What is a live-attenuated vaccine?

What is a live-attenuated vaccine?Answer: Attenuated vaccine has microbe with selective deletions of genes involved in pathogenesis. Organisms replicate...

Methemoglobinemia occurs when the ferrous (Fe2+) form of iron in hemoglobin is oxidized to the ferric (Fe3+) form and cannot bind O2. What are the clinical manifestations of methemoglobinemia?

Methemoglobinemia occurs when the ferrous (Fe2+) form of iron in hemoglobin is oxidized to the ferric (Fe3+) form and cannot bind O2. What are the clinical...

Which antibiotic is a PABA analog with a side effect profile that includes hemolysis and methemoglobinemia?

Which antibiotic is a PABA analog with a side effect profile that includes hemolysis and methemoglobinemia?Answer: Daps...

Name the three drugs commonly used in the treatment of leprosy:

Name the three drugs commonly used in the treatment of leprosy:1. Dapsone2. Rifampin3. Clofazim...

What are important side effects of INH?

What are important side effects of INH?Answer: Hepatotoxicity (avoid alcohol), peripheral neuropathy (vitamin B6 depletion), sideroblastic anemia...

What is the mechanism of action for INH?

What is the mechanism of action for INH?Answer: Although not proven, it is thought to inhibit mycolic acid synthe...

What are some common side effects of rifampin?

What are some common side effects of rifampin?Answer: Red-orange urine, induces P450 potentially leading to impaired efficacy of other drugs, GI...

Why shouldn't rifampin be used as monotherapy?

Why shouldn't rifampin be used as monotherapy?Answer: Resistance occurs rapidly when used as monotherapy. It can be used alone briefly for N. meningitidis...

What are common indications for rifampin?

What are common indications for rifampin?Answer: Treatment of M. tuberculosis and prophylaxis for N. meningitidis or H. influen...

What is the mechanism of action of rifampin?

What is the mechanism of action of rifampin?Answer: Inhibits DNA-dependent RNA poly-merase by binding to RNA polymerase and blocking elongation of...

What is the mechanism of action of ethambutol and what is its unique side effect?

What is the mechanism of action of ethambutol and what is its unique side effect?Answer: Inhibits arabinosyl transferase, an enzyme necessary to...

Which drugs are commonly used to treat Mycobacterium tuberculosis infection?

Which drugs are commonly used to treat Mycobacterium tuberculosis infection?Answer: Ethambutol, rifampin, isoniazid (INH), and pyrazinam...

What is the drug of choice for treating simple recurrent UTIs?

What is the drug of choice for treating simple recurrent UTIs?Answer: Trimethoprim-sulfamethoxazole (TMP-SMX). Give ciprofloxacin if patient has...

What are important side effects of trimethoprim?

What are important side effects of trimethoprim?Answer: Adverse effects include megaloblastic anemia, leukopenia, and granulocytope-nia. Alleviate...

What is the mechanism of action of trimethoprim?

What is the mechanism of action of trimethoprim?Answer: Inhibits bacterial dihydrofolate reduct...

What are some other side effects of sulfonamides?

What are some other side effects of sulfonamides?Answer: Induce hemolysis in glucose-6-phosphate dehydrogenase (G6PD)-deficient patients, photosensitivity,...

What is the main risk of giving sulfonamides during pregnancy?

What is the main risk of giving sulfonamides during pregnancy?Answer: Sulfonamides can displace bilirubin from plasma albumin-binding sites and induce...

Can bacteria obtain folic acid by diffusion or active transport?

Can bacteria obtain folic acid by diffusion or active transport?Answer: No, bacteria must synthesize folic acid from PA...

Which enzyme in bacterial folate synthesis is inhibited by sulfonamides?

Which enzyme in bacterial folate synthesis is inhibited by sulfonamides?Answer: Dihydropteroate synthet...

Name two antibiotics that inhibit bacterial growth by acting as p-aminobenzoic acid (PABA) analogs:

Name two antibiotics that inhibit bacterial growth by acting as p-aminobenzoic acid (PABA) analogs:1. Sulfonamides2. Daps...

Why are fluoroquinolones contraindicated in pregnant women and in children?

