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USLME Step 1 > Microbiology- First Aid > Flashcards

Microbiology- First Aid Flashcards

1
Q

Bacteria that do not Gram stain well

A

Treponema, Mycobacteria, Mycoplasma, Legionella pneumophila, Rickettsia, Chlamydia

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2
Q

Giemsa Stain

A

Chlamydia, borrelia, Rickettsiae, Trypanosomes, Plasmodium

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3
Q

PAS Stain

A

Tropheryma whipplei

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4
Q

Ziehl-Neelsen

A

Nocardia, Mycobacterium (acid fast)

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5
Q

India ink

A

Crytococcus neoformans

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6
Q

Silver stain

A

Legionella, Helicobacter pylori, pneumocystis

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7
Q

Obligate Aerobes

A

Nocardia, Pseudomonas, Mycobacterium tuberculosis

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8
Q

Obligate Anaerobes

A

Clostridium, Bacteroides, Actinomyces

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9
Q

Obligate intracellular

A

Rickettsia, Chlamydia

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10
Q

Facultative intracellular

A

Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis

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11
Q

Encapsulated bacteria

A

Strep pneumoniae, haemophilus influenzae type B, Neisseria meningitidis, Escherichia coli, Salmonella, Klebsiella pneumoniae, group B strep

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12
Q

Catalase positive

A

Pseudomonas, Listeria, Aspergillus, Candida, E.coli, S. aureus, Serratia

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13
Q

Urease positive

A

Cryptococcus, H. pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, Staph epidermis, Staph saprophyticus

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14
Q

Pigment producing bacteria

A 
Actinomyces israelii (yellow granules)
Staph aureus (yellow)
Pseudomonas aeruginosa (blue-green pigment)
Serratia marcescens (red pigment)
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15
Q

Effects of endotoxin (lipid A- mediated)

A

fever, hypotension, edema, neutrophil, chemotaxis, DIC

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16
Q

Toxins whose genes are encoded by a phage

A

shiga-like toxin, botulinum, cholera, diptheria, erythrogenic toxin (strep pyogenes)

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17
Q

Novobiocin

A

Staph Epidermidis is sensitive; Staph saprophyticus is resistant

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18
Q

Optochin

A

Strep viridans is resistant; strep pneumoniae is sensitive

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19
Q

Bacitracin

A

group B strep (agalactiae) are resistant; group A strep (pyogenes) are sensitive
Both group A and group B are beta-hemolytic

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20
Q

Staph epidermidis

A

infects prosthetic devices and IV catheters by producing adherent biofilms

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21
Q

Staph saprophyticus

A

2nd leading cause of uncomplicated UTI

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22
Q

Strep pneumoniae

A

meningitis, otitis media, pneumonia, sinusitis, alpha-hemolytic

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23
Q

Viridans group streptococci

A

Strep mutans- dental caries

Strep sanguinis- subacute bacterial endocarditis

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24
Q

Strep pyogenes

A

pharyngitis, cellulitis, impetigo, scarlet fever, toxic shock-like syndrome, necrotizing fasciitis, rheumatic fever, acute glomerulonephritis

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25
Q

Jones criteria for rheumatic fever

A

polyarthritis, carditis, subq nodules, erythema marginatum, sydenham chorea

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26
Q

Scarlet Fever

A

scarlet rash with sandpaper-like texture, strawberry tongue, circumoral pallor

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27
Q

Strep agalactiae

A

colonizes vagina causing pneumonia, meningitis, and sepsis in neonates

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28
Q

Enterococcus faecalis and faecium

A

penicillin G resistant, UTI, biliary tract infections, subacute endocarditis (post-GU/GI procedures)

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29
Q

Strep bovis

A

colonizes the gut, can cause bacteremia and subacute endocarditis in colon cancer patients

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30
Q

Corynebacterium diphtheriae

A

AB exotoxin ADP-ribosylates EF-2

Symptoms include pseudomembranous pharyngitis with lymphadenopathy, myocarditis, and arrhythmias

