title: Prevalence of Salmonella enterica serovar 4,[5],12:i:- in England and Wales, 2010.
abstract: Difficulties in accurately identifying serovar 4,[5],12:i:- as monophasic variants of Salmonella enterica serovar Typhimurium mean there is confusion in the reporting of serovars Typhimurium and 4,[5],12:i:-. To gain insight into the prevalence and diversity of these monophasic variants in England and Wales, screening for fljB, hin and the serovar 4,[5],12:i:- DT193-associated genomic island was conducted on 609 S. enterica isolates designated as definitive phage type (DT) 193, and 142 isolates serologically-defined as monophasic variants of serovar Typhimurium but belonging to phage types other than DT193. All latter 142 isolates were subtyped by multilocus variable-number tandem repeat analysis (MLVA). MLVA was also applied to 70 DT193 serologically-defined monophasic variant isolates. Results indicate that serovar 4,[5],12:i:- accounted for 108 of 209 (52%) of DT193 isolates with available serological data and 99 of 142 (70%) monophasic variant isolates belonging to other phage types. Of 609 DT193 isolates, 463 (76%) lacked fljB and hin. Moreover, genetically-related isolates of DTs 120, 191, 191a, 195, phage types U311 and U323, and reacts but does not conform (RDNC) and untypable (UT) strains were also lacking either hin and/or fljB. Of note, the serovar 4,[5],12:i:- DT193-associated genomic island was identified in not only 458 of 463 (99%) monophasic DT193 isolates, but also 25 of 139 (18%) biphasic DT193 isolates and 56 of 76 (74%) monophasic variants of other phage types. Accurate monitoring of the emergence of serovar 4,[5],12:i:- isolates is important to ascertain the public health impact of these strains; since 2012 the Health Protection Agency’s Salmonella Reference Unit has therefore begun determining full antigenic structures of all presumptive O:4 isolates in addition to routinely performing phage typing for identification of variants of serovar Typhimurium.
authors.affiliation: Health Protection Agency Colindale, London, United Kingdom. katie.hopkins@hpa.org.uk
authors.forename: K L
authors.initials: KL
authors.lastname: Hopkins
authors.forename: E
authors.initials: E
authors.lastname: de Pinna
authors.forename: J
authors.initials: J
authors.lastname: Wain
mesh_terms: D001434:Bacteriophage Typing; D004739:England / Q000453:epidemiology; D044404:Genomic Islands; D006801:Humans; D058885:Multilocus Sequence Typing; D015995:Prevalence; D012480:Salmonella Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000382:microbiology; D019779:Salmonella enterica / Q000235:genetics* / Q000302:isolation & purification*; D012486:Salmonella typhimurium / Q000235:genetics* / Q000302:isolation & purification; D012703:Serotyping / Q000379:methods*; D020080:Tandem Repeat Sequences; D014852:Wales / Q000453:epidemiology