Why are fluoroquinolones contraindicated in pregnant women and in children?Answer: Interfere with cartilage formation. In elderly, associated with...

How does resistance to fluoroquinolones develop?

How does resistance to fluoroquinolones develop?Answer: Resistance develops by point mutations of the DNA gyrase enzy...

What are common indications for fluoroquinolones?

What are common indications for fluoroquinolones?Answer: Urinary tract infections (UTIs), sexually transmitted diseases (STDs) (Chlamydia and N....

What is the mechanism of action of fluoroquinolones (ciprofloxacin, norfloxacin)?

What is the mechanism of action of fluoroquinolones (ciprofloxacin, norfloxacin)?Answer: Inhibit DNA gyrase (topoisomerase II), leading to inhibition...

Which new class of antibiotics that inhibit protein synthesis can also treat VRSA and VRE?

Which new class of antibiotics that inhibit protein synthesis can also treat VRSA and VRE?Answer: Streptogramin class; quinupristin and dalfopristin...

What important infections does linezolid treat?

What important infections does linezolid treat?Answer: Vancomycin-resistant S. aureus (VRSA), methicillin-resistant S. aureus (MRSA), and vancomycin-resistant...

What is the mechanism of action for linezolid?

What is the mechanism of action for linezolid?Answer: Inhibits the formation of the initiation complex in bacterial translat...

What is the major side effect of clindamycin?

What is the major side effect of clindamycin?Answer: Pseudomembranous colitis due to over-growth of Clostridium difficile. Remember, clindamycin...

What is the mechanism of action of clindamycin?

What is the mechanism of action of clindamycin?Answer: Blocks peptide bond formation at the 50S ribosomal subunit. It is bacteriostat...

How do bacteria usually become resistant to macrolides?

How do bacteria usually become resistant to macrolides?Answer: Methyltransferases that alter the drug-binding site on the 50S ribosome and increase...

Why are macrolides used for the treatment of community-acquired pneumonia?

Why are macrolides used for the treatment of community-acquired pneumonia?Answer: They are effective in treatingM. pneumoniae, Chlamydia pneumoniae,...

What is the mechanism of action of macrolide (erythromycin, azithromycin, clarithromycin) antibiotics?

What is the mechanism of action of macrolide (erythromycin, azithromycin, clarithromycin) antibiotics?Answer: They bind to the 50S ribosomal subunit...

What are the two distinct side effects of chloramphenicol on bone marrow?

What are the two distinct side effects of chloramphenicol on bone marrow?1. Dose-dependent bone marrow suppression2. Dose-independent aplastic anemiaIt...

What is the mechanism of action of chloramphenicol? For which conditions is it used?

What is the mechanism of action of chloramphenicol? For which conditions is it used?Answer: It prevents peptide bond formation by binding the 50S...

How do bacteria usually become resistant to tetracyclines?

How do bacteria usually become resistant to tetracyclines?Answer: Increased ability to pump tetracycline out of cell (efflux pum...

What is the risk from taking expired tetracyclines?

What is the risk from taking expired tetracyclines?Answer: May cause a Fanconi-like syndrome (proximal renal tubular dysfuncti...

Do tetracyclines work synergistically with penicillins

Do tetracyclines work synergistically with penicillinsAnswer: Unlike aminoglycosides, tetracyclines theoretically decrease the effect of penicil...

Why should tetracyclines be taken on an empty stomach?

Why should tetracyclines be taken on an empty stomach?Answer: They can be chelated and inactivated by calcium, magnesium, aluminum, iron, and other...

What is unique about doxycycline in comparison with other tetracyclines in regard to the means of elimination?

What is unique about doxycycline in comparison with other tetracyclines in regard to the means of elimination?Answer: Doxycycline is eliminated in...

Which tetracycline can be used in the treatment of SIADH (syndrome of inappropriate antidiuretic hormone)? Why?

Which tetracycline can be used in the treatment of SIADH (syndrome of inappropriate antidiuretic hormone)? Why?Answer: Demeclocycline causes nephrogenic...

Tetracyclines are commonly used to treat which common dermatological condition in teenagers?

