STAPHYLOCOCCAL PYODERMA: AN EMERGING CRISIS IN CANINE PRACTICE
←
→
Page content transcription
If your browser does not render page correctly, please read the page content below
STAPHYLOCOCCAL PYODERMA:
AN EMERGING CRISIS IN CANINE PRACTICE
A.K. Srivastava
Secretary General, Indian Society for Advancement of Canine Practice, Lucknow – 226 016.
Staphylococcus pyoderma is the most antibiotic resistance (Crossley and Archer, 1997).
common skin disease in dogs. The term pyoderma Documented cases of zoonosis are rare and limited
refers to any purulent skin disease. In veterinary to a couple of case reports (Tanner et al., 2000).
medicine the term is most commonly used to refer Staphylococcus aureus is the main pathogen
to bacterial colonization or infection of the skin in humans but has been recovered from several
and/or hair follicle. Bacterial pyoderma is second species including dogs and cats (Crossley and
only to flea allergy dermatitis as the most common Archer, 1997). Staphylococcus aureus is highly
dermatosis of dogs but this statistic is probably pathogenic and able to rapidly develop multiple
changing with the advent of newer flea-control antibiotic resistance through numerous
products. mechanisms. Methicillin -resistant Staphylococcus
The skin of normal dogs is populated with aureus infections are the source of major crisis for
small numbers of Micrococcus, alpha-hemolytic the human medical community. Cases of reverse
streptococci, Propionibacterium acnes, zoonosis are rare and often involve the pets of a
Acinetobacter and Staphylococcus spp. S. health worker who was exposed to Staphylococcus
intermedius can frequently be isolated from the aureus through the owner’s direct contact with
hair coat of normal dogs. It has been postulated infected patients in medical facilities (Manian,
that this might serve as the reservoir for infectious 2003).
organisms of the skin. S. intermedius is involved Staphylococcus schleiferi (coagulase
in approximately 90% of canine bacterial negative) was first identified in 1988 and was
pyodermas. named according to the German microbiologist
Approximately 80 percent of allergic dogs will Carl Heinz Schleiferi (Freney et al., 1988). The
have a secondary bacterial infection at the time of first case information regarding Staphylococcus
diagnosis. Canine pyoderma is caused almost schleiferi infections in humans was reported in
exclusively by Staphylococcus intermedius (Scott 1989 (Jean Pierre et al., 1989). There growing
et al., 2001). However, the increasing prevalence evidence to suggest that Staphylococcus schleiferi
of Staphylococcus aureus infections and the is a pathogenic organism with a propensity for
emergence of a new species of Staphylococcus community based nosocomial infections. Humans
schleiferi force the veterinary community to demonstrated Staphylo-coccus schleiferi carriage
become more vigilant to prevent zoonosis. in the preaxillary area. The first cases of
Staphylococcus intermedius was first reported Staphylococcus schleiferi skin infections were
in 1976 (Hajek, 1976). It is almost exclusively reported in the United States in canine patients in
pathogenic in dogs; however, it has been 2002 (Frank et al., 2003). The organism
recovered from numerous species including demonstrated multiple antibacterial resistances
humans and cats (Crossley and Archer, 1997 and including methicillin-resistance. Additional
Igimi et al., 1994). The organism is a normal studies have isolated the organism in the ears of
inhabitant of canine skin; however, in certain normal dogs as well as dogs with acute and
diseases, such as atopy, the epidermis chronic otitis. Documented cases of zoonosis and
demonstrates an increased binding affinity reverse zoonosis have not been reported; however,
allowing more organisms to colonize the skin. The if both humans and dogs have the ability to serve
additional changes in sebaceous gland secretion, as reservoir species for this opportunistic
apocrine gland secretion, vasodilatation and pathogen, then the implications for contagion,
subsequent skin temperature increases, all zoonosis and reverse zoonosis are considerable.
