Exam 4 outline Lecture 26 27 Antimicrobial drugs I and II Antimicrobial Drugs Chemotherapy the use of drugs to treat a disease Antimicrobial drugs interfere with growth of microbes within a host Antibiotic a substance produced by a microbe that in small amounts inhibits another microbe Selective toxicity a drug that kills harmful microbes without damaging the host Action of antimicrobial drugs o Inhibition of cell wall synthesis o Inhibition of protein synthesis o Inhibition of nucleic acid replication and transcription o Injury to membrane o Inhibition of synthesis of essential metabolites Microbes that produce most antibiotics o Actinomycetes Selective toxicity of antibiotics Affect only target organism NOT HUMANS o Affects microbial physiology that is not in humans o May have side effects in high concentration Can cause allergic response because they are foreign substances in our bodies Spectrum of Activity Broad effective against many species Narrow effective against few or single species Source o Discovered as natural products o Modified increase efficacy decrease toxicity to humans Bacterial Vs Bacteriostatic Bactericidal antibiotics kill TARGET organism o Only effective if organism is building new cell wall Bacteriostatic antibiotics o Prevent growth of an organism Cannot kill organism Immune system removes infection First Antibiotic Flemming discovered penicillin 1928 Florey and Chain performed clinical trials of penicillin 1940 Inhibitors of cell wall synthesis Penicillin o Breaks beta lactum ring in membrane Penicillin penicilloic acid Cephalosporins o Effective against gram negatives Polypeptide antibiotics o Bacitracin Against gram positives o Vancomycin last line against resistant S aureus Antimycobacterial antibiotics o INH Isoniazid Inhibits mycolic acid synthesis o Ethambutol Inhibits incorporation of mycolic acid Inhibitors of protein synthesis Broad spectrum Chloramphenicol o Binds 50S subunit Aminoglycosides o Changes shape of 30S o Side effect hearing loss Tetracyclines o Interferes with TRNA attachment Macrolides o Prevents translocation Oxazolidinones o Prevents formation of 70S ribosome Injury to the plasma membrane Polymyxin B Neosporin Inhibitors of Nucleic Acid Synthesis o Inhibits RNA synthesis tuberculosis or DNA gyrase UTI Competitive Inhibitors Inhibit folic acid synthesis Sulfa drugs o Competitive inhibitors block binding site o Non competitive inhibitors alter the binding site Testing Antibiotic Efficacy Kirby Bauer disk diffusion o Test strain sensitivity to multiple antibiotics Size of cleared zones reflects relative sensitivity E test o Determines MIC o Drug must be above MIC in tissue to be effective Broth dilution test Antibiotic Resistance Many mutations can lead to resistance Resistance genes on plasmids or transposons can be transferred between bacteria Can come from misuse of antibiotics o Outdated weakened o Using for inappropriate times common cold o Not completing full prescription o Using someone else s prescription o Using in animal feed Mechanisms of resistance to antibiotics Blocking entry Inactivating enzymes Alteration of target molecule Efflux of antibiotic Antiviral Drugs Nucleoside and Nucleotide Analogs Acyclovir structurally resembles the nucleoside deoxyguanosine Thymidine kinase phosphates nucleosides nucleotides incorporated into DNA Acyclovir altered thymidine kinase false nucleotide blocks DNA synthesis by DNA polymerase Protease inhibitors HIV Attachment inhibitors HIV Uncoating inhibitors influenza Preventing spread of viruses to new cells hepatitis Lecture 28 Microbial diseases of the skin and eye Describe the structure of the skin and mucous membranes and the ways pathogens can invade the skin Skin o anatomy Secretions perspiration and sebum Entry follicles and ducts Dermis subcutaneous layer o Why microbes can t live on the skin Dry salty fatty acids etc Mucous membrane o line body cavities o Attached to ectracellular matrix o Secrete mucus o Some have cilia Staphylococcus o Coagulase o Cause boild toxemias o Infections Folliculitis infection of hair follicles Stye furuncle carbuncle Toxemia Streptococcus o Hemolysins Groups A B C and O Provide examples of normal skin microbiota and state the general locations and ecological roles of its members Normal flora o Gram positive can withstand drying fatty acids low pH high salt o Some yeasts Differentiate Staphylococci from Streptococci and name several skin infections caused by each o Cause impetigo erysipelas o Infections Pyogenes Group A Erysipelas impetigo Streptokinases Hyaluronidase Cellulitis flesh eating List the causative agent mode of transmission and clinical symptoms of Pseudomonas dermatitis otitis externa and acne Pseudomonas Dermatitis Otitis externa swimmer s ear Acne Causative agent Gram negative aerobic rods Mode of transmission Clinical symptoms Swimming pool sauna Inflammation of the skin Painful ear In soap liner adhesive etc Blue green pus List the causative agent mode of transmission and clinical symptoms of these skin infections warts smallpox chickenpox shingles cold sores measles rubella These are all VIRAL infections Shingles o Moves along perepherial nerves to skin o String of red irritated skin Rubella measles o Respiratory route o Macular rash and Koplik s spots o immunodeficiency Define conjunctivitis Inflammation of conjunctiva pink eye List the causative agent mode of transmission and clinical symptoms of these eye infections neonatal gonorrheal ophthalmia inclusion conjunctivitis trachoma and herpetic keratitis neonatal gonorrheal ophthalmia inclusion conjunctivitis o transmitted to newborns eyes during passage through birth canal o At birth swimming pool treated with ointment Trachoma o Leading cause of blindness Severe conjunctivitis nodules scarring of cornea herpetic keratitis o infection of cornea may cause blindness Lecture 29 Microbial diseases of the nervous system Define central nervous system and blood brain barrier Central Nervous system Brain spinal cord meninges dura mater archnoid pia mater cerebrospinal fluid blood brain barrier Blood brain barrier capillaries that prevent the passage of some materials into the CNS Differentiate meningitis from encephalitis Meningitis inflammation of meninges Encephalitis inflammation of the brain Discuss meningitis caused by Haemophilus influenza o Mostly in children o Gram negative aerobic bacteria o Vaccination o Most common in 1985 Neisseria meningitides o Can be in healthy people o
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