A single-celled or multicellular organism without chlorophyll that
reproduces by spores and lives by absorbing nutrients from organic matter
What are the two most important type of anti-fungals, and what do they target?
Polene and Azole Drugs; target the fungal cell membrane
Which type of fungus causes the most common mucocutaneous fungal infection in oral lesions?
Opportunistic mycoses tend to show up in certain patient populations such as the immunocompromised. What are the important organisms in this group (4)?
Aspergillus, Candida, Cryptococcus, and Phycomycetes
A crystalline steroid alcohol that provides stability to fungal membranes. The chief sterol in most fungal membranes
What are the two important polyene anti-fungals? These are very lipophilic, and have a high affinity for ergosterol. Their mechanism of action is to remove ergosterol from fungal membranes, which causes leakage of cellular contents and death
Nystatin and Amphotericin B
What is the mechanism of action of Nystatin and Amphotericin B (polyene anti-fungals)?
Act like detergents and remove ergosterol from fungal membranes, which causes leakage of cellular contents and death
Which type of polyene anti-fungal is very effective for topical and oral Canaida infections?
Should Nystatin be given intravenously?
Can Amphotericin B be given intravenously?
When is Amphotericin B used?
Only for progressive, potentially life-threatening fungal infections
Why should Amphotericin B only be used in life-threatening situations?
Because it is severely nephrotoxic
Should Amphotericin B be given with penicillin?
No, because of its high nephrotoxicity
Amphotericin B is considered the most toxic IV anti-infective on the market. What can be done to reduce its toxicity upon administration?
Sodium loading with normal saline
Azole drugs block the synthesis of ergosterol by inhibiting what molecule?
Azole anti-fungals are typically well-tolerated. However, what serious adverse effect can be connected with these?
What is the cause of the liver damage that can potentially be associated with Azole anti-fungals?
They inhibit fungal and some human forms of CYP450
Which Azole has the lowest incidence of adverse side effects?
What are the three uses of Fluconazole?
1. Cryptococcal meningitis in AIDS pts
2. Oropharyngeal and esophageal candidiasis
3. Prophylaxis in HIV pts for mucosal candidiasis
Which Azole has a broader spectrum of activity than fluconazole?
What is a major adverse effect of Itraconazole?
Which azole is contraindicated for patients taking cisapride, dofetilide, ergot alkyloids, lovastatin, and simvastatin, because these drugs are metabolized by CYP3A4, an enzyme that this anti-fungal inhibits?
Which azole has activity against Fusarium?
What is a major adverse effect of Voriconazole?
Visual disturbances (blurred vision, altered perception of color)
Is Voriconazole safe for pregnant women?
Which azole has limited use because of a high incidence of side effects?
What is a major side effect of Ketoconazole?
Gynecomastia and menstrual irregularities (can inhibit testosterone and estradiol synthesis)
Which Azole is an excellent drug for oral candidiasis in AIDS patients?
What Azole is used for prophylaxis of invasive Aspergillus and disseminated candidiasis in severly immunocompromised hosts?
Which azole is active against Candida species that are resistant to other azoles?
Which azole is active against Zygomycetes?
What anti-fungal is typically reserved for nail and scalp infections that do not respond to topical therapies?
What anti-fungal is used only in combination with Amphotericin B to treat severe candida or cryptococcal infections (allows Amp B dose to be reduced)?
What is a major side effect of Flucytosine?
Very toxic to bone marrow and kidneys
What class of anti-fungals inhibits 1,3-beta-D-glucan synthase (required for biosynthesis of polysaccharides used in fungal cell wall). This anti-fungal is safe to use in renally-impaired patients.
What anti-fungal is excellent for life-threatening systemic fungal infections in patients that cannot tolerate Ampho B?
Which anti-fungal does not have major effects on CYP450 system or drugs metabolized by it?
Which anti-fungal is widely held to be safe for use in pregnant women suffering from life-threatening fungal infections?
What are obligate intracellular parasites that depend on host cell enzymes for their propagation?
What is the most common mechanism of action of anti-viral drugs?
Inhibiting viral nucleic acid synthesis
Incorporation of what terminates viral DNA or RNA replication?
Antiviral Nucleoside Analogs
Most current antiviral nucleoside analogs have modifications to which part of the molecule?
