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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
B cereus other infections
-Eye introduced by trauma -meningitis, septicemia, endocarditis, osetomyelitis
26
Corynebacterium characteristics
-Normal skin / mucous membrane flora -Curved GPR "club shaped" "pallisades" -Nonbranching -Cat+ -Nonmotile -Bile esculin - -Facultative anaerobic
27
C diphtheriae respiratory infection
-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
C. diphtheriae respiratory symptoms
1) Pseudomembrane on tonsils / throat 2) fever, malaise, sore throat
29
Diphtheria toxin
-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
Diphtheria diagnosis
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
Diphtheria treatment
1) Antitoxin --inactivates circulating toxin only 2) Pen or Ert 3) DPT vaccine
32
C jeikeium Disease
-Immunocompromised patients -Infection after invasive procedure or IV drug use -Prosthetic valve endocarditis, septicemia, meningitis, prosthetic joint infections -Rash, subcutaneous nodules
33
C jeikeium characteristics
-strict aerobe -lipophilic -nonhemolytic -urease + -nitrate + -very AbxR -treat with Vanc
34
C pseudodiphtherium
-normal resp flora -Resp tract infections in inmmunocompromised -can also cause endocarditis, UTI, wound infections -parallel rows instead of palisades -urease + -nitrate +
35
C ulcerans
-acquired from cows or raw milk -skin ulcers and pharyngitis -produces diph toxin but at much lower levels -Nitrate -
36
C urealyticum
-UTIs -urease + -treat with Vanc
37
Rhodococcus equi (formerly C equi)
-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
Listeria monocytogenes
-found in soil, water, milk, flies, ticks -> it's everywhere -causes disease in animals and humans
39
Listeria characteristics
-facultative anaerobe -GPR/GPCB on gram stain (can look like diphtheroid or strep) -flagella -tumbling motility at 25C -facultative intracellular
40
Listeria virulence
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
Listeria diseases - newborn
1) Newborn meningitis --high fatality --early onset = inhalation of infected amniotic fluid --late onset (2 weeks after birth) = infected during birth
42
Listeria disease - pregnant women
-third trimester -bacteremia / sepsis -flulike illness - fever, headache, myalgia -22% result in fetal death
43
Listeria disease - elderly and immunocompromised
-CNS infection -Endocarditis -2nd most common cause of meningitis in people >60 -most common for lymphoma patients, on steroids, or organ transplants
44
Listeria mode of tranmission
-grows in cold and room temp -deli meats, ice cream, salad, cheese, etc
45
Listeria culture
-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
Listeria treatment
-Amp -SXT
47
Erysipelothrix rhusiopathiae characteristics
-GPR (may look gram variable) pleomorphic long V-shaped filaments -cat- -glu+ -alpha-hemolytic, ppt -urease- -H2S+ -VP- -Esculin-
48
Erysipelothrix rhusiopathiae infections
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
Arcanobacterium characteristics
-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
Arcanobacterium diseases
1) Pharyngitis --similar to BHS infection --50% rash on hands and feet 2) Soft tissue infections 3) Sepsis 4) Endocarditis
51
Gardnerella vaginalis
-pleomorphic GPR/GPCB (can be gram var) -Clue cells -Normal vaginal flora -grow on human or rabbit blood agar for beta colonies -hippurate +
52
Gardnerella vaginalis disease
Bacterial vaginosis -stinky discharge -vaginal pH >4.5 -Decrease in Lactobacillus -> increase pH -> increase G vag -treat with metronidazole or clindamycin
53
Nocardia (Aerobic Actinomyces) characteristics
-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
Nocardia pathogens
-N. asteroides -N. brasiliensis -N. farcinica -N. nova
55
Nocardia virulence
-No virulence factors identified -Virulence correlated with cell wall component alterations -Superoxide dismutase -Catalase -Nocobactin -> iron chelator
56
Nocardia Pulmonary disease
-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
Nocardia Cutaneous disease
-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
Nocardia culture
-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
Nocardia treatment
-Drainage -Surgery -SXT "Treatment of Nocardia is a SNAP Sulfa for Nocardia Actinomyces give Penicillin"
60
Other Actino
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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