Tetracyclines are commonly used to treat which common dermatological condition in teenagers?Answer: Acne vulga...

What are some important side effects of tetracyclines?

What are some important side effects of tetracyclines?Answer: Photosensitivity, staining of teeth (avoid in children), liver dysfunction in pregnant...

What species of bacteria are generally susceptible to tetracyclines?

What species of bacteria are generally susceptible to tetracyclines?Answer: Chlamydia, Mycoplasma, Rickettsia, Borrelia burgdorferi, E. coli, Neisseria...

How do bacteria usually become resistant to aminoglycosides?

How do bacteria usually become resistant to aminoglycosides?Answer: Enzymatically inactivate aminoglycosides by conjugation (most important mechanism...

What are the common side effects of aminoglycosides?

What are the common side effects of aminoglycosides?Answer: Nephrotoxicity (6%-7%), ototoxicity (2%; more common with loop diuretics), birth defects...

Which aminoglycoside is often given orally before GI surgery because it is poorly absorbed and prevents organisms from reaching the peritoneal cavity?

Which aminoglycoside is often given orally before GI surgery because it is poorly absorbed and prevents organisms from reaching the peritoneal cavity?Answer: Neomycin....

What is the benefit and mechanism of giving β-lactam antibiotics with aminoglycosides?

What is the benefit and mechanism of giving β-lactam antibiotics with aminoglycosides?Answer: β-Lactam antibiotics facilitate the entry of aminoglycosides...

Why are aminoglycosides ineffective against anaerobic bacteria?

Why are aminoglycosides ineffective against anaerobic bacteria?Answer: They require oxygen for uptake into the bacteri...

What is the mechanism of action of aminoglycosides?

What is the mechanism of action of aminoglycosides?Answer: They inhibit the formation of ribosomal initiation complex and cause misreading of the...

Which antibiotics target the 30S and 50S ribosomal subunits respectively?

Which antibiotics target the 30S and 50S ribosomal subunits respectively?Answer: 30S: aminoglycosides (neomycin, amikacin, tobramycin, gentamicin)...

What is the mechanism of action of fosfomycin which is used for UTIs?

What is the mechanism of action of fosfomycin which is used for UTIs?Answer: Inhibits enolpyruvate transferase, preventing the formation of N-acetylmuramic...

Cycloserine is a second-line agent for tuberculosis. What is the mechanism of action of cycloserine? What are its side effects?

Cycloserine is a second-line agent for tuberculosis. What is the mechanism of action of cycloserine? What are its side effects?Answer: Analog of...

What is the mechanism of action of bacitracin? What preparation is used clinically?

What is the mechanism of action of bacitracin? What preparation is used clinically?Answer: Prevents dephosphorylation and thus regeneration of a...

How do certain gram-positive bacteria become resistant to vancomycin?

How do certain gram-positive bacteria become resistant to vancomycin?Answer: By mutation of the terminal D-alanine-D-alanine sequence in bacterial...

Which drug is the treatment of choice for methicillin-resistant S. aureus (MRSA) and what are its major side effects?

Which drug is the treatment of choice for methicillin-resistant S. aureus (MRSA) and what are its major side effects?Answer: Vancomycin. Nephrotoxicity,...

How do bacteria become resistant to β-lactam drugs?

How do bacteria become resistant to β-lactam drugs?Answer: Production of β-lactamases, mutations in transpeptidases (penicillin-binding proteins),...

What are the advantages of meropenem over imipenem?

What are the advantages of meropenem over imipenem?Answer: Meropenem does not need to be administered with cilastatin and causes fewer seizur...

What is the chief concern of having high plasma levels of imipenem?

What is the chief concern of having high plasma levels of imipenem?Answer: Central nervous system (CNS) toxicity/seizu...

Why is imipenem, which has the broadest coverage of all the β-lactam drugs, always given with cilastatin?

Why is imipenem, which has the broadest coverage of all the β-lactam drugs, always given with cilastatin?Answer: Cilastatin is a dehydropeptidase...

What are the only types of bacteria susceptible to aztreonam?

What are the only types of bacteria susceptible to aztreonam?Answer: Aerobic gram-negative bacte...

