METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS is no longer localized to
the gay male population and has spread to our best friends. Be sure to
use paper towels to open and close public restroom doors when leaving;
especially in university and college towns that attract Log Cabin
Republicans and friends. MRSA is the flesh eating bacteria that
requires the need for emergency amputation. In other words, feral cats
and wild coyotes are safer to hug and kiss than your ex-wife's new
boyfriend.
JR
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
MRSA UPDATE
by Robert Jay Russell, Ph.D.,
Coton de Tulear Club of America President,
www.cotonclub.com
CotonNews@[EMAIL PROTECTED]
8th, 2008. In our series of articles about therapy dog visits to
health care and nursing home facilities, we noted that antibiotic
resistant bacterial strains that could be acquired by humans or dogs
are a threat to consider. CTCA Code of Ethics Breeder Laurie Arguin
forwarded us this current article on the subject of Methicillan
Resistant Staphylococcus aureus published on April 1st on the Antech
Diagnostics, Inc. web site. Antech laboratories is a major utility for
lab analysis of specimens (blood chemistry) drawn by most
veterinarians.
We pass on this im****tant information for your consideration and again
note that we would personally avoid hospital visits with our Cotons
and would visit other health care institutions only when the
institution can inform us that MRSA is not present to their knowledge.
Soon, however, it is very likely that this and other antibiotic
resistant pathogens will be everywhere abundant, from schools to
supermarkets to malls.
April 1 2008
METHICILLIN-RESISTANT STAPHYLOCOCCUS AUREUS (MRSA) REVISITED
Background
Although methicillin-resistant Staphylococcus aureus (MRSA) is
primarily a
nosocomial pathogen, its foothold in the environment is expanding.
MRSA is a
multidrug-resistant op****tunistic pathogen that has become a serious
problem in human medicine. Other than causing outbreaks in veterinary
settings, it has
infrequently been described as an animal pathogen.
However, recent canine cases have been confirmed in North America and
overseas. Infections have involved eye, ear, urinary tract, nail bed,
abscess, and skin. In most cases, pet owners had been an inpatient,
outpatient or frequent visitor to institutional settings. Dogs can
become colonized with MRSA from humans, and can transmit it to other
dogs and people. The frequency of this is unclear, although the
presence of colonized/infected humans in a household does not
necessarily mean that the dogs are either likely to be affected or to
be sources of infection.
Contributors to the increasing im****tance of this pathogen:
* pattern of resistance to a wide range of antibiotics besides
penicillins and
cephalos****ins (=EF=AC=82-lactams)
* op****tunistic nature of the pathogen
* mechanism of resistance
Clinical and Zoonotic Potential
There is the potential for zoonotic transmission. Pet owners should be
made
aware that the dog may be carriers of MRSA. Personal hygiene
consisting of
wa****ng hands after contact minimizes the spread of MRSA. However,
while the risk of overt disease from MRSA is low in healthy people, it
may be of
significant concern in immunocompromised individuals, or for those
taking
antimicrobials.
MRSA and Veterinary Medicine
MRSA infections have been re****ted in animals since the mid-1990s but
were
considered uncommon in domestic pets and rarely caused disease.
However, since 2002, there has been a rapidly growing body of data
showing an alarming acceleration of MRSA cultures from both dogs and
cats from almost all body sites routinely tested.
Studies to date indicate that MRSA is transmitted from human to pet
because
methicillin-sensitive strains of S. aureus are not a part of the
normal colonizing flora of dogs and cats.
Recent Case Studies and Clinical Relevance
MRSA was isolated from the tracheostomy tube of a young dog in the
intensive care unit (ICU) of a veterinary teaching hospital. While the
dog had no clinical or radiographic signs of pneumonia, the finding
prompted an investigation of MRSA colonization in other animals in
this ICU. MRSA was isolated from nasal swabs from 6 of 26 (23%)
animals, 4 dogs and 2 cats obtained from 1-78 days later. No clinical
signs of MRSA infections developed, and all isolates were identical.
No colonized animals were identified during subsequent periodic
surveillance. These findings suggest that ICUs may be at particular
risk for periodic outbreaks of MRSA colonization and disease.
All animals that were identified as colonized with MRSA remained
colonized at the time of discharge from the ICU. Active eradication of
MRSA was not
recommended because there is no evidence of efficacy of treatment, and
dogs and cats almost invariably eliminate MRSA colonization if re-
infection is prevented. Owners were counseled on household infection-
control practices that might reduce the risk of MRSA transmission,
such as hand hygiene and limited contact with the colonized animal's
nose and rectum.
