Pharmacology Unit 4 Flashcards
selective toxicity-define
- feature of antibiotic therapy as effects of antimicrobial agents should be exerted on microbe and not host.
- targets biochemical differences between pathogen target and host–>exploitation of these differences
selective toxicity-examples
-inhibition of metabolic pathway in bacteria but not humans–folate metabolism (metabolize intracellularly, mammals take up from environment)
-pathways that exist in both but are different in enzyme structure–protein synthesis (bacterial ribosomes that are 30 and 50S vs. 40 and 60S.
nucleic acid synthesis (DNA gyrase vs topoisomerase)
- macromolecular structure doesn’t exist in humans (cell wall synthesis, peptidoglycan component)
- macromolecular structure differs between humans and microbes (fungal cell membrane-ergosterol)
narrow vs. extended vs. broad antibacterial spectrum: basic definitions of the 3
narrow spectrum–most effective on susceptible organism, less disturbance of host flora. GRAM POSITIVE OR NEGATIVE
broad spectrum–sacrifice efficacy for greater scope of activity for initial empiric coverage, more likely to cause superinfections. GRAM POSITIVE AND NEGATIVE
extended spectrum–effective against gram positive and gram negative
narrow antibacterial examples (gram + or -)
aminoglycosides penicillinase-resistance penicillins clindamycin vancomycin metronidazole penicillin g, v
extended antibacterial examples (gram + and -)
extended-spectrum penicillins
cephalosporins
fluoroquinolones (cip, levo)
carbapenems
broad antibacterial examples (gram + and - and atypical)
macrolides chloramphenicol fluroquinolones (moxi, gemi) sulfonamides tetracyclines trimethoprim
resistance: chromosomal vs. plasmid mediated
mutational (chromosomal) resistance: effect varies, multiple generations must happen to see appreciable resistance. proper dosing prevents survival of slightly resistant strains
plasmid mediated resistance: extrachrosomal pieces of circular DNA, carrying genetic information that can confer resistance. source of multiple drug resistances that can emerge in 1 course of treatment
resistance: mechanisms
natural
natural (intrinsic) resistance: microbes lack susceptible target for drug action
-(fungal cell walls don’t have peptidoglycan and mycoplasma have no walls).
pseudomonas auerginosa is intrinsically resistant to many antibiotics (can’t cross the membrane)
resistance: mechanisms
escape
microbes are sensitive and antibiotic reaches target but organism “escapes” consequences due to availability of purines, thymidine, serine, methionine released from purulent infections (sulfonamide resistance)
failure to lyse due to lack of osmotic pressure difference (penicillin resistance)
importance drainage surgical procedures
resistance: mechanisms
acquired
selective pressure (antibiotic administration) produces generations of organisms with biochemical traits that minimize drug action
mutational
plasmid
resistance: implications for therapy
can be minimized by only using antibiotic when needed, select based on susceptibility tests, use adequate concentration and duration to prevent emergence of first and second step mutants.
classifications of antimicrobial mechanisms of action
altered targets enzymatic destruction alternative resistant metabolic pathway decreased entry increased efflux
bactericidal agents vs bacteriostatic agents definitions
bactericidal: organisms are killed
bacteriostatic: organisms are prevented from growing
bactericidal mechanisms
inhibition of cell wall synthesis
disruption of cell membrane function
interference with dan function/synthesis
bacteriostatic mechanisms
inhibition of protein synthesis (exception is aminoglycosides, -cidal)
inhibition of intermediary metabolic pathways
advantages of bactericidal agents
- preferred in severe infections (assuming sensitive organism, drug distribution, drug safety)
- act more quickly, action is often irreversible (sustained effect after drug is eliminated from blood)
- compensate for patients with impaired host defense (diabetes, etc.)
- required for treatment of infections in locations not accessible to host immune system responses (endocarditic vegetation, CSF)
importance of pharmacokinetic and host factors in selection of antimicrobial therapy
consider pharmacodynamics (antimicrobial activity against specific organism), pharmacokinetic properties (absorption from route of administration), distribution (to site of infection), elimination (hepatic or renal) as related to duration of antimicrobial activity
absorption (oral vs. parenteral vs. topical)
oral: advantage of ease, acceptance, lower cost. can cause GI upset/diarrhea, if NPO.