contribute to the development of secondary Staphylococcus schleiferi is a unique species of
Staphylococcus intermedius pyoderma. The Staphylococcus that exhibits pathogenicity, dual
organism may modulate the immune system by species carriage and the ability to cause serious
acting as a super-antigen and can produce infection in both humans and dogs.
numerous toxins and readily demonstratesBacterial pyodermas are usually classified infectious diseases of the skin such as
based on the depth of involvement from surface to dermatophytosis, deep fungal infections, and
cellulitis. A surface infection or colonization Malassezia dermatitis very often have
involves the stratum corneum. These include such colonization or infection with S. intermedius as a
diseases as intertrigo (skin-fold pyoderma) and component.
pyotraumatic dermatitis (“hot spots”). Superficial Staphylococcus intermedius skin infection
pyoderma is the most common canine bacterial (pyoderma) may be perpetuated in some dogs by a
skin disease. The infection involves the epidermis hypersensitivity reaction to staphylococcal
below the stratum corneum and/or extends into the organisms. Dogs with idiopathic superficial or
hair follicle. Impetigo, superficial folliculitis, and deep recurrent staphylococcal skin infections may
superficial spreading pyoderma are examples of thus have quantitative differences in serum
this type of infection. A deep pyoderma occurs antistaphylococcal IgE antibodies compared with
when the infection extends through the epidermis healthy dogs. To test this hypothesis,
or hair follicle and involves a pyogenic antistaphylococcal IgG and IgE antibodies were
inflammation of the dermis or subcutis. Often measured by ELISA in groups of dogs with
times there are evidence of rupture of the hair idiopathic recurrent pyoderma, recurrent
follicle. In addition to Staphylococcus, gram- pyoderma secondary to atopic disease, non-
negative bacteria such as Proteus, Pseudomonas, recurrent pyoderma, and in healthy dogs. All
or Escheria coli can often be cultured. If an groups of dogs with prior staphylococcal skin
antibiotic is chosen that is effective against the S. infection had significantly higher mean serum
intermedius, in most cases the other organisms are antistaphylococcal IgG levels than healthy dogs (P
also eradicated. < 0.05). Dogs with recurrent deep pyoderma had
Recurrent pyoderma is defined as a bacterial the highest mean levels of antistaphylococcal IgG.
infection of the skin that responds entirely to Dogs with idiopathic recurrent superficial
appropriate systemic and/or topical therapy but pyoderma and those with recurrent pyoderma
recurs within a short period of cessation of secondary to atopy had significantly (P < 0.05)
therapy, usually within a month. higher mean levels of serum antistaphylococcal
The presence of bacterial pyoderma is IgE than other groups tested. It is concluded from
always secondary to an underlying cause. It is the these findings that S. intermedius can behave as an
obligation of the veterinarian to try to determine allergen in some dogs and elicit an IgE response.
the precipitating cause and to treat or eliminate it These results support the concept that bacterial
in an effort to prevent re-infections. Unfortunately, hypersensitivity may be responsible for initiating
sometimes we are just not clever enough to or perpetuating skin lesions in these animals.
determine that cause. In some dogs we feel that immunologic
Almost every dermatologic disease of the dog incompetence is the reason that there is a
can have bacterial pyoderma as a component. pyoderma or recurrent pyoderma. There are only
Allergic or pruritic diseases such as flea allergy crude tests available to veterinarians to use to
dermatitis, food allergy, or atopic dermatitis are access the immune system of the dog. Serum
often complicated by secondary Staphylococcal immunoglobulin quantitation and the total
infections. Diseases of cornification such as lymphocyte count are the only tests that available
congenital or idiopathic “seborrhea”, icthyosis, to private practitioners. Theoretically, an absolute
and sebaceous adenitis alter the normal surface neutrophilia with a lymphocyte count of at least
microenvironment and allow the overgrowth of 1000 cells/µl should be seen in immunologically
bacteria. Endocrine disorders including normal dogs with bacterial pyoderma.
