Microbial Diseases of Organ Systems: Skin, Nervous, Cardiovascular, Respiratory, Digestive, Urinary & Reproductive Systems

Microbial Diseases of the Skin & Wounds

Bacterial Skin & Wound Diseases

These diseases are caused by various bacteria infecting the skin and underlying tissues, leading to a range of symptoms from mild irritation to severe, life-threatening conditions.

• Folliculitis: Infection of hair follicles by Staphylococcus aureus or Staphylococcus epidermidis. Presents as pimples or pustules. May progress to furuncles (boils) or carbuncles (clusters of boils). Treatment: Topical antimicrobials; resistance is a concern.

• Staphylococcal Scalded Skin Syndrome (SSSS): Caused by toxin-producing S. aureus. Characterized by skin blisters, peeling, and fever. Treatment: IV antibiotics.

• Impetigo (Pyoderma): Caused by S. aureus and Streptococcus pyogenes. Red patches, pus-filled vesicles, mainly in children. Treatment: Topical antimicrobials.

• Erysipelas: Streptococcus pyogenes. Spreading infection, red, swollen skin, fever. Treatment: Penicillin.

• Cellulitis: S. pyogenes and S. aureus. Infection of deeper dermis and subcutaneous fat. Treatment: Cephalosporins.

• Necrotizing Fasciitis: "Flesh-eating disease" by S. pyogenes. Rapid tissue destruction, high mortality. Treatment: Surgical removal, antibiotics.

• Acne: Cutibacterium acnes. Blocked follicles, inflammatory lesions. Treatment: Antimicrobials, retinoids, UV light.

• Cat Scratch Disease: Bartonella henselae. Fever, swelling at scratch site. Treatment: Antimicrobials.

• Pseudomonas Infection: Pseudomonas aeruginosa, often in burn patients. Blue-green pigment, tissue necrosis. Treatment: Combination therapy.

• Rocky Mountain Spotted Fever: Rickettsia rickettsii. Rash, fever, tick-borne. Treatment: Antimicrobials.

• Cutaneous Anthrax: Bacillus anthracis. Black, painless ulcer. Treatment: Antimicrobials.

• Gas Gangrene: Clostridium perfringens. Necrotic tissue, gas bubbles, shock. Treatment: Surgical removal, antibiotics.

Viral Skin Diseases

Viruses can cause a variety of skin diseases, often characterized by rashes, vesicles, and systemic symptoms.

• Smallpox: Variola virus. Progressive rash, fever. Treatment: Supportive; eradicated by vaccination.

• Other Poxviruses: Orf, Cowpox, Monkeypox. Spread by direct contact.

• Herpes Simplex Virus Infections: HSV-1 & HSV-2. Painful, itchy lesions, slow healing. Treatment: Antivirals.

• Warts: Human papillomavirus (HPV). Benign epithelial growths. Treatment: Removal, antivirals.

• Chickenpox & Shingles: Varicella-zoster virus. Vesicular rash, fever. Shingles is reactivation in adults. Treatment: Vaccine available.

• Rubella: Rubella virus. Mild rash, congenital defects. Treatment: Vaccine available.

• Measles: Measles virus. Koplik spots, rash, can cause encephalitis. Treatment: Vaccine prevents disease.

• Erythema Infectiosum: Parvovirus B19. "Slapped-cheek" rash.

• Roseola: Human herpesvirus-6. Sudden high fever, rose-colored rash.

Fungal (Mycotic) Skin Diseases

Fungi infect the skin, hair, and nails, causing a range of superficial and deep infections.

• Pityriasis Versicolor: Malassezia furfur. Hypopigmented scaly patches. Diagnosed via UV fluorescence.

• Dermatophytoses: Trichophyton, Microsporum, Epidermophyton floccosum. Tinea pedis (athlete's foot), tinea capitis, tinea corporis. Treatment: Antifungals.

• Chromoblastomycosis: Four species of fungi. Wart-like lesions. Treatment: Surgical removal, antifungals.

• Phaeohyphomycosis: >30 species of soil fungi. Variable presentation.

• Mycetomas: Several soil fungi. Tumor-like lesions. Treatment: Surgical removal, antifungals.

• Sporotrichosis: Sporothrix schenckii. "Rose gardener's disease". Fixed or lymphocutaneous forms. Treatment: Itraconazole, surgery.

Parasitic Skin Diseases

Parasites can invade the skin, causing lesions and intense itching.

