ICL 2.24: Zoonotic Bacterial Diseases

Question 1

what’s the microbiology of bartonella?

Answer 1

gram (-) coccobacillus

aerobic

Question 2

what’s the microbiology of ehrlichia?

Answer 2

gram (-) coccobacillus

Question 3

what’s the microbiology of anaplasma?

Answer 3

gram (-) coccobacillus

Question 4

which stain do you use for bartonella species?

Answer 4

gram stain poorly

instead do Warthin-Starry silver staining of lymph nodes/lesions

you’ll see brown to black coccobacilli against a pale yellow/amber background

Question 5

in what media do you grow bartonella?

Answer 5

chocolate agar

hemin required

optimal growth at 34-37 C, 5% CO2

takes 14 days for colonies to grow though….

Question 6

what’s the reservoir for bartonella?

Answer 6

animal and arthropod reservoirs

do not appear to cause disease in animal reservoir hosts, but do in other animals

Question 7

how is bartonella transmitted?

Answer 7

different pathogenic species are transmitted by fleas, lice, or sandflies

NOT TICKS

Question 8

which cells do bartonella infect?

Answer 8

RBCs or endothelial cells in human hosts

primary niche of bacterial colonization is believed to involve the vascular endothelium

Question 9

what’s the unique effect that bartonella have on the body?

Answer 9

they cause vasoproliferative lesions = angiogenesis

Question 10

what is the infection process of bartonella species?

Answer 10

1. they colonize the vascular endothelium
2. at five-day intervals, bacteria are released from the primary niche into the bloodstream

(bloodborne bacteria can reinfect the endothelium to start another infection cycle)

3. bloodborne bacteria also bind to, invade, and replicate within RBCs

they specifically replicate in an intracellular membrane-bound compartment

4. eventually, they stop replicating and persist within RBCs for several weeks

different Bartonella species reach different levels of bacteremia/RBC infection rates

Question 11

how do Bartonella enter endothelial host cells?

Answer 11

dntry of Bartonella into endothelium is dependent on actin cytoskeleton

they bind to various extracellular matrix (ECM) components and membrane proteins

then single bacteria or small clusters are internalized in Bartonella-containing vacuoles (BCVs) but they stay right at the surface

it’s the injection of T4SS that interferes w/ internalization and allows bacterial clustering on surface

these clusters are surrounded by actin-rich protrusions of the host cell membrane and are eventually engulfed as large assemblies in invasome structures = looks like big bumps on cell surface EM

so the bacteria is finally taken up via the invasome!

Question 12

how do Bartonella enter host RBCs?

Answer 12

1. attachment mediated by T4SS or flagella
2. small secreted deformation factor induces pits & trenches on RBC membrane
3. dvaginations containing the bacteria pinch off into interior
4. bartonella replicate in the RBC vacuole & persist there for the lifetime of RBC

this increases the likelihood for its spread through blood-feeding insects

Question 13

how do Bartonella trigger vascular tumor formation?

Answer 13

vasoproliferative bartonellae adhere to and invade endothelial cells

they cause direct stimulation of endothelial cell proliferation and inhibition of apoptosis

they also trigger proinflammatory response that recruits macrophages and other leukocytes

at this point the bacteria produce angiogenic factor which causes the macrophages to make vascular endothelial growth factor (VEGF)

VEGF is potent stimulator of angiogenesis

“angiogenic factor” itself also directly stimulates blood vessel formation

then to top it all off, bacterial colonization/growth and macrophage activation results in hypoxic conditions which again, upregulates VEGF

all of this VEGF results in paracrine stimulation of endothelial cell proliferation

this whole combination of stuff mediates vascular tumor formation!!!! it looks like a kaposi sarcoma

Question 14

what disease does bartonella henselae cause in immunocompetent vs. immunosuppressed people?

Answer 14

healthy people = cat scratch disease

immunocompromised people = bacillary angiomatosis (BA) or peliosis

Question 15

what is the reservoir for bartonella henselae?

