{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,16]],"date-time":"2026-07-16T09:37:38Z","timestamp":1784194658013,"version":"3.55.0"},"reference-count":18,"publisher":"American Academy of Pediatrics (AAP)","issue":"1","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2001,7,1]]},"abstract":"<jats:sec>\n                  <jats:title>Objective.<\/jats:title>\n                  <jats:p>Haemophilus influenzae type b causes severe disease in nonimmune infants and young children; other serotypes are uncommon pathogens and thought to have low virulence. Some have hypothesized that with the virtual elimination of H influenzae type b, other serotypes might acquire virulence traits and emerge as important pathogens of children. We describe the clinical, epidemiologic, and molecular biologic features of 5 cases of severe disease attributable toHaemophilus influenzae type a.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Methods.<\/jats:title>\n                  <jats:p>After observing 4 cases of invasive disease caused by H influenzae type a, we reviewed microbiology records at 3 reference laboratories that perform all serotyping in Utah and surveillance databases. Strains of H influenzae type a and control strains were examined by Southern blotting with the use of the cap probe pUO38 and by pulsed-field gel electrophoresis. The putative virulence mutation, the IS1016-bexA deletion, was detected by polymerase chain reaction amplification and sequencing.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Results.<\/jats:title>\n                  <jats:p>During a 10-month period, we observed 5 children with severe invasive disease caused by H influenzae type a. No isolates of H influenzae type a had been submitted to the reference laboratories between 1992 and 1998. The median age of patients was 12 months (range: 6\u201348 months). Four of 5 had meningitis and bacteremia; 1 had purpura fulminans. Three isolates, representing 1 of 2 pulsed-field gel electrophoresis patterns, contained the IS1016-bexA deletion and were associated with particularly severe disease.<\/jats:p>\n               <\/jats:sec>\n               <jats:sec>\n                  <jats:title>Conclusions.<\/jats:title>\n                  <jats:p>We describe an unusual cluster of severe disease caused by H influenzae type a that resembles the clinical and epidemiologic features of H influenzae type b disease. Our data support the hypothesis that the IS1016-bexA deletion may identify more virulent strains of H influenzae.Haemophilus influenzae, epidemiology, virulence, serotyping, pathogenicity.<\/jats:p>\n               <\/jats:sec>","DOI":"10.1542\/peds.108.1.e18","type":"journal-article","created":{"date-parts":[[2004,8,13]],"date-time":"2004-08-13T23:55:51Z","timestamp":1092441351000},"page":"e18-e18","source":"Crossref","is-referenced-by-count":63,"title":["Invasive Serotype a <i>Haemophilus influenzae<\/i>Infections With a Virulence Genotype Resembling <i>Haemophilus influenzae<\/i> Type b: Emerging Pathogen in the Vaccine Era?"],"prefix":"10.1542","volume":"108","author":[{"given":"Elisabeth E.","family":"Adderson","sequence":"first","affiliation":[{"name":"From the Departments of Pediatrics,"},{"name":"St Jude Children's Research Center, Memphis Tennessee."}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Carrie L.","family":"Byington","sequence":"additional","affiliation":[{"name":"From the Departments of Pediatrics,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"LaShonda","family":"Spencer","sequence":"additional","affiliation":[{"name":"From the Departments of Pediatrics,"},{"name":"Medicine, and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Amy","family":"Kimball","sequence":"additional","affiliation":[{"name":"From the Departments of Pediatrics,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Musa","family":"Hindiyeh","sequence":"additional","affiliation":[{"name":"Pathology, University of Utah School of Medicine;"},{"name":"Associated Regional and University Pathologists;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karen","family":"Carroll","sequence":"additional","affiliation":[{"name":"Medicine, and"},{"name":"Pathology, University of Utah School of Medicine;"},{"name":"Associated Regional and University Pathologists;"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Susan","family":"Mottice","sequence":"additional","affiliation":[{"name":"Utah Department of Health,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"E. Kent","family":"Korgenski","sequence":"additional","affiliation":[{"name":"Primary Children's Medical Center, Salt Lake City, Utah; and"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"John C.","family":"Christenson","sequence":"additional","affiliation":[{"name":"From the Departments of Pediatrics,"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andrew T.","family":"Pavia","sequence":"additional","affiliation":[{"name":"From the Departments of Pediatrics,"},{"name":"Medicine, and"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"417","published-online":{"date-parts":[[2001,7,1]]},"reference":[{"key":"2021121010582610700_B1","doi-asserted-by":"crossref","first-page":"471","DOI":"10.1084\/jem.53.4.471","article-title":"Variation and type specificity in the bacterial speciesHaemophilus influenzae.","volume":"53","author":"Pittman","year":"1931","journal-title":"J Exp Med"},{"key":"2021121010582610700_B2","doi-asserted-by":"crossref","first-page":"229","DOI":"10.3201\/eid0402.980210","article-title":"Haemophilus influenzae invasive disease in the United States, 1994\u20131995: near disappearance of a vaccine-preventable childhood disease.","volume":"4","author":"Bisgard","year":"1998","journal-title":"Emerg Infect Dis."},{"key":"2021121010582610700_B3","first-page":"993","article-title":"Progress toward eliminatingHaemophilus influenzae type b disease among infants and children\u2014United States, 1987\u20131997.","volume":"47","author":"Centers for Disease Control and Prevention","year":"1998","journal-title":"MMWR Morb Mortal Wkly Rep."},{"key":"2021121010582610700_B4","doi-asserted-by":"crossref","first-page":"336","DOI":"10.3201\/eid0503.990304","article-title":"Bacterial vaccines and serotype replacement: lessons fromHaemophilus influenzae and prospects for Streptococcus pneumoniae.","volume":"5","author":"Lipsitch","year":"1999","journal-title":"Emerg Infect Dis"},{"key":"2021121010582610700_B5","doi-asserted-by":"crossref","first-page":"560","DOI":"10.1128\/jcm.34.3.560-563.1996","article-title":"Molecular characteristics ofHaemophilus influenzae causing invasive disease during the period of vaccination in Switzerland: analysis of strains isolated between 1986 and 1993.","volume":"34","author":"Muhlemann","year":"1996","journal-title":"J Clin Microbiol."},{"key":"2021121010582610700_B6","doi-asserted-by":"crossref","first-page":"S34","DOI":"10.1093\/infdis\/165-Supplement_1-S34","article-title":"Invasive Haemophilus influenzae disease: a population-based evaluation of the role of capsular polysaccharide serotype. 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