IV: needed for some drugs/patients has advantage of most rapid/predictable plasma levels (treating life-threatening infections). disadvantage needed with IV are greater training, expense, specific antiseptic conditions
switch to oral whenever and whenever possible
infections can be managed with local application of antibiotic (skin or mucus membranes)
distribution (CNS penetration, fetal exposure, selective accumulation-beneficial vs. harmful)
once antibiotic has been absorbed into systemic circulation must be distributed
CNS: most antibiotics distribute to tissue outside CNS, vary based in ability to cross BBB.
fetus: adverse effects may occur in the fetus that cross placenta. can be given orally, and have ability to cross gastric and placenta
selective-accumulation: certain antibiotics can result in harmful/beneficial response
beneficial: clindamycin into bone, treat osteomyelitis. concentrations of macrolides into pulmonary cells (upper respiratory infections). tetracyclines into gingival crevicular fluid. rapid excretion of nitrofurantoin
selective-increase toxicity: include amino glycoside binding to cells of inner ear, brush border. results increased ototoxicity, nephrotoxicity, tetracyclines-bind to developing bone and teeth to result in abnormal bone growth
elimination
renal: alerts to possibility of renal dosing if necessary in patients with kidney dysfunction. process where dose and frequency are adjusted based on renal function. measure SCr and CrCl
hepatic: possibility of drug-drug interactions or hepatotoxic antibiotics. no lab value to give estimate of liver function
drug classes eliminated by renal excretion
require dosage adjustment if impaired penicillins cephalosporins vancomycin aminoglycosides fluoroquinolones
drug classes eliminated by non renal mechanisms-use your mnemonic!!!
DQ CRIME
Doxycycline: non-regally eliminated tetracycline
(Q)uinolones: ciprofloxacin is really eliminated, but is non-substrate inhibitor of P450 (caffeine-theophylline)
Clindamycin: non-regally eliminated
Rifampin: inducer of P450, potential hepatotoxicity
Isoniazid: genetic polymorphism of n-acetyl transferase metabolism, potential hepatotoxicity
Metronidazole: drug-drug interaction with alcohol due to inhibition of aldehyde metabolism (Antabuse reaction)
Erythromycin-like: drug-drug interactions due to inhibition of P450 (Clar-Ery, not Azi)
Sulfonamides: n-acetylated to a more lipid-soluble metabolite-concern for renal crystalluria
strep pneumoniae
pneumonia, otitis media, sinusitis
cocci-gram +
strep pyogenes
pharyngitis
cocci-gram +
viridans streptococci
endocarditis
cocci-gram +
staph aureus
(MSSA, MRSA)
cutaneous infection, pneumonia, bacteremia, device associated infections
cocci-gram +
enterococcus faecium-faecalis
bacterimia, intraabdominal infections, UTI
cocci-gram +
neisseria gonorrheae
gonorrhea
cocci-gram -
neisseria meningitidis
meningitis
cocci-gram -
ecoli
utis, intra-abdominal infections, lower respiratory infections, bacteremias, traveler’s diarrhea
rods- gram -
pseudomonas aeruginosa
noncosomial infections at any site (UTI, pneumonia)
rods- gram -
clostridium difficile
pseudomembranous colitis
anerobes-gram + rod
clostridium perfringens-botulinim-tetani
anerobes-gram + rod
bacteriodes fragilis
intraabdominal and brain abcess
anerobes-gram - rod
clamydia
trachoma, community acquired pneumonia, urethitis
atypical
mycoplsma pneumoniae
community acquired pneumonia
atypical
side effects: direct toxicity
antibiotic effect on microbes affects host cellular processes (lack of selective toxicity)
- varies with drugs and concentrations
- can be mild/life threatening
- usually involves GI tract, liver, kidney, nervous system, blood and blood forming system
side effects: indirect toxicity
allergic reactions, hypersensitivity salt effects (salt administered with antibiotic not antibiotic) drug-drug interactions, may alter CYP450 drug metabolizing enzymes
