Microbiology Final Exam Review PDF

Microbiology Final Exam Review Tuesday, December 10 8AM TR Ch 26, Microbial Diseases Overview Skin, Soft-Tissue, and Bone Infections Respiratory Tract Infections Gastrointestinal Tract Infections Introduction Microbial Diseases: Major contributors to global mortality. Need f...

Microbiology Final Exam Review Tuesday, December 10 8AM TR Ch 26, Microbial Diseases Overview Skin, Soft-Tissue, and Bone Infections Respiratory Tract Infections Gastrointestinal Tract Infections Introduction Microbial Diseases: Major contributors to global mortality. Need for Research: ○ Emergence of new pathogens (e.g., new strains of bacteria and viruses). ○ Increasing drug resistance (e.g., antibiotic-resistant bacteria). ○ Threats of bioterrorism (e.g., use of pathogens as weapons). ○ Rapid identification and prevention to control outbreaks. The Art of Diagnosis Diagnostic Process: ○ Collecting patient history (e.g., recent travel, occupational hazards). ○ Identifying symptoms and potential causative microbes. Challenges: ○ Similar symptoms can complicate diagnosis (e.g., Vibrio cholerae vs. enterotoxigenic E. coli). ○ Accurate history is essential (e.g., travel-related diarrheal diseases). Infections of Skin, Soft-Tissue, and Bone Range and Causes: ○ Infections can range from simple boils to severe necrotizing fasciitis. ○ Caused by bacteria, fungi, and viruses. Staphylococcus aureus: ○ Boils: Common skin infection, often requiring surgical drainage and antibiotics. ○ Toxins: Produces toxic shock syndrome toxin (TSST) and exfoliative toxin. ○ MRSA: Methicillin-resistant Staphylococcus aureus, a major healthcare and community-acquired infection, treated with alternatives like vancomycin. Streptococcus pyogenes: ○ Necrotizing Fasciitis: Requires rapid surgical removal and antibiotics. ○ Cellulitis: Less aggressive, involves localized pain and swelling. ○ Virulence Factors: Includes M protein, superantigen exotoxins, hyaluronidase, and DNase. Viral Diseases Causing Skin Rashes 27  Microbiology Final Exam Review Tuesday, December 10 8AM TR Measles (Paramyxovirus): Causes a maculopapular rash, typically infects through the respiratory tract. German Measles (Togavirus): Primarily affects the skin and lymph nodes. Respiratory Tract Infections Common Diseases and Defenses: ○ Alveolar macrophages and the mucociliary escalator protect the lungs. Key Pathogens: ○ Bordetella pertussis: Causes whooping cough by binding to lung cilia. ○ Streptococcus pneumoniae: Main cause of pneumonia, particularly in the elderly and immunocompromised, prevents phagocytosis with its capsule, and can cause bacteremia and meningitis. ○ Histoplasma: A dimorphic fungus causing histoplasmosis, thrives in damp soil, presents as a mycelial form at 25℃ and as budding yeast at 37℃. Tuberculosis as a Reemerging Disease Mycobacterium tuberculosis: ○ TB: Leading cause of death from a single microbe. ○ Reemergence: Linked to the HIV epidemic, which increases susceptibility to TB. ○ Disease Progression: Primary TB involves granuloma formation, while secondary TB can reactivate, especially in immunocompromised individuals. Miliary TB involves dissemination throughout the body. Viral Diseases of the Lung Common Viruses: ○ Influenza virus (flu), rhinovirus (common cold), SARS (severe acute respiratory syndrome), and respiratory syncytial virus (RSV). RSV: ○ Major cause of pneumonia in infants and young children. ○ Causes localized lung infections, leading to inflammation and excess mucus. Gastrointestinal Tract Infections Prevalence: ○ Diarrheal diseases are a major health issue, especially in developing countries. ○ Mostly caused by viruses (e.g., rotaviruses) and bacteria (e.g., Salmonella enterica, Campylobacter). Types of Diarrhea: ○ Osmotic: Increased osmolarity leads to water retention in the intestine. ○ Secretory: Increased ion secretion due to toxins (e.g., cholera toxin). ○ Inflammatory: Inflammation caused by cytokines attracting immune cells. ○ Motility-related: Pathogen-induced increased intestinal motility. Rehydration Therapy: ○ Essential for treatment, involves water, glucose, and electrolyte balance. 28  Microbiology Final Exam Review Tuesday, December 10 8AM TR Antibiotic Use: ○ Often inappropriate for diarrhea, can disrupt normal intestinal flora and lead to conditions like Clostridioides difficile infections. Pathogenic E. coli Seven Classes: ○ EHEC: Enterohemorrhagic E. coli, causes severe bloody diarrhea. ○ EIEC: Enteroinvasive E. coli. ○ ETEC: Enterotoxigenic E. coli. ○ EPEC: Enteropathogenic E. coli. ○ EAEC: Enteroaggregative E. coli. ○ UPEC: Uropathogenic E. coli. ○ NMEC: Neonatal meningitis-causing E. coli. Shiga Toxin: ○ Produced by Shigella and EHEC, blocks protein synthesis and damages endothelial cells, leading to hemorrhage and bloody diarrhea. Rotavirus and Norovirus Key Points: ○ Rotavirus and norovirus are leading causes of intestinal disease, surpassing bacterial species. Rotavirus Characteristics: ○ Double-stranded RNA virus. ○ Leading cause of gastroenteritis globally. ○ Highly infectious, transmitted via fecal-oral route. ○ Affects all age groups, endemic worldwide. Vaccination: ○ Increasing use of rotavirus vaccine may elevate norovirus as the leading cause of diarrhea. Historical Perspective Gastric ulcers were historically attributed to spicy foods and stress. In the 1980s, J. Robin Warren and Barry Marshall identified Helicobacter pylori as the causative agent of gastric ulcers. Helicobacter pylori 29  Microbiology Final Exam Review Tuesday, December 10 8AM TR Mechanism: ○ Secretes urease: converts urea to CO2 and NH4+, neutralizing stomach acid. ○ Produces collagenase and mucinase, softening the mucous lining to access the stomach epithelium. ○ Burrows into the mucous layer, proliferates, and causes tissue damage. Virulence Factors: ○ Vacuolating toxin (VacA), neutrophil-activating protein (NAP), and CagA. Associated Risks: ○ Linked to gastric cancer. Chapter Summary Diagnosis Importance: ○ Patient histories are crucial for accurate diagnosis. Skin and Soft-Tissue Infections Examples: ○ Boils and Scalded Skin Syndrome: Caused by Staphylococcus aureus. ○ Necrotizing Fasciitis: Caused by Streptococcus pyogenes. ○ Measles (Rubella and Rubeola): Viral infections causing skin rashes. Respiratory Tract Infections Examples: ○ Pneumonia: Caused by various organisms. ○ Tuberculosis: Caused by Mycobacterium tuberculosis. ○ Respiratory Syncytial Virus (RSV): Affects infants and young children. Gastrointestinal Tract Infections Main Causes: ○ Bacteria: EHEC, Salmonella, Shigella, H. pylori. ○ Protozoa: Entamoeba, Cryptosporidium, Giardia. ○ Viruses: Rotavirus (leading cause of gastroenteritis). Urinary Tract Infections (UTIs) Main Cause: ○ Primarily caused by Gram-negative bacteria. ○ Uropathogenic Escherichia coli (UPEC) accounts for 75% of cases. 30