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International Society for Infectious Diseases
******
[1]
Date: June 2008
Source: Clinical Microbiology and Infection [edited]
MRSA in livestock animals -- an epidemic waiting to happen?
-----------------------------------------------------------
M. Wulf & A. Voss, Volume 14, Issue 6, Date: June 2008, Pages: 519-521
Abstract:
---------
Screening of pig farmers and pigs in The Netherlands has revealed that
more than 20 percent of pig farmers and 39 percent of slaughterhouse
pigs are positive for an unusual strain of methicillin-resistant
_Staphylococcus aureus_ (MRSA) belonging to sequence type (ST) 398. It
is now clear that the emergence of ST398 is not just a Dutch problem,
with human infections being described in several European countries,
Canada and Singapore. Furthermore, some human isolates have now
acquired the genes encoding Panton-Valentine leukocidin. Livestock may
become an important source of community-acquired MRSA. A concerted
effort on the part of clinicians, infection control practitioners and
veterinarians will be required to prevent further spread of this novel
strain of MRSA.
[See full text at:
(registration required)]
--
Communicated by:
Terry S. Singeltary Sr.
******
[2]
Date: July 2009
Source: EID [edited]
Methicillin-Resistant Staphylococcus aureus ST398 in Swine Farm
Personnel, Belgium.
-------------------------------------------------------------------------
Oliver Dennis et al, EID Volume 15, Number 7-July 2009
Abstract:
---------
We assessed methicillin-resistant _Staphylococcus aureus_ (MRSA) in
persons on 49 swine farms in Belgium. Surveys showed that 48 (37.8
percent) persons carried MRSA ST398 and 1 (0.8 percent) had concurrent
skin infection. Risk factors for carriage were MRSA carriage by pigs,
regular contact with pigs and companion animals, and use of protective
clothing.
[snip...]
Conclusions:
------------
Human carriage of MRSA was associated with swine colonization with
MRSA. Prevalence rate (38 percent) was higher than that for
hospitalized patients or nursing home residents in Belgium
(
farmers belonged to closely related spa types corresponding to ST398,
which are unrelated to hospital- and community-acquired strains but
identical to strains from humans in contact with pigs in other
European countries (1,2,10).
Despite the high prevalence of nasal MRSA, active MRSA skin infection
was detected infrequently (less than 1 percent), within the range
described in recent US-based studies (11). In a hospital in the
Netherlands, a lower attack rate was found for MRSA ST398 than for
other MRSA strains (12). However, invasive infections caused by MRSA
ST398 have been reported, suggesting that this genotype is pathogenic
for humans (2). In our study, MRSA strains did not harbor exotoxin.
Two MRSA genotypes were predominant. For 70 percent of farms with
multiple MRSA carriers, all strains belonged to the same genotype,
suggesting transmission within the farm. Although these strains have
been shown to not spread easily in hospitals (12), outbreaks of MRSA
ST398 in a residential care facility and a hospital probably
originated from health care workers living on pig farms (13,14). In
contrast with MRSA strains, MSSA [methicillin-susceptible]
_Staphylococcus aureus_ isolates in our study showed diverse genotypes
that frequently colonize human populations (4). MSSA isolates from 3
farmers belonged to the ST398 genotype, which is infrequently reported
in humans except in pig farmers with contact with pigs (4).
Risk factors for MRSA ST398 carriage included regular contact with
pigs but also with horses and dogs (10), suggesting that different
animals could be MRSA ST398 reservoirs or vectors, at least on pig
farms. Protective measures did not seem to reduce the risk of becoming
colonized with MRSA; this lack of effectiveness has previously been
observed for veterinarians (15). This apparent lack of protection
should be further investigated to determine routes of transmission
other than direct contact with pigs, including airborne transmission
and contact with contaminated surfaces and companion animals.
--
Communicated by:
Terry S. Singeltary Sr.
******
[3]
Date: 24 Feb 2010
Source: Veterinary Microbiology [edited]
Methicillin-resistant Staphylococcus aureus in horses and horse
personnel: An investigation of several outbreaks.
