Lecture 7: Infection 1&2

Lecture 7: Infection 1&2 REVIEW Body Defenses: · Physical Barriers ↳ skin ↳ mucous membranes · Cellular Barriers ↳ phagocytosis ↳ specific B + T cells ↳ interferons ↳ pro-inflammatory mediators · Fever + Process Barriers ↳ pyrogens WBC ① Neutrofils · up to 70% WBC · first to tissue damage/infection · lifespan up to 1 week · immature neutrofils are band cells ② Lymphocytes · innate and adaptive immunity · includes NK cells, B cells, T cells ③ Monocytes · matures into macrophages (in tissues) ④ Eosinophils · allergy response · releases enzymes + chemical mediators · destroys allergens and parasites ⑤ Basophils · allergy response (after eosinophils) · pro-inflammatory + anticoagulating - Lowered Immunity - Decreased WBC · autoimmune diseases (eg. IBD) ↳ systemic inflammation decreases synthesis and proliferation ↳ depletion due to chronic inflammation requirements · drug therapy ↳ glucocorticoids (systemic administration) ↳ immunosuppressant drugs (eg. biologics) · chronic infection/inflammation ↳ depletion due to chronic requirements (eg. Mono) · immunodeficiencies ↳ inborn errors · blood cancers (lymphomas, leukemias) ↳ destruction of production organs ↳ interference with maturation of normal WBC Causes of Infection · Pathogenicity ↳ organisms ability to evade or overcome body defenses ↳ pathogens: bacteria, viruses, fungi, parasites · Port of Entry · 2 Mechanisms of infection ↳ 1. Strength in numbers ↳ 2. toxin production · Prevention → WASH HANDS!!! Ports of Entry ① direct contact -itis = infection/inflammation ② inhalation -emia = pathogen in blood ③ ingestion · note: nosocomial vs. community acquired Microorganisms · microflora: microorganisms present on in human body ↳ Commensalism vs. mutualism · infectious disease: "pathogens" ↳ parasitism · opportunistic: any microorganism that causes disease if an opportunity arises ↳ eg. intestinal flora ↳ Common in immunocompromised Pathogens: 1. Parasites 2. Fungi 3. Viruses 4. Bacteria Parasites · 3 main groups: protozoa, helminths, arthropods ↳ protozoa eg. malaria mosquito ↳ helminth eg. tapeworm ↳ arthropods eg. lice, ticks, mites, fleas Fungi · eukaryotes · 2 groups: yeast + mold · fastidious - grows in dark, moist environment · severe disease in immunocompromised · disease: superficial or systemic (rarely systemic) ↳ superficial mycoses eg. athletes foot, thrush, ringworm ↳ Systemic eg. lung or GI Viruses · no cell structure → protein coat & nucleic acid only ↳ Retroviruses: RNA only, with reverse transcriptase (eg. HIV) · requires host cell to survive and replicate · more common and more contagious than other pathogens ↳ eg. Covid 19, influenza, common cold, laryngitis · treatment: ↳ symptom management → antivirals ↳ immune system support → IVIG ↳ prevention → immunizations Bacteria · prokaryotes · contain DNA and RNA · colonize areas with biofilms · less contagious than viruses · many secrete toxins · gram - or gram + · treatment: antibiotics Course of Infection · incubation period: pathogen present & replicating, no symptoms, infectious · prodromal stage: mild symptoms such as malaise, mild fever, headache, myalgia · acute stage: maximum amount of pathogen, maximum host response, more specific symptoms · convalescent period: pathogen decreases while host response dominates and host repairs damages · resolution: disease over 1st Step: Where is the illness? ↳ heath history, focused assessment 2nd Step: What is causing the illness? ↳ bacterial vs. viral ↳ CBC & differential, S&S, culture tests 3rd Step: Antibacterial Treatment ↳ empiric vs. focal treatment Botulism Treatment · G+, anaerobic, neurotoxin (Ach block) · treatment: antitoxin HBAT · prevention with preservatives: ↳ sodium = potassium nitrate salt Culture Testing · culture results tell us the clinical classification of bacteria ↳ staining with iodine, removing with alcohol * · Gram negatives: e. coli, Klebsiella, Pseudomonas, Salmonella, Hib, Cholera, Syphillis, Gonorrhea, Nisseria meningitidis * · Gram positives: Staphylococci, Streptococci (Pneumococci), Enterococci, Listeria, C-dif - - - Antibiotic Treatments ① Antibiotic empiric treatment · broad spectrum · based on suspected bacteria · started ASAP, can switch once bacteria known . ADME → BBB? ② Antibiotic focal treatment · focused, narrow spectrum · treatment initiated after results known · no antibiotic if viral Streptococcus Pyogenes (GAS) · commonly pharyngitis · incubation 2-4 days, highly infectious · symptoms: fever, sore throat, headache, malaise ↳ post-strep risk of glomerulonephritis or endocarditis - - · receptor-site alteration = erythromycin · decreased drug uptake = tetracyclines Antimicrobials/Antibiotics/Antiinfectives: ① cell wall synthesis inhibitors * ② protein synthesis inhibitors ③ nucleic acid inhibitors (DNA, RNA) ④ antimetabolites Bacterial Resistance · Pathways of Resistance ↳ mutation, conjugation, transformation, transduction ↳ enzymes - B-lactamase; Amidase (Penicillin) A - Kinase (Aminoglycosides) - Acetyltransferase (Chloramphenicol) · Resistant Pathogens ↳ staphylococcus aureus ↳ enterococci ↳ mycobacterium * + carbapenems Beta-lactam Antibiotics · Penicillins · Cephalosporins · Carbapenems Penicillins · -illin suffix · efficacy: G + and G· narrow-broad spectrum · Penicillins are common allergies · Ist choice treatment for pharyngitis and otitis media Clavulanic Acid & Tazobactam . B-lactamase inhibitors · combined into antibiotic preparations ↳ amoxicillin (co-amoxiclav; Augmentin) ↳ ticarcillin (co-ticardlar; Timentin) ↳ pipercillin/Tazobactam (Pip-Tax, Tazosin) * Beta-lactamase inhibitors are co-administered with beta lactamase antimicrobials to prevent antimicrobial resistance Cephalosporins · cef- prefix · largest antibiotic class · 5 generations ↳ Ist choice for skin infections ↳ higher generations cross BBB (3rd-5th gen) - efficacy for meningitis or encephalitis, MRSA Carbapenems · -penem suffix · potent, not 1st line therapy, IV · drugs: imipenem, meropenem · efficacy: broad spectrum ↳ serious and mixed infections (meningitis, aspiration pneumonia) Bacitracins · drugs: bacitracin ↳ polysporin (bacitracin & Polymyxin B) ↳ bactine (benzalkonium & lidocaine) · efficacy: G+ and G↳ topical, opthalmic, ear preparations · treatments for: conjunctivitis, skin/soft tissue lacerations, prophylactic Glycopeptide Antibiotic: Vancomycin · Ist choice for MRSA · 2nd choice for C. difficile ↳ note: Ist choice for C. diff is Flagyl