What herpesvirus drug is a guanosine analog with an acyclic group replacing ribose? This is a prototypical anti-herpes drug
What is a big problem with Acyclovir and why?
Resistance, because viral enzymes mutate and no longer add initial phophate to the drug
What are two alternative therapeutic options to Acyclovir?
Foscarnet and Cidofovir
Is Acyclovir FDA approved for use in pregnant women?
No, but there are no birth defects associated with its use
What medication is effective in near-term women with recurrent genital herpes to prevent spread of virus to newborn?
What drugs are used for acyclovir-resistant HSV or VZV?
Foscarnet and Cidofovir
What is the drug of choice for CMV patients (life and sight-threatening). Can be used prophylactically in transplant patients
Resistance to Granciclovir is associated with persistent infections. What can be used as an alternative treatment?
Toscarnet and Cidotovir
What drug has largely replaced IV and oral Ganciclovir for patients with CMV that is not life or sight threatening?
What drug is administered intravenously to delay progression of CMV retinitis in patients with AIDS, and is also effective against acyclovir-resistent HSV or VZV
What is the causative agent of chicken pox and shingles?
Varicella Zoster Virus (VZV)
What is the live attenuated virus vaccine against chicken pox?
What vaccine is used to prevent shingles?
What patient population is Zostavax indicated for?
People over 60 years of age because they are immunocompetent
What vaccine is contraindicated for immunocompromised patients and people with a history of anaphylactic shock to gelatin, neomycin, or other components of a vaccine?
What is the unique enzyme type encoded by HIV?
Reverse Transcriptase (RT)
What two factors measure the effectiveness of an HIV therapy?
1. Viral RNA load
2. CD4+ T-cell counts
What is the mechanism of action of Nucleoside Reverse Transcriptase Inhibitors (NRTI) (Anti-HIV nucleoside analogs)?
Inhibit RT -- Block transcription of viral RNA genome into DNA
What are the adverse effects of the class of nucleoside reverse transcriptase inhibits (NRTIs), especially of Stavudine and Zidovudine (4)?
1. Potentially fatal lactic acidosis
2. Peripheral lipoatrophy
3. Central fat accumulation
What Anti-HIV Nucleoside Reverse Transcriptase Inhibitor (NRTI) is most highly associated with fatal lactic acidosis?
What type of anti-HIV drugs are metabolized by and inhibitors of P-450 enzymes (CYP3A4), and can therefore interfere with metabolism of other drugs?
HIV Protease Inhibitors
What is one adverse effect of HIV protease inhibitors?
Fat redistribution (e.g., buffalo hump)
What HIV protease inhibitor is good for use with pediatric patients?
What two drugs, given together, are the treatment of choice for treatment-naive patients (patients that have not had HIV for very long)?
Lopinavir + Ritonavir
What two drugs, give together, are the treatment of choice for patients that have had extensive treatment and drug resistant problems with HIV?
Tipranavir + low dose Ritonavir
What is the standard combination therapy for treatmend of HIV-positive patients?
Highly Active Anti-Retroviral Therapy (HAART)
What are the current recommendations for initial therapy in Highly Active Retroviral Therapy (HAART)?
2 NRTIs + Efavirenz (NNRTI) or
2 NRTIs + PI combination (Lopinavir/ Ritonavir)
Prevention of perinatal HIV transmission:
Transmission usually occurs during labor or delivery, and therapy is most effective if taken throughout pregnancy. The current recommendation is AZT + NRTI + PI (or Nevirapine). However, if a woman is not on therapy at onset of pregnancy, what is the current recommendation?
Should wait until 10-12 weeks of gestation to begin therapy, and AZT administration to newborn for 6 weeks
What agents are contraindicated in pregnant women when attempting prevention of perinatal HIV transmission?
Stavudine and Didanosine (fatal lactic acidosis)
What is the mechanism of action of Anti-Influenza Drugs?
Block neuraminidase activity required for release of new virus particles from infected cells
Anti-influenza drugs are effective against symptoms related to infection with which influenza types?
Influenza A and B
What is the most effective method of preventing infection of influenza?
Annual immunization against Influenza A and B
What patient population is Type I (inactivated, administered IM) Influenza Vaccine recommended for?