• Leishmaniasis: Leishmania spp.. Cutaneous and visceral forms. Treatment: Antiparasitics.

• Scabies: Sarcoptes scabiei. Intense itching, burrows. Treatment: Anti-mite lotions.

Microbial Diseases of the Nervous System & Eyes

Bacterial Diseases

Bacteria can infect the nervous system, leading to meningitis, leprosy, and toxin-mediated diseases.

• Bacterial Meningitis: Neisseria meningitidis, Streptococcus pneumoniae, Haemophilus influenzae, Listeria monocytogenes, Streptococcus agalactiae. Sudden fever, headache, stiff neck. Treatment: IV antibiotics, vaccines available for some agents.

• Hansen's Disease (Leprosy): Mycobacterium leprae. Tuberculoid (localized) and lepromatous (disseminated) forms. Treatment: Long-term multidrug therapy.

• Botulism: Clostridium botulinum. Flaccid paralysis due to neurotoxin. Treatment: Antitoxin, supportive care.

• Tetanus: Clostridium tetani. Spastic paralysis due to tetanospasmin toxin. Treatment: Antitoxin, antibiotics, vaccine available.

Viral Diseases

• Viral Meningitis: Enteroviruses. Milder than bacterial meningitis.

• Poliomyelitis: Poliovirus. Asymptomatic or paralytic forms. Treatment: Vaccine available.

• Rabies: Rabies virus. Fatal encephalitis, hydrophobia. Treatment: Immunoglobulin, vaccine series.

• Arboviral Encephalitis: Mosquito-borne viruses (e.g., West Nile). Mild to severe encephalitis.

• Zika Virus Disease: Zika virus. Congenital microcephaly, mild symptoms in adults.

Fungal Diseases

• Cryptococcal Meningitis: Cryptococcus neoformans. Meningitis in immunocompromised. Treatment: IV antifungals.

Protozoan Diseases

• African Trypanosomiasis: Trypanosoma brucei. Sleeping sickness, CNS invasion. Treatment: Antiparasitics.

• Primary Amebic Meningoencephalopathy: Naegleria fowleri. Rapid, fatal CNS infection.

Prion Diseases

• Variant Creutzfeldt–Jakob Disease (vCJD): Abnormal prion proteins. Memory loss, death within 12 months. Treatment: None; avoid contaminated meat.

Microbial Eye Diseases

• Trachoma: Chlamydia trachomatis. Leading cause of preventable blindness. Treatment: Antibiotics, surgery.

• Sties: Staphylococcus spp.. Infection of eyelid glands.

• Ophthalmia Neonatorum: Neisseria gonorrhoeae, Chlamydia trachomatis. Inflammation in newborns. Treatment: Prophylactic antibiotics at birth.

• Conjunctivitis: Many bacteria. Redness, discharge.

• Keratitis: Various bacteria/viruses. Corneal inflammation, vision loss.

Microbial Diseases of the Cardiovascular & Systemic Systems

Bacterial Diseases

• Bacteremia & Septicemia: Bloodstream infection, often Gram-negative. Fever, chills, shock. Treatment: Prompt antibiotics.

• Endocarditis: Streptococcus, Staphylococcus. Heart valve infection. Treatment: IV antibiotics.

• Brucellosis: Brucella melitensis. Undulating fever, zoonotic. Treatment: Antibiotics.

• Tularemia: Francisella tularensis. Skin lesions, lymphadenopathy. Treatment: Avoid reservoirs, antibiotics.

• Plague: Yersinia pestis. Bubonic (lymph nodes) and pneumonic (lungs) forms. Treatment: Antibiotics, avoid rodents.

• Lyme Disease: Borrelia burgdorferi. Bull's-eye rash, arthritis. Treatment: Early antibiotics.

• Ehrlichiosis & Anaplasmosis: Tick-borne, flu-like symptoms, leukopenia.

Viral Diseases

• Yellow Fever: Yellow fever virus. Jaundice, hemorrhage. Treatment: Vaccine available.

• Infectious Mononucleosis: Epstein-Barr virus. Severe sore throat, fever, lymphadenopathy.

• Cytomegalovirus (CMV) Disease: Cytomegalovirus. Usually asymptomatic, can cause birth defects.

• Dengue Fever & Dengue Hemorrhagic Fever: Dengue virus. Fever, rash, hemorrhage. Treatment: Supportive care.