Culture Incidence from Antech Diagnostics
MRSA is most frequently cultured from canine wounds, abscesses, and
chronic pyododermas. While the percentage of S. aureus bacteria
cultured from these sites has remained unchanged since 2004 (3-5%),
the percentage of methicillin-resistant strains has increased
exponentially from 19% in 2005 to 42% in 2007. As this infection comes
from humans, the rise is not due to an increasing antibiotic
resistance in animals, but is from an increase in community acquired
MRSA in humans.
Epidemiology
Although resistance to methicillin is not itself of major concern,
methicillin
resistance is a marker for the presence of the mecA gene. This gene
encodes synthesis of an altered penicillin-binding protein that has a
low affinity for ---lactam antimicrobials, which confers resistance to
all penicillins and cephalos****ins in MRSA strains. Treatment of MRSA
is further complicated by its resistance to other antimicrobial
cl*****, and there may be few treatment options in some instances. The
impact of MRSA among hospitalized humans is difficult to quantify;
however, from 1999-2000, MRSA accounted for an estimated 125,000 +
hospitalizations, including 31,000 cases of septicemia. A recent major
concern is the emergence of MRSA as a community-associated pathogen in
humans.
In some areas, MRSA is now the most common cause of skin and soft
tissue
infections among people who attend emergency departments.
Additionally, serious and potentially life-threatening conditions such
as necrotizing pneumonia and necrotizing fasciitis, have been
re****ted, even among humans who were previously thought to be at low
risk for MRSA infection.
New epidemiologic issues that deserve consideration include the
ability of MRSA to increase undetected in a population. Transmission
of MRSA most likely occurred via the hands of health-care personnel,
as this is a common route of transmission in human health-care
settings. Transmission via colonized staff is a possibility because
nasal colonization of veterinary medical personnel can develop. The
same MRSA strains affect animals within veterinary hospitals and the
community.
Diagnosis
Nasal and perineal swabs can be used for detection of MRSA carriers,
although ideal screening sites are not yet known.
Treatment
Infection-control measures including active surveillance of all
animals in the
infected facility, barrier precautions, and hand hygiene are used to
control
apparent outbreaks. Treatment of infected animals should be based on
culture/sensitivity results, while remembering that MRSA is resistant
to all
penicillins and cephalos****ins. Fluoroquinolones are no longer very
effective,
and trimethoprim-sulfas, while often useful, cannot safely be given to
dog
breeds known to have sulfonamide hypersensitivity (e.g. Weimaraners,
Doberman pinschers, Rottweilers, Samoyeds and other white-coated
breeds, and miniature Schnauzers.)
Because of their resistance, MRSA infections should not be treated
with ?-lactam antibiotics (penicillins and cephalos****ins), even if in
vitro testing shows sensitivity to these drugs.
Antibiotics to consider include:
* choramphenicol [33mg/kg TID in dogs; 50 mg BID per cat] (~95%
sensitive)
* potentiated sulfonamides, although these antibiotics are associated
with
sensitivities which can produce significant adverse effects (65-75%
sensitive)
* clindamycin (< 40% sensitive)
* fluoroquinolones (25% sensitive)
* vancomycin [15 mg/kg q 6 hr IV with fluids]
* linezolid (Zyvox=C3=86) , a new family of antibiotics [20-30 mg/kg q 24
hr in
dogs] =C3=B1 low toxicity, very expensive
Conclusions
MRSA is an emerging veterinary and zoonotic pathogen, and veterinary
clinic
personnel must be prepared to identify infected animals. The present
case study highlights the potential for clinically inapparent
transmission of MRSA within a facility. Objective investigation of
infection-control precautions is required to determine the most
appropriate and effective responses to MRSA outbreaks. Further,
principles of due diligence dictate that veterinary clinics should
establish a plan to address MRSA, whether it be colonization or
infection of animals, in an attempt to control the spread of this
significant pathogen.
References:
Aucoin, Comp Cont Edu Vet; Supple 30,#1, 3-7, 2008; Weese et al,
JAVMA,
231:1361-1364, 2007; Willey et al, Abstract, 2007; Hanselman et al,
Emerg Infect Dis 12:1933-38, 2006;Kania et al, Am J Vet Res
65:1265-1268, 2004, Trepanier, J Vet Int Med 17:647-652, 2003.
=C2=A91997-2008 Antech Diagnostics, Inc.
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(c)2008 Dr. R. J. Russell & the CTCA
"History repeats itself, because human nature never changes." Al-
Daylam ibn Taqqiya
"Laws grind the poor, and rich men rule the law." Oliver Goldsmith,
The Traveler 1764
"Talk's cheap, whiskey's cheaper. The supply of both exceed demand."
Mr. Barnhill, Ellensburg High School Shop Teacher
"Consciousness is the only state worth consideration." Sri Paul
Twitchell, The Spiritual Notebook
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