Children aged 6-59 months
Pregnant women in any trimester
People older than 50
Which Influenza vaccine type should NOT be used in pregnant patients or the immunosuppressed? Indicated for patients 5-49 years of age
Type 2--Live-attenuated, intranasal
Patients that receive the type 2-- live-attenuated, intranasal influenza vaccine should avoid contact with what type of patietns for at least 7 days?
Severly immunocompromised patients
Currently, what are the best options for prophylaxis and early treatment of susceptible H5N1 strains of the Avian Flu?
Oseltamivir and Zanamivir
What antiviral drug blocks viral polymerases (DNA polymerization, RNA polymerization, and RT) by binding to the pyrophosphate site?
What are the clinical uses of Foscarnet (3)?
1. Acyclovir-resist HSV in AIDS patients
2. Acyclovir-resist VZV
3. CMV retinitis in immunosuppresssed patients (alternative to ganciclovir)
Glycoproteins secreted by virally-infected cells
What function do human interferons perform in Anti-hepatitis B and C drugs?
Promote an antiviral state in unaffected cells
What drug is used in combination with interferon alpha for treating chronic hepatitis C virus?
What is a key characteristic of Ribavarin, making it important for women taking it to avoid getting pregnant for at least 6 months after its discontinued use?
Can stay in RBCs for months
What drug is both teratogenic and embryotoxic for pregnant women, and so potent that pregnant women should avoid contact with anyone using it, and women should refrain from becoming pregnant for 6 months after its discontinued use?
What is a key treatment for Human Papilloma Virus (HPV)?
Should Gardasil be used by pregnant women?
Gastroenteritis with fever, V, D, and dehydration
Which type of bacteria have a single cell membrane and a thick peptidoglycan layer?
Which type of bacteria have a thin peptidoglycan layer enclosed within a dual membrane system?
Which type of antibiotics inhibit transpeptidase?
An adverse environment, signal, or condition that the bacterium must overcome in order to live, replicate, and grow in the environment
An organsim that can overcome selective pressure better than most others has a....
A mechanism of bacterial genetic exchange that involves the transfer of "naked" DNA
A mechanism of genetic exchange that involves transfer requiring cell-to-cell contact
A mechanism of genetic exchange that involves transfer mediated by a bacteriophage
Major groups of helminths (3)?
Nematodes (round worms)
What is the underlying principle of antimicrobial therapy? There are three ways to achieve this:
1. Target a process vital and unique to the invading organism
2. Use a toxic drug that can only be activated by the invading organism
3. Selective uptake of a toxic compound by the invading organism
What is the treatment goal with drugs against antimicrobials (in regard to MIC)?
To maintain circulating concentrations of the drug above the MIC, because bugs can recover if dip below the minimum inhibitory concentration
What is the most common adverse effect to antibiotics?
Miscellaneous GI effects
How can antibiotics cause an overgrowth of non-susceptible organisms?
By disturbing the normal flora
True or False:
Antiseptics and Germicides are for external use only
What is the most important class of antibacterial cell wall synthesis inhibitors?
What is the most common adverse effect of beta-lactam antibiotics?
Allergic reactions to the drug
Non-allergic toxicity of note: CNS problems (lethargy, confusion, seizures)
**Allergic reactions most common problem
What is the mechanism of action of beta-lactam antibiotics?
Inhibit cell wall synthesis by convalently binding to enzymes (a.k.a. PBPs) in the bacterial cell membrane that function in the building and remodeling of the bacterial cell wall
Beta-lactam antibiotics are most active against?
True or False:
The beta-lactam ring must be intact for it to be effective
What is the most common mechanism of resistance to beta-lactam antibiotics?
The production of beta-lactamases--microbial enzymes that hydrolyze the beta-lactam ring, rendering the antibiotic ineffective
How are penicillins most commonly excreted?
In urine as unchanged drug
What is the antibiotic of choice for many organisms, especially Gram positive bacteria?
How is the G form of penicillin administered?
Penicillin G is given by injection because of erractic oral absorption
What infection is resistant to beta-lactam penicillins, as well as most other antibiotics, and is a growing problem in hospital settings and in the community at large?
Extended spectrum antibiotics, such as Ampicillin and Amoxicillin, are active against which bacteria?
Gram positive and negative
What are two clinical uses for Amoxicillin?
Acute otitis media/sinusitis
Lower respiratory infections
What broader spectrum penicillin has the best activity against pseudomonas and is often combined with aminoglycoside?
What are the typical absorption qualities of penicillins?
