ICL 2.25: Francisella, Brucella & Acinetobacter

Question 1

what is the microbiology of actinobacter?

Answer 1

gram (-) coccus

aerobic

Question 2

what is the microbiology of francisella?

Answer 2

gram (-) pleomorphic = coccobacilli

not motile

has a capsule

Question 3

what is the micropbiology of brucella?

Answer 3

gram (-) pleomorphic = coccobacilli

not motile

strict aerobe

no capsule

Question 4

what are the similarities between francisella and brucella?

Answer 4

1. grow poorly in the lab = need 2+ days to see colonies
2. non motile
3. intracellular pathogens

Question 5

what is the microbiology of francisells tularensis?

Answer 5

gram (-) coccobacillus

strict aerobic

non-motile

Question 6

is francisella tularensis spore-forming?

Answer 6

no

but because of its capsule it can survive for months at low temperatures in water, moist soil, hay, straw, and decaying animal carcasses

Question 7

how do you grow francisella tularensis?

Answer 7

chocolate agar

requires cysteine and blood for growth

takes 2+ days for colonies to grow

Question 8

what are the virulence factors of francisella tularensis?

Answer 8

1. capsule
2. francisella pathogenicity island (FPI)
3. LPS

Question 9

how does the francisella tularensis capsule act as a virulence factor?

Answer 9

anti-phagocytic

binds complement = bacteria isn’t lysed

Question 10

how does the francisella pathogenicity island act as a virulence factor?

Answer 10

it’s required for phagosome escape and possible secretion

Question 11

how does francisella tularensis LPS act as a virulence factor?

Answer 11

its LPS has super long acyl chains and only has 4 acyl chains instead of 6

this modified LPS doesn’t stimulate TLR4 = immune evasion

so it’s not endotoxic = no cytokine-mediated inflammation and no TNFα

Question 12

what kind of pathogen is francisella tularensis?

Answer 12

intracellular pathogen

Question 13

which cells does francisella tularenis infect? what does it do?

Answer 13

it infects macrophages, dendritic cells, neutrophils, epithelial cells, etc. (basically everything)

it inhibits phagosome-lysosome fusion!!

then it somehow escapes the phagosome into the cytosol to replicate

it’ll eventually cause apoptosis of the cell so it can be released

Question 14

what is francisella related to?

Answer 14

nothing…

Francisella are not related to any other genus

Question 15

what are the francisella tularenis subspecies?

Answer 15

1. F. tularensis subsp. tularensis = type A

**type A is the most virulent subspecies; LD50 = 10 bacteria!!

2. F. tularensis subsp. holarctica = type B

Question 16

where are F. tularensis type A and B found in the world?

Answer 16

type A = strictly north america

type B = North America, Europe, Russia, and Asia

Question 17

where do most tularemia cases occur in the US?

Answer 17

1. OK
2. MO
3. AR
4. KS

Question 18

how is F. tularensis transmitted?

Answer 18

ticks are the most common

but it can also be biting flies and mosquitoes

also aerosolizing an infected bunny/reservoir and breathing in the bacteria could cause it too or ingesting an infected bunny

no person-person spread

Question 19

what time of the year is tularemia most common?

Answer 19

may, june, july = summer

Question 20

what is the reservoir for F. tularensis?

Answer 20

1. rabbits
2. house cats

can also be ground squirrels, hares, muskrats, voles, mice, water rats, and other rodents are reservoir

F. tularensis has also been found in water, soil and vegetation

Question 21

what are the possible disease states of F. tularensis?

Answer 21

1. typhoidal
2. pneumonic
3. ulceroglandular

Question 22

what is ulceroglandular F. tularensis?

Answer 22

you’ll get a cutaneous ulcer at the site of inoculation

you’ll also have proximal lymphadenopathy = super swollen lymph nodes

you can it from ticks or handling infected animals

mortality = 3%

Question 23

what is pneumonic F. tularensis?

Answer 23

you’ll get atypical pneumonia or hilar lymphadenopathy

this is the most likely presentation of F. tularensis if exposed to aerosol

so you can get it from lawn mowing, haymaking, lab exposure or bioterrorism

mortality is 60%

Question 24

what is typhoidal F. tularensis?

Answer 24

you can get septicemia and have systemic involvement

there will be no evidence of skin, mucosal or lymphatic involvement

this is what happens if the other F. tularensis presentations aren’t treated they can progress to typhoidal tularemia

mortality is 60%

Question 25

what are the clinical symptoms of acute tularemia?

Answer 25

lasts 3-5 days 1. Fever (up to 104∘F), chills 2. Malaise 3. Headache 4. Sore throat 5. Myalgia 6. Anorexia 7. Prostration 8. Erythema nodosum

Question 26

what are the clinical symptoms of prolonged tularemia?

Answer 26

lasts from day 6 to death has all the symptoms seen in acute tularemia plus: 1. cough (productive or non-productive) 2. chest pain 3. liver dysfunction

Question 27

what is the pathology of an F. tularensis infection?

