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Infectious Diseases > Bacteria > Flashcards

Bacteria Flashcards

1
Q

Diseases causing visible sulfur granules (2)

A

Actinomyces and Mycetoma

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2
Q

Actinomyces: M, C, D, T

A

M: filamentous GPR, prefers anaerobic conditions
C: especially head and neck abscesses; but can cause abscesses in many locations
D: by cx; is normal flora so can be contaminant in respiratory sample
T: PCN → amoxicillin (if allergy then doxy or clindamycin)

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3
Q

Nocardia: M, C, D, T

A

M: filamentous gram+ rod; weakly acid fast, aerobic
D: by cx
C: lung, brain abscesses, 20-30% disseminated if immunosuppressed, skin infection
T: depends on disease and host; usually involves TMP-SMX, often with imipenem; also activity from amikacin and cephalosporins

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4
Q

Mycetoma: causes, C, T

A

Causes: often polymicrobial, includes Streptomyces, Actinomadura, fungi, Nocardia
C: inoculation then chronic, indurated, subcutaneous infection, draining sinuses, sulfur granules
T: streptomycin + (TMP-SMX OR dapsone)

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5
Q

Bartonella: M, organisms (3), D

A

M: gram negative rod, fastidious, mainly intracellular
Organisms: B. henselae, B. quintana, B. bacillformis
D: hold blood cx (and do lysis centrifugation), can run PCR on tissue; serology can be helpful, Warthin-Starry stain on path

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6
Q

B. henselae: E, C, T

A

E: cats
C: cat scratch disease, bacillary angiomatosis, bacilarry peliosis, peliosis hepatitis, endocardiits, retinitis, CNS infections
T: cat scratch disease no tx or azithro, other forms consider doxy or erythromycin

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7
Q

B. bacilliformis: E, C, T

A

E: from sand fly bites in the Andes
C: Oroya fever → acute sepsis, LAD, hemolytic anemia, splenomegaly; may cause chronic angioma-like skin lesions
T: cipro

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8
Q

B. quintana: E, C, T

A

E: body lice
C: trench fever → fever, HA, arthralgias, bacteremia and sometimes endocarditis
T: for endocarditis give gentamicin + CTX +/- doxy

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9
Q

Botulism: M, E (6), C, D, T

A

M: anaerobic GPRs with spores, box car shaped
E: home canned food, wound, heroin, intranasal cocaine, Botox, bioterrorism
C: descending paralysis, bulbar sx
D: toxin assay on serum (also could do from emesis, stool, food), largely clinical diagnosis
T: antitoxin + (PCN or metronidazole)

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10
Q

Brucella: M, organisms (4), E, C, D, T

A

M: aerobic, intracellular, gram- coccobacilli
E: cattle and buffalo (B. abortus), goats, sheep, and camels (B. melitensis), pigs (B. suis), and dogs (B. canis); most common in Latin America, Middle East, Mediterranean; usually through meat or cheese
C: fever, LAD, endocarditis, bone and liver lesions, meningitis; very nonspecific
D: blood cx (difficult), serologies
T: doxycyline + (rifampin OR streptomycin OR gentamicin)

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11
Q

Burkholderia pseudomallei: M, E, D, C, T, evil cousin

A

M: aerobic GNR; grows best on specialized media
E: soil and water in SE Asia, India, Northern Australia
D: cx (can grow on normal media)
C (melioidosis): subacute or chronic PNA, can reactivate years later, can spread hematogenously and cause abscesses in many places
T: ceftazidime → TMP-SMX (alternate meropenem → doxy or amox/clav)
Evil cousin: Burkolheria mallei is a possible bioterrorism agent (acquired rarely from horses and cats) and can cause pain and drainage at skin inoculation or ulcerative tracheobronchitis and PNA from inhalation

