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Microbiology > Basic Bacteriology > Flashcards

Basic Bacteriology Flashcards

1
Q

Don’t gram stain

A

Treponema, mycobacteria, mycoplasma, legionella (intracellular), rickettsia (intracellular), chlamydia (intracellular)

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2
Q

Giemsa stain

A

Chlamydia, borrelia, rickettsia, trypanosomes, plasmodium

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3
Q

PAS stain

A

Stains glycogen and mucopolysaccharides

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4
Q

Ziehl-Neelsen/ carbon fuchsin stain

A

Acid fast bacteria and Protozoa

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5
Q

India ink

A

Stains cryptococcus

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6
Q

Silver stain

A

Stains fungi, legionella, h pylori

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7
Q

Chocolate agar

A

Stains H. Flu

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8
Q

Thayer-Martin stain

A

Stains Neisseria

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9
Q

Bordet-Gengou/Regan-Lowe medium

A

Stains B. Pertussis

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10
Q

Eaton agar

A

Stains M. Pneumo

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11
Q

MacConkey agar

A

LF turn pink

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12
Q

EMB agar

A

Stains E. coli

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13
Q

Charcoal yeast extract

A

Stains legionella

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14
Q

Sabouraud agar

A

Stains fungi

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15
Q

Glycocalyx

A

Loose network of polysaccharides that mediates adherence to surfaces

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16
Q

Intracellular bugs

A

Obligate: Rickettsia, Chlamydia, Coxiella (need host ATP)
Facultative: Salmonella, Neisseria, Brucella, Mycobacterium, Listeria, Francisella, Legionella, Yersinia pestis

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17
Q

Encapsulated bacteria

A

Strep pneumo, H. flu, Neisseria meningiditis, E Coli, Salmonella, Klebsiella, Groub B strep (capsules = anti-phagocytic; asplenics are at increased risk)

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18
Q

Urease-positive organisms

A

CHuck Norris hates PUNKSS:

Cryptococcus, H pylori, Proteus, Ureaplasma, Nocardia, Klebsiella, S. epidermidis, S. saprophyticus

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19
Q

Catalase positive organisms

A

Cats Need PLACESS to hide:

Nocardia, Pseudomonas, Listeria, Aspergillus, Candida, E. coli, Staph, Serratia

Chronic granulomatous disease (NADPH oxidase deficiency) have recurrent infections with these guys.

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20
Q

Pigment-producing bacteria

A

Actinomyces israelii (yellow granules), S. aureus (yellow), Pseudomonas (blue-green), Serratia marcescens (red)

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21
Q

Bacterial virulence factors

A

Protein A - S. aureus, binds Fc region of IgG to prevent opsonization/phagocytosis

IgA protease - S. pneumo, H. flu, Nesseria - cleaves IgA to help colonize respiratory mucosa

M protein - Group A strep, prevents phagocytosis and may –> rheumatic fever

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22
Q

Exotoxin location of genes

A

Plasmid or bacteriophage

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23
Q

Endotoxin location of genes

A

Bacterial chromosome

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24
Q

Bugs with exotoxins

A

Inhibit protein synthesis:
Corynebacterium diphtheriae, Pseudomonas aeruginosa (both inactivate elongation factor), Shigella and EHEC (Shiga and Shiga-like toxins, both increase cytokine –> HUS; Shiga also invades mucosa –> dysentery)

Increase fluid secretion:
ETEC (heat labile [increase cAMP] and heat-stable [increase cGMP] toxins –> watery diarrhea), Bacillus anthracis (edema toxin mimics AC), vibrio cholerae (overactivates AC by permanently activating Gs –> increased Cl- secretion in gut and rice-water diarrhea)

Inhibit phagocytic ability
B. pertussis (overactive AC by disabling Gi)

Inhibit release of neurotransmitter:

Clostridium - cleave SNARE (tetani prevents release of inhib NTs from Renshaw cells –> spasticity; botulinum inhibits ACh (stimulatory) –> flaccid paralysis

Lyse cell membranes: Clostridium (alpha toxin –> gas gangrene from degradation of phospholipids) and Streptococcus pyogenes (streptolysin O)

Superantigens –> shock (Staph aureus - TSST-1, Strep pyogenes - Exotoxin A) - via release of IL-1, IL-2, IFN-gamma, TNF-alpha

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25
Q

Role of endotoxin

A

LPS in G- –> activates macrophages, activates complement, activates tissue factor

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26
Q

Transformation

A

Bug can pick up naked DNA from environment

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27
Q

Conjugation

A

Bacterial sex (F+ plasmid contains genes for sex pilus and conjugation - meets up with F- and passes single strand plasmid DNA across conjugal bridge)