hypothyroidism, hyperadr-enocorticism (either Identification and quantification of subsets of
iatrogenic or naturally-occurring), and lymphocytes using markers (CD3+, CD4+, CD8+,
abnormalities of the sex hormones cause changes etc), neutrophil function tests, and in vitro
in the cornified layer and will often be lymphocyte blastogenesis are tests performed in
complicated by secondary bacterial pyoderma. some universities and in research situations. Very
Genodermatoses that cause cutaneous anatomic young or very old dogs, animals with a neoplastic
abnormalities such as color dilution alopecia, disease, or those who are receiving
black hair follicular dysplasia, and follicular immunosuppressive drug therapy (especially
dysplasia often require long term therapy with prednisone) are susceptible to bacterial skin
antibiotics as a part of their management. Parasitic infections secondary to immunoincompetence.
diseases of the dog including demodicosis, Bacterial pyoderma can be diagnosed in
scabies, and Cheyletiella infestations and other several ways. During the examination,
$! !# $ ""$characteristic clinical lesions can be seen which for an appropriate period of time (minimum of
are highly suggestive of a diagnosis. Erythema, 3 weeks; may need to extend for up to 8
alopecia, pustules, papules, crusts, and epidermal weeks for deep infections). In every case, oral
collarettes (raised borders of detaching stratum antibiotic therapy should be continued for at
corneum present at the margins of circular areas of least 1 week after a clinical cure has been seen
inflammation) are commonly seen on the skin of
or 2 weeks after the discontinuation of oral
after a clinical cure has been seen or 2 weeks
prednisone.
ning tract. The identification of large cocci,
The susceptibility of an organism to a drug
usually in pairs, is highly suggestive of pyoderma
is described in terms of the minimum inhibitory
caused by S. intermedius. The presence of rods is
concentration (MIC) of drug. Drug efficacy is
indicative of a mixed infection (with gram-
dependent upon drug concentrations reaching the
negative organisms). Many times these bacteria
MIC at the site of infection and will be enhanced
will be seen within the cytoplasm of a neutrophil
if concentrations at the site are several magnitudes
showing that they are not just contaminants. A
above the MIC. However, the concern for drug
skin biopsy is another valuable tool for the
safety prevents indiscriminate increases in dosage
diagnosis of pyoderma. Many veterinarians use
to increase the drug plasma concentration. The
the dog’s response to the use of oral antibiotics as
breakpoint MIC of a drug is the highest
a confirmation of the presence of the infection.
concentration that can be safely attained in blood
using the recommended (labeled) dosing regimen.
Organisms are considered susceptible to a drug if
the MIC is below the breakpoint MIC. Organisms
characterized by intermediate susceptibility are
inhibited at concentrations that approach
breakpoint. The MIC for a resistant organism
surpasses the breakpoint MIC of the drug, and for
that drug the risk of toxicity outweighs the
potential benefits of therapy.
The 3 essential components of successful
treatment of secondary bacterial pyoderma in dogs
include the proper selection of antibiotic,
treatment with appropriate dose and duration of
antibiotic therapy, and the identification and
control of all underlying dermatoses (allergies,
Probable-staph-pyoderma endocrinopathies, autoimmune diseases,
Treating Pyoderma keratinization defects etc.). Bacterial pyoderma is
The depth of the infection can have a a common cause of pruritus. For this reason, it is
negative impact on successful drug therapy. important to determine the cause of a patient's
Oral, systemic, antibiotics are the first choice pruritus (pyoderma, yeast dermatitis, allergies)
for the treatment of canine bacterial rather than treating the itch with steroids. Topical
pyoderma. The choice of an appropriate therapy is also of great benefit to help
antibiotic can be made empirically or based on mechanically remove organisms as well as
results of a culture and susceptibility test. A providing a non-antibiotic method of killing the
organisms. Shampoos containing chlorhexadine or
culture and susceptibility test is usually
benzyl peroxide are highly effective at reducing
recommended in those cases of bacterial the superficial colonization of Staphylococcus.
