A surge in hematopoietic stem cell transplantation (HSCT) human adenovirus A31 (HAdV-A31) infections was initially observed in late 2014/2015 at SickKids (SK) Hospital, Toronto, Canada. In response, enhanced laboratory monitoring for all adenovirus infections was conducted. Positive samples underwent genotyping, viral culture, and, in selected cases, whole-genome sequencing (WGS). HAdV-A31 specimens/DNA obtained from four international pediatric HSCT centers also underwent WGS. During the SK outbreak period (27 October 2014 to 31 October 2018), 17/20 HAdV-A31 isolates formed a distinct clade with 0 to 8 mutations between the closest neighbors. Surveillance before and after the outbreak detected six additional HAdV-A31 HSCT cases; three of the four sequenced cases clustered within the outbreak clade. Two SK outbreak isolates were identical to sequences from two patients in an outbreak in England. Three SK non-outbreak sequences also had high sequence similarity to strains from three international centers. Environmental PCR testing of the HSCT ward showed significant adenovirus contamination. Despite intense infection control efforts, we observed re-occurrence of infection with the outbreak strain. Severe but nonfatal infection was observed more commonly with HAdV-A31 compared to other genotypes, except HAdV-C1. Our findings strongly implicate nosocomial spread of HAdV-A31 over 10 years on a HSCT unit and demonstrate the value of WGS in defining and mapping the outbreak. Close linkages among strains in different countries suggest international dissemination, though the mechanism is undetermined. This large, extended outbreak emphasizes the pre-eminent role of HAdV-A31 in causing intractable pediatric HSCT outbreaks of severe illness worldwide.

Charles University Prague Czech Republic

Department of Laboratory Medicine and Pathobiology University of Torontogrid 17063 33 Toronto Ontario Canada

Department of Medical Microbiology University Hospital Motol Prague Czech Republic

Department of Paediatrics University of Torontogrid 17063 33 Toronto Ontario Canada

Division of Hematology Oncology The Hospital for Sick Childrengrid 42327 30 Toronto Ontario Canada

Division of Infectious Diseases The Hospital for Sick Childrengrid 42327 30 Toronto Ontario Canada

Division of Microbiology The Hospital for Sick Childrengrid 42327 30 Toronto Ontario Canada

Infection Prevention and Control The Hospital for Sick Childrengrid 42327 30 Toronto Ontario Canada

National Microbiology Laboratory Public Health Agency of Canadagrid 415368 d Winnipeg Manitoba Canada

Public Health Ontariogrid 415400 4 Laboratories Public Health Ontario Toronto Ontario Canada

University of Manitoba Winnipeg Manitoba Canada

See more in PubMed

Lion T. 2014. Adenovirus infections in immunocompetent and immunocompromised patients. Clin Microbiol Rev 27:441–462. 10.1128/CMR.00116-13. PubMed DOI PMC

Seidemann K, Heim A, Pfister ED, Köditz H, Beilken A, Sander A, Melter M, Sykora KW, Sasse M, Wessel A. 2004. Monitoring of adenovirus infection in pediatric transplant recipients by quantitative PCR: report of six cases and review of the literature. Am J Transplant 4:2102–2108. 10.1111/j.1600-6143.2004.00631.x. PubMed DOI

Kampmann B, Cubitt D, Walls T, Naik P, Depala M, Samarasinghe S, Robson D, Hassan A, Rao K, Gaspar H, Davies G, Jones A, Cale C, Gilmour K, Real M, Foo M, Bennett-Rees N, Hewitt A, Amrolia P, Veys P. 2005. Improved outcome for children with disseminated adenoviral infection following allogeneic stem cell transplantation. Br J Haematol 130:595–603. 10.1111/j.1365-2141.2005.05649.x. PubMed DOI

Khandelwal P, Millard HR, Thiel E, Abdel-Azim H, Abraham AA, Auletta JJ, Boulad F, Brown VI, Camitta BM, Chan KW, Chaudhury S, Cowan MJ, Angel-Diaz M, Gadalla SM, Gale RP, Hale G, Kasow KA, Keating AK, Kitko CL, MacMillan ML, Olsson RF, Page KM, Seber A, Smith AR, Warwick AB, Wirk B, Mehta PA. 2017. Hematopoietic stem cell transplantation activity in pediatric cancer between 2008 and 2014 in the United States: a Center for International Blood and Marrow Transplant Research Report. Biol Blood Marrow Transplant 23:1342–1349. 10.1016/j.bbmt.2017.04.018. PubMed DOI PMC

Leruez-Ville M, Chardin-Ouachée M, Neven B, Picard C, Le Guinche I, Fischer A, Rouzioux C, Blanche S. 2006. Description of an adenovirus A31 outbreak in a paediatric haematology unit. Bone Marrow Transplant 38:23–28. 10.1038/sj.bmt.1705389. PubMed DOI

Mattner F, Sykora KW, Meissner B, Heim A. 2008. An adenovirus type F41 outbreak in a pediatric bone marrow transplant unit: analysis of clinical impact and preventive strategies. Pediatr Infect Dis J 27:419–424. 10.1097/INF.0b013e3181658c46. PubMed DOI