Can include some plasmid genes if F+ plasmid was incorporated into bacterial chromosome (Hfr)

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28
Q

Transposition

A

Segment of DNA that can jump from plasmid to chromosome and vice versa

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29
Q

Transduction

A

Phage infects bacterium and cleaves bacterial DNA (generalized - lytic phage) or incorporates its DNA into bacterial chromosome (lysogenic) and then when phage DNA is excised, takes some bacterial with it (“specialized transduction”)

Lysogenic phase bacterial toxins:
Shiga-like, Botulinum, Cholera, Diphtheria, S. pyogenes

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30
Q

G+ lab algorithm

A

G+ = purple/blue
Catalase positive cocci = Staph –> Coag positive = aureus; Coag negative –> Novobiocin (sensitive = epidermidis, resistant = saprophyticus)
Catalase negative cocci = Strep –> hemolysis (alpha [green on blood agar] = pneumo [capsule, optochin sens, bile soluble] and viridans; beta [clear on blood agar] = pyogenes [bac sensitive], and agalactiae [bac res]; gamma = Group D (Enterococcus) vs. S. bovis)

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31
Q

Strep pyogenes

A

Group A strep!

Pyogenic sx (pharyngitis, cellulitis, impetigo, erysipelas)

Toxigenic sx (scarlet fever, TSS, necrotizing fasciitis)

Immuno sx (RF, acute GN)

Bacitracin sensitive, beta hemolytic, PYR+, M protein = virulence factor and Ig to it enhance host defenses but can also –> RF

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32
Q

ASO titer

A

Detect recent Strep pyogenes infection

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33
Q

JONES criteria

A

Criteria for acute RF (usually preceded by pharyngitis)

Joints (polyarthritis)
Heart (carditis)
Nodules (subcut)
Erythema marginatum
Sydenham chorea
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34
Q

Strep viridans

A

Alpha hemolytic, optochin res, normal flora of oropharynx

Can –> dental caries and subacute bacterial endocarditis at already damaged heart valves

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35
Q

Strep pneumo

A

G+ diplococci, encapsulated, optochin sensitive, alpha hemolytic

Sx = MOPS

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36
Q

Staph aureus

A

Inflamm sx (skin infections, pneumo, endocarditis, osteomyelitis)

Toxin-mediated sx (TSST-1, scalded skin syndrome, rapid-onset food poisoning)

MRSA

Coag positive, Catalase positive

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37
Q

Staph epidermidis

A

Catalase positive, Coag negative, novobiocin sensitive

Infect prosthetic devices (biofilm)

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38
Q

Staph saprophyticus

A

Catalase positive, Coag negative, Novobiocin resistant

Uncomplicated UTI in young women

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39
Q

Strep agalactiae

A

Group B strep

Bacitracin resistant, beta-hem, babies!

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40
Q

Group D strep

A

Enterococcus - UTI, biliary tract infxn, subacute endocarditis; VRE!

Strep bovis - colonizes gut, can –> bacteremia and subacute endocarditis, assoc with colon cancer

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41
Q

Cystine-tellurite agar

A

Grows corynebacterium diphtheriae

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42
Q

corynebacterium diphtheriae

A

Makes exotoxin that inhibits protein synthesis –> pseudomem pharyngitis with LAD, myocarditis and arrhythmias

Toxoid vaccine

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43
Q

Spore forming bacteria

A

Bacillus
Clostridium
Coxiella

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44
Q

C diff toxins

A

Toxin A: enterotoxin, binds brush border of gut

Toxin B: cytotoxin –> cytoskeletal disruption via actin depolymerization –> pseudomem colitis

Detect toxins in stool to diagnose

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45
Q

Anthrax

A

Bacillus anthracis = G+, spore-forming rod

Cutaneous: painless papule surrounded by vesicles –> black eschar

Pulmonary: inhale spores –> flu-like sx –> fever, pulmonary hemorrhage, mediastinitis, shock

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46
Q

Bacillus cereus

A

Spores (esp in reheated rice) –> enterotoxin ingestion –> food poisoning

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47
Q

Actinomyces vs. Nocardia ([an]aerobe? stain? sx? tx?)