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12
Q

Corynebacterium diphtheriae: M, E, C, D, T, isolation, ppx

A

M: club shaped (Chinese letters) GPR, facultative anaerobe
E: most cases in former USSR; unvaccinated
C: bull neck, gray pseudomembrane in pharynx, palate, uvula (bleeds when scraped), rhinorrhea; can get myocarditis (25%), neuropathies (5%); some get only a cutaneous non-healing ulcer version (homeless in US)
D: cx
T: antitoxin + (PCN or erythromycin); give vaccine after recovered
Isolation: droplet
PPx: vaccine if not up to date and erythromycin for 7-10d (latter even if vaccinated)

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13
Q

Helicobacter pylori: M, C, D, T, follow-up

A

M: curved GNR, facultative anaerobe
C: 85-90% w/o sx; ulcers (1-10%) with DU»>GU; gastric cancer (0.1-3%), MALT lymphoma
D: UBT and stool antigen > 90% sensitive and specific; from bx can do rapid urease test (>90% sensitive, 95% specific) and histology (90-98% sensitive and specific) and cx (73% sensitive, 100% specific)
T:
–Clarithro resistance 15-20%: option 1 → PPI + bismuth + metronidazole + tinidazole; option 2 → some form of sequential therapy
Follow-up: stool antigen or UBT > 4wks after treatment completed (if gastric ulcer must do endoscopy)

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14
Q

Leptospirosis: M, E, C, D, T

A

M: spirochete
E: animal urine to intact skin → seen in triathletes, veterinarians, farmers, rafters
C: fever, myalgias, HA (aseptic meningitis), conjunctival suffusion; in severe cases jaundice and pulmonary hemorrhage; often elevated bili (more than AST) and leukocytosis
D: agglutinin test
T: PCN or doxy

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15
Q

Meningococcemia: M, C, T, PPx

A

M: aerobic gram negative diplococcus; serogroups A, B, C, Y, W-135; B and C most common in US (B is not in the vaccine)
C: can start with sore throat, ear pain, coryza, abdominal pain; one complication is Waterhouse-Friderichsen (hemorrhagic adrenal infarcts)
T: PCN or CTX
PPx: give to close contacts; rifampin x2d; cipro once, CTX once

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16
Q

NTM clinical syndromes: pulmonary (4), lymphatic (3), cutaneous (6), disseminated (5)

A

Pulmonary: MAC, M. kansasii, M. abscessus, M. xenopi
Lypmhatic: MAC (80%), M. scrofulaceum → surgery most common treatment for this; M. bovis
Cutaneous: M. fortuitum, M. marinum, M. abscessus, M. chelonae, M. leprae, M. hemophilum, M. ulcerans (Buruli ulcer)
Disseminated: MAC, M. kansasii, M. haemophilum, M. chelonae, M. genovense

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17
Q

NTM diagnosis: rapid growers (4), difficult to culture (2), genetic probe (2), special growth media (1)

A

Rapid growers (<1wk): M. abscess, M. fortuitum, M. chelonae, M. immunogenum
Difficult to culture: M. genevense (very slow growth), M. leprae (no growth)
Genetic probe: MAC and M. kansasii
Special growth media: M. haemophilum

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18
Q

Criteria for pulmonary NTM

A

1) compatible clinical syndrome with no better explaination (cough, fever, fatigue, weight loss)
2) abnormal chest imaging
3) two positive cx from sputum or one from bronch or biopsy w/ granuloma and/or AFB

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19
Q

MAC (non-HIV): C (3); T, Duration

A

C1: middle-aged male smokers with pulmonary syndrome usually chronic, progressive like TB
C2: middle-aged nonsmoking women with pulmonary syndrome usually very slowly progressive
C3: those exposed to indoor hot water like hot tubs with acute dyspnea, cough, fever with infiltrates and nodules on imaging
T: often don’t need to treat
–Regimens: clarithro + ETB + rifampin (or rifabutin); if severe add streptomycin or amikacin
–Other active meds: azithro (less data than clarithro), moxifloxacin, levofloxacin
Duration: until cx negative x12mo (failure if no improvement for 6mo or cx positive at 12mo)