Which β-lactam antibiotic is safe for the treatment of gram-negative organisms such as Pseudomonas in patients with penicillin allergies?

Which β-lactam antibiotic is safe for the treatment of gram-negative organisms such as Pseudomonas in patients with penicillin allergies?Answer: Aztreonam...

Why are penicillins and cephalosporins ineffective against Mycoplasma pneumoniae?

Why are penicillins and cephalosporins ineffective against Mycoplasma pneumoniae?Answer: Mycoplasma does not have cell wal...

Which cephalosporins are commonly used as prophylaxis for gastrointestinal (GI) surgery? Why?

Which cephalosporins are commonly used as prophylaxis for gastrointestinal (GI) surgery? Why?Answer: Cefoxitin and cefotetan because they have activity...

Which cephalosporin antibiotics are often used for the treatment of community-acquired meningitis? Why?

Which cephalosporin antibiotics are often used for the treatment of community-acquired meningitis? Why?Answer: Ceftriaxone and cefotaxime because...

Which cephalosporin antibiotics have the best coverage against P. aeruginosa?

Which cephalosporin antibiotics have the best coverage against P. aeruginosa?Answer: Cefepime (fourth generation) and ceftazidime (third generat...

What are the potential problems with cephalosporins that contain N-methyl-thiotetrazole side chains?

What are the potential problems with cephalosporins that contain N-methyl-thiotetrazole side chains?Answer: Disulfiram-like reaction causing hypotension,...

What is the standard treatment of meningitis caused by L. monocytogenes?

What is the standard treatment of meningitis caused by L. monocytogenes?Answer: Ampicillin and gentami...

Ampicillin or amoxicillin can be used to treat which organisms?

Ampicillin or amoxicillin can be used to treat which organisms?Answer: Haemophilus influenzae, Escherichia coli, Listeria monocytogenes, Proteus...

Do β-lactamase inhibitors such as clavulanic acid or tazobactam improve activity of β-lactams against β-lactam-resistant P. aeruginosa?

Do β-lactamase inhibitors such as clavulanic acid or tazobactam improve activity of β-lactams against β-lactam-resistant P. aeruginosa?Answer: No,...

Which penicillin class can be used to treat Pseudomonas aeruginosa?

Which penicillin class can be used to treat Pseudomonas aeruginosa?Answer: Carbenicillin and ticarcillin (the carboxypenicillins) and piperacillin,...

What is the Jarisch-Herxheimer phenomenon?

What is the Jarisch-Herxheimer phenomenon?Answer: Acute worsening of symptoms (fever, headache, muscle pains) soon after penicillin G treatment due...

Which penicillins are the semisynthetic (anti-Staph) penicillins that are potentially more resistant to β-lactamases?

Which penicillins are the semisynthetic (anti-Staph) penicillins that are potentially more resistant to β-lactamases?Answer: Methicillin, nafcillin,...

How does probenecid increase the half-life of penicillin G?

How does probenecid increase the half-life of penicillin G?Answer: It blocks active renal secretion of penicill...

Which bacteria are potentially susceptible to penicillin G?

Which bacteria are potentially susceptible to penicillin G?Gram positives (with exceptions such as Staphylococcus aureus), Neisseria, spiro-chetes, and...

What is the difference between penicillins G and V? What is the most common adverse effect of penicillin?

What is the difference between penicillins G and V? What is the most common adverse effect of penicillin?Answer: Penicillin G is given intravenously...

What is the mechanism of action of all β-lactam antibiotics?

What is the mechanism of action of all β-lactam antibiotics?Answer: They bind to and inactivate transpep-tidases (sometimes known as penicillin-binding...

Name the major categories of β-lactam antibiotics:

Name the major categories of β-lactam antibiotics:Answer: Penicillins, cephalosporins, monobactams, and carbapen...

What are the two specific tests (to detect disease-specific antibodies) for syphilis?

What are the two specific tests (to detect disease-specific antibodies) for syphilis?1. FTA-ABS (fluorescent treponemal antibody-absorbed test)2. MHA-TP...

What disease states may cause a false-positive result with a nonspecific syphilis test?