side effects: superinfections
disturbances in ecological balance of microbial community
allows for overgrowth of normally suppressed pathogenic organism
pseudomembranous colitis due to clostridium difficile overgrowth
more commonly associated with broad spectrum antibiotics
increased if 50, pulmonary disease, prolonged duration
cell wall synthesis inhibitors: penicillins-prototype
penicilin G
cell wall synthesis inhibitors: penicillins- acid stable
penicillin V
cell wall synthesis inhibitors: penicillins- penicillinase resistant
dicloxacillin
cell wall synthesis inhibitors: penicillins- extended spectrum
amoxicillin +/- clavulanate
ampicillin +/- sulbactam
cell wall synthesis inhibitors: penicillins- anti-pseudomonal
peperacillin-tazobactam
cell wall synthesis inhibitors: penicillins- beta-lactamase inhibitor
clavulanic acid
tazobactam
cell wall synthesis inhibitors: cephalosporins- 1st
cefazolin
cephalexin
cell wall synthesis inhibitors: cephalosporins-2nd
cefuroxime
cell wall synthesis inhibitors: cephalosporins- 3rd
cefriaxone
ceftazidime
cell wall synthesis inhibitors: cephalosporins- 4th
cefepime
cell wall synthesis inhibitors: cephalosporins- 5th
ceftaroline
cell wall synthesis inhibitors: cephalosporins- carbapenems
ertrapenem imipenem-cilastin meropenem doripenem VANCOMYCIN
protein synthesis inhibitors- macrolydes
erythromycin
clarithromycin
azithromycin
protein synthesis inhibitors-tetracyclines
tetracycline
doxycycline
protein synthesis inhibitors-others
clindamycin
chloramphenicol
protein synthesis inhibitors-aminoglycosides
know characteristics of class-not individual agents
inhibitors of DNA function- fluoroquinolones
ciprofloxacin
levofloxacin
moxifloxacin
inhibitors of DNA function-other
nitrofurantoin
metronidazole
trimethoprim-sulfamethoxazole
Bacteria develop resistance to tetracyclines by which primary mechanism?
Altered ribosomal target Bypass pathway in folic acid metabolism Enzymatic inactivation Increased drug efflux Mutations of DNA gyrase
Increased drug efflux == MDR gene
Which of the following is the primary mechanism of β-lactam antibiotic resistance with Streptococcus pneumoniae?
Modification of drug target
Decreased intracellular drug levels due to changes in permeability
Decreased intracellular drug levels due to an efflux pump
Enzymatic inactivation of drug
Modification of drug target
Which of the following antibiotics are considered to exert bactericidal actions against most organisms in their spectrum at readily attained clinical levels?
Tobramycin - AG Vancomycin - GP Ceftriaxone 3rd C Clindamycin Azithromycin - MAC Levofloxacin - urFQ
Tobramycin - AG
Vancomycin - GP
Ceftriaxone 3rd C
Levofloxacin - urFQ
All of the following influence the penetration and concentration of an antibacterial agent in the cerebrospinal fluid EXCEPT:
Lipid solubility of the drug
Minimum inhibitory concentration of the drug
Protein binding of the drug
Molecular weight of the drug
Minimum inhibitory concentration of the drug
A 58-year-old male with a history of hepatitis C, cirrhosis, and ascites presents with spontaneous bacterial peritonitis. Which of the following antibiotics may require close monitoring and possible dosage adjustment in this patient given his liver disease?
Penicillin G - nPCN Tobramycin - AG Metronidazole Clindamycin Levofloxacin - urFQ Cephalexin - 1st C
Metronidazole
Clindamycin
Which drug increases the hepatic metabolism of other drugs?
Azithromycin - MAC Erythromycin - MAC Ketoconazole - AF Tobramycin - AG Rifampin - TB Metronidazole
Rifampin - TB
The persistent suppression of bacterial growth that may occur after limited exposure to some antibacterial drugs is called:
Clinical synergy Concentration-dependent killing Post antibiotic effect Sequential blockade Time-dependent killing
Post antibiotic effect
Which of the following antibiotics exhibits concentration-dependent killing?
