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40 Cards in this Set

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What is the sedimentation coefficient of bacteria?
30S + 50S = 70S
What are the 50S inhibitors?
Chloramphenicol marcolides, and clindamycin inhibits transpeptidation. They are bacteriostatic.

Streptogramins (quinupristin-dalfopristin) is bactericidal

Oxazolidinone (linezolid), binds to 23S RNA and 50S, and is bacteriostatic.
What are the 30S inhibitors?
Aminoglycosides is bactericidal (inhibits formation of initiation complex, and causes mRNA misreading), while tetracyclines (blocks aminoacyl-tRNA from binding to the ribosome) is bactiostatic.
What is the secondary use of tetracycline?
Alternative drug for syphilis, respiratory infections, and prophylaxis against chronic bronchitis, leptospirosis, and acne.
Due to Chloramphenicol toxicity, it is seldom use; however, it is useful for?
A backup drug for: salmonella, bacterial meningitis, pneumococcal in beta-lactam sensitive individuals, Rocky Mountain spotted fever when tetracycline side effects are not worth it (young children and pregnant women). Also for anaerobes, such as Bacteroides fragilis.

OTHERWISE, it is a broad-spectrum (usually bacteriostatic, with amazing spectrum of activity that kills clinically more important bacteria), against many gram-positive and gram-negative.
What are the side effects of chloramphenicol?
Myelosuppresion and, gray baby syndrome due to deficiency of UDP-glucuronyl transferase in the newborn liver.

Gray baby syndrome: vomiting, flaccidity, decrease RBCs, gray skin hue, and shock in newborns

Myelosuppresion: dose dependent anemia [reversible] and aplastic anemia [irreversible]
Tetracycline is what type of antimicrobial? And, what does it block?
Broad-spectrum bacteriostatic. It blocks the aminoacyl tRNA from binding to the ribosome.
What is the primary use of tetracycline useful for?
Rickettsia and Brucella, Chlamydia, Mycoplasma pneumoniae.

Or what a young soldier may get when crawling around in the jungle and mingling with prostitutes on leaves: Chlamydai trachomatis, walking pneumonia via Mycoplasma pneumoniae, animal and tick-borne diseases by Brucella and Rickettsia, plus it works well with acne.

Can also be used with other drugs for H. pylori infections. Otherwise, a board spectrum against gram-positive and gram-negative
What are the side effects of tetracycline?
Teeth discoloration and bone deformity in children due to chelation, Fanconi syndrome, photosensitivty, a teratogenic, and superinfection (S. aureus or C. difficile) and candidiasis (disturbance in normal flora).

Fanconi syndrome: aminoaciduria, phosphaturia, acidosis, and glycosuria
What are three macrolides?
Erythromycin, clarithromycin, and azithromycin
What is tigecycyline used for?
It is a tetracycline, with the broad spectrum of action out of the tetracyclines. Its resistance is less common as well.

Has activity against MRSA, VRE, and beta-lactamase-producing gram-negative bacteria, anaerobes, chlamydiae, and mycobacteria.
Macrolides are used to treat?
Upper respiratory infections (Mycoplasma, Legionnaires disease, sinusititis, oititis media, and bronchitis) and "atypical" bacterial pathogens (Mycoplasma, Legionella, and Chlamydia pneumonia) that are associated with community acquired pneumonia, and corynebacteria,

Otherwise, a wide-spectrum with gram positive cocci, and some gram negative.


Some STDs (Neisseria, chlamydia, syphilis in PTs allergic to penicillin), Helicobacteria pylori, and gram-positive cocci in penicillin-allergic PTs
Side effects of macrolides?
GI upset (common cause of noncompliance), acute cholestatic hepatitis, skin rash, eosinophilia, prolonged QT syndrome.
What is clindamycin (belongs to class lincosamide) useful for?
Severe infections caused by anaerobes (Bacteroides fragilis, Clostridium perfringens).

Due to its gram-positive cocci coverage, its a back up for those who are allergic to penicillin and cephalosporin and MRSA. Also recommended for prophylaxis of endocarditis for those who are allergic to penicillin.
What is a side effect if clindamycin?
Pseudomembranous colitis (penicillin family can do so as well), which is treated with metronidazole or vancomycin

Impaired liver function, skin rashes, nausea, diarrhea.
What is linezolid (class oxazolidinones) useful for?
The main indication of linezolid is the treatment of severe infections caused by Gram-positive bacteria that are resistant to other antibiotics: MRSA, PRSP, and VRE.

Also against L. monocytogenes and corynebacteria.
A 2 year old child is brought to the hospital after ingesting pills that a parent had used for bacterial dysentery when traveling outside the US. The child has been vomiting for more than 24 h and has had diarrhea with green stools. He is now lethargic with an ashen color. He has hypothermia, hypotension, and abdominal distention. What drug most likely caused this problem?
Chloramphenicol, which causes dose dependent suppression of erythropoiesis.
The mechanism of antibacterial action of tetracyclines involves?
Inhibits bacterial protein synthesis by binding to aminoacyl-tRNA
A 24 year old woman has primary syphilis. She has a history of penicillin hypersensitivity, so tetracycline will be used to treat the infection. Which statement about the proposed drug treatment of this PT is correct?
For full effectiveness, tetracycline must be taken for 15 days. Azithromycin is a backup drug for penicillin G for treatment of syphilis, as is tetracycline. Ingestion of antacids and foods containing multivalent cations can interfere with absorption of tetracyclines.
Clarithromycin and erythromycin have very similar spectra of antimicrobial activity. The major advantage of clarithromycin is that it?
Is more active against M avium complex, T gondii, and H pylori.

