Molecular subtyping to detect human listeriosis clusters.
We analyzed the diversity (Simpson's Index, D) and distribution of Listeria monocytogenes in human listeriosis cases in New York State (excluding New York City) from November 1996 to June 2000 by using automated ribotyping and pulsed-field gel electrophoresis (PFGE). We applied a scan statistic (p<or=0.05) to detect listeriosis clusters caused by a specific Listeria monocytogenes subtype. Among 131 human isolates, 34 (D=0.923) ribotypes and 74 (D=0.975) PFGE types were found. Nine (31% of cases) clusters were identified by ribotype or PFGE; five (18% of cases) clusters were identified by using both methods. Two of the nine clusters (13% of cases) corresponded with investigated multistate listeriosis outbreaks. While most human listeriosis cases are considered sporadic, highly discriminatory molecular subtyping approaches thus indicated that 13% to 31% of cases reported in New York State may represent single-source clusters. Listeriosis control and reduction efforts should include broad-based subtyping of human isolates and consider that a large number of cases may represent outbreaks.
Sauders
Brian D
BD
Wadsworth Center, New York State Department of Health, Albany, New York, USA.
Fortes
Esther D
ED
Morse
Dale L
DL
Dumas
Nellie
N
Kiehlbauch
Julia A
JA
Schukken
Ynte
Y
Hibbs
Jonathan R
JR
Wiedmann
Martin
M
D000368:Aged; D015373:Bacterial Typing Techniques / Q000379:methods*; D016000:Cluster Analysis; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008089:Listeria monocytogenes / Q000145:classification* / Q000302:isolation & purification; D008088:Listeriosis / Q000453:epidemiology* / Q000382:microbiology; D008297:Male; D009518:New York / Q000453:epidemiology; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000032:analysis; D021521:Ribotyping / Q000379:methods* / Q000706:statistics & numerical data
D012335:RNA, Ribosomal