Tobramycin - AG Vancomycin - GP Ceftriaxone 3rd C Clindamycin Azithromycin - MAC Levofloxacin - urFQ
Tobramycin - AG
Levofloxacin - urFQ
Which of the following agents is considered a narrow-spectrum agent?
Ceftriaxone - 3rd C Levofloxacin - urFQ Amoxicillin - ePCN Tobramycin - AG Doripenem - CARB Penicillin V - nPCN
Tobramycin - AG
Penicillin V - nPCN
Antimicrobial prophylaxis has been used in which of the following clinical situations?
Tuberculin skin test converters
Recurrent urinary tract infections
Recurrent genital herpes simplex infections
Gastrointestinal surgical procedures
Healthcare workers exposed to blood after needlestick injury
Dental patients with artificial heart valves undergoing extractions
Tuberculin skin test converters
Recurrent urinary tract infections
Recurrent genital herpes simplex infections
Gastrointestinal surgical procedures
Healthcare workers exposed to blood after needlestick injury
Dental patients with artificial heart valves undergoing extractions
Antibiotics are commonly administered before surgical procedures. Which of the following statements best describes an appropriate use for perioperative antimicrobial prophylaxis?
Begin antibiotic prophylaxis at least 24 hours before surgery
Include an antifungal in the regimen
Select the broadest spectrum antibiotic for complete coverage
Use antibiotic combinations as opposed to monotherapy
Administer the antibiotic just prior to the procedure
Administer the antibiotic just prior to the procedure
When using combination antibiotic therapy, it is important to administer drugs that work synergistically if possible. Which of the following represents a combination with known synergism?
A penicillin and a cephalosporin
Two drugs that work on the same step
Two drugs in which the second drug will displace the first from plasma protein-binding sites
A beta-lactam and an aminoglycoside
Two drugs that are eliminated by different routes
A sulfonamide with a dihydrofolate reductase inhibitor
A beta-lactam and an aminoglycoside
A sulfonamide with a dihydrofolate reductase inhibitor
A 24-year-old pregnant woman presents to the urgent care clinic with fever, urinary frequency and urgency. She is diagnosed with a urinary tract infection (UTI). Based on potential harm to the fetus, which of the following medications should be avoided in treating her UTI?
Nitrofurantoin Amoxicillin - ePCN Cephalexin - 1st C Gentamicin - AG Trimethoprim-sulfamethoxazole
Gentamicin - AG
Trimethoprim-sulfamethoxazole
Which of the following antibiotics is considered safe to use in neonates?
Chloramphenicol Sulfamethoxazole-Trimethoprim Doxycycline TCN Ampicillin - ePCN Ceftriaxone - 3rd C
Ampicillin - ePCN
Ceftriaxone - 3rd C
In a patient suffering from pseudomembranous colitis due to C. difficile with established hypersensitivity to metronidazole, the drug most likely to be of clinical value is:
Ampicillin - ePCN Clindamycin Doxycycline - TCN Levofloxacin - urFQ Vancomycin
Vancomycin
The primary mechanism of antibacterial action of the penicillins involves inhibition of:
Beta-lactamases Cell membrane synthesis N-acetylmuramic acid synthesis Reactions involving transpeptidation Porin insertion into membranes
Reactions involving transpeptidation
Methicillin-resistant Staphylococcus aureus is a common nosocomial pathogen that is increasing in frequency in community settings. Which of the following best describes the most common mechanism of resistance to methicillin by S. aureus?
Increased synthesis of metabolic factors Reduced permeability to beta-lactams Acquisition of the novel protein PBP2a Increased cell wall repair Increased efflux of beta-lactams
Acquisition of the novel protein PBP2a
Select the FALSE statement concerning use of ampicillin:
Antibacterial activity is enhanced by sulbactam
Causes maculopapular rashes
Drug of choice for Listeria monocytogenes infections
Eradicates most strains of methicillin-resistant Staphylococcus aureus
May cause pseudomembranous colitis with extended use
Eradicates most strains of methicillin-resistant Staphylococcus aureus
A 23-year-old male presents with acute appendicitis that ruptures shortly after admission. He is taken the OR for surgery, and post surgical cultures reveal E. coli and Bacteroides fragilis. Which of the following provides adequate empiric coverage of these two pathogens?