pyoderma that have made no clinical The overwhelming majority of first time bacterial
improvement after 2 weeks of treatment with pyodermas in dogs are caused by Staphylococcus
an antibiotic that is usually effective against intermedius. This organism has demonstrated
Staphylococcal infections. A culture and consistent sensitivity patterns making empiric
susceptibility is helpful if there is deep antibiotic selection possible. Amoxicillin with
pyoderma, for infections caused by gram- clavulanic acid and cephalexin are commonly used
negative organisms, or if the animal has been antibiotics that demonstrate good efficacy
treated previously with several different (Carlotti and Ovaert, 1988). Clindamycin,
antibiotics. It is important that the veterinarian potentiated sulfur drugs, and erythromycin also
demonstrate consistency good efficacy. The
prescribe an appropriate dose of an antibiotic
$! !# $ ""$antibiotic selected should be used for a minimum endocrine status and identify any allergic disease.
of 21 days to eliminate the infection and allow the When the underlying dermatoses are successfully
normal antimicrobial function of the skin to return controlled, the normal structures of the skin return
to a more normal and effective function. If to the natural antimicrobial functionality and the
inappropriately low doses of antibiotic are used or recurrent nature of the infection is eliminated. If
if the duration of therapy is too short, the the primary underlying dermatoses cannot be
populations of Staphylococci are altered so that identified or controlled, the patient will likely
antibacterial resistant strains are selected leading continue to develop secondary bacterial infections
to chronic/recurrent infections making additional and likely establish multi drug resistant
treatment even more difficult. For recurrent, Staphylococcus pyoderma.
resistant Staphylococcus cases, fluoroquinolones For recurrent skin infections, extended
are often selected for their perceived increased regimens of antibiotic therapy can be tried. These
potency; however, resistance may develop are to be used once the pyoderma has been
especially with inappropriately low doses or short brought under control. They do raise the potential
duration. Unfortunately, the cost of of inducing or selecting resistant strains of
fluoroquinolone therapy when dosed appropriately bacteria. There is no “best” regimen to use. Some
is very high. If the patient is on seemingly dermatologists recommend the use of an
appropriate doses of antibiotic for an appropriate appropriate antibiotic for one week followed by
duration (minimum of 21 days) without clinical one week without the drug. Eventually the length
improvement in the papular crusting alopecic of time without antibiotics may be extended. Other
lesions, a resistant Staphylococcus infection veterinarians have recommended using antibiotics
should be suspected. The percentage of excellent for 2 to 4 days per week at the full dose or even
responses to therapy, duration of therapy, and every other day. A third protocol involves a
percentage of relapses after a 3-month post maintenance recommendation of once daily
treatment follow-up period following treatment dosing. If this is successful then the dose of the
with tylosin compare favorably with results antibiotic can be lowered. As a general rule,
reported with other antibiotics commonly though, for the use of oral antibiotics to prevent
recommended for the treatment of staphylococcal recurrent pyoderma, the dose of drug should not
pyoderma in dogs (Cannon, RW, 1976; Angarano be lowered or the interval without antibiotics
and MacDonald, 1989; Guaguere and Marc, 1989; should not be extended until you have waited for
Paradis et al., 1990; Scott et al., 1993; Frank and twice the length of time expected for the
Kunkle, 1993 and Prost and Arti, 1993). This is a pyoderma to recur (i.e. if the animal can go for no
constant problem when dealing with more than 2 weeks without antibiotics before
manufacturers’ recommendations and the actual recurrence, wait a minimum of 4 weeks using a
duration of treatment needed to eliminate once daily dose before any further adjustments).
staphylococcal infection in the skin of dogs (Scott Topical antibacterial therapy is an integral
et al., 2001; Scott et al., 1994; Paradis et al., 1990 part of the initial treatment of a bacterial
and Scott et al., 1993). Other dermatoses that can pyoderma and is also useful in preventing
mimic pyoderma include Demodicosis, reoccurrence of the condition. The owner is
Dermatophytosis, Scabies and Pemphigus. Once usually instructed to shampoo the dog as often as
these differentials have been eliminated, the skin the dog needs it and as often as they are able.