• African Viral Hemorrhagic Fevers: Ebola, Marburg. High mortality, internal bleeding.

• HIV/AIDS: Human Immunodeficiency Virus. Progressive immune decline, opportunistic infections. Treatment: Antiretrovirals.

Protozoan & Helminthic Systemic Diseases

• Malaria: Plasmodium spp.. Cyclic fever, anemia. Treatment: Antimalarials.

• Toxoplasmosis: Toxoplasma gondii. Usually asymptomatic, can cause birth defects. Treatment: Antiparasitics.

• Chagas' Disease: Trypanosoma cruzi. Swelling, heart failure. Treatment: Antiparasitics.

• Schistosomiasis: Schistosoma spp.. Rash, anemia. Treatment: Antiparasitics.

Microbial Diseases of the Respiratory System

Bacterial Diseases

• Streptococcal Respiratory Diseases: Streptococcus pyogenes. Pharyngitis, scarlet fever, rheumatic fever, glomerulonephritis. Treatment: Penicillin.

• Diphtheria: Corynebacterium diphtheriae. Sore throat, fever, pseudomembrane. Treatment: Antitoxin, antibiotics, vaccine available.

• Rhinosinusitis: Various bacteria. Malaise, headache.

• Otitis Media: Streptococcus pneumoniae. Ear pain, common in children.

• Common Cold: Rhinovirus and others. Sneezing, sore throat.

• Pneumococcal Pneumonia: Streptococcus pneumoniae. Fever, cough, chest pain.

• Primary Atypical (Mycoplasmal) Pneumonia: Mycoplasma pneumoniae. Mild, long-lasting.

• Klebsiella Pneumonia: Klebsiella pneumoniae. Bloody sputum, high mortality.

• Legionnaires' Disease: Legionella pneumophila. Fever, chills, cough.

• Tuberculosis: Mycobacterium tuberculosis. Weight loss, night sweats. Treatment: Long-term antibiotics.

• Pertussis (Whooping Cough): Bordetella pertussis. Paroxysmal cough. Treatment: Vaccine available.

• Inhalational Anthrax: Bacillus anthracis. Severe cough, shock.

Viral Diseases

• Influenza: Influenza virus A & B. Fever, cough, myalgia. Treatment: Vaccine available.

• Coronavirus Respiratory Syndromes: SARS-CoV, MERS-CoV. High fever, shortness of breath.

• Respiratory Syncytial Virus (RSV) Infection: RSV. Bronchiolitis, pneumonia in children.

• Hantavirus Pulmonary Syndrome (HPS): Hantavirus. Fever, muscle aches, respiratory distress.

• Other Viral Respiratory Infections: Cytomegalovirus, Metapneumovirus, Pseudomonas virus.

Fungal Diseases

• Coccidioidomycosis: Coccidioides immitis. Pneumonia-like symptoms. Treatment: Amphotericin B.

• Blastomycosis: Blastomyces dermatitidis. High fever, respiratory symptoms.

• Histoplasmosis: Histoplasma capsulatum. Bloody sputum, skin lesions.

• Pneumocystis Pneumonia (PCP): Pneumocystis jirovecii. Common in AIDS. Treatment: Trimethoprim-sulfamethoxazole.

Microbial Diseases of the Digestive System

Bacterial Diseases

• Dental Caries: Streptococcus mutans. Holes in teeth.

• Gingivitis & Periodontal Disease: Porphyromonas gingivalis. Swollen, bleeding gums.

• Peptic Ulcer Disease: Helicobacter pylori. Abdominal pain. Treatment: Antibiotics, acid inhibitors.

• Bacterial Gastroenteritis: Various bacteria. Diarrhea, vomiting, cramps.

• Shigellosis: Shigella spp.. Severe diarrhea, dysentery.

• Traveler's Diarrhea: Escherichia coli. Watery diarrhea.

• Campylobacter Diarrhea: Campylobacter jejuni. Bloody diarrhea.

• C. diff Diarrhea: Clostridium difficile. Severe diarrhea, pseudomembranous colitis.

• Salmonellosis: Salmonella enterica. Diarrhea, fever.

• Typhoid Fever: Salmonella enterica. High fever, abdominal pain.

• Cholera: Vibrio cholerae. "Rice-water" stool, severe dehydration. Treatment: Rehydration, vaccine available.

• Staphylococcal Food Poisoning: Staphylococcus aureus. Vomiting, diarrhea.