Answer 15

domestic cats! (sometimes dogs too)

50% of cats in the U.S. are infected at some point during their life span; especially kittens

cats are more likely to be infected in warm humid climates

infected animals usually are not sick

Question 16

what are the 4 diseases that can be caused by bartonella henselae?

Answer 16

1. cat scratch disease
2. bacillary angiomatosis
3. peliosis = vascular lesions in liver or spleen; not just on the skin like BA!
4. endocarditis

Question 17

what do the colonies of B. henselae look like on agar?

Answer 17

small white irregular colonies

all different sized circles

Question 18

how is bartonella henselae transmitted?

Answer 18

cat to cat transmission is via flea bite

cat to human transmission is largely through direct contact/trauma = cat scratch, bite or even licking of wound

Question 19

what are the symptoms of cat scratch disease?

Answer 19

caused by bartonella henslae

1 week after cat scratch you may see:

1. papule or pustule at innoculation site
2. fever
3. tiredness
4. headache

1-4 weeks later bacteria travel to nearby lymph nodes like armpit, groan or neck and lymph nodes will get really big and painful

in an immunocompetent person the infection is self-limiting and nodes usually shrink to normal size within weeks to months

Question 20

do you develop protective immunity following cat scratch disease?

Answer 20

yup

antibodies produced during infection are subsequently protective

Question 21

what are the possible complications associated with cat scratch disease?

Answer 21

1. Parinaud’s oculoglandular syndrome

2. encephalitis/meningitis/myelitis

Question 22

what is Parinaud’s oculoglandular syndrome?

Answer 22

possible complication of cat scratch disease which is caused by bartonella henslae

it’s a combination of conjunctivitis and local lymphadenopathy (big bulging lymph nodes) that usually happens when the scratch is near the head

can see necrosis, vasculitis, granulomatous inflammation and cococcobacilli will be present in lesions

there’s also proliferation/dilation of blood vessels

even with all these symptoms though there’s no pain and no discharge…

in fact, it usually resolves within 2-4 months with no sequelae

you just have to make sure it doesn’t progress to encephalitis/meningitis

Question 23

describe encephalitis/meningitis associated with cat scratch disease

Answer 23

onset is sudden

fever, convulsion is often first presenting sign

children between 7-12 at risk

recovery is rapid (within 2-14 days), sequelae are rare

Question 24

what is bacillary angiomatosis?

Answer 24

disease state of bartonella henslae exhibited by immunosuppressed patients

lesions are usually seen in skin, but may also manifest in bone, GI tract, reproductive tract, lymph node, and CNS

*bacteremic!! BA lesions form in several organ systems & mucosa

BA is more often caused by B. quintana and B. bacilliformis

Question 25

what are the symptoms of bacillary angiomatosis?

Answer 25

1. reddish vascular nodules, multiple lesions, tenderness lesions are undistinguishable from that of Kaposi’s sarcoma 2. fever, chills, malaise, headache, anorexia 3. characterized by proliferation of vascular endothelial cells and neutrophils/bacteria scattered throughout lesion

Question 26

how do you treat bacillary angiomatosis?

Answer 26

erythromycin 2-4 weeks or longer if needed

Question 27

what is the host and vector of bartonella quintana?

Answer 27

only human hosts lice vectors no known animal vectors!

Question 28

how is bartonella quintana transmitted?

Answer 28

body lice B. quintana multiplies in the lice intestine and is transmitted to humans by feces through altered skin --> lice feed alot which provokes scratching and allows the lice feces filled with bacteria to enter! poor personal hygiene conditions most current cases are seen in homeless and/or chronic alcoholism

Question 29

what do bartonella quintana infections cause in immunocompetent patients?

Answer 29

1. trench fever 2. endocarditis 3. chronic bacteremia

Question 30

what do bartonella quintana infections cause in immunocompromised patients?

Answer 30

bacillary angiomatosis it's actually associates more with bone/subcutaneous than BA caused by B. henselae

Question 31

what are the symptoms of trench fever?