A

Actinomyces = anaerobe; Nocardia = aerobe

A = gram pos; N = gram pos and weakly acid fast

A -> oral/facial abscesses that drain through sinuses, yellow “sulfur granules”
N -> pulmonary infections or cutaneous infxns following trauma in IC pts

Sulfonamides for Nocardia, Penicillin for Actinomyces (SNAP)

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48
Q

AIDS prophylaxis regimens with CD4 counts

A
  • M. avium: prophylaxis with azithromycin when CD4+ count less than 50
  • PCP: TMP-SMX, dapsone, atovaquone when CD4 less than 200
  • Toxo: TMP-SMX, CD4
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49
Q

Gram negative lab algorithm

A

Gram stain –> pink = G-

Diplococci? Neisseria meng = maltose fermenter; N. gonorrhoeae = maltose non-fermenter

Rod-cocci = Haemophilus, Pasteurella, Brucella, Bordetella

Rods –> LF (Klebsiella, E Coli, Enterobacter); NLF –> oxidase positive (pseudomonas) vs. oxidase negative (Salmonella, Proteus, Yersinia [all produce H2S], Shigella)

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50
Q

Cause of Waterhouse-Friedrichsen syndrome

A

Neisseria meningiditis (adrenal failure due to hemorrhage)

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51
Q

Meningitis treatment (N.meng or H. flu)

A

Ceftriaxone; rifampin for prophylaxis in close contacts

  • Vaccine for HiB now routine; vaccine for N.meng exists but not routine
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52
Q

Symptoms of H. flu

A

Epiglottitis (cherry red), Meng, Otitis media, Pneumo

Treat mucosal infxns with amox +/- clavulanate

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53
Q

Pseudomonas symptoms/disease associations

A 
Pneumo (can be chronic in CF)
sepsis
otitis externa
UTIs
Drug use
Diabetes
Osteomyelitis (esp with puncture wounds, burns)

Also, ecthyma gangrenosum (rapidly progressive, necrotic cutaneous lesion caused by pseudomonas bacteremia, especially in IC pts)

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54
Q

E coli virulence factors

A

Fimbriae - cystitis and pyelo

K capsule - PNA, neonatal meng

LPS endotoxin - septic shock

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55
Q

Types of E Coli

A

EIEC - invasive dysentery –> necrosis and inflam

ETEC - traveler’s diarrhea, no inflamm or invasion

EPEC - no toxin, adheres to apical surface and flattens villi –> no abs

EHEC/STEC - shiga-like toxin –> HUS (anemia, thrombocytopenia, renal failure due to microthrombi)

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56
Q

Klebsiella

A

Aspiration (DM and alcoholics) Lobar pneumo with currant jelly sputum

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57
Q

Campylobacter jejuni

A

Bloody diarrhea, esp in kids; fecal-oral transmission

Can –> guillan-barre and reactive arthritis

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58
Q

Typhoid fever

A

Caused by Salmonella typhi

Sx: rose spots on abdomen, constipation, ab pain, fever

Tx: ceftriaxone or fluoroquinolone

Oral vaccine = live/att; IM vaccine with capsular polysacch

59
Q

Dysentery

A

Causes:
Campylobacter
Salmonella (not typhi) - makes H2S, found in poultry, eggs, pets
Shigella (makes shiga toxin, which is invasive, so low infectious dose, cell-to-cell (not hematogenous) spread)
Entamoeba histolytica (amebiasis - cysts in water, can also get liver abscess)

60
Q

Vibrio cholerae mechanism of action

A

Enterotoxin permanently activates Gs –> increased cAMP –> watery diarrhea

61
Q

Pseudoappendicitis

A

Caused by yersinia enterocolitica (right lower ab pain due to mesenteric adenitis or terminal ileitis)

Pet feces, contaminated milk

62
Q

H. pylori diagnosis and treatment

A

Diagnosis: urea breath test (catalase, oxidase, and urease +) or fecal antigen test

Tx: PPI, clarithro, amoxicillin

63
Q

Stages of syphilis

A

Primary - painless chancre

Secondary - disseminated disease, maculopapular rash (ON HANDS AND SOLES), condyloma lata

Tertiary - gummas, aortitis, Argyll Robertson pupil (accomodates but doesn’t react to light), neuro sx (general paresis/ataxia)

VDRL/RPR positive (nonspecific) –> confirm with FTA-Abs

64
Q

Congenital syphilis sx and prevention

A

Snuffles, saddle nose, notched teeth, facial abnormalities (linear scars), mulberry molars, short maxilla, saber shins

Treat mom early in preg!