It can be administered less frequently.
A primary mechanism underlying the resistance of gram-positive organisms to macrolide antibiotics is?
Methylation of binding sites on the 50S ribosomal subunit.
A 26 year old woman was treated for gonorrhea at a neighborhood clinic. Since she was allergic to beta-lactams, a single intramuscular injection of spectinomycin was administered, and she was given a prescription for oral doxycycline to be take for 7 days. Two weeks later she returns to the clinic with mucopurulent cervicitis. On questioning, she admits that she did not have the prescription filled because she has no money. The best course of action at this point would be to?
Treat her with a single dose of azithromycin. Oral doxycycline would have eradicated C trachomatis that can cause Cervicitis or urethritis 2 - 3 weeks after treatment of gonorrhea.
A 55 year old PT with a prosthetic heart valve is to undergo a periodontal procedure involving scaling and root planing. Several years ago, the PT had a severe allergic reaction to procaine penicillin G. Regarding prophylaxis against bacterial endocarditis, what is appropriate?
Administer clindamycin orally 1 h before the procedure.
A 24 year old woman comes to the clinic with complains of dry cough, headache, fever, and malaise, which have lasted 3 or 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 expectorated sputum fails to reveal any bacterial pathogens. The PT informs the attending physician that her husband is not sick but that a colleague at work has symptoms similar to those she is experiencing. The PT has no history of serious medical problems. The PT is taking loratadine for allergies, multivitamins, and supplementary iron tablets. She is an avid consumer of coffee and caffeinated beverages. The physician makes an initial diagnosis of community acquired pneumonia.

What drug is most suitable?

If this PT were to be treated with erythromycin, what should she avoid?

The PT should not be given telithromycin because of what?

A 5-d course of treatment for community-acquired pneumonia would be effective in this PT with little risk of drug interactions if the drug prescribed were?
Doxycycline (Is it caused by TYPICAL pathogen, S. pneumoniae, H influenzae, or M catarrhalis, OR by an ATYPICAL pathogen Legionella, Mycoplasma, or C pneumoniae?; therefore, treat with a drug that covers both spectrums instead of using a double-drug therapy)

Decrease her intake of caffeinated beverages (Erythromycin inhibits CYP1A2, which metabolizes methylxanthines.

Hepatotoxicity

Azithromycin has a half-life more than 70 h, allowing for once-daily dosing and does not inhibit CYP450, unlike other macrolides involved in drug metabolism.
In a PT with culture-positive enterococcal bacteremia who has failed to respond to vancomycin because of resistance, the treatment most likely to be effective is?
Linezolid
Doxycycline can be used for?
It can be used for prevention of malaria and treatment of amebiasis.

Has better effect against chronic bronchitis (pneumonococci, H influenzae, M catarrhalis) and better activity in Lyme disease compared to other tetracyclines.
Streptogramins can be used for?
Management of infections caused by multidrug-resistant streptococci
What drug inhibits bacterial protein synthesis, has a narrow spectrum of activity, has been used in the management of abdominal abscess caused by Bacteroides fragilis, and may cause antibiotic associated colitis?
Clindamycin. DOC for B fragilis is metronidazole. Carbapenems, chloramphenicol, clindamycin, and ticarcillin (with clavulanic acid) are alternative drugs.
Why would a surgeon use clindamycin with an aminoglycoside?
When the GI is perforated, gram-negative and anaerobic bugs are released. Aminoglycosides cover the aerobic gram-negative bugs and clindamycin covers the anaerobes.
How do you treat pseudomembrane colitis?
Vancomycin or metronidazole (preferred: cheaper and vancomycin may contribute to vancomycin resistant enterococcus).
What happens with tetracycline during digestion and what benefit does doxycycline have?
Tetracycline chelates cations in milk (milk products), yogurt, aluminum hydroxide, Ca++ and Mg++. When chelated, it will pass through the intestine without being absorbed.

Doxycycline chelates cations poorly, therefore, is better absorbed with food.
What are broad spectrum bacterial protein synthesis inhibitors?
Chloramphenicol and tetracyclines
What are moderate spectrum bacterial protein synthesis inhibitors?
Macrolides and Ketolide
What are narrow spectrum bacterial protein synthesis inhibitors?
Lincosamides, streptogramins, and linezolid
Demeclocycline, similar to tetracycline, is used for?
To treat SIADH since it acts as a competitive antagonists at the V2 receptors. Demeclocycline inhibits renal actions of ADH.
Streptogramins are?
A nasty medication that should only be use as a lost option (e.g., life threatening VRE--vancomycin resistant Enterococcus). They cause pain upon IV, with arthralgia-myalgia syndrome.

Streptogramins (quinupristin-dalfopristin)
Telithromycin is similar to what?
Macrolide, and has the same MOA and similar spectrum antimicrobial activity. Macrolide-resistant strains are susceptible to telithromycin. Prolonged QT interval and hepatic dysfunction are the side effects.
What is streptogramins used for?
Quinupristin-dalfopristin (combination of two streptogramins) are bactericidal and have antibacterial activity for MRSA and VRSA.
What are the SE of the streptogramin, quinupristin-dalfopristin?
Infusion-related arthralgia and myalgia.
Tetracycline clinical use

VACUUM THe BedRoom
Vibriio cholera, Acne, Chlamydia, Ureaplasma Urealyticum, Mycoplasma pneumoniae, Tularemia, H. pylori, Borrelia burgdorferi, Rickettsia