notable sweet, fruity grape-like odor

Reservoir and Transmission

• Reservoir: Environmental water sources, humidifiers, and moist environments

• Transmission:

  • Respiratory droplets

  • Direct contact with skin lesions

  • Indirect contact through fomites

Virulence Factors

• Single polar flagellum, capsule, exoenzyme elastase, endotoxin, and exotoxin

Pseudomonas Diseases

Common Infections

1. Burn wound infection

2. Otitis externa

3. Respiratory infections

4. Hot tub folliculitis

5. Healthcare-associated infections, particularly Ventilator-Associated Pneumonia

Management & Prevention

• Appropriate antibiotic therapy due to multidrug resistance

• Maintenance of hygiene

Haemophilus influenzae

General Information

• Opportunistic pathogen, part of indigenous microbiota of the upper respiratory tract

• Classification:

  • GS: Gram (-)

  • MR: Bacilli

  • MT: Nonmotile

  • AR: Facultative anaerobe

  • O: Encapsulated with pili

Reservoir and Transmission

• Reservoir: Human upper respiratory tract

• Transmission: Respiratory droplets and indirect contact via fomites

Virulence Factors

• Capsule and pili presence

Haemophilus Diseases

Common Infections

1. Bacterial meningitis (common in children under 5)

2. Ear infections

3. Respiratory infections (acute epiglottitis with "cherry red" epiglottis and thumb sign on x-ray)

Management & Prevention

• Appropriate antibiotic therapy

• Hib vaccine

Bordetella pertussis

General Information

• Always a pathogen

• Classification:

  • GS: Gram (-)

  • MR: Bacilli

  • MT: Nonmotile

  • AR: Facultative anaerobe

  • O: Encapsulated with pili

Reservoir and Transmission

• Reservoir: Human upper respiratory tract

• Transmission: Respiratory droplets and indirect contact through fomites

Virulence Factors

• Capsule and pili presence; produces toxin: tracheal cytotoxin

Pertussis Disease

Symptoms

• Known as "whooping cough"; pathogen confined to tracheobronchial mucosa

  • Tenacious mucus leads to spasmodic coughing

  • Highly contagious among non-immune individuals, grants lifetime immunity upon recovery

Management & Prevention

• Appropriate antibiotic therapy

• DPT vaccine

• Supportive therapy: adequate nutrition, fluids, oxygen therapy, patient isolation