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HCLD Micro > Aerobic Gram Pos Rods > Flashcards

Aerobic Gram Pos Rods Flashcards

1
Q

Bacillus characteristics

A

-Large rod (boxcar)
-Endospore forming
-Aerobic / facultative anaerobe
-Mesophilic
-Cat+
-Motile (peritrichous flagella) (NOT anthrax)
-Characteristics can vary based on strain

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2
Q

Bacillus habitat

A

-Everywhere - soil, water, all pH, salt conc, etc.
-Endospores are resistant to heat, desiccation, radiation, and disinfectants
-Most are not clinically relevant
–Clinically relevant groups are: B. cereus group, B. megaterium, B. subtilis, B. licheniformis, Bacillus pumilus, and Bacillus simplex
–Only B. anthracis is obligate pathogen of animals -> rest are entomopathogens

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3
Q

Bacillus infection

A

-Inhalation
-Digestion
-Injection
-Injury

Typically immunocompromised or comorbid

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4
Q

B. anthracis transmission

A

-Wild/domesticated mammals ingest from soil/water/vegetation (rarely infected carcasses)
-Flies (biting and nonbiting) can act as vectors (endemic areas)
-Human infection typically from handling infected animal carcasses or processing hides etc. (industrial vs. nonindustrial)
-Vax !! has decreased incidence
-Incidences of infection from contaminated heroin in Europe
-Human-to-human is RARE -> only from abscess drainage

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5
Q

B. anthracis - historical

A

-Koch - Germ Theory of Disease (Thank you!)

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6
Q

B. anthracis ANTHRAX disease states / chance of death

A

1) Cutaneous - 1%
2) GI - 25-60%
3) Inhalation - 46%
4) Injectional - 33%

-Taken up by macrophages -> rods activate -> reproduce in lymphatic system -> invade bloodstream (HIGH concentration)

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7
Q

Anthrax symptoms

A

1) Start mild (fever, malaise, GI)
2) Lymphohematogenous dissemination leads to dyspnea, cyanosis, severe pyrexia, and disorientation, followed by circulatory failure, shock, coma, and death.

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8
Q

Cutaneous anthrax

A

-Incubation avg 1-6 days
-small papule -> ring of vesicles -> swollen blackened eschar
–“malignant” because will continue to spread w/o abx
–No fever, pus, or pain
–Death due to swelling close to airways if infection on face or neck OR if progresses to systemic
-Lesions resolve w/in a few weeks

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9
Q

GI anthrax

A

-Ingestion of undercooked infected meat
-Two forms
–1) lesions in oral cavity -> sore throat, lymphadenopathy, neck/chest edema
–2) lesions in intestines -> nausea, vomiting, pain, diarrhea, ascites

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10
Q

Inhalation anthrax

A

-Woolsorter’s disease
-NOT pulmonary -> infection is in lymph nodes, not lungs -> mediastinal hemorrhage
-Bioterrorism threat (ALL 5 deaths/11 cases out of 22 in 2001 attack)
-Incubation 4-6 days
-Fever, chills, fatigue, chills, nausea/vomiting, pleural effusion

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11
Q

Injection anthrax

A

-IV drug users
-Does not resemble cutaneous anthrax
-Site necrosis with rapid transition to septic shock
-Need surgical debridement

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12
Q

B. anthracis virulence

A

-Plasmid-encoded factors (pXO1 and pXO2)
-Turned on by increase in temp to 37C, CO2 concentration, and serum proteins

-Exotoxins (pXO1)
–EF (Edema factor) = A subunit -> inc. cAMP -> disrupts neutrophils -> disrupts water homeostasis
–PA (protective antigen) = Bish subunit -> promotes entry of EF into phagocytic cells
–LF (Lethal factor) = zinc metalloprotease -> inactivates protein kinase -> stimulates mphage TNF / interleukin-1B

-Capsule (pXO2)
–inhibits phagocytosis of the vegetative bacteria
–only bacteria with capsule composed of protein

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13
Q

Anthrax treatment

A

Cipro and Doxy

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14
Q

B. cereus characteristics

A

-Hemolytic
-Motile
-PenR
-PEA growth
-No capsule

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15
Q

B. cereus infection

A

-Opportunistic
-Local and systemic infections
-Systemic usually in immunocompromised / comorbid
-Most common = foodborne but can also be wounds

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16
Q

B. cereus food poisoning

A

-Spores in food -> heat can’t kill
-Enterotoxins released
-Nausea, diarrhea, vomiting

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17
Q

B. cereus enterotoxins

A

2 types
1) Heat-labile (Nhe) -> similar to LT from cholera/Ecoli
–Nausea, abdominal pain, diarrhea for 12-24 hours
2) Heat-stable (cereulide) -> similar to Staph aureus -> severe nausea and vomiting, limited diarrhea
–only on plasmid ces gene cluster

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18
Q

B. cereus treatment

A

NO abx -> disease caused by enterotoxins

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19
Q

Bacillus culture

A

If you need spores, grow first on TSA or NA w/ manganese and then put in fridge instead of BAP

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20
Q

Handling of B. anthracis

A

-Schedule 3 agent
-50% lethal dose for humans is 8,000 to 10,000 B. anthracis spores
-Handwashing with soap and water or with chlorhexidine gluconate, and the use of hypochlorite-releasing towels, may reduce endospore contamination of the skin.