What disease states may cause a false-positive result with a nonspecific syphilis test?Answer: Hepatitis B, infectious mononucleosis, leprosy, and...

What are the two nonspecific tests (to detect nonspecific antibodies) for syphilis?

What are the two nonspecific tests (to detect nonspecific antibodies) for syphilis?1. VDRL (Venereal Disease Research Laboratory)2. RPR (rapid plasma...

What bacterial species causes IgM cold autoimmune antibodies?

What bacterial species causes IgM cold autoimmune antibodies?Answer: Mycoplasma pneumon...

How does polymerase chain reaction (PCR) work?

How does polymerase chain reaction (PCR) work?PCR amplifies bacterial DNA using bacterial-specific primers, free DNA bases, and DNA polymerase, allowing...

Name two types of bacteria that are identified by immunofluorescence:

Name two types of bacteria that are identified by immunofluorescence:1. Chlamydia2. Spiroche...

Describe direct and indirect immunofluorescence.

Describe direct and indirect immunofluorescence.Answer: Direct immunofluorescence detects specific bacterial antigens by using antibodies conjugated...

How does ELISA (enzyme-linked immunosorbent assay) work?

How does ELISA (enzyme-linked immunosorbent assay) work?Answer: An enzyme linked to either a bacterial antigen or antibody reacts in direct proportion...

What bacteria is identified by the Elek test? How does the Elek test work?

What bacteria is identified by the Elek test? How does the Elek test work?Answer: Corynebacterium diphtheriae. Antitoxin (antibody to diphtheria...

What other tests are used to determine the presence of a capsule? How do the tests work?

What other tests are used to determine the presence of a capsule? How do the tests work?Answer: Latex agglutination. Latex beads complexed to antibodies...

Name some bacteria that are Quellung positive:

Name some bacteria that are Quellung positive:Cryptococcus (not bacteria), Pseudomonas, 'Neisseria meningitidis, H. influenzae, Klebsiella, and Streptococcus...

What does the Quellung test detect?

What does the Quellung test detect?Answer: Capsule. Quellung is the German word for "swellin...

Which bacteria produce a black pigment on bile-esculin agar?

Which bacteria produce a black pigment on bile-esculin agar?Answer: Group D streptococci and enteroco...

In addition to respiratory bursts, what other free radical-generating system is found in macrophages?

In addition to respiratory bursts, what other free radical-generating system is found in macrophages?Answer: Inducible nitric oxide synthase (iNOS)...

What enzyme forms hypochlorite (HOCL•−) from peroxide (H2O2) and chloride (CI−)?

What enzyme forms hypochlorite (HOCL•−) from peroxide (H2O2) and chloride (CI−)?Answer: Myeloperoxidase. Hypochlorite is 50 times more potent than...

What enzyme degrades peroxide (H2O2) into H2O and oxygen, and thereby protects bacteria?

What enzyme degrades peroxide (H2O2) into H2O and oxygen, and thereby protects bacteria?Answer: Catal...

What enzyme converts superoxide (O2•−) to peroxide (H2O2)?

What enzyme converts superoxide (O2•−) to peroxide (H2O2)?Answer: Superoxide dismut...

What enzyme produces superoxide (O2•−) from oxygen (O2)?

What enzyme produces superoxide (O2•−) from oxygen (O2)?Answer: Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the neutrophil cell...

Neutrophils and monocytes engulf bacteria and kill them by what mechanism?

Neutrophils and monocytes engulf bacteria and kill them by what mechanism?Answer: Oxygen-dependent (respiratory burst) and oxygen-independent (muramidase,...

What group of receptors allows neutrophils and macrophages to recognize conserved bacterial structures such as lipopolysaccharide (LPS)?

What group of receptors allows neutrophils and macrophages to recognize conserved bacterial structures such as lipopolysaccharide (LPS)?Answer: Toll-like...

What immune cells are involved in innate immunity?

What immune cells are involved in innate immunity?Answer: NK cells, neutrophils, macropha...

The acute-phase response represents a group of proteins released from the liver as part of innate immunity. Name the function of the following acute-phase proteins: C-reactive protein

The acute-phase response represents a group of proteins released from the liver as part of innate immunity. Name the function of the following acute-phase...