65
Q

VDRL false positives

A

VDRL:

Viral infection
Drugs
RF
Lupus and leprosy

66
Q

Jarisch-Herxheimer reaction

A

Flu-like syndrome after abx are started –> kill some bugs (usu spirochetes) that release endotoxin

67
Q

Pasteurella multocida

A

Animal bite

Cellulitis, osteomyelitis

68
Q

Rickettsia types and transmission

A

Prowazekii - epidemic typhus, louse

Rickettsii - RMSF, dermacentor (dog tick) - rash starts at wrists and ankles

Typhi - endemic typhus, fleas

typhus: rash starts on trunk

69
Q

Clue cells

A

Vaginal epithelial cells covered with Gardnerella bacteria (“stippled”)

fishy smell to discharge, nonpainful

70
Q

Rashes

A

Syphilis - hands and soles

R. rickettsii (RMSF) - wrists and ankles

R. typhi/prowazekii - central rash (spares palms and soles)

Coxsackie A (hand, foot, and mouth dz) - palms and soles

Measles - starts at head/neck and spreads downward; Koplik spots in mouth

Rubella - pink macules beginning at head and moving down –> desquamation

Roseola - rose-colored macules several days after fever

Parvo B19 - slapped cheek rash on face

VZV/Chickenpox - vesicular rash begins on trunk and spreads to extremities

71
Q

Ehrlichiosis (dz + histo) vs. Anaplasmosis (dz + histo)

A

Ehrlichia, vector is tick

Histo: monocytes with morulae in cytoplasm

Anaplasma, vector is tick

Histo: granulocytes with morulae in cytoplasm

72
Q

Chlamydia (types + tx)

A

Trachomatis - reactive arthritis (Reiter syndrome), follicular conjunctivitis, nongonococcal urethritis, PID

  • Serotype A,B,C - chronic infxn in Africa (can –> blindness)
  • Serotype D-K - urethritis/PID, ectopic preg, neonatal pna with eosinophilia, neonatal conjunctivitis
  • Serotypes L1-3: lymphogranuloma venereum (small, painless ulcers on genitals –> swollen, painful ln)

Pneumo/psittaci - atypical PNA, aerosol transmission

Tx: Azithro

73
Q

Atypical PNA

A

Mycoplasma pneumo
Chlamydia

Treat with doxy

74
Q

Systemic mycoses

A

Histo (Mississipi, Ohio River) – pneumo, fills macrophages

Blasto (east of histo) –> inflamm lung dz, granulomatous nodules, ~size of RBC

Coccidioidomycosis - SW –> PNA a nd meng, spherules filled with endospores bigger than RBC

Paracoccidioidomycosis - Latin America - budding yeast looks like “captain’s wheel”

75
Q

Opportunistic mycoses

A
  • Candida albicans (thrush in IC, vulvovaginitis in DM or with abx, diaper rash, endocarditis in IVDU, chronic mucocut candidiasis)
  • Aspergillus fumigatus (ABPA, aspergillomas, aflatoxins; dz esp in IC and those with chronic granulomatous disease), branch at acute angles
  • Cryptococcus (meng, cryptococcosis) - in soil and pigeon droppings, stain with India Ink, see “soap bubble” lesions in brain
  • Mucor/Rhizopus (mucormycosis, esp in ketoacidotic DM and/or neutropenic pts) - fungi grow in vv and penetrate crib plate
  • Pneumocystis jirovecii –> PCP (diffuse interstitial PNA with ground glass appearance on CXR), esp in IC pts, diag by lavage or bx; stain with silver stain
  • Sporothrix schenckii –> Sporotrichosis; yeast spores introduced via trauma (eg rose thorn) –> local ulcer with nodules along draining lymphatics; can be disseminated in IC; treat with KI or itraconazole
76
Q

Protozoa - GI

A

Giardia (steatorrhea)
Entamoeba histolytica (anchovy paste, liver abscess, dysentery)
Cryptosporidium (severe diarrhea in AIDS)

77
Q

Protozoa - CNS infections

A 
Toxoplasma gondii (ring-enhancing lesions on CT/MRI, esp in AIDS reactivation) - cysts in meat, cat feces
Naegleria fowleri
Trypanosoma brucei (African sleeping sickness - ant variation --> recurring fevers; treat with melarsoprol and re
78
Q

Intestinal Nematodes/Roundworms

A

Treat with bendazoles

EAT:
Enterobius vermicularis/pinworm - tape test
Ascaris lumbricoides (roundworm)
Trichinella spiralis (undercooked meat)

Larvae penetrate skin –> coughed to lungs:
Strongyloides stercoralis
Ancylostoma duodenale (hookworm) - anemia
Necator (hookworm) - anemia

79
Q

Tissue nematodes (roundworms)