Tobramycin - AG Vancomycin Ceftriaxone - 3rd C Piperacillin-tazobactam - apPCN Clindamycin
Piperacillin-tazobactam - apPCN
Select the FALSE statement concerning penicillin G:
It is eliminated from the body primarily by renal excretion.
It has reliable antimicrobial activity against most gram positive cocci.
It is less reliably absorbed following oral administration than penicillin VK.
It is effective in treating infections caused by penicillinase-producing organisms.
It is more effective in killing rapidly growing bacteria than bacteria in the stationary phase.
It is effective in treating infections caused by penicillinase-producing organisms.
A 20-year-old female presents to the emergency department with headache, stiff neck, and fever of 2 days duration and is diagnosed with bacterial meningitis. Which of the following agents is the best choice for treatment of meningitis?
Acyclovir Piperacillin-tazobactam - apPCN Ceftriaxone - 3rd C Cefotaxime - 3rd C Tobramycin - AG Cefazolin - 1st C
Ceftriaxone - 3rd C
Cefotaxime - 3rd C
A 21-year-old man was seen in a clinic with a complaint of dysuria and urethral discharge of yellow pus. Gram stain of the urethral exudate showed gram-negative diplococci. The most appropriate treatment of gonorrhea in this patient is:
Amoxicillin (ePCN) orally for 7 days
Ceftriaxone (3rd C) intramuscularly as a single dose
Tetracycline (TCN) orally for 7 days
Benzathine penicillin G (nPCN) as a single intramuscular dose
Vancomycin intramuscularly as a single dose
Ceftriaxone (3rd C) intramuscularly as a single dose
A major distinction between 1st and 3rd generation cephalosporins is:
3rd generation agents have less activity against Pseudomonas
3rd generation agents have increased activity against chlamydia
1st generation agents have increased penetration into the CNS
3rd generation agents have increased activity against resistant gram-negative organisms
1st generation agents have greater activity against methicillin-resistant Staphylococcus aureus
3rd generation agents have increased activity against resistant gram-negative organisms
A 45-year-old male presented to the hospital ED with severe cellulitis and a large abscess on his left leg. Incision and drainage were performed on the abscess, and cultures revealed methicillin-resistant Staphylococcus aureus. Which of the following antibiotics would be appropriate for this infection?
Ceftaroline - 5th C Piperacillin-tazobactam - apPCN Vancomycin Ceftriaxone - 3rd C Doxycycline - TCN Clindamycin
Ceftaroline - 5th C
Vancomycin
Doxycycline - TCN
Clindamycin
Amoxicillin (ePCN) shares all of the following properties with cephalexin (1st C ) EXCEPT:
Inhibition of cell wall synthesis Bactericidal action Elimination primarily by the kidneys Beta-lactam ring in structure High susceptibility to bacterial beta-lactamases
High susceptibility to bacterial beta-lactamases
Select the FALSE statement concerning inhibitors of cell wall synthesis:
Second generation cephalosporins have good-to-excellent activity against anaerobic organisms.
The concentration of penicillin G in the CSF is higher when administered to patients with meningococcal meningitis than it is when given to normal, uninfected patients.
First generation cephalosporins have greater activity against Pseudomonal infections than third generation cephalosporins.
First generation cephalosporins (e.g., cefazolin) should not be given to patients with a Type I anaphylactic reaction to amoxicillin.
First generation cephalosporins have greater activity against Pseudomonal infections than third generation cephalosporins.
Which of the following adverse reactions is associated with vancomycin?