Decreased by food (except Amoxicillin)
Take 1 hr before or 2 hrs after a meal
What is a concern with the excretion method of penicillins?
Have rapid excretion in urine --> Patients with renal insufficiency can have high levels of penicillin build up and cause seizures
Allergic reactions are classified as immediate, accelerated, or delayed. Which is most common with penicillins, and what are some common symptoms seen?
Delayed---days to weeks post exposure
See skin rashes, pruritis, urticaria
What is "ampicillin rash"?
A non-allergic skin rash seen in patients with infectious mononucleosis and lymphatic leukemia
Can also happen with amoxicillin
What are three qualities describing beta-lactamase inhibitors?
Poor antimicrobial effects
Irreversibly inhibit bacterial lactamases
Used only in combination with penicillins
What is one notable use for beta-lactamase inhibitors?
Mixed aerobic and anaerobic infections such as intra-abdominal infections
Cephalosporins are similar to penicillins in what three ways?
Mechanism of action
What first generation cephalosporin has good tissue penetration and is often used for surgical prophylaxis (cardiac, thoracic, vascular, craniotomy, orthopedic, head and neck, C-section, etc.)?
What second generation cephalosporin is widely used for prophylaxis during abdominal surgery due to activity against anaerobes?
Third and Fourth Generation Cephalosporins tend to do what better than the first two generations?
Cross into CSF better
Are cephalosporins safe to give to patients that have previously exprienced anaphylactic shock from penicillin?
Is cross reactivity of most 2nd, 3rd, and 4th generation cephalosporins with penicillins high or low?
Low (2005 study showed it to be below 1%)
What are two toxicities associated with Cephalosporins?
CNS excitation from high doses
Bleeding abnormalities and alcohol intolerance especially associated with NMTT side chain-- inhibits clotting factors
Ceftriaxone (3rd gen used for gonorrheae and meningitis) should not be mixed with IV solutions containing what ion? Why is this contraindicated?
Fatalities in neonates
Contraindicated for all ages
Do not co-admin in same or different infusion lines or sites within 48 hours of each other
Imipenem is metabolized by what renal enzyme?
What can be done to block the metabolism and nephrotoxicity of imipenem?
Co-administer it with Cilistatin
What is the drug of choice for enterobacterial infections (nosocomial pathogens responsible for range of infections: lower resp tract, skin, soft tissue, UTI, ophthalmic, etc.)?
What drug has a low degree of cross allergenicity with other beta-lactam antibiotics due to the beta-lactam ring not being fused to a second ring?
Which drug (and drug class) has a narrow spectrum, and is effective for Gram (-) bacilli only (e.g., Pseudomonas aeruginosa)?
Summary of Beta-lactams (no actual question!)
--High degree of selective toxicity
--Most bacteria will respond to beta-lactams
*resistance most commonly due to inactivation of beta-lactamases
--High incidence of allergic reactions
*cross allergic reactions can occur (~5%)
--Primarily renal excretion
--CNS symptoms occur at high levels
*Carbapenemas most problematic
When are other inhibitors of cell wall synthesis useful (Vancomycin, Bacitracin, Fosfomycin, etc.)?
Useful against Beta-lactamase-producing microbes because do not contain beta-lactam rings
What are the adverse effects of Vancomycin (3)?
Causes tissue necrosis if given IM
Must be given by slow infusion
Nephrotoxic and is excreted from the kidney (must monitor kidney function)
What is the main use for Vancomycin?
*bacterias resistant to safer drugs
What are some notable clinical uses of Vanco?
Sepsis, endocarditis, severe skin and soft tissue infection caused by MRSA
Taken orally for antibiotic-associated colitis (if resistant to metronidazole)
What cell wall synthesis inhibitor is used topically for surface lesions of skin, in wounds, and on mucous membranes?
What cell wall synthesis inhibitor is taken orally and used for urinary tract infections in a single dose; safe for pregnant women?
Most inhibitors of bacterial protein synthesis are considered to be what, with the important exception of Aminoglycosides?
What type of elimination do macroglides engage in?
Do macroglides enter the CSF?
No. They are well distributed throughout the body but do not enter CSF well (even if meninges are inflamed)
What drug has a similar spectrum of activity to pen G and is often used in patients with penicillin allergy?
True or False:
Cross resistance is complete between Erythromycin and other macroslides
What is the best absorbed oral form of Erythromycin?
