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Chapter 11: Bacterial Diseases

Rickettsia rickettsii

  • Disease: Rocky Mountain spotted fever
  • Route of Transmission: Tick bite
  • Symptoms: Rash (including on the soles and palms), fever, headache, potentially leading to death due to kidney and heart failure.

Brucella melitensis

  • Disease: Brucellosis or undulate fever
  • Route of Transmission: Direct handling of infected animals or consumption of unpasteurized milk
  • Symptoms: Malaise (general weakness and tiredness), swollen lymph nodes, and a fever that spikes every evening, accompanied by heavy sweating.

Bordetella pertussis

  • Disease: Whooping cough (pertussis)
  • Route of Transmission: Respiratory route
  • Symptoms: Comprises three stages: catarrhal stage, paroxysmal stage, and convalescence phase.

Neisseria gonorrhoeae

  • Disease:
      - Ophthalmia neonatorum
      - Gonorrhea
      - Pelvic inflammatory disease (PID)
  • Route of Transmission: Via the birth canal or sexually
  • Symptoms:
      - Males: Painful urination and pus discharge
      - Females: Typically asymptomatic unless it spreads to PID, leading to further complications.

Pseudomonas aeruginosa

  • Disease: Dermatitis (inflammation of the skin), outer ear infections, infections in burn patients and cystic fibrosis patients
  • Route of Transmission: Waterborne, direct contact, nosocomial infections (hospital-acquired)
  • Symptoms: Acts as an opportunistic pathogen, capable of colonizing hair follicles and causing a self-limiting rash. Infected areas may exhibit blue-green pus due to pigment production.

Moraxella lacunata

  • Disease: Conjunctivitis (pink eye)
  • Route of Transmission: Direct contact
  • Symptoms: Inflammation of the membrane that covers the eye and lines the eyelids.

Legionella pneumophila

  • Disease: Legionnaire’s disease or legionellosis
  • Route of Transmission: Respiratory route
  • Symptoms: High fever, cough, and general symptoms of pneumonia.

Coxiella burnetii

  • Disease: Q fever
  • Route of Transmission: Transmitted by aerosols from infected animals or via contaminated milk from cows
  • Symptoms: Fever, severe headache; can develop into hepatitis and endocarditis.

Vibrio cholerae

  • Disease: Cholera
  • Route of Transmission: Contaminated water or foods
  • Symptoms: Profuse watery diarrhea, vomiting, fever absent; loss of electrolytes can lead to shock and death.

Escherichia coli

  • Disease:
      - Urinary tract infection (UTI)
      - Traveler’s diarrhea
  • Route of Transmission: Fecal/oral
  • Symptoms (UTI):
      - Frequent painful/burning urination
      - Difficulty voiding bladder
      - Cloudy, foul-smelling urine
      - Presence of blood in urine
      - Abdominal pain and fever

Disease in Depth: Bacterial Urinary Tract Infections

Escherichia coli and Other Bacteria
  • Millions of individuals in the U.S., especially females, are affected by bacterial UTIs annually, which includes approximately 600,000 cases of healthcare-associated UTIs.
  • UTIs are rare in males due to anatomical differences.
  • Pathogenesis:
      1. E. coli is commonly introduced into the urethra through fecal contamination.
      2. Bacteria adhere to epithelial cells in the urethra using fimbriae.
      3. E. coli colonizes epithelial cells and multiplies through binary fission.
  • Signs and Symptoms: Mild infections may present few symptoms; however, more severe cases involve frequent, urgent, and painful urination (dysuria), cloudy blood-tinged urine, and mental confusion, especially in the elderly.
  • Epidemiology:
      - Predominantly affects women due to shorter urethra and anatomical proximity to the anus.
      - Increased risk factors: diabetes, nursing home residents, elderly men with prostate issues, catheterized patients, and those with inadequate fluid intake.
  • Pathogen: Enteric bacteria, primarily E. coli (70% of cases), alongside other intestinal flora such as Proteus and Klebsiella, contribute to UTIs.
  • Virulence Factors:
      - E. coli possesses flagella for movement and fimbriae for attachment to urinary epithelial cells.
      - Some strains of E. coli can evade the immune response by forming biofilms within bladder epithelial cells.
  • Diagnosis: Urinalysis metrics include leukocytes, erythrocytes, and detection of E. coli.
  • Treatment and Prevention: Mild cases can resolve without intervention; however, antimicrobial options include cephalosporins, sulfonamides, and penicillins. Preventive measures emphasize proper hygiene practices such as front-to-back wiping after defecation.

