title: Pertussis outbreak, southeastern Minnesota, 2012.
abstract: OBJECTIVE
  To describe clinical and laboratory findings from the 2012 southeastern Minnesota pertussis outbreak.
  
  
  METHODS
  Patients were selected for 2 parts of the study. In the first part, nasopharyngeal swabs from a convenience sample of 265 unique patients were used for both the clinician-requested polymerase chain reaction (PCR) test and culture. B pertussis isolates were tested for macrolide susceptibility and typed using whole genome sequencing and pulsed-field gel electrophoresis. Pertactin gene sequences were analyzed to identify pertactin-deficient B pertussis. In the second part, all patients seen at Mayo Clinic in Rochester, Minnesota, who had PCR results positive for Bordetella pertussis or Bordetella parapertussis between January 1, 2012, and December 31, 2012, were analyzed for patient demographic features and vaccination records.
  
  
  RESULTS
  One hundred sixty patients had results positive for B pertussis, and 21 patients had results positive for B parapertussis. Among the 265 swabs cultured, B pertussis was detected by both culture and PCR in 11. One swab was positive for B pertussis by culture alone, and 13 were positive by PCR alone. Polymerase chain reaction detected B pertussis more frequently than did culture (P=.001). No macrolide resistance was detected. All 12 isolates tested had an altered pertactin gene, including 9 with a signal sequence deletion, 2 with insertion sequence disruptions, and 1 with a premature stop codon. Nine and 3 isolates were pertactin types prn1 and prn2, respectively. Whole genome sequencing and pulsed-field gel electrophoresis detected the presence of multiple B pertussis strains. The mean age of patients with pertussis was younger than that of those without pertussis (15.6 and 25.5 years, respectively; P=.002). Compared with those whose test results were negative for B pertussis, fewer patients with positive results had received whole-cell pertussis vaccine (P=.02). In the subgroup who had received acellular vaccine exclusively, the time since the most recent pertussis vaccination in those with results positive for B pertussis was longer than that in those with negative results (1363 vs 1010 days; P=.004).
  
  
  CONCLUSIONS
  The 2012 pertussis outbreak in southeastern Minnesota included multiple strains of B pertussis, all putatively lacking pertactin. Our findings may indicate decreased efficacy of (and waning immunity from) acellular vaccines as contributors to the outbreak.
authors.affiliation: Department of Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Alexander G
authors.initials: AG
authors.lastname: Theofiles
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN.
authors.forename: Scott A
authors.initials: SA
authors.lastname: Cunningham
authors.affiliation: Department of Surgery, Mayo Clinic, Rochester, MN; Center for Individualized Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Chia
authors.affiliation: Department of Surgery, Mayo Clinic, Rochester, MN; Institute for Genome Biology, University of Illinois at Urbana-Champaign, Urbana.
authors.forename: Patricio R
authors.initials: PR
authors.lastname: Jeraldo
authors.affiliation: Center for Individualized Medicine, Mayo Clinic, Rochester, MN.
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Quest
authors.affiliation: Department of Health Sciences Research, Mayo Clinic, Rochester, MN.
authors.forename: Jayawant N
authors.initials: JN
authors.lastname: Mandrekar
authors.affiliation: Division of Clinical Microbiology, Department of Laboratory Medicine and Pathology, Mayo Clinic, Rochester, MN; Division of Infectious Diseases, Mayo Clinic, Rochester, MN. Electronic address: patel.robin@mayo.edu.
authors.forename: Robin
authors.initials: R
authors.lastname: Patel
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001886:Bordetella pertussis / Q000235:genetics / Q000302:isolation & purification; D002648:Child; D002675:Child, Preschool; D004279:DNA, Viral / Q000032:analysis; D004196:Disease Outbreaks / Q000517:prevention & control / Q000706:statistics & numerical data*; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D005838:Genotype; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008910:Minnesota / Q000453:epidemiology; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D060888:Real-Time Polymerase Chain Reaction; D014611:Vaccination; D014917:Whooping Cough / Q000453:epidemiology* / Q000517:prevention & control / Q000821:virology; D055815:Young Adult
chemical_list: D004279:DNA, Viral; D010567:Pertussis Vaccine