Aaa138

Evaluation of Subgingival Bacteria in the Dog and
Susceptibility to Commonly Used Antibiotics
Mirko Radice, DVM; Piera Anna Martino, DBSc, PhD; Alexander M Reiter, Dipl Tzt, Dr med vet progression from a healthy periodontium to gingivitis andperiodontitis, there is a shift from a gram-positive oriented, aerobic facultative flora to a predominantly gram-negative, The aim of the present investigation was to evaluate the anaerobic flora.22 Periodontopathogens are bacteria that cause subgingival aerobic and anaerobic flora of 13 dogs with gingivitis and periodontitis. A catalase-positive form of the gram periodontal disease and the susceptibility of these bacteria negative Porphyromonas gingivalis is considered to be the key to antibiotics currently approved in Italy for treatment of periodontopathogen in cats and dogs15,23-25 and is recognized as P. canine infections. Of the anaerobic bacteria, Bacteroides gulae.26 Other canine and feline Porphyromonas organisms fragilis was most frequently isolated, followed by include P. assacharolytica, P. cangingivalis, P. canoris, P. cansulci, Peptostreptococcus + Porphyromonas gingivalis and P. endodontalis, P. circumdentaria, P. crevioricanis, P. salivosa, P. Prevotella intermedia. Of the aerobic bacteria, α-hemolytic denticanis, and P. gingivicanis.11,27-30 Additional black-pigmented Streptococcus was most frequently isolated, often associated anaerobic bacteria associated with periodontal disease include with Escherichia coli or Pasteurella multocida. Resistance Prevotella intermedia23 and Bacteroides spp.17,18,31,32 Pathogen- of anaerobic and aerobic bacteria to various antibiotics was related oral spirochetes also are considered to play an important generally high. Anaerobic bacteria appeared to be role in periodontal disease, but cultivation studies in cats and dogs susceptible to amoxicillin + clavulanic acid, doxycycline, have only been reported sparsely.8,32-35 and erythromycin; aerobic bacteria appeared to be Previous studies showed that amoxicillin + clavulanic acid susceptible to amoxicillin + clavulanic acid, erythromycin, and clindamycin had high in vitro susceptibility against anaerobes gentamycin, and sulfa-trimethoprim. Bacteroides fragilis and enrofloxacin high in vitro susceptibility against aerobes from was resistant to all of the antibiotics tested. The emerging subgingival plaque samples in cats and dogs.36,37 Although worldwide problem of bacterial resistance to antibiotics periodontal disease is caused by bacteria, antibiotic therapy should resulting from overuse and misuse of antibiotics is not be the primary treatment strategy.38,39 Unfortunately, there is a discussed. J Vet Dent 23 (4); #$% - &*, 2006
tendency among veterinarians to use antibiotics as part of themanagement of any animal with periodontal disease or other oralcondition. Resistance of plaque bacteria to antibiotics has clearly been demonstrated in humans,40-43 and a similar pattern of bacterial Periodontal disease is an infectious condition of the tooth resistance development may be present in cats and dogs.
supporting tissues (gingiva, periodontal ligament, alveolar bone, The aim of the present investigation was to evaluate the and cementum) and is considered to be the most common disease subgingival flora (aerobic and anaerobic bacteria) of dogs with in companion animals. The accumulation of plaque on tooth periodontal disease and the susceptibility of these bacteria to surfaces is responsible for the development of gingivitis and antibiotics currently approved in Italy for treatment of canine infections. Furthermore, the emerging problem of bacterial Gingivitis is inflammation of the gingiva and is reversible, if resistance to antibiotics in human and veterinary medicine is plaque is removed by home or professional oral hygiene procedures.2 In addition to toxins and tissue-destructive enzymesproduced by periodontopathogenic bacteria, the host's response to Materials and Methods
plaque leads to the release of agents from damaged neutrophils Thirteen client-owned dogs with various degrees of that can cause injury to the body's own tissues.1 Inflammation periodontal disease (ranging from gingivitis to periodontitis as may spread along the periodontal space and ultimately progresses assessed by means of periodontal probing) were included in this to periodontitis, which is diagnosed as loss of attachment study. There were three Yorkshire terriers, one German shepherd, (gingival recession, resorption of alveolar bone, and formation of one poodle, and eight mixed-breed dogs. Two dogs received periodontal pockets). The periapical region of the tooth root may sporadic oral hygiene at home. A professional scaling and become affected, leading to retrograde pulpal infection. Thus, polishing had been performed on all dogs 6-months prior to endodontic disease can occur as a result of severe periodontal sample collection. Antibiotics had been given to most of the dogs disease. Eventually the tooth becomes mobile and is lost due to in the past for conditions other than periodontal disease. However, spontaneous exfoliation or professional extraction.1 no attempt was made to assess details of antibiotic history Gingivitis and periodontitis are referred to as ‘bacterial because owners were not able to verify names of antibiotics used, infections', but several hundred bacterial species have been dates and routes of administration, duration of therapies, etc.
identified to date in normal and diseased mouths of cats and Dogs had not received antibiotic therapy for at least 2-weeks dogs.3-21 With maturation of plaque in subgingival areas and before bacterial sampling. ??? J.VET.DENT. Vol. 23 No. 4 December 2006 219