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31
Q

Spore-forming bacteria

A

Bacillus anthracis, Clostridium perfringens, Clostridium tetani, Bacilus cereus, Clostridium botulinum, Coxiella burnetii

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32
Q

Anthrax

A

Bacillus anthracis, a gram + spore-forming rod that is the only bacterium that contains a polypeptide capsule

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33
Q

Cutaneous anthrax

A

boil-like lesion–> ulcer with black eschar

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34
Q

Pulmonary anthrax

A

inhalation of spores–> flu-like symptoms that rapidly progress to fever, pulmonary hemorrhage, mediastinitis, and shock

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35
Q

Bacillus cereus

A

nausea and vomiting, watery nonbloody diarrhea, reheated rice syndrome

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36
Q

Listeria monocytogenes

A
  • acquired by ingestion of unpasteurized dairy products and deli meats, via transplacental trasmission, or by vaginal transmission during birth
  • only gram + to produce LPS
  • causes amnionitis, septicemia, spontaneous abortion, granulomatosis infantiseptica, neonatal meningitis, meningitis in immunocompromised patients, mild gastroenteritis
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37
Q

Types of mycobacteria and their findings

A

Tuberculosis- TB
Kansassi- pulmonary TB like symptoms
Avium-intracellulare- disseminated non TB disease in AIDS

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38
Q

TB symptoms

A

fever, night sweats, weight loss, and hemoptysis

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39
Q

Lepromatous M. Leprae

A

diffuse infection over skin, leonine facies, communicable, humoral Th2 response

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40
Q

Tuberculoid M. Leprae

A

limited to a few hypoesthetic hairless skin plaques, characterized by cell-mediated Th1- type response

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41
Q

Lactose-fermenting enteric bacteria

A

Citrobacter, Klebsiella, E.coli, Enterobacter, Serratia

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42
Q

Haemophilus influenzae

A

Epiglottitis, meningitis, otitis media, pneumonia

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43
Q

H. influenzae culture

A

Chocolate agar with factor V (NAD+) and X (hematin)

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44
Q

Legionella pneumophila

A
  • Gram negative rod
  • Grows on charcoal yeast extract culture with iron and cysteine
  • Aerosol transmission from environmental water source
  • Severe pneumonia, fever, GI and CNS symptoms (Legionnaires’ disease)
  • mild flu-like syndrome (Pontiac fever)
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45
Q

Hemolytic uremia syndrome

A

anemia, thrombocytopenia, acute renal failure

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46
Q

Klebsiella

A
  • Intestinal flora that causes lobar pneumonia in alcoholics and diabetics when aspirated
  • red currant jelly sputum
  • gram negative lactose fermenting rods
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47
Q

Salmonella typhi

A
  • Typhoid fever
  • Rose spots on abdomen, fever, headache, and diarrhea
  • Remain in gallbadder (carrier state)
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48
Q

Campylobacter jejuni

A
  • oxidase positive
  • bloody diarrhea
  • fecal oral transmission
  • common antecedent to Guillain-Barre syndrome and reactive arthritis
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49
Q

Vibrio Cholera

A
  • oxidase positive
  • comma shaped
  • rice water diarrhea that activates Gs (increases cAMP)
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50
Q

Yersinia enterocolitica

A
  • transmitted from pet feces, contaminated milk, pork

- mesenteric adenitis that can mimic Crohn disease or appendicitis

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51
Q

Helicobacter pylori

A
  • gastritis and peptic ulcers (especially duodenal)
  • curved rod that is catalase, oxidase and urease positive
  • triple therapy: PPI, clarithromycin, amoxicillin or metronidazole
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52
Q

Spirochetes

A

Borrelia (biggest), Leptospira, Treponema

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53
Q

Leptospira interrogans

A
  • transmitted by water contamination of animal urine
  • leptospirosis: flu-like, jaundice, photophobia with conjunctival erythema without exudate
  • Weil disease: severe form with jaundice, azotemia, fever, hemmorhage, and anemia
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54
Q