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20
Q

MAC (HIV): T, Duration

A

T: clarithro + ETB +/- rifabutin; get clarithro and azithro susceptibility testing (background resistance is 17%)
Duration: treat until CD4 >100 for 12mo

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21
Q

M. kansasii: C, T, Duration

A

C: pulmonary (similar to TB), can get disseminated disease (with pulmonary involvement) if CD4 <200
T: INH + ETB + Rif (rif susceptibility testing indicated and if resistant consider sulfas, macrolide, aminoglycosides, moxifloxacin or levofloxacin)
Duration: 12mo after cx negative

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22
Q

M. xenopi: C, T, Duration

A

C: usually pulmonary, more in those from rural areas
T: clarithro + INH + Rif + ETB (can often use just three drugs total)
Duration: 2mo after culture negative

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23
Q

M. marinum: C, T, Duration

A

C: granulomatous, nodular, ulcerative lesion 1-2mo after water exposure (salt water or freshwater including pools and aquariums)
T: ETB + (clarithro or Rif); other options include sulfas or doxy
Duration: 1-2mo after sx resolve

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24
Q

M. ulcerans: C, T

A

C: chronic cutaneous ulcers; more in Africa than US
T: debridement, streptomycin and rifampicin

25
Q

M. haemophilum: C, T

A

C: in immunosuppressed patients (HIV, ESRD, etc), mostly causes tender ulcerative or nodule skin lesions (often of extremities)
T: some combination of Rif, clarithro, quinolones, sulfas, and aminoglycosides

26
Q

Rapid growers (3/4): C, T, Duration

A

C: all three cause skin/soft tissue infections (often after mild trauma or surgery), pulmonary disease occurs mostly in M. abscessus (cavitation <15%); pedicures and piercings have caused outbreaks of M. fortuitum
T: depends on organism
–M. abscessus: no reliable drug regimen so may need surgery; can try periodic clarithro + amikacin + (cefoxitin or imipenem or linezolid); linezolid is 48% susceptible or intermediate in vitro
–M. fortuitum: always test susceptibility; clarithro (if susceptible) + 1-2 of the following → ciprofloxacin/levofloxacin, doxycycline, sulfonamide (if severe can add amikacin, cefoxitin, imipenem); also consider linezolid (96% susceptible or intermediate in vitro)
–M. chelonae: can do clarithro with moxifloxacin/ciprofloxacin, doxy, or linezolid for 4-6mo (add tobra or imipenem if severe); linezolid is 94% susceptible or intermediate in vitro
Duration: usually 4-6mo for skin and 10-12mo for lung

27
Q

M. immunogenum: C, T

A

C: bacteremia, catheter associated infections, septic arthritis; more common in leukemia
T: uncertain but susceptible to amikacin and clarithromycin (resistant to ciprofloxacin, doxy, cefoxitin, tobra, sulfamethoxazole)

28
Q

M. leprae: C, T

A

C: 3 types

  • -Lepromatous: high bacillary load, diffuse involvement, anergy, deformity of facial structures
  • -Tuberculoid: paucibacillary, 12mo of dapsone + rifampin + clofazimine; tuberculoid → >6mo of dapsone and rifampin
29
Q

Pertussis: M, C, D, T, PPx

A

M: aerobic gram negative coccobacilli, fastidious (grows well on chocolate blood agar with cephalexin)
C: 3 phases
–Catarrhal: 7-10d, like a viral URI but can be with WBCs as high as >50,000 (lymph predominant)
–Paroxysmal: 1-6wks, paroxysms of cough with long inspiratory gasp, can come with sweats and sometimes post-tussive emesis; in adults only 40-50% get sweats, only 20-40% get whoop, only 40% have post-tussive emesis so sx may just be limited to prolonged cough
–Convalescent: 2-3wks but new viral URI can precipitate again
D: PCR of respiratory secretions best test; Bordetella pertussis from N-P culture (special media) also works but limited sensitivity
T: treat if <8wks if healthcare worker); give azithro x5d or clarithro x7d or TMS if can’t take macrolides
PPx: give same regimen as used for treatment to close contacts regardless of vaccination status