Answer 27

pathology mainly in lymph nodes, lungs, spleen, liver, and kidneys there's an influx of neutrophils, macrophages, and lymphocytes that may form granulomas granulomas develop necrotic centers, sometimes caseating, typical of other granulomatous conditions the infected macrophages can't kill the bacteria so they undergo apoptosis --> francisella is released --> it infects new macrophages and travels through the lymphatics and infects other tissues and organs

Question 28

how do you diagnose an F. tularensis infection?

Answer 28

1. risk factors = rabbit hunting, ticks, sick cat 2. microscopic examination of secretions, exudates, biopsy but not very sensitive, francisella gram stains poorly and it's hard to find sufficient organisms in specimens 3. culture of ulcer scrapings, lymph node biopsy, or sputum = sensitive and specific but just use chocolate agar 4. serology confirms diagnosis = compare titer with second titer 2 weeks later (4x)

Question 29

how do you treat F. tularensis?

Answer 29

1. doxycycline 2. ciprofloxacin F. tularensis produces B-lactamases, so B-lactams are ineffective

Question 30

how do you prevent F. tularensis infections?

Answer 30

no vaccine

Question 31

how do you grow brucella?

Answer 31

special Brucella medium requires a week or more for visible growth on media strict aerobe

Question 32

which tissues does Brucella infect?

Answer 32

1. epididymis 2. placenta 3. breast 4. uterus prefers to infect organs that are rich in erythritol because it metabolizes easier than glucose infection causes sterility, abortions, or asymptomatic lifelong carriage

Question 33

what kind of pathogen is brucella?

Answer 33

intracellular pathogen replicates and persists within macrophages prevents phagolysosome fusion --> persist/multiply within endosomal compartment

Question 34

what are the virulence factors of brucella?

Answer 34

1. urease | 2. LPS

Question 35

how does urease act a virulence factor for brucella?

Answer 35

buffers bacteria from low pH of stomach urea --> CO2

Question 36

what are the 2 types of LPS in brucella?

Answer 36

alterations in LPS O-antigen result in smooth or rough colony phenotypes -->- smooth isolates much more virulent than rough rough colonies lack O-antigen (B. canis) smooth = has O-antigen rough = lacks O-antigen either LPS form is much less stimulatory than LPS from other gram negatives

Question 37

how does LPS act as a virulence factor for brucella?

Answer 37

has hella long acyl chains that are not recognized by TLR4 this LPS also inhibits apoptosis of infected macrophages smooth LPS O-antigen groups block complement C3 binding also the O-antigen amido groups are difficult to degrade so they block MHCII presentation of infected macrophages

Question 38

what are the 4 brucella species that cause human disease?

Answer 38

1. B. melitensis** 2. B. abortus 3. B. suis 4. B. canis

Question 39

where is brucellosis endemic?

Answer 39

Mediterranean Basin** Middle East Latin America S.E. Europe Asia Africa

Question 40

where is brucellosis common in the US?

Answer 40

Most U.S. cases in Texas and California CA, TX, IL, FL = half of U.S. cases

Question 41

how do you get brucellosis?

Answer 41

1. abraded skin 2. inhalation 3. conjunctiva 4. ingestion no person-person spread it's shed in high numbers in milk, urine, birth products ****human disease is most often associated with consumption of contaminated unpasteurized dairy products (mainly milk and cheese)

Question 42

what disease state does brucellosis cause?

Answer 42

causes sterility and abortions (pregnancy tolerance --> bacterial replication)

Question 43

which groups are at risk for brucellosis?

Answer 43

1. ingestion of unpasteurized milk, cheese, other dairy products 2. slaughterhouse workers (reduced with brucellosis control measures in cattle) 3. veterinarians (RB51 vaccine is B. abortus rough strain; rifampicin resistant) 4. lab workers (highly infectious; BSL-3 required) 5. hunters (feral swine, bison, elk)

Question 44

what are the 3 forms of brucellosis?

Answer 44

1. acute form 2. undulant form 3. chronic form

Question 45

what is the acute form of brucellosis?

Answer 45

<8 weeks from illness onset nonspecific "flu-like" symptoms include undulating fever, malodorous sweats, malaise, anorexia, headache, myalgia, and back pain

Question 46

what is the undulant form of brucellosis?

Answer 46

<1 year from illness onset 1. intermittent fevers, arthralgia, myalgia 2. epididymo-orchitis in males 3. spontaneous abortions in females 4. neurologic symptoms may occur ≥ 5% of cases

Question 47

what is the chronic form of brucellosis?

Answer 47

>1 year from onset symptoms may include chronic fatigue syndrome, depression, and arthritis hepatomegaly, splenomegaly, lymphadenopathy endocarditis in only 2% of cases but these can progress to death (80% of brucellosis endocarditis lethal)

Question 48

what are the key symptoms of brucellosis in general?

Answer 48

1. undulating fever 2. malodorous perspiration 3. arthralgia

Question 49

how do you diagnose brucellosis?