Salmonella species

  • Disease: Salmonellosis
  • Route of Transmission: Fecal/oral route
  • Symptoms: Nausea, abdominal pain, diarrhea (12-36 hours post-ingestion), and fever due to endotoxin release. Common sources include undercooked eggs and meat products.

Shigella dysenteriae

  • Disease: Bacillary dysentery or shigellosis, including traveler’s diarrhea
  • Route of Transmission: Fecal/oral route
  • Symptoms: Bloody, mucoid diarrhea, abdominal cramps, fever, intense inflammation, and production of a neurotoxin.

Klebsiella pneumoniae

  • Disease: Urinary and respiratory tract infections
  • Route of Transmission: Normal flora or direct contact
  • Symptoms: Known for persistence on surfaces; significantly causes septicemia in children and pneumonia in individuals with a history of alcohol use.
      - Septicemia: Presence of bacteria in blood, leading to fever and potential organ damage.

Yersinia pestis

  • Disease: Bubonic plague and pneumonic plague
  • Route of Transmission: Flea bite (bubonic) or respiratory route (pneumonic)
  • Symptoms: Bruising and the formation of buboes (enlarged lymph nodes).

Haemophilus influenzae Type b

  • Disease: Meningitis, earaches, epiglottitis, septic arthritis, bronchitis, and pneumonia
  • Route of Transmission: Airborne
  • Symptoms: Presentation usually begins with headache, light sensitivity, high fever, and neck stiffness, leading to convulsions and coma in severe cases.

Campylobacter

  • Disease: Outbreaks of foodborne intestinal disease; recognized as a leading cause of foodborne illness in the U.S.
  • Route of Transmission: Foodborne
  • Symptoms: Diarrhea, abdominal cramps, and fever (vomiting not typically present); associated with poultry, milk, and water.

Helicobacter pylori

  • Disease: Gastritis and gastric ulcers
  • Route of Transmission: Unknown
  • Symptoms: Strong association with stomach cancer.
  • Bacteria invade and attach to gastric epithelial cells, leading to mucosal erosion and inflammation.

Clostridium tetani

  • Disease: Tetanus or lockjaw
  • Route of Transmission: Puncture wound
  • Symptoms: Headaches, fever, irritability, muscle spasms, and paralysis of face and neck muscles.

Clostridium botulinum

  • Disease: Botulism
  • Route of Transmission: Ingestion of toxin or bacilli
  • Symptoms: Nausea, absence of fever, diplopia (double vision), dysphagia (difficulty swallowing), and potential respiratory/cardiac failure leading to death.

Clostridium perfringens

  • Disease: Gas gangrene and food poisoning
      - Necrosis: Death of tissue, often due to loss of blood supply.

Clostridium difficile

  • Disease: Antibiotic-associated diarrhea
  • Route of Transmission: Normal gut flora or fecal/oral route
  • Symptoms: Thrives in antibiotic-treated individuals, and can be rapidly fatal in immunocompromised hosts.

Bacillus anthracis

  • Disease: Anthrax
  • Route of Transmission:
      - Respiratory route
      - Spore entrance through abrasions
  • Symptoms: Endospores can survive in soil for long periods; in humans, causes necrotic pustulated lesions followed by septicemia and pneumonia.

Staphylococcus aureus

  • Disease: Folliculitis (pimples), impetigo in neonates, sty, boils (furuncle), carbuncles, postoperative and catheter infections, scalded skin syndrome, food poisoning
  • Route of Transmission: Normal flora and post-surgical infections.

