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Volume 17, Number 6—June 2011
Letter

Lethal Necrotizing Pneumonia Caused by an ST398 Staphylococcus aureus Strain

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To the Editor: The prevalent colonization of livestock with methicillin-resistant Staphylococcus aureus (MRSA) sequence type (ST) 398 in many countries is a cause for consternation. However, understanding of the emergence of these organisms and their public health implications is embryonic. The perceptions that all MRSA found in livestock are of ST398 lineage or that livestock are the only reservoirs of ST398 oversimplify a complex epidemiology, therefore, prudence is required when attributing human infections with S. aureus ST398 to livestock reservoirs. The fatal infection of a young girl with ST398 methicillin-susceptible S. aureus (MSSA) is tragic (1). However, the conclusion by the authors that “the spread of S. aureus ST398 among livestock is a matter of increasing concern because strains of this sequence type were able to acquire PVL [Panton-Valentine leukocidin] genes” is misleading.

The authors report no history of livestock exposure and the spa type reported (t571) is relatively rare among livestock isolates (2,3). The isolate from the fatal case was tetracycline-susceptible and positive for PVL toxin, while livestock ST398 isolates have been almost uniformly tetracycline resistant and PVL negative. Notably, spa type t571 ST398 MSSA was detected in 9 families from the Dominican Republic living in Manhattan, New York, without contact with livestock (4). Furthermore, t571 was the only spa type of MSSA identified in a study in the Netherlands of ST398 isolates, including 3 independent cases of nosocomial bacteremia in Rotterdam with no apparent livestock contact (5). spa type t571 was the predominant (11%) MSSA type in patients at a Beijing, China, hospital (6). More recently, a study of t571 MSSA strains from cases of bloodstream infections in France determined that the isolates differed from pig-borne strains and shared similarities with strains from humans in China and virulent USA300 strains (7). These observations concur with a hypothesis that ST398 strains of diverse genotype and geographic origin may also be epidemiologically distinct (8), and livestock contact is a notably inconsistent feature of invasive ST398 infections (5,710).

The possibility that variants of the ST398 lineage may persist in human populations without livestock contact should not be dismissed. The incidence and severity of clinical infections with ST398 S. aureus in livestock workers as yet have been minimal. Understanding the public health implications of ST398 S. aureus requires systematic investigation of their epidemiology in animals and humans. Human clinical cases of ST398 S. aureus infection should not be indiscriminately attributed to livestock, particularly if isolates are genotypically dissimilar to those occurring commonly in animals.

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Peter R. Davies, Elizabeth A. Wagstrom, and Jeffrey B. Bender
Author affiliations: Author affiliation: University of Minnesota, St. Paul, Minnesota, USA

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References

  1. Rasigade  J-P, Laurent  F, Hubert  P, Vandenesch  F, Etienne  J. Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain. Emerg Infect Dis. 2010;16:1330. DOIPubMedGoogle Scholar
  2. de Neeling  AJ, van den Broek  MJ, Spalburg  EC, van Santen-Verheuvel  MG, Dam-Deisz  WD, Boshuizen  HC, High prevalence of methicillin resistant Staphylococcus aureus in pigs. Vet Microbiol. 2007;122:36672. DOIPubMedGoogle Scholar
  3. Graveland  H, Wagenaar  JA, Heesterbeek  H, Mevius  D, van Duikeren  E, Heedrik  D. Methicillin resistant Staphylococcus aureus ST398 in veal calf farming: human MRSA carriage related with animal antimicrobial usage and farm hygiene. PLoS ONE. 2010;5:e10990. DOIPubMedGoogle Scholar
  4. Bhat  M, Dumortier  C, Taylor  B, Miller  M, Vasquez  G, Yunen  J, Staphylococcus aureus ST398, New York City and Dominican Republic. Emerg Infect Dis. 2009;15:2857. DOIPubMedGoogle Scholar
  5. van Belkum  A, Melles  DC, Peeters  JK, van Leeuwen  WB, van Duijkeren  E, Huijsdens  XW, Methicillin-resistant and -susceptible Staphylococcus aureus sequence type 398 in pigs and humans. Emerg Infect Dis. 2008;14:47983. DOIPubMedGoogle Scholar
  6. Chen  H, Liu  Y, Jiang  X, Chen  M, Wang  H. Rapid change of methicillin-resistant Staphylococcus aureus clones in a Chinese tertiary care hospital over a 15-year period. Antimicrob Agents Chemother. 2010;54:18427. DOIPubMedGoogle Scholar
  7. van der Mee-Marquet  N, François  P, Domelier-Valentin  AS, Coulomb  F, Decreux  C, Hombrock-Allet  C, Emergence of unusual bloodstream infections associated with pig-borne-like Staphylococcus aureus ST398 in France. Clin Infect Dis. 2011;52:1523. DOIPubMedGoogle Scholar
  8. Stegger  M, Lindsay  JA, Sørum  M, Gould  KA, Skov  R. Genetic diversity in CC398 methicillin-resistant Staphylococcus aureus isolates of different geographical origin. Clin Microbiol Infect. 2010;16:10179.PubMedGoogle Scholar
  9. Ekkelenkamp  MB, Sekkat  M, Carpaij  N, Troelstra  A, Bonten  MJ. Endocarditis due to methicillin-resistant Staphylococcus aureus originating from pigs. Ned Tijdschr Geneeskd. 2006;150:24427.PubMedGoogle Scholar
  10. Welinder-Olsson  C, Florén-Johansson  K, Larsson  L, Öberg  S, Karlsson  L, Åhrén  C. Infection with Panton-Valentine leukocidin–positive methicillin-resistant Staphylococcus aureus t034. Emerg Infect Dis. 2008;14:12712. DOIPubMedGoogle Scholar