-----------------------------------------------------------------------------
E. van Duijkeren et al, Veterinary Microbiology Volume 141, Issues
1-2, 24 February 2010, Pages 96-102
Abstract:
---------
At the Veterinary Microbiological Diagnostic Center, the Netherlands,
the percentage of methicillin-resistant _Staphylococcus aureus_ (MRSA)
isolates found in equine clinical samples increased from 0 percent in
2002 to 37 percent in 2008. MRSA of spa-type t064, belonging to MLST
ST8 and spa-types t011 and t2123, both belonging to the
livestock-associated MLST ST398, predominated.
During an outbreak of post-surgical MRSA infections in horses at a
veterinary teaching hospital in 2006/2007, MRSA isolates of spa-type
t2123 were cultured from 7 horses and 4/61 personnel which indicated
zoonotic transmission. After intervention the outbreak stopped.
However, another outbreak occurred in 2008, where 17 equine MRSA
isolates of spa-type t011 (n = 12), t2123 (n = 4), and t064 (n = 1)
were found. This time, 16/170 personnel were positive for MRSA with
spa-type t011 (n = 11) and t2123 (n = 5). Personnel in close contact
with horses were more often MRSA-positive (15/106) than those without
(1/64).
Screening of horses upon admission showed that 9.3 percent were
MRSA-positive predominantly with spa-type t011. Weekly cross-sectional
sampling of all hospitalized horses for 5 weeks showed that 42 percent
of the horses were MRSA-positive at least once, again predominantly
with spa-type t011, which suggests that nosocomial transmission took
place. A total of 53 percent of the environmental samples were
MRSA-positive, including samples from students' and staff members'
rooms, and all were spa-type t011. This indicates that humans
contribute to spreading the organism. Culturing of samples employing
high-salt pre-enrichment performed better than a comparable method
without pre-enrichment.
Our results show that nosocomial transmission occurs in equine clinics
and suggests that personnel play a role in the transmission.
--
Communicated by:
Terry S. Singeltary Sr.
[Our thanks to Terry for finding these and other recent articles.
Obviously this is a [question of what is suitable for one situation
might be unsuitable for another], as far as different types of
antibiotics go or stay. - Mod.MHJ]
******
[4]
Date: 18 Feb 2010
From: Hurd, H. S [VDPAM]
RE: Antibiotic resistance & agricultural uses - USA (02)
--------------------------------------------------------
When considering MRSA it is important to categorize the data being
discussed on 2 axes: 1) route of human exposure; and 2) type of
infection/colonization. Confusing these items will lead to a
misrepresentation of the risk.
1) Route can include:
a) Direct Exposure to animals; e.g., What also may be called
"occupational exposure";
b) Foodborne; This is the classic route taken by pathogens such as
Salmonella or Campylobacter -- this route is very rare for MRSA;
c) Fomite contact; if MRSA is on the meat brought home, it may get
implanted into the human. According to the CDC, this is not a likely
route.
2) Type of infection/colonization:
a) Infection; this is usually observed with some signs of illness or
lesions -- maybe isolation of the organism from internal issues;
b) Colonization; this is represented by the ability to recover the
living organism from an individual with no clinical signs, i.e., no
harm done.
The papers [1 through 3] seem to be describing the direct route of
colonization, "occupational non-harmful colonization." Less than 1
percent had "infection" described. Evidence of "occupational
colonization" cannot be easily construed as major public health threat.
Note that very few cases of the farm (ST 398) types have been found in
non-farm related human illness
--
Scott Hurd
Iowa State University
VDPAM, VMRI Bld 4
[see also:
Antibiotic resistance & agricultural uses - USA 20100216.0552
2000
----
Antibiotic resistance & agricultural uses - USA (02) 20000511.0718
Antibiotic resistance & agricultural uses - USA 20000429.0649
Antibiotic resistance, surveillance - Europe 20000103.0003
1998
----
Antibiotic resistance trends - Europe 19990204.0170
Antibiotic resistance: Internet surveillance (02) 19981219.2407
Antibiotic resistance: Internet surveillance 19981216.2373
Antibiotic resistance, livestock - USA 19980807.1542
Antibiotic resistance, livestock - USA 19980805.1509]]
.....................jw/mhj/ejp/jw
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