Lyme disease

A
  • Borrelia burgdorferi
  • Ixodes tick
  • Initial symptoms: erythema migrans, flu-like symptoms, facial nerve palsy
  • monoarthritis, migratory polyarthritis, AV nodal block, encephalopathy, facial nerve palsy, polyneuropathy
  • doxycycline ceftriaxone
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55
Q

VDRL false positives

A

mononucleosis, EBV, hepatitis, drugs, SLE, leprosy

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56
Q

Jarisch-Herxheimer

A

flu-like syndrome after abx are started due to killed bacteria releasing pyrogens

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57
Q

Gardnerella vaginalis

A
  • vaginosis (fishy smell of vagina, nonpainful, associated with sexual activity)
  • vaginal epithelial cells covered with gardnerella
  • tx metronidazole, clindamycin
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58
Q

Rickettsia rickettsii

A
  • tick vector
  • Rocky mountain spotted fever
  • rash starts in palms and soles, spreads to trunk, palms, and soles
  • headache, fever, rash
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59
Q

Rickettsia typhi/prowazekii

A

-rash starts centrally and spreads out, spares palms and soles

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60
Q

Ehrlichia chaffeenis

A
  • tick vector
  • Ehrlichiosis
  • monocytes with morulae (berry like inclusions in the cytoplasm)
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61
Q

Anaplasma

A
  • tick vector
  • granulocytes with morulae in cytoplasm
  • Anaplasmosis
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62
Q

Coxiella burnetii

A
  • spores inhaled as aerosol
  • pneumonia
  • no rash
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63
Q

Mycoplasma pneumoniae

A
  • pneumonia (insidious onset, headache, nonproductive cough, patchy or diffuse interstitial infiltrate)
  • grown on Eaton agar
  • IgM
  • Tx, macrolide, doxycycline, fluoroquinolone
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64
Q

Systemic mycoses

A
  • pneumonia
  • dimorphic (mold in cold, yeast in heat)
  • tx is fluconazole or itraconzaole for local infection and amphotericin B for systemic infection
  • mimic TB (granuloma formation)
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65
Q

Tinea versicolor

A
  • Malassezia furfur
  • hypo/hyperpigmented patches
  • hot/humid weather
  • spaghetti and meatball appearance
  • topical miconazole, selenium sulfide
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66
Q

Giardiasis

A
  • Giardia lamblia
  • bloating, flatulence, foul-smelling, fatty diarrhea
  • cysts in water
  • trophozoites or cysts in stool
  • metronidazole
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67
Q

Amebiasis

A
  • Entamoeba histolytica
  • bloody diarrhea
  • liver abscess
  • RUQ pain (rupture of submucosal abscess of colon)
  • cysts in water
  • trophozoites (with RBC’s in the cytoplasm)
  • cysts in stool
  • metronidazole or iodoquinol (for asymptomatic cyst passers)
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68
Q

Cryptosporidium

A
  • severe diarrhea in AIDS
  • water diarrhea in immunocompetent
  • oocysts in water
  • acidfast stain
  • nitazoxanide in immunocompetent
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69
Q

Toxoplasmosis

A
  • Toxoplasma gondii
  • brain abscess in HIV
  • chorioretinitis, hydrocephalus, intracranial calcifications
  • cysts in meat or oocysts in cat feces, placental transmission
  • serology or biopsy (tachyzoite)
  • sulfadiazine+pyrimethamine
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70
Q

Naegleria fowleria

A
  • rapidly fatal meningoencephalitis
  • swimming in freshwater lakes (enters via cribiform plates)
  • ameobas in spinal fluid
  • amphotericin B
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71
Q

Trypanosoma brucei

A
  • African sleeping sickness (enlarged lymph nodes, recurring fever, somnolence, coma)
  • antigenic variation
  • tsetse fly
  • suramin for blood-borne disease or melarsoprol for CNS penetration
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72
Q