30
Q

Rhodococcus: M, C, D, T

A

M: GPR, weakly acid fast, aerobe
C: indolent PNA, brain and skin abscesses in immunosuppressed hosts
D: cx (cx are salmon pink)
T: (vancomycin OR imipenem OR meropenem) + (fluoroquinolone OR rifampin) then oral therapy transition

31
Q

LTBI treatment

A
  • -preferred regimens are INH for 9mo or weekly rifapentine and INH x 12wks (latter with DOT)
  • -if INH resistant exposure consider rifampin for 4mo
32
Q

TB treatment

A

Initial phase: 2 months of RIP; add ETB if INH resistance prevalence >4%; can d/c ETB if isolate is pan-susceptible
Continuation phase: 4 months if RI; if cx positive at 8wks duration of RI is for 6mo after cx negative; can consider weekly rifapentine and INH in this phase if HIV-, no cavitary TB, and smear- at 8wks

33
Q

MDR TB treatment

A

use 4-5 susceptible drugs and include AG (or at least an injectable) if possible; drugs include FQs (moxifloxacin preferred to levofloxacin), AGs (streptomycin, capreomycin, kanamycin), PZA, maybe rifamycins, cycloserine, ethionamide, bedaquiline (this last one is only if no other good drugs available)

34
Q

TB and HIV DDIs

A
  • -If using rifampin: cannot use PIs and only safe NNRTI is EFV (dose EFV at 800mg if >60kg); can use RTG (dose 800mg q12); cannot use elvitegravir
  • -If using rifabutin: need to decrease dose if used with ATV, NFV, PIs (cannot use with SQV); need to increase dose if used with EFV (no change with NVP, ETV), cannot use with RPV; RTG likely ok without dose change
35
Q

Legionella: M, C, D, T

A

M: GNR, prefers aerobic conditions and it’s own media
C: 50% have N/V/D; 50% have confusion, 35% have chest pain
D: urine antigen only detects L. pneumophilia subtype 1 which causes 85% of Legionella pneumonia; PCR will turn positive for any Legionella; need buffered charcoal yeast extract to grow
T: levofloxacin, moxifloxacin. azithromycin x10d

36
Q

Mycoplasma pneumonia: M, C, D, T

A

M: aerobic, fastidious, no cell wall
C: can cause severe tracheobronchitis, cough usually last >14d and often non-productive, can be associated with post-tussive syncope, incontinence, or vomiting; clinically very similar to pertussis; high attack rate within families
–Extrapulmonary: cold agglutinin hemolysis (50-75% of cases), encephalitis, meningitis, transverse myelitis, rash, bullous myringitis
D: PCR from respiratory secretions
T: doxycycline, azithromycin, clarithromycin, fluoroquinolones (but 69% of isolates from China were resistant to macrolides in 2010 study)

37
Q

Strep pyogenes PNA: M, E, C

A

M: group A Strep, GPC, B-hemolytic, prefers anaerobic conditions
E: often follows viral infection (second most common bacterial pneumonia post-influenza; follows Strep pnuemo)
C: 40% develop an empyema; also complicated by mediastinitis, pericarditis

38
Q

Fusobacterium necrophorum: M, C

A

M: anaerobic GNR
C: pharyngitis, tonsillitis leading to suppurative phlebitis of the jugular vein leading to hematogenous spread to lung where abscesses are formed (Lemierre’s syndrome)