Swartling L, Allard A, Törlen J, Ljungman P, Mattsson J, Sparrelid E. 2015. Prolonged outbreak of adenovirus A31 in allogeneic stem cell transplant recipients. Transpl Infect Dis 17:785–794. 10.1111/tid.12443. PubMed DOI

Houldcroft CJ, Roy S, Morfopoulou S, Margetts BK, Depledge DP, Cudini J, Shah D, Brown JR, Romero EY, Williams R, Cloutman-Green E, Rao K, Standing JF, Hartley JC, Breuer J. 2018. Use of whole-genome sequencing of adenovirus in immunocompromised pediatric patients to identify nosocomial transmission and mixed-genotype infection. J Infect Dis 218:1261–1271. 10.1093/infdis/jiy323. PubMed DOI

Ali S, Krueger J, Richardson SE, Sung L, Waespe N, Renzi S, Chiang K, Allen U, Ali M, Schechter T. 2019. The yield of monitoring adenovirus in pediatric hematopoietic stem cell transplant patients. Pediatr Hematol Oncol 36:161–172. 10.1080/08880018.2019.1607961. PubMed DOI

Sarantis H, Johnson G, Brown M, Petric M, Tellier R. 2004. Comprehensive detection and serotyping of human adenoviruses by PCR and sequencing. J Clin Microbiol 42:3963–3969. 10.1128/JCM.42.9.3963-3969.2004. PubMed DOI PMC

Myers CE, Houldcroft CJ, Roy S, Margetts BK, Best T, Venturini C, Guerra-Assunção JA, Williams CA, Williams R, Dunn H, Hartley JC, Rao K, Rolfe KJ, Breuer J. 2021. Using whole genome sequences to investigate adenovirus outbreaks in a hematopoietic stem cell transplant unit. Front Microbiol 12:667790. 10.3389/fmicb.2021.667790. PubMed DOI PMC

Stapleton PJ, Eshaghi A, Seo CY, Wilson S, Harris T, Deeks SL, Bolotin S, Goneau LW, Gubbay JB, Patel SN. 2019. Evaluating the use of whole genome sequencing for the investigation of a large mumps outbreak in Ontario, Canada. Sci Rep 9:12615. 10.1038/s41598-019-47740-1. PubMed DOI PMC

Bolger AM, Lohse M, Usadel B. 2014. Trimmomatic: a flexible trimmer for Illumina sequence data. Bioinformatics 30:2114–2120. 10.1093/bioinformatics/btu170. PubMed DOI PMC

Katoh K, Standley DM. 2013. MAFFT multiple sequence alignment software version 7: improvements in performance and usability. Mol Biol Evol 30:772–780. 10.1093/molbev/mst010. PubMed DOI PMC

Nguyen LT, Schmidt HA, von Haeseler A, Minh BQ. 2015. IQ-TREE: a fast and effective stochastic algorithm for estimating maximum-likelihood phylogenies. Mol Biol Evol 32:268–274. 10.1093/molbev/msu300. PubMed DOI PMC

Letunic I, Bork P. 2019. Interactive Tree Of Life (iTOL) v4: recent updates and new developments. Nucleic Acids Res 47:W256–W259. 10.1093/nar/gkz239. PubMed DOI PMC

Treangen TJ, Ondov BD, Koren S, Phillippy AM. 2014. The Harvest suite for rapid core-genome alignment and visualization of thousands of intraspecific microbial genomes. Genome Biol 15:524. 10.1186/s13059-014-0524-x. PubMed DOI PMC

Johansson ME, Brown M, Hierholzer JC, Thörner A, Ushijima H, Wadell G. 1991. Genome analysis of adenovirus type 31 strains from immunocompromised and immunocompetent patients. J Infect Dis 163:293–299. 10.1093/infdis/163.2.293. PubMed DOI

Hofmayer S, Madisch I, Darr S, Rehren F, Heim A. 2009. Unique sequence features of the human adenovirus 31 complete genomic sequence are conserved in clinical isolates. BMC Genomics 10:557. 10.1186/1471-2164-10-557. PubMed DOI PMC

Ruis C, Bryant JM, Bell SC, Thomson R, Davidson RM, Hasan NA, van Ingen J, Strong M, Floto RA, Parkhill J. 2021. Dissemination of Mycobacterium abscessus via global transmission networks. Nat Microbiol 6:1279–1288. 10.1038/s41564-021-00963-3. PubMed DOI PMC

Matthes-Martin S, Feuchtinger T, Shaw PJ, Engelhard D, Hirsch HH, Cordonnier C, Ljungman P, Fourth European Congress on Infections in Leukemia . 2012. European guidelines for diagnosis and treatment of adenovirus infection in leukemia and stem cell transplantation: summary of ECIL-4 (2011). Transpl Infect Dis 14:555–563. 10.1111/tid.12022. PubMed DOI

Jeulin H, Salmon A, Bordigoni P, Venard V. 2011. Diagnostic value of quantitative PCR for adenovirus detection in stool samples as compared with antigen detection and cell culture in haematopoietic stem cell transplant recipients. Clin Microbiol Infect 17:1674–1680. 10.1111/j.1469-0691.2011.03488.x. PubMed DOI