Overview of Major Bacterial Diseases: Transmission, Symptoms, and Clinical Features

Bacterial Diseases

Introduction

This study guide provides an overview of significant bacterial diseases, focusing on their causative agents, routes of transmission, characteristic symptoms, and clinical relevance. Understanding these diseases is essential for microbiology students, especially for case study exams and clinical identification.

Rickettsial Diseases

Rickettsia rickettsii

• Disease: Rocky Mountain spotted fever

• Route of Transmission: Tick bite

• Symptoms: Rash (especially on soles and palms), fever, headache; can progress to kidney and heart failure, potentially fatal.

Brucellosis

Brucella melitensis

• Disease: Brucellosis or undulant fever

• Route of Transmission: Direct handling of infected animals or unpasteurized milk

• Symptoms: Malaise, weakness, fever that spikes every evening, swollen lymph nodes.

Bordetella Infections

Bordetella pertussis

• Disease: Whooping cough (pertussis)

• Route of Transmission: Respiratory route

• Symptoms: Catarrhal stage, paroxysmal stage (severe coughing), convalescence phase.

Neisseria Infections

Neisseria gonorrhoeae

• Disease: Gonorrhea, Ophthalmia neonatorum, Pelvic Inflammatory Disease (PID)

• Route of Transmission: Sexual contact or birth canal

• Symptoms: Males: painful urination, pus discharge; Females: often asymptomatic, can progress to PID.

Neisseria meningitidis

• Disease: Meningococcal meningitis

• Route of Transmission: Respiratory droplets

• Symptoms: Sudden fever, headache, stiff neck, nausea, vomiting.

Pseudomonas Infections

Pseudomonas aeruginosa

• Disease: Dermatitis, otitis externa, infections in burns and cystic fibrosis patients

• Route of Transmission: Waterborne, direct contact, nosocomial (hospital-acquired)

• Symptoms: Blue-green pus due to pigment, inflammation, fever.

Moraxella and Legionella Infections

Moraxella lacunata

• Disease: Conjunctivitis (pink eye)

• Route of Transmission: Direct contact

• Symptoms: Inflammation of the membrane covering the eye and eyelids.

Legionella pneumophila

• Disease: Legionnaire's disease, legionellosis

• Route of Transmission: Respiratory route (inhalation of contaminated aerosols)

• Symptoms: High fever, cough, pneumonia.

Coxiella and Vibrio Infections

Coxiella burnetii

• Disease: Q fever

• Route of Transmission: Aerosols from animals, contaminated milk

• 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, rapid dehydration, loss of electrolytes, shock, and death.

Enteric Bacterial Diseases

Escherichia coli

• Disease: Urinary tract infection (UTI), traveler's diarrhea

• Route of Transmission: Fecal/oral

• Symptoms: Frequent painful urination, burning, cloudy urine, abdominal pain, fever.

Salmonella enterica

• Disease: Salmonellosis

• Route of Transmission: Fecal/oral

• Symptoms: Nausea, abdominal pain, diarrhea 12-36 hours after ingestion, fever from endotoxin.

• Source: Uncooked eggs, meat products.

Shigella dysenteriae

• Disease: Bacillary dysentery (shigellosis)

• Route of Transmission: Fecal/oral

• Symptoms: Bloody, mucous diarrhea, cramps, fever, intense inflammation, neurotoxin production.

Klebsiella pneumoniae

• Disease: Urinary and respiratory tract infections

• Route of Transmission: Normal flora or direct contact

• Symptoms: Major cause of septicemia in children and pneumonia in alcoholics.

Yersinia and Haemophilus Infections

Yersinia pestis

• Disease: Bubonic plague, pneumonic plague

• Route of Transmission: Flea bite (bubonic), airborne (pneumonic)

• Symptoms: Bruising, buboes (enlarged lymph nodes).

Haemophilus influenzae

• Disease: Meningitis, epiglottitis, arthritis, bronchitis, pneumonia

• Route of Transmission: Airborne

• Symptoms: Headache, light sensitivity, fever, neck stiffness; can lead to convulsions and coma.

Foodborne Bacterial Diseases

Campylobacter jejuni

• Disease: Foodborne intestinal disease

• Route of Transmission: Foodborne (poultry, milk, water)

• Symptoms: Diarrhea, abdominal cramps, fever; no vomiting.

Helicobacter pylori

• Disease: Gastritis, gastric ulcers

• Route of Transmission: Unknown

• Symptoms: Strongly associated with stomach cancer, ulceration of stomach wall.

Clostridial Diseases

Clostridium tetani

• Disease: Tetanus (lockjaw)

• Route of Transmission: Puncture wound

• Symptoms: Headaches, fever, irritability, paralysis of face and neck.