39
Q

Yersinia pestis: M, E, C, D, T, PPx, Control

A

M: bipolar GNR, aerobic, stains well on Geimsa, safety pin
E: in US, most cases are in CA and four corners area; from flea bite of infected rodent (also seen in outdoor cats in CO); bioterrorism
C: three types
–Bubonic: lymphadenitis with fever, HA sometime
–Pneumonic: about 1 case every 1 years in US; concern for bioterrorism (also consider anthrax and tularemia, but plague is one that causes hemoptysis); may progress very rapidly and is 100% fatal if not treated
–Septic: usually an evolution from an untreated bubo
D: cx (grows on standard media), DFA, serology
T: streptomycin (or gentamicin) then transition to oral drugs like doxy (maybe cipro or third generation cephalosporin)
PPx: doxycycline or cipro for 7d
Control: viable in the environment for only a few hours at night (less in day); in healthcare setting N95 and negative pressure isolation for at least 48hrs or until sputum is negative (don’t need if just bubonic)

40
Q

Francisella tularensis: M, E, C, D, T, PPx, Control

A

M: pleomorphic aerobic GNR, doesn’t grow well (need chocolate agar)
E: : from ticks or meat from rabbit, squirrels, beavers; bioterrorism
C: red, tender LN and ulceration at site of inoculation (can progress to sepsis); can get severe PNA from inhalation
D: cx (but difficult), serology
T: streptomycin or gent (alternative doxy or cipro)
PPx: doxy (or ciprofloxacin) for prophylaxis for 14d
Control: not viable for long in environment if released as agent of bioterrorism but otherwise can persist in the soil for days; not transmissible in healthcare setting

41
Q

Bacillus anthracis: M, E, C, D, T, PPx, Control

A

M: aerobic GPR, spores
E: animal fur/hide exposure; bioterrorism
C: skin disease with ulcerative lesion/eschar (usually painless) and little vesicles around it and a lot of edema; inhalation disease with severe pneumonia and shock (common to have large bloody pleural effusion and wide mediastinum with enlarged nodes), sometimes melena and meningitis
D: cx (can take from skin vesicle), more common to show up in blood than sputum (grows on standard media)
T: consider ciprofloxacin (first line agent) + (meropenem or imipenem or PCN if susceptible – need CNS penetration) + (linezolid or clindamycin – inhibit toxin production); need to drain pleural fluid
PPx: doxycycline or ciprofloxacin for 60d (maybe amoxicillin)
Control: once patient and clothes are washed, do not need to isolate; also spores survive for days at most on soil (if buried can be for longer) – this is only category A agent that lasts more than a few hours in the environment

42
Q

Neisseria gonnorrhoeae (disseminated): C, D, T

A

C: two overlapping syndromes

  • -arthritis: purulent infection
  • -constellation of tenosynovitis (usually hands), dermatitis (80% sensitive; look for mucosal disease with NAAT or cx as this is usually your best chance to isolate it

T: only need 7-10d of abx and no surgical drainage

43
Q

Borrelia recurrentis: M, E, C, D, T

A

M: spirochete
E: lice exposure, most in East Africa and South America; often refugee camps
C (epidemic relapsing fever): relapsing fever → sudden onset fevers, HA, breaks after a few days then every 6-10d it relapses
D: can see spirochetes on blood smear
T: single dose of tetracycline or erythromycin

44
Q

Rickettsia akari: M, E, C, T

A

M: obligate intracellular
E: mites on mice
C (Rickettsialpox): eschar at site of innoculation, vesicular rash
T: doxy

45
Q

Orientia tsutsugamushiL M, E, C, T

A

M: obligate intracellular, Rickettsial family
E: chiggers in SE Asia
C (scrub typhus): eschar at site of inoculation, fevers, altered mental status, rash, low platelets, lymphocytes, elevated LFTs
T: doxy

46
Q

Rickettsia prowazekii: M, E, C

A

M: obligate intracellular
E: from human lice (poor sanitation) and flying squirrels
C: non-specific, low platelets, elevated LFTs