A
  • Onchocerca (blackfly - river blindness)
  • Loa loa (deer, horse, or mango fly; worm in conjunctiva and skin swelling)
  • Wucheraria bancrofti (mosquito - elephantiasis from worm in lymphatics)
  • Toxocara canis (fecal-oral; larva migrans)

Tx: diethylcarbamazine (ivermectin for onchocerca)

80
Q

Cestodes (tapeworms)

A
  • Taenia (ingest larvae for intestinal form, eggs for cysticerc)
  • Diphyllobothrium latum (fish, B12 def)
  • Echinococcus granulosus (dog feces, hydatid cysts in liver)

Tx: praziquantel; albendazole for echinococcus

81
Q

Schistosoma

A

Tx: praziquantel

Schistosoma (snail = host; S.mansoni, S. haematobium (SCCA of bladder + pulm HTN)

Clonorchis (from fish, biliary tract inflamm, cholangiocarcinoma)

82
Q

DNA viruses

A
  • Herpesviruses (1 = oral, 2 = genital, 3 = VZV, 4 = EBV [mono, Burkitt, HL, nasopharyngeal ca; infects B cells and atypical lymphos on smear = reactive T cell; Monospot +], 5 = CMV (AIDS retinitis, PNA; monospot -, owl eye inclusions in infected cells), 6 = roseola, 8 = Kaposi sarcoma); Tzanck test = smear of opened skin vesicle to diagnose, or viral culture for skin/genitalia
  • Hepadnavirus (HBV), has reverse transcriptase
  • Adenovirus (febrile pharyngitis, acute hemorrhagic cystitis, PNA, conjunctivitis)
  • Parvo (B19 - “slapped cheeks” of Erythema Infectiosum/fifth dz, aplastic crisis in SCD, RBC destruction (hydrops fetalis in fetus)) - SINGLE STRANDED
  • Papilloma - HPV (16,18 – cervical cancer)
  • Polyoma (JC - progressive multifocal leukoencephalopathy in HIV, BK - kidney in transplant pts)
  • Poxvirus (smallpox, cowpox, molluscum contagiosum)
83
Q

RNA viruses

A

Reovirus - DS - coltivirus (Colorado tick fever) and rotavirus

Single Strand +:

Picorna

  • Poliovirus
  • Echo (aseptic meng)
  • Rhino (common cold)
  • Coxsackie (A = hand,foot,mouth; B = pleurodynia, myocarditis)
  • Hep A

Hepevirus

Calicivirus (noro)

Flaviviruses (HCV, Yellow fever, Dengue, St. Louis encephalitis, WNV)

Togaviruses (Rubella, EEE/WEE)

Retroviruses (HTLV, HIV)

Coronaviruses (common cold + SARS)

SS -:

Orthomyxo (flu)
Paramyxo (Parainfluenza - croup, RSV - bronchiolitis in babies, Measles/Rubeola - cough, coryza, conjunctivitis, Mumps) - all have surface F protein that –> fusion of resp epith cells into multinucleated cells
Rhabdoviruses (Rabies)
Filoviruses (Ebola/Marburg)
Arena (LCMV, Lassa Fever)
Bunya (California encephalitis, Hantavirus, Rift valley fevers)
Delta (only replicates in presence of Hep B)

84
Q

Genetic drift vs shift

A

Drift - small changes based on random mutations in HA (entry) of NA (exit) genes –> EPIDEMICS

Shift - Reassortment of viral genome sequences –> major changes in virus (eg flus) and PANDEMICS

85
Q

Congenital infections

A

TORCHES

Toxoplasma - chorioretinitis, hydrocephalus, intracranial calcifications
Rubella - “blueberry muffin rash” (extramedullary hematopoeisis)
CMV - ventricular calcifications, rash, ID
HIV
Syphilis (facial abnormalities/scars, saddle nose, “snuffles,” notched teeth, short maxilla, mulberry molars, saber shins, deafness

86
Q

Rabies virus

A

Bullet-shaped

Negri bodies in Purkinje cells of CBL and HC

Long incubation post-exposure, travels to CNS by binding ACh receptors and then migrating retrograde up nerve axons

Sx: fever, malaise –> agitation, photophobia, hydrophobia, hypersalivation –> paralysis and coma –> death

87
Q

Hepatitis D virus

A

RNA delta virus

Needs Hep B virus:

  • Superinfection (HDV after HBV) - short incubation
  • Coinfection (HDV with HBV) - long incubation
88
Q