Babesia

A
  • babesiosis
  • fever, hemolytic anemia
  • Ixodes tick, northeastern U.S.
  • blood smear either ring or Maltese cross
  • Tx, atovaquone, azithromycin
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73
Q

Trypanosoma cruzi

A
  • Chagas disease
  • dilated cardiomyopathy, megacolon, megaesophagus
  • reduviid bug
  • Tx, benznidazole, nifurtimox
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74
Q

Leishmania donovani

A
  • visceral leishmaniasis
  • spiking fevers, hepatosplenomegaly, pancytopenia
  • sandfly
  • macrophages containing amastigotes
  • Tx, amphotericin B, sodium stibogluconate
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75
Q

Trichomonas vaginalis

A
  • vaginitis
  • foul smelling, greenish discharge, itching and burning
  • trophozoites on wet mount
  • metronidazole for patient and partner
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76
Q

Enterobius vermicularis (pinworm)

A
  • fecal oral
  • intestinal infection causing anal pruritis
  • scotch tape test
  • bendazoles or pyrantel pamoate
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77
Q

Ascaris lumbricoides (giant roundworm)

A
  • fecal oral
  • intestinal infection
  • bendazoles or pyrantel pamoate
78
Q

Strongyloides stercoralis

A
  • larvae in soil penetrate the skin
  • intestinal infection causing vomiting, diarrhea, epigastric pain
  • ivermectin or albendazole
79
Q

Ancylostoma duodenale, Necator americanus (hookworm)

A
  • larvae penetrate skin
  • intestinal infection causing anemia by sucking blood from intestinal walls
  • bendazoles or pyrantel pamoate
80
Q

Onchocerca volvulus

A
  • female blackfly
  • hyperpigmented skin and river blindness
  • ivermectin
81
Q

Loa loa

A
  • deer, horse, mango fly
  • swelling in skin, worm in conjunctiva
  • diethylcarbamazine
82
Q

Wuchereria bancrofti

A
  • female mosquito
  • blocks lymphatic vessels
  • elephantiasis (takes 9 mo to 1yr)
  • diethylcarbamazine
83
Q

Toxocara canis

A
  • fecal oral
  • visceral larva migrans
  • albendazole or mebendazole
84
Q

Taenia solium

A
  • ingestion of larvae encysted in undercooked pork, eggs
  • intestinalinfection
  • cysticercosis, neurocysticercosis
  • praziqunatel, albendazole
85
Q

Diphyllobothrium latum

A
  • ingestion of larvae from raw freshwater fish
  • vitamin B12 deficiency (pernicious anemia)
  • praziquantel
86
Q

Echinococcus granulosus

A
  • ingestion of eggs from dog feces
  • hydatid cysts in liver, anaphyalxis if antigens released
  • albendazole
87
Q

Schistosoma

A
  • snails are host, cercariae penetrate skin of humans
  • liver and spleen granulomas, fibrosis and inflammation
  • chronic infection can lead to squamous cell carcinoma of the bladder (painless hematuria)
  • praziquantel
88
Q

Clonorchis sinensis

A
  • undercooked fish
  • biliary tract inflammation, pigmented gallstones, associated with cholangiocarcinoma
  • praziquantel
89
Q

Live attenuated vaccinations

A

smallpox, yellow fever, chickenpox, Sabin polio virus, MMR, intranasal influenza

90
Q

Inactivated vaccinations

A

rabies, injected influenza, salk polio, HAV vaccines

91
Q

Recombinant vaccinations

A

HBV, HPV (types 6,11,16,18)

92
Q

Naked (nonenveloped viruses)

A

Papillomavirus, adenovirus, parvovirus, polyomavirus, calicivirus, picornavirus, reovirus, hepevirus

93
Q

Hepadnavirus (HBV)

A
  • acute or chronic hepatitis
  • vaccine
  • reverse transcriptase
94
Q

Adenovirus

A
  • febrile pharyngitis
  • acute hemorrhagic cystitis
  • pneumonia
  • conjunctivitis (pink eye)
95
Q