47
Q

R. rickettsii: E, C, D, T

A

E: all over the US but mainly in south Atlantic states
C (RMSF): fever (99%), HA (91%), rash (88%), myalgia (93%), N/V (60%); rash classically involves palms and soles; low WBCs at times, thrombocytopenia common, hyponatremia in 50%; no eschar
D: skin biopsy with DFA or PCR, rise in serologies over 2wks
T: doxy

48
Q

R. parkeri, akari, africae: E, C, T

A

E: parkeri from ticks, akari from mites, africae from African ticks
C: similar to RMSF but all cause a tache noir (eschar at site of inoculation)
T: doxy

49
Q

Ehrlichiosis: E, C, D, T

A

E: New England, SE, South Central US
C: leukopenia, thrombocytopenia, increased LFTs, rash is rare (contrast RMSF)
D: look for morulae on blood smear (2-3%), PCR and serology
T: doxy

50
Q

Anaplasmosis: E, C, D, T

A

E: New England, upper Midwest
C: leukopenia, thrombocytopenia, increased LFTs, rash is rare (contrast RMSF)
D: look for morulae on blood smear (>20%), PCR and serology
T: doxy

51
Q

B. hermsii, turicatae, parkeri: E, C, D, T

A

E: Ornithodoros soft tick exposure, worldwide, in US mostly between 2,000-7,000ft elevation
C (endemic relapsing fever): sudden onset fevers, HA, usually milder than louse-borne disease; fever breaks after 4-10d then relapses; thrombocytopenia and elevated LFTs
D: can see spirochetes on blood smear (note: Lyme serologies may be positive)
T: doxy or erythromycin for 5-10d

52
Q

Lyme disease: M, E, C, D, T

A

M: spirochete
E: no transmission in 24hrs, 8% in 48hrs, 69% in 72hrs
C: early localized (single erythema migrans), early disseminated (multiple EMs, AV block, 7th nerve palsy, radiculopathy, meningitis), late (monoarticular or oligoarticular arthritis, rarely encephalopathy, peripheral neuropathy), post-Lyme disease syndrome (11.5% w/ sx after effective tx)
D: ELISA + Western blot, PCR for synovial fluid and maybe CSF)
T: ppx w/ doxy 200mg x2, tx early w/ amox or doxy x10-14d (use CTX if cardiac or neurologic complications x12-28d), late with amox or doxy x28d

53
Q

Acinetobacter: M, T

A

M: gram negative coccobacillus

T (% susceptible): minocycline (79%), doxycycline (60%), amikacin (34%), amp/sulbactam (26%). Imipenem (37%), colistin

54
Q

Staph aureus: uncomplicated bacteremia (4)

A

1) negative echo, 2) clear BCx and no fevers at 72hrs, 3) no prosthetic material, 4) no evidence of metastatic infection

55
Q

Staph aureus: complications of bacteremia (5)

A

1) endocarditis (12% native valve, 40% prosthetic valve), 2) vertebral osteo (3.3%), epidural abscess (2.5%), septic arthritis (6%), cardiac device infection (>28%)

56
Q

PPD >5mm considered positive (5)

A

1) HIV, 2) close contact of active case, 3) fibrotic CXR, 4) steroids (prednisone >=15mg for >=2-4wks, 5) on immunosuppressions/transplant
* Up to 20% with active TB don’t react (may be as high as 80% with HIV). NTM can cause false positives (not with IGRA though)

57
Q

PPD >10mm considered positive (6)

A

1) from high prevalence country, 2) IVDU, 3) homeless, 4) medically underserved, 5) in long-term care facility, 6) job with high-risk of transmission to vulnerable population

58
Q

NAAT Mycobacteria testing: genetic probe vs. GenProbe/GeneXpert

A

Genetic probe: TB vs. MAC vs. M. kansasii
GenProbe/GeneXpert: TB vs. not-TB (98% sensitive on smear+, 70% sensitive on smear-; 99% specific); latter identifies rifampin resistance

Infectious Diseases (11 decks)

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