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21
Q

Bacillus Diagnosis

A

1) Culture / PCR - lesion, biopsy, fluids
2) Serum -> LF toxin - pulmonary, GI, fluids

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22
Q

Bacillus lab testing

A

1) Gram stain: large GPR (may be Gvar depending)
2) Polychrome methylene blue - capsule visualization
3) Endospore stain (malachite green + safranin)
4) Latex agglutination / IA for toxins (Nhe & HBL)
5) PCR for pXO1 / pXO2
6) MALDI -> spores inactivated by trifluoroacetic acid

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23
Q

B anthracis culture characteristics

A

-Nonhemolytic
-Nonmotile
-Medusa-head colonies
-Colonies stand upright when lifted (beaten egg whites)
-PenS
-“String of pearls” rxn

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24
Q

B cereus GI infection types

A

1) Diarrheal
-8-16 hours incubation
-Occasional vomiting
-12-24 hours of illness
-Meat products, soups, pudding, veggies

2) Emetic
-1-5 hours incubation
-Diarrhea and vomiting
-6-24 hours of illness
-Fried or boiled rice

Must culture suspected food to confirm infectious dose present.

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25
Q

B cereus other infections

A

-Eye introduced by trauma
-meningitis, septicemia, endocarditis, osetomyelitis

26
Q

Corynebacterium characteristics

A

-Normal skin / mucous membrane flora
-Curved GPR “club shaped” “pallisades”
-Nonbranching
-Cat+
-Nonmotile
-Bile esculin -
-Facultative anaerobic

27
Q

C diphtheriae respiratory infection

A

-Colonizes pharynx
-Forms pseudomembrane
–fibrin, leukocytes, dead epis, bacteria
–can lead to suffocation
–removing membrane releases more toxin so DO NOT DO IT
-“Exotoxin rockets”
-spread by droplets or hand-to-mouth
-2-5 day incubation

28
Q

C. diphtheriae respiratory symptoms

A

1) Pseudomembrane on tonsils / throat
2) fever, malaise, sore throat

29
Q

Diphtheria toxin

A

-Phage (remember D in ABCDS)
-A (cytotoxicity) and B (Binding) subunits
-Once bound, A disrupts protein synthesis via creating ADPR to shut down EF-2

30
Q

Diphtheria diagnosis

A

1) Microscopy
–GPR palisades on gram stain
–Babst-Ernst granules w/ Methylene blue
2) Culture
–Loeffler medium / Pai agar
–Cystine-tellurite blood agar (CTBA)
—Potassium (K) tellurite inhibits most other bact.
—black/brown colonies
3) Toxin test = Elek test
–Streak out bact
–Soak filter paper in toxin
–See X if +

31
Q

Diphtheria treatment

A

1) Antitoxin
–inactivates circulating toxin only
2) Pen or Ert
3) DPT vaccine

32
Q

C jeikeium Disease

A

-Immunocompromised patients
-Infection after invasive procedure or IV drug use
-Prosthetic valve endocarditis, septicemia, meningitis, prosthetic joint infections
-Rash, subcutaneous nodules

33
Q

C jeikeium characteristics

A

-strict aerobe
-lipophilic
-nonhemolytic
-urease +
-nitrate +
-very AbxR
-treat with Vanc

34
Q

C pseudodiphtherium

A

-normal resp flora
-Resp tract infections in inmmunocompromised
-can also cause endocarditis, UTI, wound infections
-parallel rows instead of palisades
-urease +
-nitrate +

35
Q

C ulcerans

A

-acquired from cows or raw milk
-skin ulcers and pharyngitis
-produces diph toxin but at much lower levels
-Nitrate -

36
Q

C urealyticum

A

-UTIs
-urease +
-treat with Vanc

37
Q

Rhodococcus equi (formerly C equi)

A

-infects animals
-lives in soil and manure
-infects immunocompromised by inhalation
-Necrotizing pneumonia that looks like TB or Nocardia
-Nodules that cavitate
-Pleural effusion
-partially acid-fast
-salmon-pink colonies on SBA

38
Q

Listeria monocytogenes

A

-found in soil, water, milk, flies, ticks -> it’s everywhere
-causes disease in animals and humans

39
Q

Listeria characteristics

A

-facultative anaerobe
-GPR/GPCB on gram stain (can look like diphtheroid or strep)
-flagella
-tumbling motility at 25C
-facultative intracellular

40
Q

Listeria virulence

A

1) Listeriolysin O
–kills mphage
2) Catalase
3) Superoxide dismutase
4) Phospholipase C
–escape from mphage
5) Surface protein P60 induces penetration into cells
6) H-antigen flagella

