Microbiology and Parasitology Summary

CHAPTER 17 SUMMARY also known as “flesh-eating disease,” leading to tissue destruction. Microbiology and Parasitology 2. Viral Infections: Introduction...

CHAPTER 17 SUMMARY also known as “flesh-eating disease,” leading to tissue destruction. Microbiology and Parasitology 2. Viral Infections: Introduction Herpes Simplex Virus (HSV): Causes cold sores or fever blisters around the mouth (HSV-1) or genital lesions (HSV-2). The Infectious diseases are caused by virus can remain dormant and reactivate under pathogenic microorganisms, including stress or immunosuppression. bacteria, viruses, fungi, and parasites. These Varicella-Zoster Virus (VZV): pathogens can infect different tissues and Causes chickenpox in primary infections and systems of the human body. shingles upon reactivation. The chapter emphasizes the need 3. Fungal Infections: to understand how microorganisms infect different parts of the body and cause disease. Dermatophytosis: A fungal This knowledge is essential for healthcare infection caused by dermatophytes such as professionals in diagnosing, treating, and Trichophyton species, affecting keratinized preventing infections. tissues like the skin, hair, and nails. Common conditions include athlete’s foot (tinea pedis), ringworm (tinea corporis), and jock itch (tinea Infectious Diseases of the Skin cruris). The skin, as the body’s first line of defense, can 4. Parasitic Infections: be breached by pathogens leading to infections. Scabies: Caused by Sarcoptes scabiei, a mite that burrows into the skin causing intense itching and a rash, often in the 1. Bacterial Infections: folds of the skin. Impetigo: A highly contagious skin Cutaneous Leishmaniasis: Caused infection caused primarily by Staphylococcus by the protozoan Leishmania transmitted by aureus or Streptococcus pyogenes. It presents sandfly bites, leading to ulcerated skin lesions. as honey-colored crusts, mainly on the face, arms, and legs. Cellulitis: A deep infection of the Infectious Diseases of the Ears skin and subcutaneous tissues, usually 1. Otitis Externa (Outer Ear Infection): caused by S. aureus or S. pyogenes. It results in redness, swelling, and tenderness, typically Commonly known as “swimmer’s on the legs. ear,” this infection affects the ear canal and is caused by bacteria such as Pseudomonas Folliculitis, Furuncles, and aeruginosa and Staphylococcus aureus. Carbuncles: These are infections of hair follicles and deeper layers of the skin caused by Symptoms include itching, S. aureus. Folliculitis is localized, while redness, and discharge from the ear, along with furuncles (boils) and carbuncles (clusters of pain, especially when the outer ear is touched. boils) represent more severe infections. 2. Otitis Media (Middle Ear Infection): Necrotizing Fasciitis: A severe An infection of the middle ear, infection caused by S. pyogenes or mixed flora, often occurring in children, caused by bacteria such as Streptococcus pneumoniae and Common Cold: Caused by Haemophilus influenzae. rhinoviruses, coronaviruses, or adenoviruses. Symptoms include a runny nose, sore throat, Presents with ear pain, fever, and and cough. fluid accumulation behind the eardrum, which can lead to hearing loss if untreated. Pharyngitis: Inflammation of the throat, caused by Streptococcus pyogenes 3. Otitis Interna (Inner Ear Infection): (strep throat) or viruses. Affects the structures of the inner Sinusitis: Inflammation of the ear, causing dizziness, hearing loss, and sinuses, often caused by bacteria following a tinnitus. It can result from viral infections, like viral infection. those causing the common cold or flu. 2. Lower Respiratory Tract Infections (LRTIs): Infectious Diseases of the Eyes Pneumonia: Inflammation of the 1. Conjunctivitis (Pink Eye): lung tissue caused by bacteria (Streptococcus pneumoniae), viruses (influenza), or fungi. Inflammation of the conjunctiva, Symptoms include fever, cough, and difficulty caused by bacteria (Haemophilus influenzae, breathing. Staphylococcus aureus), viruses (adenoviruses), or allergens. Tuberculosis (TB): Caused by Mycobacterium tuberculosis, a slow-growing Symptoms include redness, bacterium that primarily affects the lungs. TB discharge, itching, and tearing. is a serious public health issue worldwide. 2. Keratitis: Bronchitis: Inflammation of the Inflammation of the cornea caused bronchi, often following a viral infection. by bacteria (e.g., Pseudomonas), viruses Symptoms include coughing and mucus (herpes simplex), fungi, or protozoa (e.g., production. Acanthamoeba). It is a serious infection that 3. Viral Infections: can lead to scarring or blindness if untreated. Influenza (Flu): A viral respiratory 3. Trachoma: infection caused by influenza viruses. It can A chronic infection caused by lead to severe complications such as Chlamydia trachomatis, leading to eyelid pneumonia, especially in the elderly and scarring and in severe cases, blindness. It is a immunocompromised individuals. major cause of blindness in developing COVID-19: Caused by SARS-CoV- countries. 