Intro to antimicrobial therapy Flashcards
What is the normal flora of the oral cavity?
Streptococci viridans, sanguis, mutans, Lactobacilli, Staph (aureus and epidermidis), Corynebacterium sp., Bacteroides sp., Actinomyces sp.
What is the normal flora of the nose?
Staph epidermidis/aureus, Corynebacteria, Neisseria sp., Haemphilus sp, Strep pneumoniae
What is the normal flora of the nasopharynx?
Non-hemolytic streptococci/Alpha-hemolytic streptococci. Strep pneumoniae and pyognenes,
H. influenzae, Neisseria meningitidis
What is the normal flora of the lower respiratory tract?
Usually sterile. The individual becomes infected by the pathogen descending from the nasopharynx
What is the normal flora of the external ear?
Staph epidermidis/aureus and Corynebacterium sp.
What is the normal flora of the GI tract?
Enterobacteriaceae, Enterococci, Bacteroides, Staphylococci, Lactobacilli, Clostridia. usually anaerobic and gram negative
What is the normal flora of the urethra?
Staph epidermidis, Enterococcus faecalis, Alpha-hemolytic streptococci, E coli, Proteus, Corynebaceria sp, Acinetobacter sp, Mycoplasma sp, Candida sp, Mycobacterium smegmatis
What is the noraml vaginal flora?
Corynebacterium sp, Staphylococci, Nonpyogenic streptococci (Group B strep), E coli, Lactobacillus acidophilus, Flavobacterium sp, Clostridium sp, Viridans streptococci,
What is the MIC (minimum inhibitory conc)?
Lowest concentration of antimicrobial that inhibits growth of bacteria.
What is the breakpoint?
The MIC that is used to designate between susceptible and resistant.
What are mechanisms of antibiotic resistance?
Enzymatic inactivation. Antibiotic uptake reduction. Increased antibiotic removal. Alteration of bacterial target sites
Describe how beta-lactamases degrade antibiotics
Bacterial enzymes that split the beta-lactam ring of penicillin, cephalosporins, carbapenems and monobactams. Aminoglycoside, ciprofloxacin and trimethoprim-sulfamethoxazole resistance often all on same plasmid
What patient factors modify drug choice?
For maximal efficacy the antibiotic must be present at the site of infection in a concentration greater than the MIC. Drug penetration may be hampered depending on the site of the infection (soft tissue vs. bone)
What are patient consideration to determine high risk for less common or resistant pathogens?
Medical history, Travel history, Antibiotic use in the last 3-6 months, Residing in a long term care facility
What are the different ways to isolate a bacteria?
Rapid antigen testing. Wound culture and sensitivity. Throat culture. Sputum culture. Blood cultures
What are appropriate measures of drug therapy?
Start empiric antibiotic therapy. Use as narrow a spectrum drug as possible. If patient is very ill or source of infection is unclear choose broader spectrum. When culture and sensitivity results are known change antibiotic if necessary. Consult antibiogram
What should be included in patient education of antibiotic therapy?
Complete full course of therapy. Do not take antibiotics prescribed for another person. Handwashing. Report failure to respond to therapy
What antibiotics are 30S protein synthesis inhibitors?
aminoglycosides (Gentamicin, Tobramycin, Amikacin) and tetracyclines (tetracycline, doxycycline, minocyline)
What antibiotics are 50S protein synthesis inhibitors?
macrolides (erythromycin, clarithromycin, azithromycin), others- chloramphenicol, clindamycin, linezolid, streptogramins
What antibiotics are DNA synthesis inhibitors?
fluoroquinolones (cipro, oflaxacin, norfloxacin, levofloxacin, gatiflocacin, moxifloxacin) and metronidazole
What antibiotic is an RNA synthesis inhibitor?
rifampin
What antibiotic is a mycolic acid synthesis inhibitor?
isoniazid
What antibiotics are folic acid synthesis inhibitors?
sulfonamides, trimethoprim,
What are causative agents and treatment options for native valve endocarditis?
strep viridans/mutans, beta-hemolytic group A. treat w/vanco
What are causative agents and treatment options for IV drug user endocarditis?
s. aureus, enterococcus, gram (-) aerobic bacilli. treat w/vanco
What are causative agents and treatment options for prosthetic valve endocarditis?
strep viridans/mutans, beta-hemolytic group A, s. aureus, enterococcus, gram (-) aerobic bacilli. treat w/ naficillin, oxacillin, cefaxolin, or vanco + rifampin + gentamicin
What are causative agents and treatment options for intraabdominal infections?
e. coli, enterococcus, bacteroides fragilis, gram (-) aerobic bacilli. treat w/ cipro, levo. Clindamycin DOC for bacteriodes fragilis. metronidazole, beta-lactam/beta-lactamase inhibitors
What are causative agents and treatment options for generalized cellulitis?
s. aureus, GABS, pseudomonas. treat w/1st gen cephalosporins (cephalexin), macrolides, dicloxacillin, Penicillin V, or amoxicillin
What are causative agents and treatment options for diabetic ulcers?
staph, GABS, gram (-) aerobic bacilli, anaerobes. treat w/cefazolin, cefuoxime
What are causative agents and treatment options for animal bites?
pasturella multocida. treat w/Augmentin
What are causative agents and treatment options for necrotizing fasciitis?
GABS, C. perfingens. Treat w/ PCN G, cefoxitin, chloramphenicol, clindamycin, or metronidazole
What are causative agents and treatment options for urinary tract infections?
e.coli, gram (-) aerobic bacilli, enterococcus, staph saprophyticus. treat w/ fluoroquinolones, sulfonamides, cephalosporins.
What are causative agents and treatment options for aspiration pneumonia?
anaerobic and aerobic mouth flora. treat w/ clindamycin
What are causative agents and treatment options for lower/hospital acquired respiratory infections?
pseudomonas, gram (-) aerobic bacilli. treat w/ cipro, tobramycin, amikcain, or piperacillin/tazobactam
What are causative agents and treatment options for for respiratory tract infection of HIV patient?
pneumocystis carinii, S. pneumoniae. treat w/ trimethoprim-sulfamethoxazole (bactrim, septra), or pentamadine
What are causative agents and treatment options for upper respiratory tract infections?
s. pneumo, h. flu, m. cat, GAS. Treat w/2nd gen fluoroquinolones, clindamycin, augmentin, cephalosporins, macrolides other than azithromycin, vanco, doxycycline
What are causative agents and treatment options for lower respiratory tract infections?
klebsiella, mycoplasma pneum, chlamydia pneum. treat w/macrolides, 2nd gen fluoroquinolones
What are causative agents and treatment options for meningitis in neonates?
e.coli, enterococcus, GBS, listeria, monocytogenes, bacteriodes fragilis, gram (-) aerobic bacilli. treat w/ampicillin + gentamicin
What are causative agents and treatment options for meningitis in kids 2mos-12yrs?
s. pneumo, n. meningitis, h. flu. treat w/ vanco + cefriaxone or cefotazime
What are causative agents and treatment options for meningitis in adults?
s. pneumo, n. meningitis. treat w/ceftriaxone + vanco. if > 50yr or immunocompromised +ampicillin.
What are prophylaxis measures to prevent bacterial endocariditis in susceptible individuals?
30-60 minutes prior to dental procedures
Amoxicillin 2 grams PO. For PCN allergy, Clindamycin 600 mg, Azithromycin 500 mg, Clarithromycin 500 mg, or vancomycin
What antibiotics frequently cause c.diff?
ampicillin/amoxicillin, cephalosporins, clindamycin, fluoroquinolones