41
Q

Listeria diseases - newborn

A

1) Newborn meningitis
–high fatality
–early onset = inhalation of infected amniotic fluid
–late onset (2 weeks after birth) = infected during birth

42
Q

Listeria disease - pregnant women

A

-third trimester
-bacteremia / sepsis
-flulike illness - fever, headache, myalgia
-22% result in fetal death

43
Q

Listeria disease - elderly and immunocompromised

A

-CNS infection
-Endocarditis
-2nd most common cause of meningitis in people >60
-most common for lymphoma patients, on steroids, or organ transplants

44
Q

Listeria mode of tranmission

A

-grows in cold and room temp
-deli meats, ice cream, salad, cheese, etc

45
Q

Listeria culture

A

-Optimal temp 30-35C but can grow 0.5-45C
-Umbrella in motility media at room temp only
-Cat+
-Beta-hemolytic
-CAMP+
-Bile esculin +
-Glucose+
-VP/MR+

46
Q

Listeria treatment

A

-Amp
-SXT

47
Q

Erysipelothrix rhusiopathiae characteristics

A

-GPR (may look gram variable) pleomorphic long V-shaped filaments
-cat-
-glu+
-alpha-hemolytic, ppt
-urease-
-H2S+
-VP-
-Esculin-

48
Q

Erysipelothrix rhusiopathiae infections

A

Typically in patients with heart disease or alcoholism

1) Erysipeloid (localized skin disease)
–hands and fingers b/c inoculated through work activities
-elevated purple lesion w/ discoloration in the middle
-fever, arthralgia, lymphangiitis, lymphadenopathy
-heals in 3-4 weeks/months
2) Septicemia / Endocarditis (38% mortality)
3) Diffuse cutaneous infection
–exacerbation of lesion

49
Q

Arcanobacterium characteristics

A

-cat-
-nonmotile
-glu+
-Beta-hemolytic
-Black spot on agar when colony scraped off
-Inhibits CAMP (reverse CAMP)
-pleomorphic GPR w/ rudimentary branching
-PenR
-Erythromycin S

50
Q

Arcanobacterium diseases

A

1) Pharyngitis
–similar to BHS infection
–50% rash on hands and feet
2) Soft tissue infections
3) Sepsis
4) Endocarditis

51
Q

Gardnerella vaginalis

A

-pleomorphic GPR/GPCB (can be gram var)
-Clue cells
-Normal vaginal flora
-grow on human or rabbit blood agar for beta colonies
-hippurate +

52
Q

Gardnerella vaginalis disease

A

Bacterial vaginosis
-stinky discharge
-vaginal pH >4.5
-Decrease in Lactobacillus -> increase pH -> increase G vag
-treat with metronidazole or clindamycin

53
Q

Nocardia (Aerobic Actinomyces) characteristics

A

-Aerobic
-Branched, finely beaded, GPR (but many not stain well with gram stain)
-weakly acid-fast (modified acid-fast +)
-slow-growing (1 week or more)
-found in soil

54
Q

Nocardia pathogens

A

-N. asteroides
-N. brasiliensis
-N. farcinica
-N. nova

55
Q

Nocardia virulence

A

-No virulence factors identified
-Virulence correlated with cell wall component alterations
-Superoxide dismutase
-Catalase
-Nocobactin -> iron chelator

56
Q

Nocardia Pulmonary disease

A

-N. asteroides
-inhalation
-typically immunocompromised (~10% are not)
-40% of diagnosis made during autopsy
-confluent bronchopneumonia that resembles TB (abscesses and cavitations)
-progresses faster than TB (weeks-months instead of years)
-no lung scarring or granulomas
-no “sinus” formation or “sulfur granules”
-dissemination to brain

57
Q

Nocardia Cutaneous disease

A

-N. brasiliensis
-Inoculated into skin during minor trauma (splinter or thorn)
-Localized abscess -> destroys tissue and bone
-“Actinomycotic mycetomas”
-Swelling, draining, yellow-orange “sulfur granules”

58
Q

Nocardia culture

A

-Normal media; 22-37C
-3-6 days to grow
-will grow on MTM & BCYE
-chalky, matte, velvet appearance
-crumbly breadcrumbs
-can be orange or tan
-may produce aerial hyphae
-parafin bait test -> parafin substrate

59
Q

Nocardia treatment

A

-Drainage
-Surgery
-SXT
“Treatment of Nocardia is a SNAP
Sulfa for
Nocardia
Actinomyces give
Penicillin”

60
Q

Other Actino

A

1) Actinomadura
–mycetomas
–similar to Nocardia
–differentiate bc cellobiose / xylose +
2) Streptomyces
–mycetomas
–sputum, wound, blood, brain
3) Tropheryma whipplei
–Whipple disease
–facultative intracellular
–impairs breakdown of foods and absorption of nutrients
–diarrhea, weight loss, malabsorption, neurological changes —> fatal
–SXT for 1 year

HCLD Micro (13 decks)

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