Answer 31

caused by bartonella quintana sudden onset of severe headache, *pain in the shin bones*, elevated temperature may also see fatigue, restlessness, dizziness, macular truncal rash, NVD, splenomegaly between days 3-7, the temperature would suddenly drop to normal then you'd see recurrence of ~5 day cycle, with each attack being less severe trench fever often results in prolonged disability but no fatalities reported "quintana" = occuring every 5 days!

Question 32

what disease does bartonella baciliformis cause?

Answer 32

Carrion's disease = Oroya fever + verruga peruana

Question 33

what is Carrion's disease?

Answer 33

caused by bartonella baciliformis a biphasic disease that is endemic in the valleys of the South American Andes consists of both the Oroya fever = phase 1 and verruga peruana = phase 2

Question 34

how is Carrion's disease transmitted?

Answer 34

caused by bartonella baciliformis transmitted by the sandfly (Phlebotomus verracarum) no known animal reservoir

Question 35

what are the two phases of Carrion's disease? what happens during them?

Answer 35

PHASE 1 = Oroya fever (acute) highly fatal febrile anemia fever, headache, pain in the shins, splenomegaly caused by massive invasion and lysis of RBCs from a hemolysin that B. bacilliformis produces (other bartonella species don't produce it) PHASE 2 = Verruga peruana (chronic) if you survive oroya fever, the disease will progress to chronic secondary phase of verruga peruana the bacteria colonize the vascular endothelium and cause vasoproliferative eruptions of the skin = verruga these lesions are identical to BA lesions caused by B. henselae and B. quintana but they're limited to the skin they develop within 1-2 months & persist months to years it correlates with development of humoral response

Question 36

how do you treat B. henselae infections?

Answer 36

Cat scratch disease = antibiotic treatment not recommended bacillary angiomatosis = erythromycin or tetracycline; 2-3 months

Question 37

how do you treat B. quintana infections?

Answer 37

doxycycline for 4 weeks plus gentamicin for 2 weeks

Question 38

how do you treat B. bacilliforimis infections?

Answer 38

erythromycin, doxycycline, ciprofloxicin; 1-2 week

Question 39

how do you diagnose bartonella infections?

Answer 39

diagnosis is hard and you often have to use symptoms, history and geography so like evidence of cat scratch/bite (CSD, BA), trip to South America (Carrion’s disease), poor living conditions (trench fever) are important for diagnosis serologic tests like ELISA are msot practical for diagnosis but they're only effective after humoral response has occurred you can't culture this bacteria!!!

Question 40

FLASHCARD: microbiology, pathology, epidemiology, clinical, diagnosis and treatment of bartonella

Answer 40

MICROBIOLOGY: Curved, pleomorphic Gram – bacillus, poor Gram strain (Warthin-Starry in tissues), fastidious growth (use chocolate agar for 14 days), infect erythrocytes and endothelial cells in humans, different species transmitted by different arthropod vectors PATHOLOGY: Infects endothelial cells after introduced into skin by vector (B.h.-flea, B.q.-human louse, B.b.-sandfly). Released at intervals into bloodstream to infect erythrocytes (RBCs). Disease severity is related to relative ability of each strain to achieve high numbers in blood and/or lyse RBCs; B.h. is mild, B.q. is moderate, and B.b. is severe EPIDEMIOLOGY: B.h. is found in more temperate zones and associated with animal-transmission via fleas or biting/scratching. Mainly transmitted to human via cat-scratch, and most cases are children. B.q. is only transmitted via louse, so seen in areas with poor hygiene or war-associated populations. B.b. is only found in valleys of Andes mountains, where transmitted via bite of sandfly CLINICAL: Cat scratch disease (B.h.) is usually mild and self-limiting, with swollen lymph nodes; however, immunosuppressed can develop more severe disease and vascular tumors (bacillary angioedema). Trench fever (B.q.) exhibits a “Quintana”, where every ~5 days see onset of severe headache, pain in shin bones, and elevated temperature that lasts 3-7 days, followed by ~5 days normal; debilitating, but not fatal. B.b. cause two disease: Oroya fever (acute) has massive invasion & lysis of RBCs, fever, headache, shin pain. Splenomegaly; highly fatal febrile anemia. Second is verruga peruana (chronic) where form large numbers of vascular tumors (bacillary angioedema) DIAGNOSIS: Mainly diagnose by symptoms and epidemiology for each. Culture is impractical. Can stain lesions (Wartin-Starry) or test for antibodies for each bacteria. Treat Oroya fever ASAP! TREATMENT: CSD is usually self-limited. DOC is doxycycline, or erythromycin

Question 41

which genuses are in the anaplasmataceae family?