Hepatitis E virus

A

Fecal oral transmission, esp waterborne

RNA hepevirus

Short incubation, no cancer risk

High mortality in pregnant women

89
Q

ALT vs AST in viral vs. alcoholic hepatitis

A

Viral: ALT > AST
Alcoholic: AST > ALT

90
Q

Hepatitis B markers

A

HBsAg - surface, indicates hep B infection

Anti-HBs - indicates immunity to Hep B

HBcAg - core antigen

Anti-HBc - indicates infection, may be only positive marker during window period b/w acute disease and convalescence

HBeAg - core antigen, indicates active replication and thus high transmissibility

Anti-HBe - low transmissibility

91
Q

HIV genes

A

env (gp120 - attach to host CD4 T cells; gp41 - fusion and entry)

gag (p24) - capsid protein

pol - reverse transcriptase

92
Q

HIV entry into cell

A

Binds CD4 + coreceptor (CCR5 on macrophages in early disease, CXCR4 on T cells in later disease)

  • CCR5 mutation –> decreased susc to HIV
93
Q

HIV diagnosis

A

ELISA (high sensitivity); positive result –> Western blot (more specific)

94
Q

Viral load tests in HIV

A

Prognostic

AIDS when

95
Q

HIV diseases with CD4 counts

A
96
Q

Atypical pneumonias

A

Mycoplasma
Legionella
Chlamydia

97
Q

Bugs that cause osteomyelitis in sickle cell disease

A

Salmonella, Staph aureus

98
Q

Three vaginal infections and their differences in inflammation, discharge, histo

A

Bacterial vaginosis - no inflamm, thin/white discharge with fishy odor, clue cells, high pH

Trichomoniasis (protozoan) - strawberry cervix, grey/green/foul-smelling discharge, motile trichomonads, elevated pH

Candida - inflammation, thick/white/cottage cheese discharge; can see pseudohyphae on slide, normal pH

99
Q

ToRCHHeS

A

Toxo - chorioretinits, hydrocephalus and intracranial calcifications

Rubella - PDA, cataracts, deafness

CMV - hearing loss, seizures, periventricular calcifications, petechial rash

HIV - chronic diarrhea, recurrent infxns

Herpes simplex 2 - encephalitis, herpetic lesions

Syphilis - hydrops fetalis; if survives –> facial abnormalities, deafness, saber shins etc

Also Parvo B19 –> hydrops fetalis

100
Q

Penicillinase resistant penicillins

A

Dicloxacillin, nafcillin, oxacillin

Narrow spectrum

Bulky R group –> resistance to beta lactamase

Used for staph aureus (not MRSA)

101
Q

Aminopenicillins

A

Amoxicillin, ampicillin

  • extended spectrum PCN (HHELPSS) + enterococci:
H. flu
H. pylori
E. coli
Listeria
Proteus 
Salmonella
Shigella
102
Q

Abx that block cell wall synthesis

A

Penicillin
Cephalosporins
Carbapenems
Monobactams

103
Q

Abx that block folic acid synthesis

A

Sulfonamides - inhibit folate synthesis by mimicking PABA that inhibit dihydropteroate synthase (Dapsone = closely related - treats lepromatous leprosy); tx for G+, G-, Nocardia, Chlamydia;; can –> hemolysis if G6PD deficient, nephrotox, photosensitivity, kernicturus; res = altered enzyme, decreased uptake, increased PABA synth

Trimethoprim - inhibit dihydrofolate reductase; used with sulfonamides (synergy) for UTIs, Shigella, Salmonella, PJP treatment and prophylaxis, toxo prophylaxis; can –> megalo anemia, leukopenia, granulocytopenia (give folate supplement)

104
Q

Abx that block DNA topoisomerase

A

Fluroquinolones - “flox”

Don’t take with antacids!

treat GNR, Neisseria

tox: GI upset, superinfxns, skin rashes, headaches, dizziness; contraind: preg, nursing, kids (may damage cartilage, prolong QT), old people/people on steroids (tendonitis or tendon rupture)
res: mutated target (DNA gyrase), efflux pumps

105
Q

Abx that damage DNA

A

Metronidazole

  • used for GET GAP (anaerobes below the diaphragm)
Giardia
Entamoeba
Trichomonas
Gardnerella vaginalis
Anaerobes
  • can –> disulfiram-like rxn (severe flushing, tachy, hypotension) with alcohol
106
Q