Teratogenic effects Red man syndrome Ototoxicity QT prolongation Severe GI upset Nephrotoxicity
Red man syndrome
Ototoxicity
Nephrotoxicity
Vancomycin:
Is bacteriostatic Binds to penicillin-binding proteins Is active against MRSA Has advantage of oral bioavailability Requires dosage reduction in renal impairment Is inactivated by beta-lactamases
Is active against MRSA
Requires dosage reduction in renal impairment
Select the FALSE statement concerning the bio-disposition of beta-lactam antibiotics:
1st generation cephalosporins cause the blood-brain barrier poorly even when the meninges are inflamed
Lability of some penicillins in gastric acid can limit their oral absorption
Ceftriaxone (3rd C) is eliminated by both renal and biliary-fecal excretion
Benzathine penicillin G (nPCN) is used via intramuscular injection
The renal tubular reabsorption of amoxicillin (ePCN) is inhibited by probenecid
The renal tubular reabsorption of amoxicillin (ePCN) is inhibited by probenecid
A 25-year-old male, otherwise healthy, comes to your office with symptoms of nasal congestion, clear rhinorrhea, and headache of 4 days duration. He reports that he was treated with penicillin V for strep throat as a 10 year-old with no adverse responses. Six weeks ago he received a single IM dose of ceftriaxone for a gonococcal infection. Current clinical guidelines suggest that a reasonable initial course of action should be treatment with:
Azithromycin
High dose amoxicillin
Amoxicillin plus clavulanate
Oral 3rd generation cephalosporin (Cefdinir-Omnicef)
Ibuprofen as needed for pain and saline nasal lavage
Ibuprofen as needed for pain and saline nasal lavage
The primary mechanism of resistance of gram-positive organisms to macrolide antibiotics is:
Decreased activity of uptake mechanisms
Decreased permeability of drug through cytoplasmic membrane
Synthesis of drug-inactivating acetyltransferases
Synthesis of esterases that hydrolyze the lactone ring
Methylation of drug binding sites on the 50S ribosomal subunit
Methylation of drug binding sites on the 50S ribosomal subunit
Clarithromycin and erythromycin have very similar spectra of antimicrobial activity. Advantages of clarithromycin include:
Does not inhibit drug metabolizing enzymes
Eradicates mycoplasmal infections in a single dose
Has greater activity against H. pylori
Is active against methicillin-resistant strains of staphylococci
Is active against strains of Streptococci that are resistant to erythromycin
Greater duration of activity
Has greater activity against H. pylori
Greater duration of activity
A 24-year-old woman comes to a clinic with complaints of dry cough, headache, fever, and malaise for 3-4 days. She appears to have some respiratory difficulty and chest examination reveals rales but no other obvious signs of pulmonary involvement. However, extensive patchy infiltrates are seen on chest x-ray film. Gram stain of sputum does not show any bacterial pathogens. Patient has no history of serious medical problems. The patient is taking loratadine for allergies, multivitamins, and iron supplements. She is an avid consumer of coffee and caffeinated beverages. The initial diagnosis is community-acquired pneumonia and a suitable drug choice would be:
Amoxicillin Azithromycin Erythromycin Clindamycin Doxycycline
Azithromycin
Erythromycin
Doxycycline
If the patient with CAP were prescribed erythromycin you should advise her to:
Avoid exposure to sunlight
Avoid taking supplemental iron tablets
Decrease her intake of caffeinated beverages
Have her serum creatinine checked before starting therapy
Temporarily stop the antihistamine
Decrease her intake of caffeinated beverages
Select the TRUE statement regarding the pharmacologic actions of macrolide antibiotics:
Erythromycin use is associated with less GI upset than clarithromycin.
Possess bactericidal action via irreversible inhibition of protein synthesis.
Erythromycin can elevate plasma levels of co-administered drugs metabolized by CYP450.
Erythromycin has a longer half-life and requires less frequent administration than clarithromycin.
Macrolides are more effective than metronidazole against anaerobic infections.
Erythromycin can elevate plasma levels of co-administered drugs metabolized by CYP450.
