MIC 205 1st Edition Lecture 19Outline of Last LectureI. Controlling microbial growth in the bodyII. Drugsa. Antimicrobial actionOutline of Current Lecture III. Administration of Antimicrobial DrugsIV. Side effectsV. Development of resistant organismsVI. Defense mechanismsCurrent Lecture Administration of Antimicrobial Drugs- Intravenous (IV)- direct injection into the blood, lots of drug fast and lasts long- Intramuscular (IM)- direct injection into muscle tissue, lots of drug fast but doesn’t last long- Oral- prescriptions (but some don’t follow instructions) lower level of concentration in the body- EXTERNAL: topical (local)- direct application onto the skin, creams/pasteSafety/Side effects of drugs- Toxicityo Potential damage to organs and systems in body (kidneys, liver, nerves)- Allergieso Typically rare, but penicillin is common- Disruption of normal florao Yeast infections- imbalance of right and wrong bacteria: overgrowth of normal yeastin vagina (vaginitis) or mouth (thrush)o Pseudomembranous colitis- C. diff infection in the colon (spore forming microbe)Development of Resistant Organisms- Bacteria can become resistant in 2 ways:o Spontaneous mutations of chromosomal genesThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.o Acquisition of antibiotic resistance plasmids via transformation, transduction, conjugation- Bacterial resistant mechanismso Production of an enzyme that inactivates or destroys an antibiotic (penicillin and other beta-lactams)o Beta lactam prevents cell wall synthesis (new cell walls) The ability to produce beta-lactamase enzyme is one of the most common resistances in disease causing bacteriao Prevention of drug entry into bacterial cell via changes in membrane proteins (tetracycline)o Alteration of drug’s receptor within the bacterial cell wall or membrane (antimetabolites)o Alteration of the cell’s metabolic chemistryo Expression of multidrug resistance proteins that pump drugs out of the cell before they actMethods for stopping resistance- High concentration of drug for long enough to kill it- Use antimicrobial agents in combination- Limit use of antimicrobials to necessary cases- Develop new variations of existing drugs by adding side chainsPurines and Pyrimidines are in DNA nucleotide synthesisDefense mechanisms (natural—not drugs)- Innate defenses:o Natural “inborn” resistance to most pathogens- Nonspecific defenseso First line: skin, mucous membranes, microbial antagonismo Second line: phagocytosis, inflammation, fever, signaling molecules Nonspecific defenses are “innate” they are present before birth prior to exposure to pathogens- Specific defenseso Third line: lymphocytes, antibodies (specific immune response) Innate Defenses:- Natural resistance - Our bodies don’t provide the correct environment for these pathogensNon Specific Defenses- First line defense:- External anatomical structures that protect the body from the outside environment- Secreted enzymes and chemicals degrade pathogens before they enter- Generalized response (doesn’t target specific pathogens)o Epithelia and dermiso Mucous membranes Epithelium- outer covering of mucous o Tear ducts (lacrimal apparatus) Tears include chemicals and enzymes (lysozyme) with antimicrobial propertieso Microbial antagonism Resident microbes that compete with potential pathogens- Consume resources so other microbes don’t- Change pH of skino Secrete antimicrobial enzymes  Perspiration by sweat glands Sebum secreted from oil glands Sneezing Coughing Tears Scratching Ear wax Urine/other wasteNonspecific- Second line