Antibiotics that block RNA synthesis

A

Rifampin

107
Q

Antibiotics that block protein synthesis

A

50S subunit:

chloramphenicol - inhibit peptidyl transferase, used for meng, RMSF but toxic (aplastic anemia and gray baby; res = plasmid-encoded acetyltransferase inactivates drug)

macrolides - “ithromycin” - block peptide transfer/translocation; treat atypical pneumonias, chlamydia, B pertussis; can case arrythmia (increased QT), GI issues, cholestatic hep, rash, eosinophilia; inhibit cyt C; res: methylation of rRNA binding site so drug can’t bind

streptogramin
clindamycin (blocks peptide transfer)

linezolid (prevents formation of initation complex, G+, inc VRE and MRSA; can –> bone marrow supp, peripheral neuropathy; res = point mutation of rRNA)

30S subunit:
- aminoglycosides (inhibit init complex formation); “-micin” + “kacin” - require O2 so ineffective against anaerobes, use for GNR; res = bacterial enzymes inactivate drug; can –> nephrotox, ototox, teratogenic

TCN (inhibit A site t-rna binding, accum intracellularly so good for rickettsia and chlamydia, also borrelia and mycoplasma; can –> GI distress, tooth discoloration, decreased bone growth; resistance = decreased uptake or increased efflux by plasmid-encoded transport proteins)

108
Q

Cephalosporins

A

First gen: PEcK
Proteus
E coli
Klebsiella

Second gen: HENPEcKS
H. flu
Enterobacter
Neisseria
Proteus
E coli
Klebsiella
Serratia marcescens

Third gen: ceftriaxone, cefotaxime etc

Fourth gen: cefepime (gram neg, esp pseudomonas)

Fifth gen: ceftaroline (broad, inc MRSA, no pseudomonas)

109
Q

Carbapenems

A

Broad spectrum, beta lactamase resistant

Administer with cilastatin to inhibit renal metabolism

Lots of side effects (CNS toxicity)

  • For gram pos cocci, GNR, anaerobes
110
Q

Monobactam

A

Aztreonam

Beta lactamase resistant

Treats GNR only

No cross allergy with PCN

111
Q

Vancomycin

A

Inhibits cell wall peptidoglycan by binding D-ala-D-ala (not susc to beta lactamases, but yes to AA modification to D-ala-D-lac

  • May –> nephrotox, ototox, flushing (red man syndrome - give antihistamines and slow infusion to prevent)
  • Treats G+ only!!
112
Q

Daptomycin

A
  • lipopeptide (disrupts cell membrane)
  • used for GPC, esp Staph aureus
  • can –> myopathy, rhabdo
113
Q

Rifamycins

A

Rifampin - TB (prophylaxis + tx - induces cyt P450)

Rifabutin - MAC proph/tx

Res: mut decrease drug binding to RNA pol (develops fast)

114
Q

Kat G

A

Encodes Bacterial catalase-peroxidase that’s needed to convert isoniazid to active metabolite (used for proph and treatment of TB)

115
Q

Ethambutol

A

Decreased carb polymerization of mycobacterium cell wall by blocking arabinosyltransferase

Can –> optic neuropathy

116
Q

Prophylaxis for endocard/dental procedures

A

Amoxicillin

117
Q

Prevention of gonococcal conjunctivitis in newborns

A

Erythromycin ointment

118
Q

Prevention of post-surgical infection with Staph aureus

A

Cefazolin

119
Q

Prophylaxis of strep (in child with prior RF or pregnant woman)

A

Penicillin

120
Q

Amphotericin B mechanism

A

Binds ergosterol in fungal membrane and makes pores to allow leakage of electrolytes

Keep hydrated to decrease nephrotoxicity, supplement with K and Mg

For serious, systemic mycoses

Class: polyene (also nystatin - too toxic for systemic use; eg “swish and swallow” for thrush)

121
Q

Azole mechanism

A

Inhibit cyt P450 that converts lanosterol to ergosterol (some off target –> inhibition of host cytochrome P450, also testosterone synth inhibition)

122
Q

Terbinafine mechanism

A

Inhibits fungal squalen epoxidase - used for dermatophytoses (esp oncychomycosis)

123
Q

Echinocandin mechanism

A

Inhibit cell wall synthesis in fungi

Used for invasive aspergillosis and candida

“-fungin”

124
Q

Griseofulvin mechanism

A

Interferes with MT function –> disruption of mitosis

Treats superficial fungal infxns (eg dermatophytes)

Teratogenic and carcinogenic, induces cyt P450

125
Q

Nifurtimox - used to treat ____?

A

T. cruzi treatment

126
Q

Pyrimethamine - used to treat ____?

A

Toxo

127
Q

Suramin and melarsoprol - used to treat ____?

A

T. brucei

128
Q

Stibogluconate - used to treat ____?

