Chronic Q Fever
1. Overview
Definition
Chronic Q fever คือ chronic infection จาก
Coxiella burnetii
ที่เกิด:
- months
to years หลัง infection
Major manifestations
1.
Endocarditis
2.
Vascular infection
2. Epidemiology
Occurrence
เกิดประมาณ:
- 1–5% ของ symptomatic acute Q fever
Important
หลายคน:
- ไม่เคยรู้ว่ามี acute Q fever มาก่อน
3. Risk Factors
High-yield risk factors
- valvular
disease
- prosthetic
valve
- vascular
aneurysm
- vascular
graft
- pregnancy
- immunosuppression
- age
>50 years
Epidemiology
พบบ่อยใน:
- males
4. Clinical Syndromes
A. Culture-negative endocarditis
Most common manifestation
Symptoms
- prolonged
fever
- malaise
- weight
loss
- anemia
- thrombocytopenia
- hepatosplenomegaly
Important
presentation อาจเป็น:
- progressive
heart failure
- embolic
stroke
Key clinical pearl
“Culture-negative endocarditis”
ต้องคิดถึง Q fever เสมอ
โดยเฉพาะ endemic setting
5. Q Fever Endocarditis
Important echocardiography clue
vegetation:
- often
small
- absent
ได้
Common findings
- degenerative
valve changes
- thickened/calcified
leaflets
- perivalvular
leak
Important
negative TEE:
- ไม่ rule out disease
6. Vascular Infection
Common site
Abdominal aorta
Involvement
- native
vessel
- prosthetic
graft
Symptoms
- abdominal
pain
- fatigue
- weight
loss
- elevated
inflammatory markers
Fever
variable
อาจไม่มีได้
7. Dangerous Complications
A. Aortoenteric fistula
classic catastrophic complication
Presentation
- GI
bleeding
- hematochezia
- hemorrhagic
shock
Mortality
สูงมาก
B. Ruptured aneurysm
C. Contiguous vertebral spread
→ back
pain
8. Bone and Joint Infection
Presentation
- focal
pain
- chronic
osteomyelitis
- septic
arthritis
Common sites
Adults:
- spine
- long
bones
- prosthetic
joints
9. Other Rare Manifestations
- granulomatous
hepatitis
- interstitial
lung disease
- lymphadenitis
10. When to Suspect Chronic Q Fever
Important clues
- culture-negative
endocarditis
- vascular
graft infection
- unexplained
aneurysm infection
- prolonged
inflammatory syndrome
Epidemiologic clues
- livestock
exposure
- endemic
area
- prior
acute Q fever
11. Diagnosis
Core principle
Diagnosis ต้องอาศัย:
1.
compatible syndrome
2.
microbiology
3.
imaging
12. Serology
Hallmark
High phase I IgG
Important thresholds
ขึ้นกับ criteria:
- ≥1:800
- ≥1:6400
Important caveat
high phase I IgG:
- ไม่เท่ากับ chronic Q fever เสมอ
เพราะ persist หลัง acute
infection ได้
13. PCR
Important
positive PCR:
- definitive
evidence
Limitation
negative PCR:
- ไม่ exclude disease
เพราะ sensitivity:
- ~56–70%
14. Culture
Important practical point
routine culture:
- ไม่ขึ้น
15. Echocardiography
Important limitation
sensitivity ต่ำกว่า IE ทั่วไป
Recommendation
ถ้า TTE nondiagnostic:
→ perform TEE
But:
negative TEE
- ยังไม่ rule out disease
16. FDG PET/CT
Very important modality
ช่วย:
- localize
infection
- detect
vascular infection
- detect
occult foci
- monitor
treatment response
Particularly useful in:
- vascular
infection
- unclear
endocarditis
- multifocal
disease
17. Other Imaging
Vascular disease
- CT
angiography
- contrast
CT
Osteomyelitis
MRI = best test
18. Diagnostic Criteria
หลาย systems:
- Duke
criteria
- Dutch
consensus
- French
NRC
- CDC
criteria
Updated Duke criteria
ปัจจุบัน:
- positive
PCR
- PET/CT
findings
ถือเป็น major criteria ได้
19. Treatment
First-line regimen
Doxycycline + Hydroxychloroquine
Doxycycline
100 mg PO BID
Hydroxychloroquine
200 mg PO q8h
20. Why Hydroxychloroquine?
ช่วย:
- alkalinize
phagolysosome
- improve
doxycycline activity
21. Monitoring During Therapy
Drug levels
target:
- doxycycline:
5–10 mcg/mL
- hydroxychloroquine:
0.8–1.2 mcg/mL
22. Hydroxychloroquine Toxicity
Major concern
retinal toxicity
Recommendation
baseline ophthalmologic exam
+
every 6 months
Other concerns
- QT
prolongation
- GI
symptoms
- skin
pigmentation
23. Alternative Regimens
ถ้าใช้ hydroxychloroquine ไม่ได้:
- doxycycline
+ fluoroquinolone
เช่น:
- moxifloxacin
- ofloxacin
24. Pregnancy
Chronic Q fever in pregnancy
rare แต่ complicated มาก
Suggested regimen
TMP-SMX + folic acid
หลังคลอด:
→ standard therapy
25. Duration of Therapy
Native infection
≥18 months
Prosthetic material
≥24 months
Longer duration if:
- persistent
infection
- rising
titers
- persistent
PET uptake
- undrained
focus
26. Surgery
Endocarditis
indications เหมือน IE ทั่วไป:
- heart
failure
- severe
valve dysfunction
- uncontrolled
infection
Vascular infection
มักต้อง:
- surgical
repair
- graft
surgery
- EVAR
- abscess
drainage
Important
surgery associated with improved survival
ใน vascular infection
27. Monitoring and Follow-up
Clinical follow-up
- 1
month after treatment
- then
every 3 months
Serology
- q3
months first year
- q6
months years 2–5
PCR
- 3
months
- 12
months
- end
of treatment
Echocardiography
สำหรับ endocarditis:
- every
6 months
FDG PET/CT
- 12
months
- 24
months
- end
of treatment
28. Stopping Therapy
Suggested criteria
- fourfold
decrease in phase I IgG
- negative
phase II IgM
หลังครบ minimum duration
Important
serology:
- ไม่ควรใช้เป็น criterion เดียว
29. Prognosis
Major complications
- heart
failure
- stroke
- aneurysm
rupture
- arterial
fistula
- abscess
Mortality
สูงสุดใน:
- combined
vascular + endocarditis
30. Important Clinical Pearls
Culture-negative endocarditis
→ think
Q fever
PET/CT extremely useful
โดยเฉพาะ vascular disease
Negative TEE
ไม่ exclude Q fever endocarditis
High phase I IgG alone
ไม่พอสำหรับ diagnosis
Treatment prolonged มาก
18–24+ months
31. Key Take-home Points
- Chronic
Q fever มักเกิด months–years หลัง infection
- Major
manifestations:
- endocarditis
- vascular
infection
- Risk
factors:
- valvular
disease
- vascular
graft/aneurysm
- pregnancy
- immunosuppression
- Hallmark
serology:
- high
phase I IgG
- Blood
culture ปกติไม่ขึ้น
- PET/CT
มีบทบาทสำคัญมาก
- First-line
treatment:
- doxycycline
+ hydroxychloroquine
- Duration:
- 18–24
months minimum
- ต้องติดตามระยะยาวอย่างใกล้ชิด
- Mortality
และ complication สูง โดยเฉพาะ vascular
infection
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