Methicillin-Resistant Staphylococcus aureus (MRSA)

  - Consideration of antibiotic resistance challenges in clinical treatment.

Streptococcus

  • Disease: Strep throat, ear infections, sinus infections, puerperal sepsis, impetigo in older individuals, erysipelas, Scarlet fever, rheumatic fever
  • Route of Transmission: Respiratory droplets or direct contact

Streptococcal Pharyngitis (Strep Throat)

  • Mechanism of Infection:
      1. Streptococcus pyogenes enters via respiratory droplets from coughs/sneezes.
      2. Symptoms include a reddened throat, swollen lymph nodes, and tonsillar abscesses, leading to fever and malaise.
      3. Potential complications include laryngitis, bronchitis, and extension into scarlet and rheumatic fever states.
  • Diagnosis and Treatment: Importance of throat culture; standard treatment involves penicillin or erythromycin for penicillin-allergic individuals.

Enterococcus faecium and faecalis

  • Disease: Urinary tract infections, endocarditis, postoperative infections
  • Route of Transmission: Normal flora or nosocomial
  • Symptoms: Similar urinary symptoms to other UTIs, including frequent painful urination and potential fever.

Endocarditis

  • Definition: Potentially fatal inflammation of the endocardium, resulting in vegetations that may complicate the condition.

Listeria monocytogenes

  • Disease: Listeriosis, particularly affecting neonates and immunocompromised individuals
  • Route of Transmission: Foodborne or in utero
  • Symptoms: Often asymptomatic in healthy adults but can have severe implications for pregnant women and their fetuses.

Mycoplasma pneumonia

  • Disease: Atypical pneumonia or walking pneumonia
  • Route of Transmission: Respiratory
  • Symptoms: Characterized by milder symptoms compared to classical pneumonia, facilitating persisting chronic infections.

Mycobacterium tuberculosis

  • Disease: Tuberculosis (TB)
  • Route of Transmission: Respiratory droplet transmission
  • Symptoms: Includes weight loss, persistent cough, rust-colored sputum, chest pain, malaise, and night sweats.
  • Pathogenesis:
      - TB represents a significant public health concern, prone to resurgence due to antibiotic resistance and current epidemiological trends.
      - The bacterium infects the respiratory tract via inhalation; macrophages engulf the bacteria but fail to eliminate them, resulting in chronic infections and the formation of tubercles.
  • Diagnosis: Tuberculin skin test and chest X-rays to observe lung lesions.
  • Treatment: Combination therapy with isoniazid, rifampin, and additional antibiotics, with the BCG vaccine applied in endemic zones.

Corynebacterium diphtheriae

  • Disease: Diphtheria
  • Route of Transmission: Spread by respiratory aerosols
  • Symptoms: Includes sore throat, fever, malaise, and neck swelling, with risks for severe heart, kidney, and nerve damage.

Gardnerella vaginalis

  • Disease: Vaginitis (inflammation of the vagina)
  • Route of Transmission: Normal flora in many women or their partners
  • Symptoms: Sensitive to pH changes, leading to foul odor and discharge.

Chlamydia trachomatis

  • Disease:
      - Trachoma (eye infection)
      - Nongonococcal urethritis
      - Pelvic inflammatory disease (PID)
      - Lymphogranuloma venereum
  • Route of Transmission: STD or via direct contact
  • Prevalence: Most common sexually transmitted disease and a leading cause of infertility.

Treponema pallidum

  • Disease: Syphilis
  • Route of Transmission: Sexual or congenital
  • Symptoms: Progress through three distinct stages:
      - Primary: Painless chancre (ulcer) for a few days.
      - Secondary: Widespread rash and flu-like symptoms.
      - Tertiary: Serious multisystem involvement including neurological and circulatory distresses.

Borrelia burgdorferi

  • Disease: Lyme disease
  • Route of Transmission: Hard ticks
  • Symptoms: Characteristic bull's-eye skin lesions, fever, headache, muscle pain, joint swelling, fatigue, with possible future neurological and cardiac issues.

Objectives

  • Identify unique symptoms or characteristics of each disease discussed.