Parvovirus (B19)

A
  • aplastic crises in sickle cell disease
  • “slapped cheeks” rash (erythema infectiosum)
  • RBC destruction in fetus–> hydrops fetalis and death
  • pure RBC aplasia
  • rheumatoid arthritis
96
Q

Papillomavirus (HPV)

A
  • warts (1,2,6,11)

- cervical cancer (16,18)

97
Q

Polyomavirus

A
  • JC virus causing progressive mutlifocal encephalopathy

- BK virus in kidney transplant patients

98
Q

Poxvirus

A
  • small pox
  • cowpox
  • molluscum contagiosum (flesh colored dome lesions with central umbilicated dimple)
99
Q

Negative-stranded RNA viruses (RNA-dependent RNA polymerase)

A

Arenavirus, Bunyavirus, Paramyxovirus, Orthomyxovirus, Filovirus, Rhabdovirus

100
Q

Segmented viruses (RNA)

A

Bunyavirus, orthomyxovirus, arenavirus, reovirus

101
Q

Picornavirus

A
  • Poliovirus, Echovirus, Rhinovirus, Coxsackievirus, HAV
  • polyprotein
  • viral meningitis (except rhinovirus)
  • enterovirus (except rhinovirus)
102
Q

Rhinovirus

A
  • picornavirus
  • noneveloped RNA virus
  • destroyed by stomach acid
  • common cold
103
Q

Yellow fever virus

A
  • flavivrus (arbovirus)
  • Aedes mosquitoes
  • high fever, black vomitus, jaundice
104
Q

Rotavirus

A
  • infantile gastroenteritis
  • segmented dsRNA virus (reovirus)
  • villous destruction with atrophy leads to decreased absorption of Na and loss of K
105
Q

Influenza

A
  • orthomyxovirus
  • enveloped, negative ssRNA
  • hemagglutinin promotes viral entry, neuraminidase promotes progeny virion release
106
Q

Rubella virus

A
  • togavirus
  • fever, postauricular lymphadenopathy, arthralgias, fine rash
  • TORCHES (blueberry muffin appearance)
107
Q

Paramyxovirus

A
  • parainfluenza (croup)
  • mumps
  • measles
  • RSV (bronchiolitis, pneumonia)
  • F (fusion) protein that transforms respiratory epithelial cells into multinucleated cells
108
Q

Measles

A
  • paramyxovirus
  • Koplik spots on buccal mucosa
  • maculopauplar rash
  • sequelae include subacute sclerosing panencephalitis, encephalitis, giant cell pneumonia
  • cough, rhinitis, conjunctivitis
109
Q

Mumps

A
  • paramyxovirus

- parotitis, orchitis, viral meningitis

110
Q

Rabies

A
  • rhabdovirus
  • bullet shaped virus
  • Negri bodies (cytoplasmic inclusions in purkinje cells)
  • fever, malaise–> agitation, photophobia, hydrophobia–> paralysis, coma–> death
111
Q

Prions

A
  • conversion of PrPc–> PrPsc (beta-pleated)

- spongiform encephalopathy, dementia, ataxia, death

112
Q

Toxoplasma gondii (TORCHS)

A

neonatal chorioretinitis, hydrocephalus, intracranial calcification

113
Q

Rubella (TORCHS)

A

PDA or pulmoanry artery hypoplasia, cataracts, deafness, blueberry muffin rash

114
Q

CMV (TORCHS)

A

hearing loss, seizures, petechial rash, blueberry muffin rash

115
Q

HSV-2 (TORCHS)

A

encephalitis, herpetic lesions

116
Q

Syphillis (TORCHS)

A

stillbirth, hydrops fetalis, facial abnormalities such as notched teeth, saddle nose, short maxilla, saber shins and CV VIII deafness

117
Q

Penicillin G/V Mechanism

A
  • Bind penicillin-binding proteins (transpeptidases)
  • block transpeptidase cross-linking of peptidoglycan
  • activate autolytic enzymes
118
Q