Viral Diseases

• Oral Herpes: HSV-1. Cold sores.

• Mumps: Mumps virus. Parotitis, fever.

• Viral Gastroenteritis: Caliciviruses, Rotavirus. Vomiting, diarrhea.

• Viral Hepatitis (A, B, C, D, E): HAV, HBV, HCV, HDV, HEV. Jaundice, liver damage. Treatment: Antivirals, vaccines for HAV & HBV.

Protozoan Diseases

• Giardiasis: Giardia intestinalis. Chronic diarrhea.

• Cryptosporidiosis: Cryptosporidium spp.. Severe watery diarrhea.

• Amebiasis: Entamoeba histolytica. Asymptomatic or severe colitis, liver abscess.

Helminthic Diseases

• Tapeworm Infestations: Taenia spp.. Abdominal pain, weight loss.

• Pinworm Infestations: Enterobius vermicularis. Perianal itching.

• Anisakiasis: Anisakis simplex. Nausea, vomiting, abdominal pain.

Microbial Diseases of the Urinary & Reproductive Systems

Bacterial Diseases of the Urinary System

• Bacterial Urinary Tract Infections (UTIs): Escherichia coli and others. Frequent, urgent urination, pain.

• Leptospirosis: Leptospira interrogans. Abrupt fever, headache, muscle stiffness. Zoonotic.

• Streptococcal Acute Glomerulonephritis: Group A Streptococcus. Inflammation of glomeruli, hypertension.

Nonvenereal Diseases of the Reproductive System

• Staphylococcal Toxic Shock Syndrome (TSS): S. aureus toxin. Sudden fever, vomiting, shock.

• Bacterial Vaginosis: Various anaerobic bacteria. Thin, white vaginal discharge.

• Vaginal Candidiasis: Candida albicans. Severe itching, thick discharge.

Sexually Transmitted Bacterial Diseases

• Gonorrhea: Neisseria gonorrhoeae. Painful urination, discharge.

• Syphilis: Treponema pallidum. Chancre, rash, tertiary complications.

• Chlamydial Infections: Chlamydia trachomatis. Discharge, pain, can cause PID.

Sexually Transmitted Viral Diseases

• Genital Herpes: HSV-2 (most cases), HSV-1 (some cases). Painful blisters.

• Genital Warts: HPV. Papillomas, risk of cervical cancer.

Sexually Transmitted Protozoan Diseases

• Trichomoniasis: Trichomonas vaginalis. Vaginal discharge, irritation. Treatment: Metronidazole or tinidazole.

Summary Table: Major Microbial Diseases by Organ System

System	Bacterial	Viral	Fungal	Protozoan/Helminthic
Skin & Wounds	Folliculitis, SSSS, Impetigo, Cellulitis, Necrotizing Fasciitis, Cat Scratch Disease, Pseudomonas, Anthrax, Gas Gangrene	Smallpox, HSV, HPV, VZV, Measles, Rubella	Dermatophytoses, Sporotrichosis, Mycetomas	Leishmaniasis, Scabies
Nervous System & Eyes	Meningitis, Leprosy, Botulism, Tetanus	Polio, Rabies, Arboviruses, Zika	Cryptococcal Meningitis	Trypanosomiasis, Naegleria
Cardiovascular & Systemic	Bacteremia, Endocarditis, Brucellosis, Tularemia, Plague, Lyme	Yellow Fever, EBV, CMV, Dengue, HIV/AIDS	—	Malaria, Toxoplasmosis, Chagas, Schistosomiasis
Respiratory	Streptococcal, Diphtheria, Pneumonia, TB, Pertussis, Anthrax	Influenza, SARS/MERS, RSV, Hantavirus	Coccidioidomycosis, Blastomycosis, Histoplasmosis, PCP	—
Digestive	Caries, Gingivitis, Ulcers, Gastroenteritis, Shigellosis, Salmonellosis, Cholera	Oral Herpes, Mumps, Rotavirus, Hepatitis	—	Giardiasis, Cryptosporidiosis, Amebiasis, Tapeworms, Pinworms, Anisakiasis
Urinary & Reproductive	UTIs, Leptospirosis, Glomerulonephritis, TSS, Vaginosis	Genital Herpes, HPV	Candidiasis	Trichomoniasis

Additional info: These notes expand on the original bullet points with definitions, examples, and treatment options, providing a comprehensive overview suitable for exam preparation in a college-level microbiology course.