Streptococcus suis meningitis in adults in Vietnam.
BACKGROUND
Streptococcus suis infection is an emerging zoonosis in Asia. We determined the detailed epidemiological, clinical, and microbiological characteristics of S. suis meningitis in adults.


METHODS
We prospectively studied 450 patients with suspected bacterial meningitis. Four hundred thirty-five (96.7%) of the patients participated in a trial to determine the effect of adjunctive dexamethasone treatment. For patients with S. suis infection, bacterial DNA load at hospital admission and during treatment was analyzed in cerebrospinal fluid specimens using quantitative real-time polymerase chain reaction. S. suis strains were characterized using pulsed-field gel electrophoresis and multilocus sequence typing. Putative virulence factors, including extracellular protein factor, suilysin, and muramidase released protein, were detected using polymerase chain reaction and Western blot assay. Predictors of outcome were identified using logistic regression analysis.


RESULTS
S. suis was the most common pathogen and was detected in 151 (33.6%) of the patients. Fifty (33.1%) of these 151 patients reported exposure to pigs or pork. Mortality was low (2.6%; 4 of 151 patients died), but mild to severe hearing loss occurred in 93 (66.4%) of 140 patients. Severe deafness at hospital discharge was associated with age >50 years (odds ratio, 3.65; 95% confidence interval, 1.15-11.6), a strain carrying the epf gene (odds ratio, 3.42; 95% confidence interval, 1.02-11.4), and dexamethasone therapy (odds ratio, 0.23; 95% confidence interval, 0.06-0.78) but was not associated with cerebrospinal fluid bacterial DNA load. Bacterial DNA was still detectable in 58 (63%) of 92 cerebrospinal fluid samples after 6-10 days of antimicrobial treatment. Ninety-one of 92 S. suis strains had serotype 2. Thirty-three (36%) of these epidemiologically unrelated strains belonged to 1 pulsed-field gel electrophoresis cluster of multilocus sequence type 1, indicating clonal spread.


CONCLUSIONS
S. suis serotype 2 is the most frequent cause of bacterial meningitis in adults in southern Vietnam and is associated with substantial morbidity attributable to hearing loss.
Mai
Nguyen Thi Hoang
NT
Hospital for Tropical Diseases, Ho Chi Minh City, Vietnam.
Hoa
Ngo Thi
NT
Nga
Tran Vu Thieu
TV
Linh
Le Dieu
le D
Chau
Tran Thi Hong
TT
Sinh
Dinh Xuan
DX
Phu
Nguyen Hoan
NH
Chuong
Ly Van
LV
Diep
To Song
TS
Campbell
James
J
Nghia
Ho Dang Trung
HD
Minh
Tran Ngoc
TN
Chau
Nguyen Van Vinh
NV
de Jong
Menno D
MD
Chinh
Nguyen Tran
NT
Hien
Tran Tinh
TT
Farrar
Jeremy
J
Schultsz
Constance
C
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000704:Analysis of Variance; D000818:Animals; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification*; D003907:Dexamethasone / Q000627:therapeutic use; D005260:Female; D015600:Glasgow Coma Scale; D006801:Humans; D008297:Male; D016920:Meningitis, Bacterial / Q000453:epidemiology*; D008875:Middle Aged; D009345:Neisseria meningitidis / Q000235:genetics / Q000302:isolation & purification; D013290:Streptococcal Infections / Q000453:epidemiology*; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000302:isolation & purification; D017011:Streptococcus suis / Q000235:genetics* / Q000302:isolation & purification; D016896:Treatment Outcome; D014744:Vietnam / Q000453:epidemiology; D055815:Young Adult; D015047:Zoonoses / Q000453:epidemiology
D004269:DNA, Bacterial; D003907:Dexamethasone