Skip directly to site content Skip directly to page options Skip directly to A-Z link Skip directly to A-Z link Skip directly to A-Z link
Volume 16, Number 2—February 2010

Methicillin-Resistant Staphylococcus aureus ST398, Italy

On This Page
Article Metrics
citations of this article
EID Journal Metrics on Scopus

Cite This Article

To the Editor: It has recently become apparent that livestock can constitute a new methicillin-resistant Staphylococcus aureus (MRSA) reservoir and be a source of a novel and rapidly emerging type of MRSA. These livestock-associated MRSA clones are nontypeable by use of pulsed-field gel electrophoresis with SmaI and belong to sequence type (ST) 398 (1). MRSA ST398 clones account for 20% of all MRSA in the Netherlands (2), but the emergence of such clones has been described worldwide (3). Although ST398 transmission has been reported primarily between animals, persons with occupational exposure to livestock are at higher risk for MRSA carriage than the general population. Even though MRSA ST398 usually causes colonization, several cases of infections of variable clinical relevance, varying from skin and soft tissue infections (4) to endocarditis (5) and pneumonia (6), have been described over the past few years. Most instances of ST398 human carriers have been identified among persons who work at pig farms (7). Data regarding MRSA colonization of dairy farmers are less exhaustive and, to our knowledge, only 1 instance of direct transmission between cattle and humans has been proven. MRSA isolates from cows with subclinical mastitis in 2007 in Hungary were indistinguishable from MRSA isolates from the tonsil swab of a farmer who worked with these animals (8). We report a case of MRSA ST398 invasive disease in a cattle farmer, as well as a case of MRSA ST398 necrotizing fasciitis.

In early April 2008, a 52-year-old man was admitted to an intensive care unit in Manerbio, Italy, because of severe sepsis and a large ulcerative and suppurative lesion on the right side of his neck. His medical history was unremarkable. He was a worker at a dairy farm, was obese, and did not report any previous contact with the healthcare system. At the time of hospital admission, he was oriented and cooperative. His temperature was 38.4°C, heart rate was 125 beats per minute, and blood pressure was 165/75 mm Hg. Arterial blood gas analysis showed hypoxemia and mild hypocapnia (PaO2 53 mm Hg and PaCO2 33.8 mm Hg on room air). Leukocyte count was 21,280 cells/μL (81.9% polymorphonuclear cells), and platelet count was 310,000 cells/μL. After blood samples were collected and aggressive surgical debridement of affected tissue was performed, empirical treatment with intravenous teicoplanin and imipenem was started. On the basis of histologic appearance of the intraoperative material and computed tomography scan images, necrotizing fasciitis was diagnosed. Culture of blood and necrotic tissue yielded MRSA. On day 3 after admission, antimicrobial drug therapy was changed to teicoplanin and clindamycin and, on day 7, to linezolid. Fever resolved in 3 days and the patient’s condition progressively improved. The patient was discharged after 31 days of antimicrobial drug therapy. The MRSA isolate was susceptible to all the non–β-lactam antimicrobial drugs tested (excluding tetracycline), carried the staphylococcal cassette chromosome mec type V, and was negative for Panton-Valentine leukocidin (PVL) genes. Multilocus sequence typing and sequence typing of the tandem repeat region of protein A gene (spa typing) showed that the isolate belonged to ST398 and spa type 899, respectively.

Some issues are of concern. Although the MRSA isolate was PVL negative, its virulence resembled that of PVL-positive strains. Furthermore, it was resistant to tetracycline, as we expected because oxytetracyclines are the antimicrobial drugs most frequently used in pig and cattle farming (3). The major limitation of our study was that data regarding MRSA colonization of the farm are missing, so cattle-to-human transmission cannot be proven. However, because our patient did not have any other potential risk factor, dairy cows were probably the source of the human infection. In countries where community-acquired MRSA is common, all patients with serious S. aureus infections should be treated for MRSA until antimicrobial susceptibilities are known. Our report suggests that even in countries where community-acquired MRSA is still rare, being a cattle farmer may be considered an indication for early treatment against MRSA.

The expanding knowledge of this zoonotic potential may undermine existing nosocomial MRSA control programs. In countries where a search and destroy policy (9) is adopted, such as the Netherlands, pig and cattle farmers may warrant screening and isolation at the time of hospital admission. Nevertheless, the first MRSA ST398 nosocomial outbreak has already been described (10).