What is an adverse effect of Erythromycin?
Acute cholestatic hepatitis (fever, jaundice, impaired liver function)--believed to be an allergic reaction
What is a notable clinical use of Erythromycin?
Penicillin allergic patients with staph, strep, or pneumococci infection
What are 4 advantages of Clarithromycin over Erythromycin?
Relatively more potent
Better absorbed, less GI upset
Longer half-life--BID dosing vs QID for erythromycin
What macrolide has a long half-life (~3 days) --> QD dosing; is not metabolized --> does not affect metabolism of other drugs in liver; and has very low plasma levels
What drug is highly effective against anaerobic pathogens, including Bacteroides fragilis, and has excellent penetration into bone.
What is a concern with Clindamycin?
Antibiotic-associated colitis caused by an overgrowth of C. diff --> requires immediate treatment with metronidazole or vancomycin
What is a notable clinical use of Clindamycin?
Severe anaerobic infections (Bacteroides)
What is one of the few antibiotics effective against Salmonella--treats Typhoid fever, and is effective against anaerobes?
Use of Chloramphenicol is limited due to what serious toxicity?
Aplastic anemia due to stem cell damage (RBC, WBC, and platelets)
What antibiotics are primarily used for bacteria resistant to older drugs (MRSA, Vanco-resistant E. Faecium)
What is Streptogramin primarily indicated for?
Infections from vancomycin-resistant strains of E. faecium
What antibiotic is reserved for treatment of infections caused by multiple drug resistant, Gram (+) bacteria?
What antibiotic class form insoluble complexes with cations found in antacids, multivitamins, and dairy products?
Where are tetracyclines distributed, and what are they primarily used for based on this?
High concentrations in skin and saliva;
Used for dermatological and dental
What is the tetracycline of choice for renally impaired patients?
What is an adverse effect of Tetracyclines that makes them contraindicated for pregnant women and children under 8?
Damage developing teeth and bone
When is renal toxicity primarily seen in patients taking Tetracyclines, and what should be done as a preventive measure?
Usually associated with taking expired Tets; advise patients to throw out outdated Tets
Which is the drug of choice among the Tetracyclines?
What are Tetracyclines primarily indicated for?
STDs (gonorrhea, syphilis, chlamydia)
What is a newly developed Tetracycline indicated for complicated skin and intra-abdominal infections; works well for many organisms that are Tet-resistant but also CANNOT be give to pregnant women or children under 8?
What is the mechanism of action of Aminoglycosides?
Which antibiotic type work synergistically with beta-lactam antibiotics--this combination is frequently used to treat severe infections?
True or False:
Aminoglycosides can be mixed in the same injection solution as beta-lactams
False--they chemically inactivate one another
Which class of Aminoglycosides is the most widely used aminoglycoside, is used to treat Gram (-) infections, and if often used synergistically with beta-lactams to treat severe infections (sepsis, pneumonia) resistant to other antibiotics often found in immunocompromised patients?
Which Aminoglycoside is especially active against Pseudomonas aeruginosa?
Which class of antibiotics inhibit DNA gyrase and are highly active against Gram (-) bacteria?
What antibiotic is a 2nd generation fluoroquinolone, has excellent Gram (-) activity, and is the most effective quinolone for P. aeruginosa?
What antibiotic is a generation 4 fluoroquinolone and is effective against anaerobes?
Fluoroquinolones are all orally effective, but have drug interactions with what type of ions?
Di- and tri-valent cations (antacids, multivitamins)
What is the distribution of Fluoroquinolones?
Penetrate well into prostrate and bone
What are the adverse effects of Fluoroquinolones? Who are they contraindicated for?
Adverse effects on cartilage development (permanent in animals, not known in humans)
Contraindicated for pregnancy
Not recommended for children under 18
What is an adverse side effect of Fluoquinolones, seen especially with norfloxacin? And what is the recommendation to counteract this side effect?
Drink copious amounts of water
What are some notable clinical uses of Fluoroquinolones (4)?
Most Gram (-) organisms
Excellent Pseudomonas activity
Soft tissue, bone, joint, intra-abdominal and respiratory infections (except norfloxacin bc of poor absorption from gut)
What is the most common treatment use for Rifamycins?
