Emerg Infect DisEmerging Infect. DisEIDEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control and Prevention21749803335809610-139410.3201/eid1706.101394Letters to the EditorLetterLethal Necrotizing Pneumonia Caused by an ST398 Staphylococcus aureus StrainNecrotizing Pneumonia and ST398 S. aureusDaviesPeter R.WagstromElizabeth A.BenderJeffrey B.Author affiliation: University of Minnesota, St. Paul, Minnesota, USAAddress for correspondence: Peter R. Davies, Center for Animal Health and Food Safety, 136 Andrew Boss Laboratory, 1354 Eckles Ave, St. Paul, MN 55108, USA; email: davie001@umn.edu6201117611521153RasigadeJ-P , LaurentF , HubertP , VandeneschF , EtienneJ . Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain.Emerg Infect Dis. 2010;16:1330. 10.3201/eid1608.100317Keywords: bacteriapneumoniaStaphylococcus aureusST398methicillin resistanceMRSAlivestockletter

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.

Suggested citation for this article: Davies PR, Wagstrom EA, Bender JB. Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Jun [date cited]. http://dx.doi.org/10.3201/eid1706.101394

ReferencesRasigade 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 10.3201/eid1608.10031720678343de 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 10.1016/j.vetmic.2007.01.02717367960Graveland 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 10.1371/journal.pone.001099020544020Bhat 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 10.3201/eid1502.08060919193274van 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 10.3201/eid1403.076018325267Chen 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 10.1128/AAC.01563-0920176895van 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 10.1093/cid/ciq05321148535Stegger 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;16:1017919681955Ekkelenkamp MB, Sekkat M, Carpaij N, Troelstra A, Bonten MJ Endocarditis due to methicillin-resistant Staphylococcus aureus originating from pigs. Ned Tijdschr Geneeskd. 2006;150:2442717131705Welinder-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 10.3201/eid1408.07142718680653
Emerg Infect DisEmerging Infect. DisEIDEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control and Prevention DOI: 10.3201/eid1706.110465ArticleLethal Necrotizing Pneumonia Caused by an ST398 Staphylococcus aureus StrainRasigadeJean-PhilippeLaurentFredericHubertPhillipeVandeneschFrançoisEtienneJeromeAuthor affiliations: Hospices Civils de Lyon, Lyon, France (J.P. Rasigade, F. Laurent, J. Etienne, F. Vandenesch);Assistance Publique–Hôpitaux de Paris, Paris, France (P. Hubert)Address for correspondence: Jean-Philippe Rasigade, Centre de Référence des Staphylocoques, Centre de Biologie Est, Groupement Hospitalier Est, 59 Boulevard Pinel, Bron, 69677 France; email: jean-philippe.rasigade@chu-lyon.frDaviesPR , WagstromEA , BenderJB . Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain[letter]. Emerg Infect Dis. 2011;17:11523. 10.3201/eid1706.101394

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).

Suggested citation for this article: Rasigade J-P, Laurent F, Vandenesch F, Etienne J. Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain [letter]. Emerg Infect Dis [serial on the Internet]. 2011 Jun [date cited]. http://dx.doi.org/10.3201/eid1706.110465

ReferencesDavies PR, Wagstrom EA, Bender JB Lethal necrotizing pneumonia caused by an ST398 Staphylococcus aureus strain [letter] Emerg Infect Dis. 2011;17:11523 10.3201/eid1706.10139421749803Rasigade 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 10.3201/eid1608.10031720678343Wulf M, Voss A MRSA in livestock animals—an epidemic waiting to happen? Clin Microbiol Infect. 2008;14:51921 10.1111/j.1469-0691.2008.01970.x18325034van 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 10.1371/journal.pone.000938520195538Schijffelen 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 10.1186/1471-2164-11-37620546576Rasigade 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 10.1086/65200820367458Ferber D Infectious disease. From pigs to people: the emergence of a new superbug. Science. 2010;329:10101 10.1126/science.329.5995.101020798295