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Cite This Article

DOI: 10.3201/eid1706.101394

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In Response: We thank Davies et al. (1) for their interest in our report of a lethal case of necrotizing pneumonia caused by a sequence type (ST) 398 Staphylococcus aureus strain (2). We fully agree with their request that ST398 S. aureus infections not be systematically attributed to contact with livestock. They correctly pointed out that several characteristics of the incriminated strain, including methicillin and tetracycline susceptibility, spa type, and the presence of genes encoding the Panton-Valentine leukocidin (PVL), differed from the usual genetic features of strains isolated from livestock (3,4). However, we did not state or suggest in our report that the case originated from livestock contact. Our aim in reporting this case was to warn that S. aureus of the ST398 lineage, regardless of its host specificity, is able to acquire PVL genes and provoke severe PVL-related infection in humans. This observation adds support to the need for controlling the increasing animal reservoir of ST398 methicillin-resistant S. aureus (MRSA). Indeed, the recent whole-genome analysis of an ST398 strain by Schijffelen et al. (5) highlighted several specific features of the ST398 genetic background, including the absence of a type I restriction and modification system. Such features have been proposed to promote horizontal gene transfer and the uptake of mobile genetic elements such as the phage-encoded PVL genes (5). Although phage-mediated dissemination of PVL genes into MRSA lineages does not seem to be the preeminent pathway leading to the emergence of highly epidemic PVL-positive MRSA (6), this eventuality should not be dismissed with respect to the ST398 lineage, which possesses all the required features to become the next MRSA “superbug” (7).

References

  1. Davies  PR, Wagstrom  EA, Bender  JB. Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain [letter]. Emerg Infect Dis. 2011;17:11523. DOIPubMedGoogle Scholar
  2. Rasigade  JP, Laurent  F, Hubert  P, Vandenesch  F, Etienne  J. Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain. Emerg Infect Dis. 2010;16:1330. DOIPubMedGoogle Scholar
  3. Wulf  M, Voss  A. MRSA in livestock animals—an epidemic waiting to happen? Clin Microbiol Infect. 2008;14:51921. DOIPubMedGoogle Scholar
  4. van Cleef  BA, Verkade  EJ, Wulf  MW, Buiting  AG, Huijsdens  XW, van Pelt  W, Prevalence of livestock-associated MRSA in communities with high pig-densities in The Netherlands. PLoS ONE. 2010;5:e9385. DOIPubMedGoogle Scholar
  5. Schijffelen  MJ, Boel  CH, van Strijp  JA, Fluit  AC. Whole genome analysis of a livestock-associated methicillin-resistant Staphylococcus aureus ST398 isolate from a case of human endocarditis. BMC Genomics. 2010;11:376. DOIPubMedGoogle Scholar
  6. Rasigade  JP, Laurent  F, Lina  G, Meugnier  H, Bes  M, Vandenesch  F, Global distribution and evolution of Panton-Valentine leukocidin-positive methicillin-susceptible Staphylococcus aureus, 1981–2007. J Infect Dis. 2010;201:158997. DOIPubMedGoogle Scholar
  7. Ferber  D. Infectious disease. From pigs to people: the emergence of a new superbug. Science. 2010;329:10101. DOIPubMedGoogle Scholar

Table of Contents – Volume 17, Number 6—June 2011

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Page created: September 01, 2011
Page updated: September 01, 2011
Page reviewed: September 01, 2011
The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.
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