Micro - Brucella
intro
6 species, 4 of which can cause human brucellosis
B Melitensis (goats/sheep)
B abortus (cattle)
B suis (pigs)
B canis (dogs/foxes)
zoonosis
small gram -ve coccobacillus
non-motile
non-capsulated
strict aerobic intracellular pathogen
Biosafely level 3 (hazard in lab)
infection leads to abortion in animals
endemic in Ire + UK
notifiable
Transmission
contact with infected animal/animal foetus/animal conjunctiva
consumption of infected food (milk)
airborne
inhalation of aerosols/aerosols landing on eye
portals of entry: ingestion, inhalation, conjuntivae, cuts in skin
occupational hazard
human-human rare (but possible in transfusions + transplants)
tends to infect erythritol (a sugar)-rich organs (breast, uterus, epididymis, animal placenta)
rarely causes human abortion as human placenta lack erythritol
ingested by neutrophils/macrophages, multiplies in regional lymph nodes, enters blood stream, spreads to organs + RES (90% in phagocytic cells in liver)
small non-caseating granulomata produced in target sites
Acute Brucellosis
incubation = 2-4 wks
50% get ILI
Chronic Brucellosis
occurs in un/inadequately txed cases
recurs over months/yrs
evening depression (often present to psych), sweating episodes, aches/weakness, insomnia
Multi-system complications
bone
joint
neuro
haematological
pneumonia
GI
endocarditis
ocular
dermatological
epididymis
orchitis
Dx
clinical suspicion
blood cultures
do multiple sets as is only 30-50% sensitive in acute infection
BM aspirate
liver Bx
serology
serum agglutination test (SAT)
complement fixation test
Coomb's test
+ve = titre > 1:160
blood PCR
Tx
combination intracellular Tx for long duration
doxycycline + rifampicin/streptomycin/ciprofloxacin for 6 wks
if pregnant ir doxycycline intolerant: rifampicin + gentamicin for 6-9 months
prevention
pasteurisation
eradicate infected animals
vaccinate healthy animals (live attenuated B abortus)
post-exposure prophylaxis
notify