Macrophages release various cytokines in innate immunity. Name the function of the following cytokines: Tumor necrosis factor-α (TNF-α)

Macrophages release various cytokines in innate immunity. Name the function of the following cytokines: Tumor necrosis factor-α (TNF-α)Answer: Induces...

What is the role of complement in innate immunity?

What is the role of complement in innate immunity?Answer: Opsonization/phagocytosis, cytolysis, and chemota...

What disease is associated with autosplenectomy?

What disease is associated with autosplenectomy?Answer: Sickle cell ane...

Name two types of DNA forms found in bacteria:

Name two types of DNA forms found in bacteria:1. Chromosomal DNA2. Plasmid...

Are bacteria haploid or diploid?

Are bacteria haploid or diploid?Answer: Hapl...

By what process do bacteria multiply?

By what process do bacteria multiply?Answer: Binary fiss...

What are some of the facultative intracellular organisms?

What are some of the facultative intracellular organisms?Brucella, Salmonella typhi, Francisella tularensis, Legionella, Mycobacterium, Yersinia, and...

What are facultative intracellular organisms?

What are facultative intracellular organisms?Answer: Organisms that can survive both intracellularly and extracellula...

How do obligate intracellular organisms generate ATP?

How do obligate intracellular organisms generate ATP?Answer: They cannot produce their own ATP, so they utilize the ATP of a host cell. Therefore,...

What are obligate intracellulai organisms?

What are obligate intracellulai organisms?Answer: Organisms that can only survive within host cells (eg, Chlamydia and Rickettsia)Mnemonic: Rob Cells...

Why are obligate anaerobes unable to grow in the presence of oxygen?

Why are obligate anaerobes unable to grow in the presence of oxygen?Answer: Because they do not have enzymes such as superoxide dismutase, catalase,...

How do microaerophilic bacteria tolerate low levels of oxygen?

How do microaerophilic bacteria tolerate low levels of oxygen?Answer: They have superoxide dismutase, but no catala...

How do microaerophilic bacteria generate adenosine triphosphate (ATP)?

How do microaerophilic bacteria generate adenosine triphosphate (ATP)?Only through fermentation. They do not have an electron transport syst...

How are facultative anaerobes different from obligate aerobes?

How are facultative anaerobes different from obligate aerobes?Facultative anaerobes are aerobic bacteria which have catalase and superoxide dis-mutase,...

Why do obligate aerobes require oxygen?

Why do obligate aerobes require oxygen?Obligate aerobes require oxygen because their metabolism requires oxygen as the final electron acceptor. They use...

What are some of the obligate anaerobic bacteria?

What are some of the obligate anaerobic bacteria?Gram positive: Clostridium, ActinomycesGram negative: Bacteroi...

What are some of the obligate aerobe bacteria?

What are some of the obligate aerobe bacteria?Gram positive: Nocardia, Bacillus Gram negative: Neisseria, Pseudomonas, Bord-etella, Legionella, BrucellaAcid-fast:...

How are bacteria groups separated according to their oxygen requirements?

How are bacteria groups separated according to their oxygen requirements?Obligate aerobes require oxygen for metabolism (eg, Pseudomonas); facultative...

During what phase have nutrient sources been exhausted?

During what phase have nutrient sources been exhausted?Death ph...

During what phase do spores form?

During what phase do spores form?Stationary ph...

In what phase does bacterial growth equal that of bacterial death?

In what phase does bacterial growth equal that of bacterial death?Stationary ph...

During what phase do β-lactam drugs act?

During what phase do β-lactam drugs act?Log pha...

During what phase is growth the fastest?

During what phase is growth the fastest?Log ph...

During what phase do bacteria have the highest metabolic activity but without cell division?

During what phase do bacteria have the highest metabolic activity but without cell division?Lag ph...

What are the four phases of bacterial growth?

What are the four phases of bacterial growth?1. Lag phase2. Logarithmic phase (log)3. Stationary phase4. Death ph...

What is a fomite?

What is a fomite?An inanimate object that can harbor and spread infections (eg, blankets with smallpox or hospital bed rails with methicillin-resistant...