Mycobacterial diseases, and primarily for treatment of TB
True or False:
Rifamycins are not used alone
True, because resistance develops readily
What antibiotic is effective against anaerobic bacteria (Bacteroides and Clostridium), antibiotic-associated enterocolitis, and is the drug of choice for E. histolytica infections?
When are inhibitors of cell membrane function primarily used, and why (these include Daptomycin, Colistin)?
Last resort drugs bc most are too toxic for routine use
What inhibitor of cell membrane function is effective against Gram (+) organisms that are resistant to other drugs (MRSA, etc), and is used for skin and soft tissue infections?
What is the mechanism of action of "sulfa" drugs?
Compete with para-aminobenzoic acid (PABA) for the enzyme Dihydropteroate synthase
Are sulfa drugs broad or narrow spectrum antibiotics?
True or False:
Most sulfa drugs are highly protein bound in serum (i.e. not active when protein bound) --> can displace other protein-bound drugs and proteins and limits renal elimination of sulfanomides
What is the most serious complication of Sulfonamides?
What are some methods to prevent crystalluria in patients taking Sulfonamides (3)?
High fluid intake
Alkalinization of the urine (to make sulfas more soluble)--use sodium bicarbonate
Using mixtures of sulfa drugs in which each drug dose is lower than what would be taken individually
Sulfonamides are contraindicated in pregnant women because of possible....?
Kernicterus possible in neonates (displacement of bilirubin from albumin)
What is a severe allergic reaction associated with Sulfa drugs?
Stevens-Johnson Syndrome--> (rare, skin and mucous membrane eruptions-->detachment of epidermis-->potentially fatal)
**epidermis sloughs off
What inhibits dihydrofolate reductase?
What is the most common bacterial cause of UTIs, estimated to cause ~80% of cases?
What urinary antiseptic is contraindicated for patients with glucose-6-phosphate dehydrogenase deficiency, because it causes hymolytic anemia and peripheral neuropathy in these patients?
Which antibiotic inhibits pyruvyl transferase (cell wall synthesis enzyme), has a single dose (3 g for adults) cure for uncomplicated UTIs, and is safe for use in pregnant patients?
What is the treatment plan for mycobacterial tuberculosis (very general)?
Long-term treatment with combinations of drugs
What combination of drugs, given for 9 months, can cure most susceptible TB?
Isoniazid (INH) and Rifampin
What is the drug of choice for prophylaxis and treatment of active and latent infections of TB; it inhibits mycolic acid biosynthesis (cell wall)
What is given with Isoniazid (INH) to prevent the neuritis (in adults) and convulsions (in kids) usually associated with its administration?
Pyridoxine (Vit B6)--> INH depletes B6
What is a major adverse effect of Isoniazid?
INH-induced hepatitis--> most frequent major toxicity (1% of pts); can be fatal-->must discontinue use immediately
What is the most widely used drug in combination with Isoniazid or other first line agents for treatment of TB?
What are the adverse effects of Rifampin (3)?
Induces liver P450 enzymes--> inhibits effectiveness of oral contraceptives
Red-orange coloration of urine, tears, body fluids
Hepatoxic--> cholestatic jaundice and hepatitis
What other rifamycins are recommended in place of Rifampin for AIDS pts taking protease inhibitors or NNRTIs (2)?
What drug inhibits cell wall synthesis by blocking arabinosyl transferase? Adverse effects associated with this drug include Retrobulbar neuritis (loss of visual acuity, red-green color blindness-->vision checks recommended periodically) and is therefore contraindicated for children too young to permit assessment of red-green color blindness?
What drug is highly effective in comination with INH and rifampin for short term (6 month) regimens, but has liver toxicity as an adverse effect (1-5% of pts) so much monitor pt liver function with its use?
In combination chemotherapy for TB, what is the initial 'standard' 4 drug regimen?
When are second-line ant-TB drugs used?
Reserved for use following the emergence of resistance to first-line agents
When is the second-line anti-TB drug Streptomycin sulfate used?
When an injectable drug is needed
Is INH used to treat other mycobacterial diseases?
No, only used for TB
What is the drug of choice for Leprosy? What is the dosing regimen? What other drug can be used?
Once a week dosing
What is the most prominent and important use of antibiotic prophylaxis--use of drugs to prevent infections?
When were new guidelines issued for prophylactic use of antibiotics in dentistry to prevent bacterial endocarditis?