lesions should be cultured and antibiotic Shampoos containing benzoyl peroxide,
sensitivity profile performed to help guide chlorhexadine, triclosan, or ethyl lactate are
antimicrobial selection. generally prescribed and owners are advised to let
Secondary bacterial infections are associated the shampoo contact the dog for a minimum of 10
with abnormal function of the skin’s natural minutes before rinsing. Use of a final leave-on
antimicrobial defenses (sebum, pH, epidermal rinse after bathing will assure that the active
turnover, etc.) caused by the underlying skin ingredient remains in contact with the skin and
disease. Allergies (environmental allergies, food haircoat. Antibiotic creams or ointments are useful
allergy, and flea allergy) and endocrinopathies for spot treatment. Mupirocin is an excellent
(hypothyroidism and Cushing’s disease) are the topical antibiotic. Vets should try to avoid using
most common primary diseases associated with products that contain corticosteroids.
secondary bacterial pyoderma. Other possible Immunomodulatory therapy using products
underlying dermatoses include autoimmune skin such as Staphage Lysate, Immunoregulin
disease and keratinization defects. Aggressive (Propionibacterium acnes bacterin), or Levamisol
diagnostic workups should be used to explore the may alter lymphocyte and phagocyte immune
$! !# $ ""$function by modifying the intracellular cyclic Chirurg Anim Cie 1988; 23: 519-522.
nucleotides of leukocytes. Cimetidine has also Crossley, K.B. and Archer, G.L. (1997). The
been proposed as an immunomodulatory drug Staphylococci in human disease (K.B.
because lymphocytes have H2 receptors that Crossley, G.t. Archer eds.).Churchill
theoretically act to modulate cytokine production. Livingston, NewYork
The zoonotic potential of Staphylococcus Frank LA, Kunkle GA. Comparison of the
intermedius, Staphylococcus aureus and efficacy of cefadroxil and generic and
Staphylococcus schleiferi is becoming proprietary cephalexin in the treatment of
increasingly concerning. All three species have the pyodermas in dogs. J Am Vet Med Assoc
potential to cause disease in both dogs and 1993; 203: 530-533.
humans. This is propelling the veterinary Frank, L.A., Kania, S.A., Hnilica, K.A., Wilkes,
community into a situation that is very similar to R.P. and Bemis, D.A. (2003). Isolation of
our human physician counterparts in their attempts Staphylococcus schleiferi from dogs with
to control Staphylococcus aureus and its multidrug pyoderma. Journal of American Veterinary
resistant strains. The days of indiscriminate use of Medical Association. 15(4): 451454.
antibiotics in veterinary dermatology are rapidly Freney, J., Brun, Y., Bes, M., Meugnier, H.,
coming to an end. It is simply a matter of time Grimont, F., Grimont, P.A.D., Nervi, C. and
before sufficient cases of zoonotic infections are Fleurette, J. (1988). Staphylococcus
documented and publicized causing a fundamental lugdunensis and Staphylococcus schleiferi sp.
and drastic reform in the veterinary profession. two species from human clinical specimens.
Soon, the most common skin disease in dogs may International Journal of Systemic
be regarded as a zoonotic infection with Bacteriology. 38(2): 168-72.
significant human health implications. This will Guaguere E, Marc JP. Utilisation de la
impact almost every aspect of pet ownership and cephalexinedans le traitement des
veterinary care; antibiotic use, isolation of infected pyodermites. Prat Med Chirurg Anim Cie
patients, canine hospital visitation, guide dog 1989; 24:124-129.
access to public facilities, and owner liability for Hajek, V. (1976). Staphylococcus intermedius,a
contagious zoonotic infections. new
species isolated from animals.International J.