Answer 41

1. anaplasma 2. ehrlichia 3. neorickettsia 4. wolbachia

Question 42

which bacteria cause human ehrlichioses?

Answer 42

1. Ehrlichia chaffeensis** 2. Ehrlichia ewingii 3. Anaplasma phagocytophilum** 4. Neorickettsia sennetsu all of these are in the anaplasmataceae family

Question 43

what is the microbiology of anaplasmataceae family?

Answer 43

gram (-) cocci obligate intracellular pathogens = can't grow them on media outside of a cell lack LPS and peptidoglycan*

Question 44

how are anaplasmataceae family bacteria transmitted?

Answer 44

all transmitted by ticks

Question 45

what cell type do anaplasmataceae family bacteria infect?

Answer 45

they infect different *leukocyte* populations they remain in phagocytic vacuoles and prevent fusion with lysosome then they divide to form vacuole-bound colonies known as morulae --> a single cell can havae 3-15 morulae **morulae are diagnostic for anaplasmataceae infection!! they look like little spots inside neutrophils

Question 46

how are Ehrlichia chaffeensis and Anaplasma phagocytophilum transmitted?

Answer 46

Wild rodents are reservoirs for A. phagocytophilum deer are reservoirs for E. chaffeensis (yellow) each bacteria are usually transmitted to humans by the bite of infected ticks that have acquired the infection by taking a blood meal from respective reservoir wild animals A. phagocytophilum and E. chaffeensis infect primarily granulocytes and monocytes, respectively these infected leukocytes circulate throughout the body to cause systemic diseases human brain infection is rare, but E. chaffeensis has been observed in human cerebrospinal fluid mononuclear cells

Question 47

which cells do Anaplasma phagocytophilum infect?

Answer 47

granulocytes = neutrophils, basophils, eosinophils

Question 48

which cells do Ehrlichia chaffeensis infect?

Answer 48

monocytes

Question 49

what is a marker for cell death?

Answer 49

elevated aminotransferase levels

Question 50

what disease does ehrlichia chaffeensis cause?

Answer 50

human monocytic ehrlichiosis (HME)

Question 51

what disease does anaplasma phagocytophilum cause?

Answer 51

1. human granulocytic anaplasmosis (HGA) | 2. tick borne fever

Question 52

what are the symptoms of HGA?

Answer 52

HGA = human granulocytic anaplasmosis which is caused by anaplasma phagocytophilum 1. fever, chills, malaise 2. thombocytopenia 3. elevated aminotransferase 4. rash, circular skin lesion 5. intracytoplasmic inclusions in neutrophils

Question 53

where in the US are anaplasma phagocytophilum infections most common?

Answer 53

they cause human granulocytic anaplasmosis areas where HGA may occur is based on distribution of vector tick species = ixodes scapularis this distribution is consistent with the fact that the vector of HGA also transmits Borrelia burgdorferi = often see co-infection most of the recognized HGA cases have originated from states that also have a high incidence of Lyme disease = Connecticut, Massachusetts, New York, Minnesota, and Wisconsin in the western United States, the HGA agent is transmitted by the western blacklegged tick = ixodes pacificus

Question 54

which age group is more susceptible to anaplasma phagocytophilum infections?

Answer 54

elderly

Question 55

what are the symptoms of HME?

Answer 55

HME = human monocytic ehrlichiosis which is caused by ehrlichia chaffeensis bacteria it's called chaffeensis because it was first seen at fort chaffee during boot camp fever, headache, pharyngitis, nausea, vomiting & dehydration 3 days after onset PE revealed prominent cervical lymphadenopathy, splenomegaly, and no rash CBC showed significant left shift = lots of immature cells = active infection

Question 56

how is ehrlichia chaffeensis transmitted?