Penicillin G/V use

A

gram positive (S. pneumoniae, S. pyogenes, Actinomyces), N. meningitis, T. pallidum

119
Q

Ampicillin, amoxicillin

A
  • Bind penicillin-binding proteins (transpeptidases)
  • block transpeptidase cross-linking of peptidoglycan
  • activate autolytic enzymes
120
Q

Ampicillin, amoxicillin use

A
  • Penicillin coverage

- H. influenzae, E.coli, L. monocytogenes, P. mirabilis, Salmonella, Shigella

121
Q

Oxacillin, nafcillin, dicloxacillin

A
  • Penicillinase (beta-lactamase) resistant

- Used for S. aureus except for MRSA

122
Q

Ticarcillin, piperacillin

A
  • Penicillin use and coverage

- Additional coverage of pseudomonas and gram negative rods

123
Q

Beta lactamase inhibitors

A

Clavulanic Acid, Sulbactam, Tazobactam

124
Q

Cephalosporins

A
  • beta lactam durgs
  • less susceptible to penicillinases
  • Listeria, Chlamydia, Mycoplasma, MRSA, Enterococci are not covered
125
Q

Cefazolin, Cephalexin (1st generation)

A
  • Gram positive cocci
  • Proteus mirabilis
  • E.coli
  • Klebsiella pneumoniae
  • S. aureus wound infection prophylaxis
126
Q

Cefoxitin, cefaclor (2nd generation)

A

Gram positive cocci, H. influenzae, Enterbacter aerogenes, Neisseria, Proteus, E.coli, Klebsiella pneumoniae, Serratia marcescens

127
Q

Ceftriaxone, cefotaxime, ceftazidime (3rd generation)

A

serious gram-negative infections resistant to other beta lactams

128
Q

Cefepime (4th generation)

A

Pseudomonas and gram positive organisms

129
Q

Ceftaroline (5th generation)

A

broad gram positive and gram negative coverage including MRSA but NOT pseudomonas

130
Q

Aztreonam

A
  • monobactam
  • no allergic cross reactivity with penicillins
  • prevents peptidoglycan cross-linking
  • gram-negative rods
131
Q

Carbapenems

A

imipenem, meropenem, ertapenem, doripenem
Note: imipenem is co-administered with cilastatin (an inhibitor of renal dehydropeptidase I to decrease inactivation by the kidney)

132
Q

Carbapenems (use)

A

gram-positive cocci, gram-negative rods and anaerobes

133
Q

Carbapenem toxicity

A

GI distress, skin rash, CNS toxicity (seizures)

134
Q

Vancomycin mechanism

A

inhibits cell wall peptidogylcan formation by binding D-ala D-ala portion of cell wall precursors

135
Q

Vancomycin use

A

gram positive only (MRSA, entercocci, C. difficile)

136
Q

Vancomycin (toxicity)

A

nephrotoxicity, ototoxicity, thrombophlebitis, diffuse flushing aka Red Man syndrome

137
Q

Aminoglycosides

A

gentamicin, neomycin, amikacin, tobramycin, streptomycin

138
Q

Aminoglycosides mechanism

A
  • bactericidal, inhibit formation of initiation complex and cause misreading of mRNA, also block translocation
  • ineffective against anaerobes because requires O2 for uptake
139
Q

Aminoglycosides toxicity

A

nephrotoxicity, neuromuscular blockade, ototoxicity, teratogen

140
Q

Tetracyclines

A

tetracycline, doxycycline, minocycline

141
Q

Tetracycline mechanism

A

bacteriostatic, bind to 30s and prevent attachment of amino-acyl tRNA

142
Q

Tetracycline use

A

Borrelia burgdorferi, mycoplasma pneumonia, rickettsia, chlamydia (intracellular penetration)

143
Q

Tetracycline toxicity

A

GI distress, discoloration of teeth and inhibition of bone growth in children, photosensitivity, contraindicated in pregnancy

144
Q

Macrolides

A

azithromycin, clarithromycin, erythromycin

145
Q

Macrolides mech.

