Brucella Serology, immunology rotation. R3, Clinical Microbiology Residency

1. BRUCELLA SEROLOGY
Manual and uptodate

2. MANUAL
• OMP25, L7, L12 and fusion proteins are found in all brucella spp:
• Important as diagnostic tools & vaccines
• Brucella virulance factors:
• Urease  to avoid stomach acidity
• Vacule  to escape from immune system
• LPS and outer membrane protein 25 (OMP25)  to survive within mononuclear
cells

3. MANUAL
• Granuloma formation in B.abortus > B.melitenisis
• Brucella lives 3 weeks in milk but can be killed by pasturization, exposure to
UV light, acidity or antiseptics and disinfectant
• Human to human transmission is very rare mostly in newborns & breast milk
• Lab aquired infection is very important route (ID <102 organisms)
• Incubation period 1-4w
• Risk factors of relapse: positive BC, & use of less effective Abx
• Most common complication is arthritis, then genitals, neurological (CSF
culture yield 5-30% so serology on CSF is important), cardiac, pulmonary
and renal
• Mortality <1%

4. MANUAL
• Serology can be done on serum and CSF
• Culture is the gold standard, bone marrow is 15-20% yield > blood
(which is 50-80%)
• Brucella can grow in  BA, CHOC, MAC, TM & Martin lewis (in
contaminated samples) all agar manupulation under BSC

6. MANUAL
• Serology is the most common used diagnostic tool
• IgM first then 10-14 days IgG
• Several Ag for B.melitenisis and B.abortus are used (B.canis are limited or
none)
• Points in Tests :
• Slide agglutination (rose bangal) and tube agglutination:
• Can’t differentiate between types of Abs
• Dx cut off is >160
• Used in monitoring treatment and follow up  better indicator for treatment because they
decline with ttt faster than others
• Brucellacapt:
• Immunocapture technique
• Rapid and easy , can be used for follow up  but Abs can persist for 2-3 y
• ICT:
• For screening and surveillance in endemic areas
• Rapid, easy and cheap
• High (>90%) sensitivity and specificity

7. MANUAL
• False negative serology: (repeat testing 1-2 weeks if highly suspected)
• If B.canis is the cause
• Very early disease
• Use of slide or tube agglutination alone  which will miss chronic or focal disease
• Cross reactivity false positive agglutination & CF in brucella with:
• Yersenia enteroclitica O:9, E.coli O:157 & hermanni, salmonella enterica O:30
• S.maltophilia, v.cholerae O:1, F.tularensis
• Cross reaction happen due to similarities in O specific side chains of LPS
• Combination of agglutination and non agglutination test is best for Diagnosis to
overcome false (-)
• Prognosis:
• Decline indicate good prognosis
• Persistence of Abs indicates bad prognosis (persistence has been reported in cured patients)
• Resurgence of Abs indicates relapse or reinfiction (Resurgence in IgG & IgA not IgM)
• Limitations of serology:
• Lack of standardization due to different Ag preparations and different methods
• Detection of high Abs titers in some patients despite treatment and cure

9. MANUAL
• AST is rarly indicated due to:
• Rare Abx resistants
• Lack of plasmids
• Lab saftey
• Poor clinical correlation to in in-vitro results
• Can be done by MHA BMD or Etest on BMHA (CLSI only doxy and
tetra)

10. https://www-uptodate-com.library.iau.edu.sa/contents/brucellosis-epidemiology-microbiology-clinical-
manifestations-and-diagnosis?source=history_widget

11. TREATMENT OF NON-PREGNANT ADULT
WITH UNCOMPLICATED BRUCELLOSIS
Major
Regimen
s
Doxycycline 100 mg orally twice daily for six weeks +
Streptomycin 1 g intramuscularly once daily for the first
14 to 21 days. (Gentamicin may be substituted for
streptomycin; equal efficacy has been demonstrated)
Doxycycline 100 mg orally twice daily + Rifampicin 600
to 900 mg (15 mg/kg) orally once daily. Both drugs for 6
weeks
Alternati
ve
Regimen
Fluoroquinolones (ciprofloxacin 500 mg twice daily)
have good in vitro activity against Brucella spp and can
be used in combination with Doxycycline or Rifampicin.
They may be useful in the setting of drug resistance,
antimicrobial toxicity, and some cases of relapse
Uncomplicated brucellosis (eg, not having spondylitis,
neurobrucellosis, or endocarditis)

12. NON-PREGNANT ADULT WITH
UNCOMPLICATED BRUCELLOSIS
Major
Regimen
s
Doxycycline 100 mg orally twice daily for six weeks +
Streptomycin 1 g intramuscularly once daily for the first
14 to 21 days. (Gentamicin may be substituted for
streptomycin; equal efficacy has been demonstrated)
Doxycycline 100 mg orally twice daily + Rifampicin 600
to 900 mg (15 mg/kg) orally once daily. Both drugs for 6
weeks
Alternati
ve
Regimen
Fluoroquinolones (ciprofloxacin 500 mg twice daily)
have good in vitro activity against Brucella spp and can
be used in combination with Doxycycline or Rifampicin.
They may be useful in the setting of drug resistance,
antimicrobial toxicity, and some cases of relapse
Uncomplicated brucellosis (eg, not having spondylitis,
neurobrucellosis, or endocarditis)
Monotherapy and regimens
shorter than six weeks are not
accepted treatment strategies
for brucellosis

13. https://www.uptodate.com/contents/brucellosis-treatment-and-prevention?search=brucellosis-microbiology-epidemiology-and-
pathogenesis&source=search_result&selectedTitle=2~106&usage_type=default&display_rank=2#H3902227185
In Pregnancy
Pregnant <36 weeks
Treat with rifampin plus
TMP-SMX, both for six
weeks
Pregnant >36 weeks
Administer rifampin
monotherapy until delivery,
given risk of neonatal
kernicterus with the use of
TMP-SMX in the last
month of pregnancy.
After delivery, we continue
combination therapy as in
nonpregnant adults; the
total duration of treatment
is six weeks.

14. MANUAL
• Complicated brucellosis
• Triple therapy of doxy + rif + aminoglycoside or CRO for 2-3 months
• Causes of relapses:
• Short (<6w) treatment
• Monotherapy
• Post exposure prophilaxis
• Rif or doxy 3-6 weeks empiraclly
• Baseline serology in 0,2,4,6,24 weeks & monitor symptoms weekly for 6
months

15. REFERENCES