Answer 56

lone star tick = western US NOT efficiently transmitted to egg; larvae have to feed on an infected deer disease distribution directly correlates with the geographic distribution of the Lone Star tick

Question 57

where are ehrlichia chaffeensis often seen in the US?

Answer 57

Arkansas, Missouri, Oklahoma, North Carolina, South Carolina, and Georgia

Question 58

what is the reservoir of ehrlichia chaffeensis?

Answer 58

deer but can also be found in dogs, foxes, coyotes, wolves, raccoons, opossums, goats, and mice vector = lone star tick

Question 59

what are the similarities between HME and HGA disease?

Answer 59

HME = caused by ehrlichia chaffeensis; infects monocytes/macrophages HGA = caused by anaplasma phagocytophilum; infects granulocytes symptoms appear 1-21 days after infection (tick-bite) most common symptoms are fever, headache, chills, muscle aches and pains, fatigue, and malaise rash is infrequent (more common for HME) common clinical findings are thrombocytopenia (71%), leukopenia (49%), anemia (37%), and elevated hepatic transaminase levels (71%)

Question 60

what are the effects on the immune system that HME and HGA have?

Answer 60

HME infects monocytes while HGA infects granulocytes so the immune system is adversely affected due to infection and killing of leukocytes this lessens the ability to fight other infections so you see many complications and getting sick from other diseases

Question 61

is HME or HGA more deadly?

Answer 61

Hospitalization is required for 50% of symptomatic patients with both diseases but HME mortality rate is higher rates higher in elderly

Question 62

how do E. chaffeensis and A. phagocytophilum infect cells?

Answer 62

they infect different cell types but they both: bind to surface receptors that promote non-inflammatory uptake then they're both internalized into endosome but do not fuse with lysosome they replicate within endosomal vacuole to form morulae

Question 63

what virulence factors do E. chaffeensis and A. phagocytophilum have?

Answer 63

both bacteria lack LPS and peptidoglycan so they do not elicit a strong initial inflammatory response they also downregulate ROI in monocytes and granulocytes, respectively plus both can inhibit apoptosis of respective host cell types

Question 64

describe the biphasic life cycle of E. chaffeensis and A. phagocytophilum

Answer 64

kind of like chlamydia!! initially, small dense-cored cells bind to host cells, are internalized and develop into large reticulate cells = EB reticulate cells then mature into dense-cored cells or compact into clumps = RB --> formation of morulae!!

Question 65

which of the following have two different cell phases during their normal life cycle? A. orientia tsutsumagushi B. rickettsia rickettsi C. neisseria gonorrheae D. coxiella burnettii E. bacillus anthracis

Answer 65

D. coxiella burnettii

Question 66

how do diagnose HME and HGA?

Answer 66

indirect immunofluorescence assay (IFA) is generally considered the reference standard but it takes a while for antibodies to develop.... PCR is the most rapid and specific diagnostic assay for HME and HGA E. chaffeensis and A. phagocytophilum can only be cultured in host cells base treatment on epidemiologic and clinical clues = tick exposure, fever, general malaise (sometimes see variable rash, but not diagnostic), thrombocytopenia, decrease in lymphocytes, increased aminotransferase levels, anemia morulae are only detected in blood smears in 60% of patients but if they're there they are diagnostic!

Question 67

how do you treat HME and HGA?

Answer 67

doxycycline!

Question 68

how do you prevent HME and HGA?