A

Leishmaniasis

129
Q

HIV life cycle and antivirals’ mechanisms at each step

A
  1. Fusion - Maraviroc (binds CCR5 - inhibits interaction with gp120) prevents attachment; Enfuvirtide prevents penetration (binds gp41)
  2. Uncoating and reverse transcription - blocked by NRTIs [all nucleosides except tenofovir, so need to be phosphorylated to be active –> chain term; ZDV (zidovudine/AZT) used for proph and to decrease fetal transmission)and NNRTIs (different binding site from NRTIs, don’t need phosphorylation, may –> rash and hepatotox)
  3. DNA integration - blocked by integrase inhibitors (“-gravir”) - increase Cr kinase
  4. transcription
  5. Translation
  6. Proteolytic processing - blocked by protease inhibitors (“-navir”)
  7. Packaging and assembly –> budding –> release

Standard regimen = 2 NRTI + 1 NNRTI or 1 protease inhibitor or 1 integrase inhibitor

130
Q

Virus life cycles (general) with antiviral mechanisms at each step

A
  1. Binding to host cell and endocytosis - blocked by interferon-alpha, which inhibits production of receptor proteins in host (HBV, HCV)
  2. Uncoating - blocked by amantadine and rimantadine (no longer used for flu b/c of resistance)
  3. Nucleic acid synthesis (blocked by guanosine analogs - acyclovir [HSV, VZV], ganciclovir [CMV], famciclovir [zoster], only phosphorylated and thus fxal in viral cells (res when this kinase is mutated), can –> kidney pbs if pt isn’t adequately hydrated; viral DNA/RNA pol inhibitors - Cidofovir (nephrotox), Foscarnet [HSV, CMV], res via mutated polymerase; Guanine nucleotide synthesis - Ribavirin [RSV, HCV]
  4. Virion assembly
  5. Release of progeny - inhibited by neuraminidase inhibitors (oseltamivir, Zanamivir - used for flu)
131
Q

Hep C drugs

A

Ribavirin (inhibits syntehsis of guanine) - teratogen!

Simeprevir (protease inhib) - don’t use as monotherapy! can –> photosens

Sofosbuvir (RNA pol inhibitor) - don’t use as monotherapy!

132
Q

Abx to avoid in preg

A 
Sulfonamides - kernicterus
Aminoglycosides - ototox
Fluoroquinolones - cartilage damage
Clarithromycin - embryotoxic
TCN - teeth, bone growth
Ribavirin - teratogen
Griseofulvin - teratogen
Chloramphenicol - gray baby (lack liver enzyme to metabolize it)

SAFe Children Take Really Good Care

133
Q

Treatment for local infection with systemic mycoses?

systemic infection?

A

local = fluconazole or itraconazole

system = “big guns” - aka amphotericin B

134
Q

Bugs causing brain abscess most commonly

A

Strep viridans, Staph aureus

if after dental procedure, oral anaerobes

135
Q

Common causes of meng in newborn? children? adults? elderly?

A

newborn: GBS, E Coli, Listeria

Kids: Strep pneumo, N meng, HiB, enteroviruses

Adults: Strep pneumo, N. meng, Enteroviruses, HSV2 (1 = encephalitis)

Elderly: Strep pneumo, GNR, Listeria

136
Q

Common causes of pna - in neonates, kids, adults, elderly

A

Neonates: GBS, E coli

Kids: viruses (eg RSV), mycoplasma, Chlamydophila, Strep pneumo

Adults (

137
Q

Amoebas with ingested RBC

A

Entamoeba

sx = bloody diarrhea, abd cramps, pus in stool, RUQ pain and liver abscesses

tx =metronidazole, iodoquinol

138
Q

Acid-fast cysts in the stool

A

Crypto (cysts in water –> diarrhea), Toxo (cysts in raw meat or cat feces)

139
Q

Macrophages containing amastigotes

A

Leishmania donovani (transmitted by sandfly)

sx = HSM, malaise, anemia, weight loss

140
Q

Tear-shaped trophozoites with two nuclei in stool

A

Giardia

sx = bloating, flatulence, nonbloody diarrhea, steatorrhea

transmitted via cysts in water

141
Q

Myelin basic protein

A

may be present in CSF with demyelination (eg with PML from JC virus reactivation)

diag: bx or PCR for JC virus in CSF

142
Q

protein and glucose in bacterial meng

A

protein elevated, glucose normal

143
Q

CMV encephalitis vs PML

A

CMV - more systemic sx; histo: giant cells with eosinophilic inclusions; enhanicing periventricular WM lesions

PML: nonenhancing T2-hyperintense lesions

Microbiology (2 decks)

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