Vector-borne & Zoonotic Bacteria
Bartonella henselae
Diagnosis/Labs
- Fastidious
o Need Chocolate/Blood Agar
o Hemin required & takes 14
days
o Small white irregular colonies
- Major reservoir is domestic cat
o 50% of cats infected at some
point during their lives
- Zoonotic reservoirs (Cats)
- Carried in gut of cat fleas
All Bartonella species
-
Culture is impractical
Infect endothelium + RBCs
Need serologic tests (ELISA)
Aminoglycosides: Only treatment
that works for Bartonella
- Whartin-Starry Stain (Silver) of
angiogenic lesions
- PCR of 16S rRNA
Bartonella quintana
- Human-specific pathogen
- Carried in gut of human body lice
Bartonella bacilliformis
- Human-specific pathogen
- Carried in gut of sandflies
- Suspect in trip to South America
- Most severe Bartonella
©2009 Mark Tuttle
Gram Negative (but stain poorly), Coccobacilli, Aerobic
Symptoms
1. Catch Scratch Disease
- Cutaneous papule at site of scratch (1 wk)
- Lymph node enlargement
(2 wk)
- Lymph nodes gradually shrink
(3 mo)
- Fever, malaise, fatigue, headache
- Would cultures no bacteria
- High AB titers for Bartonella henselae
- Infection is self-limiting
- Seen in fall and winter months
- 3-61% of general population is positive for AB
o Suggests can get asymptomatic infection
- Complications
o Parinaud’s oculoglandular syndrome
 Conjunctivitis + local lymphadenopathy
 Coccobacilli present in lesions
 No pain, discharge
 Resolves in 2-4 months, no sequelae
o Encephalitis/meningitis
 1-7% of cases
 Cranial/peripheral nerves involved
 Recovery is rapid: 2-14 days, rare sequelae
2. Bacillary Angiomatosis (Immunocompromised)
- Painless lesions that resemble tumors
o Small blood vessels ↑ (angiogenesis)
o Many colonies of bacteria
- Lesions on skin, bone, GI, GU, lymph, CNS
- Indistinguishable from Karposi’s Sarcoma
3. Peliosis: Vascular lesions in liver or spleen
4. Endocarditis
Pathogenesis
- Reservoirs are animals and arthropods
o Does not cause disease in non-human hosts
- Largely infect RBCs/Endothelial cells in humans
- Unique among bacteria  Angiogenesis
o Adherence to endothelial cells
o Inhibition of apoptosis
o Invasion is actin-dependent and results in
bacteria in membrane-bound compartments
o Trigger NF-кβ proinflammatory cytokines –
recruits macrophages which they invade
o Hypoxia-inducible factor (HIF-1) angiogenic
factor released and stimulates production of
VEGF by macrophages/PMNs
Infection Cycle (5 days)
- Primary niche is vascular endothelium
- Released into blood stream – Cyclic fever
- Invade and replicate inside RBCs
o Replicate in membrane-bound (not cytplsm)
- Persist in RBCs for a few weeks
- Transmitted to blood-sucking arthropod
Treatment
Cat Scratch Fev
- None neces.
Angiomatosis
- Rifampin
- Erythromicin
- Doxycycline
- Azytrhomcyin
Gram Negative (but stain poorly), Coccobacilli, Aerobic
Trench Fever: Living conditions ↓ (eg. homeless)
- Severe headache, pain in shin bones, cyclic fever
- Transmitted to humans by lice feces that is
scratched and inoculated into blood
- Erythromycin
- Doxycycline
Gram Negative (but stain poorly), Coccobacilli, Aerobic
Carrion’s Disease (Biphasic)
1.Oroya fever: Acute phase. Highly fatal (40% mortal)
- ↑ invasion/lysis of RBCs. Shin pain. Splenomegaly
2.Verruga peruana: Chronic secondary stage
- Follows develop of humoral response
- Verruga: eruptions of endothelium on skin
- Can also be chronic, asymptomatic bacteremia
- Lesions are identical to BA lesions of Bartonella
henselae
-
Chloramphenicol
Penicillin
Erythromycin
Doxycycline
Anaplasmatacease family
©2009 Mark Tuttle
•Gram stain poor (Lack LPS + PG) •Coccoid •Obligate intracellular (No culture) •Transmitted by ticks •Infect leukocytes + prevent fusion: *morulae*
Name
Anaplasma
phagocytophilum
Diagnosis/Labs
- PCR of blood cells
- Can’t culture -> Morulae seen in
neutrophils in mice
Ixodes scapularis
+ pacificus ticks
Erlichia
chaffeensis
Symptoms
Human Granylocytic Anaplasmosis (HGA)
- Primarily infects neutrophils