Answer 68

no vaccine so just avoid tick exposure

Question 69

FLASHCARD: microbiology, pathology, epidemiology, clinical, diagnosis, and treatment of Ehrlichia chaffeensis & Anaplasma phagocytophilum

Answer 69

MICROBIOLOGY: Gram – coccobacilli, lack LPS & peptidoglycan, will not Gram-stain, obligate growth within either monocytes (E.c.) or neutrophils (A.p.) for growth/persist within morulae. Appear to have 2 forms, with inert small elementary body that infects host cell, then transform into larger reticulate body that multiplies within morulae before transform back to elementary body for release. PATHOLOGY: After introduced into skin via tick-bite, migrate to bloodstream to infect either macrophages or neutrophils. Eventually cause reduction in these WBC, result in suppressed immunity. Can go on the infect multiple organs. EPIDEMIOLOGY: E.c. is hosted/transmitted by Amblyomma americanum (Lone star tick) and A.p. by Ixodes ticks, and thus disease is only acquired within their ranges. Disease is more common in Spring-Summer, in males, and in elderly patients. CLINICAL: E.c. (Human monocytic ehrlichiosis; HME) and A.p. (Human granulocytic ehrlichiosis; HGE) cause similar disease. After incubation of 1-2 weeks, become sick very quick. Most commonly see high fever, severe headache, fever, malaise, thrombocytopenia, and general illness, but often do not associate tick-bite. Rash is rare, but can occur. Commonly can lead to hospitalization. Fatal outcome is low if treat rapidly. DIAGNOSIS: Difficult to diagnose. Cannot culture on medium. Initial diagnosis is on clinical symptoms and epidemiology. May be able to detect morulae within monocytes or neutrophils in blood smear. Eventually can detect antibodies in blood or PCR on blood cells. Ixodes ticks carry multiple pathogens (e.g. Borrelia, Babesia, Powassan virus), so should consider all options. TREATMENT: DOC is tetracyclines (doxycycline)

Question 70

what is the microbiology of babesiosis microti?

Answer 70

trick question they are eukaryotic parasites, NOT a bacteria

Question 71

how is babesiosis microti transmitted?

Answer 71

blacklegged tick = ixodesscapularis same tick vector as B. burgdorferi and A. phagocytophilum so an individual tick can carry and transmit any combination of these 3 pathogens

Question 72

where are babesiosis microti infections seen in the US?

Answer 72

geographic distribution and seasonality is same as Lyme disease and Anaplasmosis most U.S. cases are B. microti and seen in upper Midwest and Northeast U.S. recent increase in Babesiosis most likely due to the expansion of the white-tailed deer population in endemic regions --> deer do not carry infection, just provide blood meal for ticks

Question 73

what is the lifecycle of babesia microti?

Answer 73

1. tick takes a blood meal from mouse 2. diploid turns into gamete form in the mouse and then the tick takes another blood meal and ingests gametes 3. fertilization in gut 4. ookinete enters salivary gland 5. tick bites human and sporozoites are introduced into host 6. can be transmitted between humans via blood transfusion

Question 74

what are the symptoms of babesiosis?

Answer 74

most patients develop non-specific symptoms 1-4 weeks after inoculation intermittent fever, fatigue, malaise, headache, chills, sweats, myalgia babesia causes lysis of RBCs so you often see splenomegaly, hemolytic anemia, lymphopenia, thrombocytopenia, elevated serum lactate dehydrogenase, and elevated RBC sedimentation rate symptoms last for week to months (or longer) if untreated, but usually resolves however, patients with complicating conditions can have severe or fatal disease

Question 75

how do you prevent babesia microti infections?

Answer 75

no vaccine avoid tick exposure

Question 76

how do you diagnose babesiosis?

Answer 76

definitive initial test is Giemsa or Wright stain of thin blood smears -- babesia too small to see on thick smear PCR can be performed, if available antibodies can be detected by IFA or immunoblot if tests are negative & symptoms persist, can inject patient blood into small rodent

Question 77

when should you consider babesiosis?

Answer 77

Residence/travel in endemic area Received recent blood transfusion Should be considered in patient with Lyme disease or HGA diagnosis since all pathogens are carried by the same tick co-infection is common

Question 78

what do babesia look like on a thin blood smear?

Answer 78

you can see tetrads of replicating merozoites arranged in a cross-like pattern maltese cross is diagnostic!

Question 79

how do you treat babesiosis?

Answer 79

two combination options, both are great 1. atovaquone + azithromycin 2. clindamycin + quinine 7-10 days or 6 weeks if persistent relapsing infection