Answer 49

1. history!!!! 2. culture from blood i gold standard must use enriched blood agars to culture; takes 2 weeks to grow 3. speciic antibodies are present in almost all brucellosis patients IgM early 1st week then IgG must see 4x increase in titer for diagnosis

Question 50

what is the Ruiz-Castaneda test?

Answer 50

used to diagnose brucellosis blood sample inoculated into vial containing both agar slant and broth media; must rotate vial daily to allow bacteria from broth to form colonies on agar but takes 7-21 days to grow....

Question 51

what is the lysis centrifugation test?

Answer 51

used to diagnose brucellosis collect blood --> lyse RBCs in water and sodium citrate --> pellet bacteria --> plate takes 2-4 days to grow; faster than Ruiz castaneda

Question 52

how do you treat brucellosis?

Answer 52

because of slow growth, latency, and granuloma formation, need to treat with at least 2 antibiotics for 6 weeks doxycycline and rifampicin ***except vets because the RB51 vaccine they give to animals is rifampicin resistant so you treat them with doxy and streptomycin

Question 53

is there a brucellosis vaccine?

Answer 53

no there's a live attenuated vaccines for B. abortus and B. melitensis are used in animals but not in humans because they cause disease

Question 54

where is actinobacter found in nature?

Answer 54

tolerate many environments; soil, skin, water, moist and dry surfaces also part of normal flora of skin and oropharynx common in hospitals (burn units, intensive care); easy to culture

Question 55

which acinetobacter species is responsible for most human disease?

Answer 55

A. baumannii it's not a risk for immunocompotent people!

Question 56

what diseases can A. baumannii cause?

Answer 56

1. pneumonia 2. septicemia 3. wound infections

Question 57

what are the risk factors to acinetobacter infections?

Answer 57

1. combat injuries: present in 1/3 of cases from Iraq and Afghanistan** 2. ventilator-associated pneumonia: 5 - 10% of long-term ICU patients 3. Burn units and skin/soft tissue wounds: 2% 4. UTIs: 1.6% catheter-associated 5. diabetes 6. chronic lung disease

Question 58

how do you treat acinetobacter infections?

Answer 58

alot of acinetobacter is resistant to multiple antibiotics so first perform antimicrobial susceptibility testing 1. broad-spectrum cephalosporin = ceftazidime or cefepime 2. β-lactamase inhibitor (sulbactam) with β-lactam (ampicillin)** 3. carbapenem = imipenem, meropenem, doripenem 4. colistin**

Question 59

is acinetobacter resistance a problem?

Answer 59

often resistant to multiple antibiotics antibiotic resistance is rapidly spread via integrons, transposons, insertion elements they're resistant to B-lactams, aminoglycosides, quinolones, tetracyclines

Question 60

FLASHCARD: micro, virulence factors, epidemiology, clinical, diagnosis, treatment of francisella tularensis

Answer 60

MICROBIOLOGY: Gram– coccobacilli but capsule may interfere; non-motile; requires cysteine and blood to culture; slow growing VIRULENCE FACTORS: LPS is tetra-acylated, acyl chains 16-18 carbons long, monophosphorylated EPIDEMIOLOGY: Type A (subsp. tularensis) > Type B (subsp. holarctica); ticks > rabbits > other animals; ~120 cases/yr; MO, AR, OK CLINICAL: flu-like; ulceroglandular lesion may be present DIAGNOSIS: Culture of ulcer, lymph node or sputum --> Agglut Ab; serology TREATMENT: Doxycycline or cipro

Question 61

FLASHCARD: micro, pathology, epidemiology, clinical, diagnosis, treatment of brucella

Answer 61

MICROBIOLOGY: very small Gram– coccobacilli; no capsule; flagella does not stimulate TLR5 PATHOLOGY: LPS acyl chains 28 carbons long, monophosphorylated , O-Ag blocks complement and MHC-II presentation EPIDEMIOLOGY: B. melitensis >>> B. abortus > B. suis > B. canis; Mediterranean or unpasteurized cheese from C. America; Veterinarians CLINICAL: Undulating fever, chills, malodorous sweats, arthralgia, malaise, anorexia, headache, myalgia, and back pain DIAGNOSIS: Blood culture (two weeks) --> Agglut Ab; serology TREATMENT: Doxycycline and rifampicin 6 weeks

Question 62

FLASHCARD: microbiology, pathology, epidemiology, clinical, diagnosis, treatment of acinetobacter

Answer 62

MICROBIOLOGY: Gram– coccobacilli; form biofilms on medical instruments PATHOLOGY/VIROLOGY: LPS potent inducer of inflammation EPIDEMIOLOGY: Combat injuries Iraq and Afghanistan; ventilator-associated pneumonia; burn units CLINICAL: pneumonia, septicemia, wound infections DIAGNOSIS: Agar culture TREATMENT: Sulbactam (small mol. B-lactamase inhibitor) with ampicillin; or colistin (polymixin E)