It is difficult to prevent persons with constant exposure to MRSA in their work or home setting from becoming MRSA carriers. Revisiting policies for the use of antimicrobial drugs on livestock farms, as well as improving hygiene measures, may therefore be necessary in infection control programs. However, before final recommendations can be made, further investigation is needed to determine the prevalence of MRSA among livestock and their handlers.


Laura SoaviComments to Author , Roberto Stellini, Liana Signorini, Benvenuto Antonini, Palmino Pedroni, Livio Zanetti, Bruno Milanesi, Annalisa Pantosti, Alberto Matteelli, Angelo Pan, and Giampiero Carosi
Author affiliations: University of Brescia, Brescia, Italy (L. Soavi, R. Stellini, L. Signorini, A. Matteelli, G. Carosi); Presidio Ospedaliero di Manerbio, Manerbio, Italy (B. Antonini, P. Pedroni, L. Zanetti, B. Milanesi); Istituto Superiore di Sanità, Rome, Italy (A. Pantosti); Istituti Ospitalieri di Cremona, Cremona, Italy (A. Pan)



  1. Huijsdens  XW, van Dijke  BJ, Spalburg  E, van Santen-Verheuvel  MG, Heck  ME, Pluister  GN, Community-acquired MRSA and pig-farming. Ann Clin Microbiol Antimicrob. 2006;5:26. DOIPubMedGoogle Scholar
  2. van Loo  I, Huijsdens  X, Tiemersma  E, de Neeling  A, van de Sande-Bruinsma  N, Beaujean  D, Emergence of methicillin-resistant Staphylococcus aureus of animal origin in humans. Emerg Infect Dis. 2007;13:18349.PubMedGoogle Scholar
  3. Wulf  M, Voss  A. MRSA in livestock animals—an epidemic waiting to happen? Clin Microbiol Infect. 2008;14:51921. DOIPubMedGoogle Scholar
  4. Pan  A, Battisti  A, Zoncada  A, Bernieri  F, Boldini  M, Franco  A, Community-acquired methicillin-resistant Staphylococcus aureus ST398 infection, Italy. Emerg Infect Dis. 2009;15:8457. DOIPubMedGoogle Scholar
  5. Ekkelenkamp  MB, Sekkat  M, Carpaij  N, Troelstra  A, Bonten  MJ. Endocarditis due to methicillin-resistant Staphylococcus aureus originating from pigs [in Dutch]. Ned Tijdschr Geneeskd. 2006;150:24427.PubMedGoogle Scholar
  6. van Rijen  MM, van Keulen  PH, Kluytmans  JA. Increase in a Dutch hospital of methicillin-resistant Staphylococcus aureus related to animal farming. Clin Infect Dis. 2008;46:2613. DOIPubMedGoogle Scholar
  7. Wulf  MW, Sorum  M, van Nes  A, Skov  R, Melchers  WJ, Klaassen  CH, Prevalence of methicillin-resistant Staphylococcus aureus among veterinarians: an international study. Clin Microbiol Infect. 2008;14:2934. DOIPubMedGoogle Scholar
  8. Juhasz-Kaszanyitzky  E, Janosi  S, Somogyi  P, Dan  A, van der Graaf-van Bloois  L, van Duijkeren  E, MRSA transmission between cows and humans. Emerg Infect Dis. 2007;13:6302. DOIPubMedGoogle Scholar
  9. Dutch Working Party on Infection Prevention. Policy for methicillin-resistant Staphylococcus aureus. 2007 [cited 2009 Dec 10].
  10. Wulf  MW, Markestein  A, van der Linden  FT, Voss  A, Klaassen  C, Verduin  CM. First outbreak of methicillin-resistant Staphylococcus aureus ST398 in a Dutch hospital, June 2007. Euro Surveill. 2008;13(9):pii 8051.


Cite This Article

DOI: 10.3201/eid1602.091478

Related Links


Table of Contents – Volume 16, Number 2—February 2010

EID Search Options
presentation_01 Advanced Article Search – Search articles by author and/or keyword.
presentation_01 Articles by Country Search – Search articles by the topic country.
presentation_01 Article Type Search – Search articles by article type and issue.



Please use the form below to submit correspondence to the authors or contact them at the following address:

Laura Soavi, Institute of Infectious and Tropical Diseases, Spedali Civili, Piazzale Spedali Civili 1, 25123 Brescia, Italy

Send To

10000 character(s) remaining.


Page created: December 13, 2010
Page updated: December 13, 2010
Page reviewed: December 13, 2010
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.