A

inhibit protein synthesis by blocking translocation, binds the 23S rRNA of the 50S ribosomal subunit, bacteriostatic

146
Q

Macrolides use

A

Atypical pneumonias (mycoplasma, chlamydia, legionella), STD (chlamydia) and gram positive cocci (pt’s with penicillin allergies)

147
Q

Macrolides toxicity

A

GI dysmotility, Arrhythmia caused by prolonged QT, acute cholestatic hepatitis, rash, eosinophilia

148
Q

Chloramphenicol mech.

A

blocks peptidyltransferase at 50s ribosomal subunit, bacteriostatic

149
Q

Chloramphenicol use

A

meningitis (H. influenzae, N. meningitis, S. pneumoniae), Rickettsia rickettsii

150
Q

Chloramphenicol toxicity

A

anemia, aplastic anemia, gray baby syndrome

151
Q

Clindamycin mech.

A

blocks peptide transfer (translocation) at 50s subunit, bacteriostatic

152
Q

Clindamycin use

A

anaerobic infections (Bacteroides, Clostridium perfringens), invasive Group A strep

153
Q

Clindamycin toxicity

A

pseudomembranous colitis (C.dificile), fever, diarrhea

154
Q

Sulfonamides mech

A

inhibit folate synthesis, inhibit dihydropteroate synthase

155
Q

Sulfonamides use

A

gram-positive, gram-negative, nocardia, chlamydia

156
Q

Sulfonamides toxicity

A

hypersensitivity, hemolysis if G6PD deficient, nephrotoxicity, photosensitivity, kernicterus, displace other drugs from albumin

157
Q

Trimethoprim mech.

A

inhibits bacterial dihydrofolate reductase (dihydrofolic acid–> tetrahydrofolic acid)

158
Q

Trimethoprim use

A

used in combination with sulfonamides for UTI’s, shigella, salmonella, pneumocystis jirovecii, pneumonia tx and prophylaxis and toxoplasmosis prophylaxis

159
Q

Trimethoprim toxicity

A

megaloblastic anemia, leukopenia, granulocytopenia

160
Q

Fluoroquinolones (-floxacin) mech.

A

inhibit DNA gyrase (topoisomerase II) and topoisomerase IV, bactericidal

161
Q

Fluoroquinolones (-floxacin) use

A

gram-negative rods of urinary and GI tracts (pseudomonas), Neisseria, some gram-positive organisms

162
Q

Fluoroquinolones (-floxacin) toxicity

A
  • GI upset, superinfections, skin rashes, headache, dizziness, tendon rupture
  • contraindicated in pregnant women, nursing women, and children<18 yr
163
Q

Metronidazole mech.

A
  • forms free radical toxic metabolites in the bacterial cell that damage DNA
  • bactericidal, antiprotozoal
164
Q

Metronidazole use

A
  • Giardia, Entamoeba, Trichomonas, Gardnerella vaginalis, -Anaerobes (bacteroides, C. difficile)
  • triple therapy with PPi and clarithromycin
165
Q

Metronidazole toxicity

A

disulfiram-like reaction, headache, metallic taste

166
Q

Isoniazid mech.

A

decrease synthesis of mycolic acids, bacterial catalase-peroxidase needed to convert isoniazid to active metabolite

167
Q

Isoniazid Use

A

prophylaxis for M. tuberculosis

168
Q

Isoniazid toxicity

A

neurotoxicity, hepatotoxicity

169
Q

Rifamycins (rifampin, rifabutin) mech.

A

inhibits DNA-dependent RNA polymerase

170
Q

Rifamycins (rifampin, rifabutin) use

A
  • M. tuberculosis
  • used for meningococcal prophyalxis
  • prophylaxis for contacts with HiB
171
Q

Rifamycins (rifampin, rifabutin) toxicity

A

minor hepatotoxicity, orange body fluids, enzyme (P-450) inducer

172
Q

TB treatment drugs

A

Rifampin, isoniazid, pyrazinamide, ethambutol

173
Q

Amphotericin B mech.