A 26-year-old woman was treated for gonorrhea at a neighborhood clinic. She was treated with a single IM dose of ceftriaxone and given a prescription for oral doxycycline (100 mg bid x 7d). Two weeks later she returned to the clinic with a mucopurulent cervicitis. On questioning she admitted not having the prescription filled. The best course of action at this point would be to:
Delay drug treatment until the infecting organism is identified
Rewrite the original prescription for oral doxycycline
Treat her in the clinic with a single oral dose of amoxicillin
Treat her in the clinic with a single oral dose of azithromycin
Write a prescription for oral erythromycin for 7 days
Treat her in the clinic with a single oral dose of azithromycin
A 5-year-old kindergarten student presents with headache, fever, and cough of 2 days duration. Sputum is scant and nonpurulent and a Gram stain reveals many white cells but no organisms. Since this patient appears to have atypical (mycoplasmal) pneumonia, you should initiate treatment with:
Azithromycin (Zithromax) Doxycycline Cephalexin (Keflex, a 1st generation cephalosporin) Chloramphenicol Either A or B
Azithromycin (Zithromax)
A 19-year-old woman with recurring sinusitis has been treated with different antibiotics on several occasions. During the course of one such treatment she developed a severe diarrhea and was hospitalized. Sigmoidoscopy revealed colitis and pseudomembranes were confirmed histologically. Which of the following drugs is mostly to have caused this superinfection?
Clindamycin (Cleocin) Clarithromycin (Biaxin) Metronidazole (Flagyl) Penicillin V K Vancomycin
Clindamycin (Cleocin)
Doxycycline is:
Bactericidal
Excreted mainly in the urine
Eliminated rapidly and is dosed 4 times a day
More effective than tetracycline against H. pylori
Recommended therapy for community-acquired pneumonia
Recommended therapy for community-acquired pneumonia
A patient is being discharged from the hospital on a 3-week course of clindamycin. Which of the following potential adverse effects should be discussed with her?
Nephrotoxicity Drug interactions due to enzyme induction C. difficile diarrhea Skin rash Ototoxicity
C. difficile diarrhea
Regarding the mechanism of action of aminoglycosides, the drugs:
Are bacteriostatic
Bind irreversibly to the 30S ribosomal subunit
Cause misreading of the code on the mRNA template
Inhibit peptidyl transferase
Cause breakup of polysomes
Bind irreversibly to the 30S ribosomal subunit
Cause misreading of the code on the mRNA template
Cause breakup of polysomes
An aspirate from a peritoneal abscess grows two organisms. One is Escherichia coli while the other has the following characteristics: Gram-negative bacillus, obligate anaerobe, catalase-positive, and possesses a polysaccharide capsule. From your recommended training in microbiology you recognize this organism is most likely Bacteroides fragilis. From your required training in pharmacology you know that antibiotics with activity against such an anaerobe include all of the following EXCEPT:
Cefoxitin (2nd generation cephalosporin) Clindamycin (Cleocin) Metronidazole (Flagyl) Gentamicin, an aminoglycoside Piperacillin-Tazobactam
Gentamicin, an aminoglycoside
All of the following statements about the clinical uses of the aminoglycosides are accurate EXCEPT:
They are effective in the treatment of Pseudomonal infections
Owing to their polar nature, aminoglycosides are not absorbed after oral administration
MRSA are usually sensitive to aminoglycosides
Antibacterial action is concentration-dependent
Ototoxicity due to aminoglycosides includes vestibular function and is often irreversible
The earliest sign of aminoglycoside-induced nephrotoxicity is an increased blood creatinine
MRSA are usually sensitive to aminoglycosides
A 30-year-old pregnant female has cellulitis caused by MRSA. Which of the following would be the most appropriate option for outpatient therapy?
Amoxicillin-clavulanate Ceftaroline Clindamycin Doxycycline Minocycline Vancomycin
Clindamycin
You notice that an otherwise healthy patient has developed a mild case of oral candidiasis (thrush) while receiving antibiotic treatment for a respiratory infection. Which of these drugs is a broad-spectrum antibacterial agent that would most likely have caused this fungal superinfection?
Penicillin V Dicloxacillin Doxycycline Clindamycin (Cleocin) Clarithromycin
Doxycycline