Clostridium botulinum

• Disease: Botulism

• Route of Transmission: Ingestion of toxin or bacilli

• Symptoms: Nausea, no fever, diplopia (double vision), dysphagia (difficulty swallowing); may cause respiratory and cardiac failure.

Clostridium perfringens

• Disease: Gas gangrene

• Symptoms: Necrosis (death of tissue), gangrene (loss of blood supply).

Clostridium difficile

• Disease: Antibiotic-associated diarrhea

• Transmission: Normal gut flora, fecal/oral route

• Symptoms: Severe diarrhea, rapidly fatal in compromised hosts.

Bacillus and Staphylococcus Infections

Bacillus anthracis

• Disease: Anthrax

• Route of Transmission: Respiratory route or spore entrance through abrasions

• Symptoms: Endospores can survive up to 60 years; black necrotic pustule, respiratory distress, sepsis.

Staphylococcus aureus

• Disease: Folliculitis, impetigo, scalded skin syndrome, food poisoning, MRSA

• Route of Transmission: Normal flora, post-operative infections

• Symptoms: Pimples, boils, abscesses, fever, rapidly spreading infections.

Streptococcal and Enterococcal Infections

Streptococcus pyogenes

• Disease: Strep throat, scarlet fever, rheumatic fever, impetigo, necrotizing fasciitis

• Route of Transmission: Respiratory or direct contact

• Symptoms: Sore throat, fever, rash, swelling of neck; can result in heart or kidney damage.

Enterococcus faecium and faecalis

• Disease: UTI, endocarditis, post-operative infections

• Route of Transmission: Normal flora or nosocomial

• Symptoms: Painful urination, burning, difficulty voiding, cloudy urine, fever.

Listeria and Mycoplasma Infections

Listeria monocytogenes

• Disease: Listeriosis (meningitis in neonates, immunocompromised)

• Route of Transmission: Foodborne or in utero

• Symptoms: May be asymptomatic in healthy adults; pregnant women advised against eating unpasteurized dairy.

Mycoplasma pneumoniae

• Disease: Atypical pneumonia

• Route of Transmission: Respiratory

• Symptoms: Walking pneumonia: mild fever, cough, malaise.

Mycobacterium and Corynebacterium Infections

Mycobacterium tuberculosis

• Disease: Tuberculosis

• Route of Transmission: Respiratory droplets

• Symptoms: Weight loss, cough, chest pain, malaise, night sweats.

Corynebacterium diphtheriae

• Disease: Diphtheria

• Symptoms: Sore throat, fever, malaise, swelling of neck; can result in heart or kidney damage.

Sexually Transmitted Bacterial Diseases

Gardnerella vaginalis

• Disease: Vaginitis

• Route of Transmission: Normal flora in most women or sexual partners

• Symptoms: Sensitive to pH changes, foul odor, discharge.

Chlamydia trachomatis

• Disease: Trachoma, nongonococcal urethritis, PID, lymphogranuloma venereum

• Route of Transmission: STD or direct contact

• Symptoms: Leading cause of infertility, blindness (trachoma).

Treponema pallidum

• Disease: Syphilis

• Route of Transmission: Sexually or congenitally

• Symptoms: Primary: painless ulcer; Secondary: rash, flu-like symptoms; Tertiary: neurological, circulatory involvement, gummas.

Borrelia Infections

Borrelia burgdorferi

• Disease: Lyme disease

• Route of Transmission: Hard ticks

• Symptoms: Bull's eye skin lesions, fever, headache, myalgia, joint pain, fatigue, later neurological and cardiac problems.

Summary Table: Selected Bacterial Diseases

Disease	Causative Agent	Transmission	Key Symptoms
Rocky Mountain Spotted Fever	Rickettsia rickettsii	Tick bite	Rash, fever, headache, kidney/heart failure
Whooping Cough	Bordetella pertussis	Respiratory droplets	Severe cough, paroxysms
Cholera	Vibrio cholerae	Contaminated water/food	Watery diarrhea, dehydration
Tuberculosis	Mycobacterium tuberculosis	Respiratory droplets	Weight loss, cough, night sweats
Lyme Disease	Borrelia burgdorferi	Tick bite	Bull's eye rash, fever, joint pain
Syphilis	Treponema pallidum	Sexual/congenital	Ulcer, rash, neurological symptoms

Objectives

• Be familiar with symptoms for the Case Study Exam.

• Identify unique symptoms or characteristics of each disease.

Additional info: Some diseases may present with atypical symptoms or overlap in clinical features. Always consider epidemiological context and laboratory confirmation for diagnosis.