2, this respiratory disease can range from mild symptoms to severe pneumonia and acute respiratory distress syndrome (ARDS). Infectious Diseases of the Respiratory System Respiratory infections can be divided into Infectious Diseases of the Oral Region upper and lower respiratory tract infections. 1. Dental Caries (Tooth Decay): Caused by Streptococcus mutans 1. Upper Respiratory Tract Infections and other acid-producing bacteria that (URTIs): metabolize sugars and destroy tooth enamel and dentin. Infectious Diseases of the Genitourinary 2. Periodontal Diseases: System Gingivitis: Inflammation of the 1. Urinary Tract Infections (UTIs): gums due to plaque buildup, caused by Most commonly caused by bacterial biofilms. Escherichia coli, UTIs affect the bladder Periodontitis: A more severe form, (cystitis) or kidneys (pyelonephritis). affecting the supporting structures of the teeth, Symptoms include frequent leading to tooth loss if untreated. urination, pain during urination, and flank 3. Oral Thrush (Candidiasis): pain in cases of kidney infection. A fungal infection caused by 2. Sexually Transmitted Infections (STIs): Candida albicans, presenting as white patches Gonorrhea: Caused by Neisseria on the oral mucosa, often in gonorrhoeae, leading to urethritis in men and immunocompromised individuals or those on pelvic inflammatory disease (PID) in women. broad-spectrum antibiotics. Chlamydia: Caused by Chlamydia trachomatis, often asymptomatic but can Infectious Diseases of the Gastrointestinal cause PID and infertility in women. Tract Syphilis: Caused by Treponema 1. Gastroenteritis: pallidum, progressing through stages from sores (chancre) to systemic involvement, Inflammation of the stomach and including the nervous system. intestines, caused by viruses (e.g., rotavirus, norovirus), bacteria (e.g., Salmonella, E. coli), Human Papillomavirus (HPV): or parasites (e.g., Giardia lamblia). Causes genital warts and is linked to cervical cancer. Symptoms include diarrhea, vomiting, abdominal pain, and dehydration. 3. Vaginal Infections: 2. Peptic Ulcers: Bacterial Vaginosis: Caused by an imbalance of normal vaginal flora, leading to Caused by Helicobacter pylori, this overgrowth of bacteria like Gardnerella infection leads to ulceration of the stomach vaginalis. lining, resulting in pain, bleeding, and in severe cases, perforation. Yeast Infections: Caused by Candida albicans, leading to itching, 3. Hepatitis: discharge, and irritation. Inflammation of the liver caused by viruses (Hepatitis A, B, C, D, E). Each type has different modes of transmission, ranging Infectious Diseases of the Circulatory from fecal-oral (Hep A, E) to bloodborne (Hep B, System C). 1. Septicemia: A life-threatening condition where bacteria or their toxins enter the bloodstream, leading to systemic inflammation and Vaccination post-exposure can prevent disease potentially septic shock. onset. 2. Endocarditis: Opportunistic Infections Infection of the heart valves or Opportunistic infections occur when the host’s inner lining of the heart, usually caused by immune system is weakened, making them bacteria such as Staphylococcus aureus or vulnerable to infections that typically wouldn’t Streptococcus viridans. It presents with fever, cause disease in healthy individuals. heart murmurs, and embolic phenomena. 3. Lyme Disease: 1. Pneumocystis Pneumonia (PCP): Caused by the spirochete Borrelia A fungal infection caused by burgdorferi, transmitted by the bite of infected Pneumocystis jirovecii, commonly seen in ticks. It initially causes a characteristic patients with HIV/AIDS or those on bullseye rash and can lead to joint, heart, and immunosuppressive therapy. Symptoms nervous system complications if untreated. include cough, fever, and difficulty breathing. 4. Malaria: 2. Candidiasis: A parasitic infection caused by Caused by Candida albicans, Plasmodium species, transmitted by Anopheles leading to infections in various parts of the mosquitoes. It affects red blood cells and the body including the mouth (thrush), throat, and liver, leading to cyclical fevers, chills, and genitals. anemia. 3. Cytomegalovirus (CMV) Infection: A common viral infection in Infectious Diseases of the Central Nervous immunocompromised patients, particularly System (CNS) those with HIV/AIDS or transplant recipients. 1. Meningitis: CMV can affect the eyes (retinitis), gastrointestinal system, and lungs. Inflammation of the meninges caused by bacteria (e.g., Neisseria meningitidis, Streptococcus pneumoniae) or viruses. Symptoms include headache, stiff neck, and photophobia, and it can be fatal if untreated. 2. Encephalitis: Inflammation of the brain, typically viral in origin (e.g., herpes simplex virus, West Nile virus). It leads to altered mental status, seizures, and neurological deficits. 3. Rabies: A viral infection transmitted by the bite of infected animals. Once symptoms appear, the disease is nearly always fatal.