A

binds ergosterol, forms membrane pores that allow leakage of electrolytes

174
Q

Amphotericin B use

A
  • serious, systemic mycoses
  • cryptococcus, blastomyces, coccidioides, histoplasma, candida, mucor
  • concurrently supplement K and Mg
175
Q

Amphotericin B toxicity

A

fever, chills, hypotension, nephrotoxicity, arrhythmias, anemia, IV phlebitis

176
Q

Nystatin

A

topical, mouthwash form of amphotericin B

177
Q

Azoles mech.

A

inhibit ergosterol synthesis by inhibiting the Cyp-450 enzyme lanosterol–> ergosterol

178
Q

Azoles use

A
  • local and less serious systemic mycoses
  • chronic cryptococcal meningitis in AIDS patients
  • candidal infections
  • itraconazole for blastomyces, coccidioides, histoplasma
  • clotrimazole and miconazole for topical fungal infections
179
Q

Azoles toxicity

A
  • testosterone synthesis inhibition (gynecomastia)

- liver dysfunction

180
Q

Flucytosine mech

A

inhibits DNA and RNA biosynthesis by conversion to 5-fluorouracil by cytosine deaminase

181
Q

Flucytosine use

A

systemic fungal infections (especially meningitis caused by Cryptococcus) in combination with amphotericin B

182
Q

Flucytosine toxicity

A

bone marrow suppression

183
Q

Echinocandins (caspofungin, micafungin, anidulafungin)

A

Mechanism: inhibits cell wall synthesis by inhibiting synthesis of beta-glucan
Use: invasive aspergillosi, candida
Toxicity: GI upset, flushing (histamine release)

184
Q

Terbinafine

A

Mechanism: inhibits the fungal enzyme squalene epoxidase which inhibits lanesterol synthesis
Use: dermatophytoses (especially onychomycosis)
Toxicity: GI upset, headaches, hepatotoxicty, taste disturbance

185
Q

Griseofulvin

A

Mechanism: interferes with microtubule function; disrupts mitosis; deposits in keratin-containing tissues
Use: oral treatment of superficial infections; inhibits growth of dermatophytes (tinea, ringworm)
Toxicity: teratogenic, carcinogenic, confusion, headaches, increased P-450, warfarin metabolism

186
Q

Antiprotozoan therapy

A

pyrimethamine (toxoplasmosis), suramin and melarsoprol (T. brucei), nifurtimox (T.cruzi), sodium stibogluconate (leishmaniasis)

187
Q

Chloroquine

A

Mechanism: blocks detoxification of heme into hemozoin; heme accumulates and is toxic to plasmodia
Use: treatment of plasmodia except for P. falciparum
Toxicity: retinopathy, retinitis

188
Q

Zanamivir, oseltamivir

A

inhibit influenza neuraminidase

189
Q

Ribavirin

A

Mechanism: inhibits synthesis of guanine nucleotides by competitively inhibiting inosine monophosphate dehydrogenase
Use: RSV, chronic hepatitis C
Toxicity: hemolytic anemia, teratogen

190
Q

Acyclovir, famciclovir, valacyclovir mechanism

A

monophosphorylated by HSV/VZV thymidine kinase and not phosphorylated in uninfected cells to form guanosine analog thus inhibiting viral DNA polymerase by chain termination

Note: ganciclovir has similar mechanism for CMV

191
Q

Foscarnet mechanism

A

viral DNA polymerase inhibitor that binds to the pyrophosphate-binding site of the enzyme
Note: used when -vir drugs fail

192
Q

Cidofovir

A

Mechanism: preferentially inhibits DNA polymerase, does not require phosphorylation from virus kinase
Use: CMV retinitis, acyclovir-resistant HSV
Toxicity: nephrotoxicity

USLME Step 1 (16 decks)

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