Key Features of Canine Pyoderma of Systemic Bacteriology. 26(4): 401-408
•Pyoderma is the most common skin disease in Igimi, 5., Atobe, H., Tohya, Y., Inoue, A.,
dogs. Takahashi, E. and Konishi, S. (1994).
•Assume everything has pyoderma until you rule Characterization of the most frequently
it out. encountered Staphylococcus sp. in cats.
•Use the highest antibiotics dose possible to avoid Veterinary Microbiology. 39: 255-260.
resistance. Jean-Pierre, H., Darbas, H., Jean-Roussenq, A.
•Always treat for a minimum of 21 days. and Boyer, G. (1989). Pathogenicity in Two
•Secondary pyoderma can and usually does Cases of Staphylococcus schleiferi, a
complicate every other primary skin disorder. recently described species. Journal of
•Find and control the primary/underlying disease. Clinical Microbiology. 27(9): 2110-2111.
Manian, F.A.(2003). Asymptomatic Nasal
•Allergies and endocrinopathies are the most
Carriage of Mupirocin-Resistant,
common primary/underlying diseases.
Methicillin-Resistant Staphylococcus aure
Monitor for resistant infection, especially if the
-us (MRSA) in a pet dog associated with
infection is not improving.
MRSA infection in household contacts.
Clinical InfectiousDiseases.36:26-28.
References
Paradis M, Lemay S, Scott DW, Miller WH Jr.
Angarano DW, MacDonald JM. Efficacy of
Efficacy of enrofloxacin in the treatment of
cefadroxil in the treatment of bacterial
canine bacterial pyoderma.Vet Dermatol
dermatitis in dogs. J Am Vet Med Assoc1989;
1990; 1: 123-127.
194: 57-59.
Prost C. Arti I. Utilisation de la lincomycine dans
Cannon RW. Clinical evaluation of Tribrissen.
le traitement des pyodermites du chien. Prat
New antibacterial agent for dogs and cats. Vet
MMd Chirurg Anim Cie 1993; 28: 495-498.
Med Small Anim Clin 1976; 71:1090-1091.
Scott DW, Miller WH Jr, Griffin CE. (2001).
Carlotti D, Ovaert P. Utilisation de l’association
Muller and Kirk's Small Animal
amoxycilline-acide clavulanique dans le
Dermatology, 6th Ed. (Scott, et al.,eds.).
traitement de pyodermites du chien. Prat Md
$! !# $ ""$W.B. Saunders, Philadelphia. Staphylococcus intermedius infection in
Scott DW, Miller WH Jr, Cayatte SM, Bagladi dogs. Canine Pract 1993; 18: 29-33.
MS. Efficacy of tylosin tablets for the Tanner, M.A., Everett, c.L. and Youvan, D.C.
treatment of pyoderma due to (2000).Molecular phylogenetic evidence for
Staphylococcus intermedius infection in noninvasive zoonotic transmission of
dogs. CanVet J1994;35:617-621. staphylococcus intermedius from a canine
Scott DW, Miller WH Jr, Wellington JR. The pet to a human. Journal Clinical Microbiol.
combination of ormethoprim and sulfadime- 38(4): 1628-1631
thoxine in the treatment of pyoderma due to
===0===
SUBSCRIPTION
The Indian Journal of Canine Practice is a biannual Journal. Subscribers will receive
June and December Issues during the period of their subscription.
The Subscription rates are as under:-
India Abroad
For Institutions Rs.1000.00 $100 or £ 72
(Annual subscription only)
Corporate Members Free Free
For Canine Practitioners, Scientists,
Academicians and Students
Annual Subscription Rs.500.00 $25 or £ 18
Three Year Subscription Rs.900.00 $25 or £ 18
Life Members Free Free
Currency abbreviations used are Rs. (Indian Rupees), $ (US Dollars) and £ (British
Pounds)
For subscription, please write to The Editor, I.J.C.P., Department of Clinical Medicine,
College of Veterinary & animal Sciences, Hebbal, Banglore – 560 024, Karnataka; India.
$! !# $ ""$You can also read