- Flu-like symptoms (Fever, malaise)
- Pain in legs
- High liver enzymes
- Low leukocyte levels
Human Monocytic Erlichiosis (HME)
- Primarily infects monocytes
- Flu like symptoms + GI symptoms
- Cervical lymphadenopathy
- Splenomegaly
- No rash
Lone Star Ticks
- See “left shift” in WBCs
o Band forms ↑↑
- See with Lone Star tick in SE USA
- 98% similar to Erlichia canis
- Not efficiently transmitted
transovarian in Lone Star ticks
- Reservoir is white-tailed deer
Erlichia ewingii
Neorickettsia
sennetsu
- Granulocytic erlichosis. Similar to E. Canis
- Uncommon in USA. See in Japan and Malaysia. Mononucleosis-like illness
- Sennetsu fever. More mild than other erlichoses
Pathogenesis
- Infects older people preferentially where as
Lyme infects young
- Symptoms appear 1-21 days after tick bite
- Similar symptoms to Rocky Mountain
Spotted Fever (same fam as Rickettsia)
- Rash is infrequent
- Thrombocytopenia, leucopenia, anemia,
elevated hepatic transaminase
- Immune system is adversely effected
o Can see opportunistic infections
- Mortality rate: 2-10%
- Recovery rate is very slow
Virulence Mechanisms
- Prevent fusion of endosome (pH constant)
- Inhibit apoptosis of host cells
Treatment
- Tetracyclines
Doxycycline
Francisella and Brucella
©2009 Mark Tuttle
•Gram negative (poor stain) •Coccobacilli •Poorly growing in lab •Strictly aerobic •Overlap in antigenicity assays
Francisella tularensis
Diagnosis/Labs
- BCYE/Chocolate agar culture
- Serology used to confirm
diagnosis, but can cross-react
with Brucella
- Strictly aerobic
- Is a Group A NIAID pathogen
- Possible bioweapon
- Subspecies
o tularensis (Type A) Worst
o holarctica (Type B)
o novicida – not really human
o mediasiatica – not really human
- Intracellular pathogen
Symptoms
- Nonspecific symptoms
- Dry, nonproductive cough
- Infiltrates in lung fields
Ulceroglandular Tularemia
- Painful papule develops at site
- Localized lymphadenopathy
Oculoglandular Tularemia
- Inoculation into the eye
- Painful conjunctivitis
- Regional lymphadenopathy
Pneumonic Tularemia
- Inhaled aerosolized blood?
- Pneomonitis with signs of sepsis
- Develops rapidly – High mortality
Pathogenesis
- Inhalation of aerosolized blood (Ex. Rabbit lawnmower)
- Intracellular in macropahges – inhibits lysosome fusion –
multiply and persist
- Pathogenic strains have anti-phagocytic capsule
- Despite fastidiousness, can survive for weeks at low
temperatures in water, moist soil, hay, straw, decaying animals
- Type A (tularensis): North American wild rabbits
o Vectors: ticks and tabanid flies
- Type B (holarctica): Northern hem. Rodents + hares.
o Vectors: ticks, mosquitoes, tabanid flies
- One of the most infectious known pathogens
Treatment
- Gentamycin
- Streptomycin
- Can’t use Blactams
Vaccine
- Live-attenuated
but not available
in USA
- Nonspecific symptoms
- Malodorous sweating
- Maculopapular rash on arms, trunk,
legs
o Nonpruritic and nonhemorrhagic
-
- Infects tissues rich in erythritol
o Placenta, epididymis, breast, uterus
o Localization causes sterility, abortions, asymptomatic
chronic carriage
- Colonies can assume both smooth and rough forms
o Smooth forms are much more virulent
- Mild or asymptomatic disease in natural host, but may be
shedding of bacteria in milk etc
- US disease most often associated with unpasteurized diary
products
- Tetracycline +
rifampin
because
intracellular
Vaccine
- Live attenuated
for cattle
- Cause disease in
humans
- Respiratory infections
- UTIs from catheters
- Seen in nosocomial wound infections
- Part of normal for a of skin and oropharynx
- Not pathogenic in healthy humans, but causes disease in
immunosuppressed
-
Brucella melitensis, B. abortus, B. suis, B. canis
-
Strictly aerobic
Require complex media
Intracellular pathogen
Endemic in Mediterranean
Acinetobacter baumannii
- Resistant to multiple antibiotics
- Resistance spreads rapidly via
integrons
- Transposable elements
containing antibiotic ressitence
genes