title: Inapparent Streptococcus agalactiae infection in adult/commercial tilapia.
abstract: We report on inapparent infections in adult/commercial tilapia in major tilapia fish farms in Guangdong. A total of 146 suspected isolates were confirmed to be S. agalactiae using an API 20 Strep system and specific PCR amplification. All isolates were identified as serotype Ia using multiplex serotyping PCR. An MLST assay showed single alleles of adhP (10), atr (2), glcK (2), glnA (1), pheS (1), sdhA (3) and tkt (2), and this profile was designated 'unique ST 7'. The analysis of virulence genes resulted in 10 clusters, of which dltr-bca-sodA-spb1-cfb-bac (62, 42.47%) was the predominant virulence gene profile. The PFGE analysis of S. agalactiae yielded 6 distinct PFGE types (A, B, C, D, F and G), of which Pattern C (103) was the predominant type, accounting for approximately 70.55% (103/146) of the total S. agalactiae strains. Therefore, unlike what has been found in juvenile tilapia, in which PFGE pattern D/F is the major prevalent pattern, we found that pattern C was the major prevalent pattern in inapparent infected adult/commercial tilapia in Guangdong, China. In conclusion, we close a gap in the current understanding of S. agalactiae epidemiology and propose that researchers should be alert for inapparent S. agalactiae infections in adult/commercial tilapia to prevent a potential threat to food safety.
authors.affiliation: Guangdong Provincial Institute of Public Health, Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Jiufeng
authors.initials: J
authors.lastname: Sun
authors.affiliation: Guangdong Provincial Center for Aquatic Animal Disease Control and Prevention. Guangzhou, Guangdong, 510222, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Fang
authors.affiliation: Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Bixia
authors.initials: B
authors.lastname: Ke
authors.affiliation: Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Dongmei
authors.initials: D
authors.lastname: He
authors.affiliation: Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Yuheng
authors.initials: Y
authors.lastname: Liang
authors.affiliation: Guangdong Provincial Center for Aquatic Animal Disease Control and Prevention. Guangzhou, Guangdong, 510222, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Ning
authors.affiliation: Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Hailing
authors.initials: H
authors.lastname: Tan
authors.affiliation: Guangdong Provincial Center for Aquatic Animal Disease Control and Prevention. Guangzhou, Guangdong, 510222, China.
authors.forename: Hualin
authors.initials: H
authors.lastname: Peng
authors.affiliation: Guangdong Provincial Center for Aquatic Animal Disease Control and Prevention. Guangzhou, Guangdong, 510222, China.
authors.forename: Yunxin
authors.initials: Y
authors.lastname: Wang
authors.affiliation: Guangdong Provincial Center for Aquatic Animal Disease Control and Prevention. Guangzhou, Guangdong, 510222, China.
authors.forename: Yazhou
authors.initials: Y
authors.lastname: Ma
authors.affiliation: Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Changwen
authors.initials: C
authors.lastname: Ke
authors.affiliation: Guangdong Provincial Center for Disease Control and Prevention. Guangzhou, Guangdong 511430, China.
authors.forename: Xiaoling
authors.initials: X
authors.lastname: Deng
mesh_terms: D000818:Animals; D002681:China; D016521:Electrophoresis, Gel, Pulsed-Field; D005393:Fish Diseases / Q000175:diagnosis / Q000382:microbiology*; D005398:Fisheries; D005516:Food Microbiology; D059022:Food Safety; D005798:Genes, Bacterial; D006801:Humans; D005810:Multigene Family; D058885:Multilocus Sequence Typing; D060885:Multiplex Polymerase Chain Reaction; D012703:Serotyping; D013290:Streptococcal Infections / Q000175:diagnosis / Q000382:microbiology / Q000662:veterinary*; D013292:Streptococcus agalactiae / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology; D017210:Tilapia / Q000382:microbiology*; D014774:Virulence / Q000235:genetics