Sample collection was performed under general anesthesia at the detachment of microbial cells. Two dilutions (Log10) were the right maxillary canine tooth (104) and the right maxillary made for all samples that were plated on Tryptic Soy Agar plates fourth premolar tooth (108) since both teeth had been excluded with 5 % sheep bloodb for aerobic bacteria and on Brucella Agarc from prior periodontal probing. A sterile endodontic paper point for anaerobic bacteria. The plates were incubated aerobically for was inserted into the depth of the gingival sulcus or periodontal 24 to 48-hours at 37°C, and anaerobicallyd for 48 to 72-hours at pocket at buccal aspects of the teeth. The paper point was removed after a few seconds and placed into tubes containing a The anaerobic flora was identified by growth on Brucella transport liquid media (thioglycollate broth)a for growth of Agare, a medium containing Vit K and haemin. Gram's staining, aerobic and anaerobic bacteria. The samples were immediately Schaffer & Fulton's staining for spores, and API System 20Af transported to the reference laboratory and were vortexed to allow were used as biochemical reference methods.
Aerobic bacteria were identified by their macroscopic (e.g., morphology of colonies, presence of hemolysis) and microscopic (using Gram-staining) characteristics; moreover, biochemical Signalment of the 13 dogs enrolled in the study.
tests were performed using macro- or micromethodsg. For theidentification of Streptococcus strains, the presence of hemolysis (α partial or β total) and the growth on Mitis Salivarius Agarh, a medium for the isolation and identification of the streptococci of the oral cavity, were evaluated. For identification of Pasteurella multocida, the lack of growth on Mac Conkey Agari was Evaluation of microbial sensitivity/resistance to antibiotics was performed using the Kirby-Bauer reference method or the agar disk diffusion test. A bacterial suspension, performed in saline buffer (0.9 % NaCl), was delivered onto a Mueller-Hinton plate, and then the disks containing different antibiotic moleculeswere placed on the plate. After incubation at 37°C under aerobic or anaerobic atmosphere for 24 to 48-hours, the susceptibility of each microorganism was recorded to the following antibiotics:amikacin, amoxicillin + clavulanic acid, doxycycline,erythromycin, gentamycin, kanamycin, metronidazole (only foranaerobes), and sulfa-trimethoprim.k Isolation of anaerobic bacteria.
Results of variables of signalment (sex, age, weight, and diet) Anaerobic bacteria of the 13 dogs enrolled in the study are reported in Table 1. The Peptostreptococcus + Porphyromonas majority of dogs were male (84.6 %), 5 to 10-years of age (53.8 %), < 12.0 kg (61.5 %), and eating a mixed (soft and dry) diet Bacteroides fragilis Prevotella intermedia Of the anaerobic bacteria (Table 2), Bacteroides fragilis was most frequently isolated from subgingival samples, followed byPeptostreptococcus + Porphyromonas gingivalis, and Prevotella Anaerobic bacteria intermedia. Of the aerobic bacteria (Table 3), α-haemolyticStreptococcus was most frequently isolated, often associated with Peptostreptococcus + Escherichia coli or Pasteurella multocida.
Porphyromonas gingivalis Susceptibility of anaerobic and aerobic bacteria to various antibiotics is shown in Tables 4-8. Resistance of isolated bacteriato tested antibiotics was generally high. Anaerobic bacteriaappeared to be susceptible to amoxicillin + clavulanic acid,doxycycline, and erythromycin, while aerobic bacteria appearedto be susceptible to amoxicillin + clavulanic acid, erythromycin, gentamycin, and sulfa-trimethoprim. Bacteroides fragilis was resistant to all of the antibiotics tested.
The aim of the present investigation was to evaluate the subgingival aerobic and anaerobic bacterial flora of 13 dogs with J.VET.DENT. Vol. 23 No. 4 December 2006

periodontal disease and the susceptibility of these bacteria to veterinarians, and diagnostic uncertainty. Several recent studies antibiotics currently approved in Italy for treatment of canine showed that pediatricians prescribe antibiotics significantly more infections. Except for the high prevalence of Bacteroides fragilis, often, if they perceive parents expect them, and significantly less the predominant subgingival flora obtained in this study confirms often, if they feel parents do not expect them.55-58 The best way to results reported in previous studies.15,17,18,23-25,31,32 Of the anaerobic combat this situation is to educate patients/patient owners and bacteria, Bacteroides fragilis was most frequently isolated, doctors/veterinarians to decrease both demand and over- followed by Peptostreptococcus + Porphyromonas gingivalis and prescribing. Unfortunately, there is a tendency to use antibiotics as Prevotella intermedia. The reason for the unusually high part of the management of any animal with periodontal disease or prevalence of Bacteroides fragilis is not clear. Differing results other oral condition, although there is no apparent justification for between isolation studies may be due to differences in study this practice. Similar to dogs in the present study, resistance of methodology, including sample population utilized and isolation plaque bacteria to antibiotics has clearly been demonstrated in techniques applied. Of the aerobic bacteria, α-haemolyticStreptococcus was most frequently isolated, often associated with Escherichia coli or Pasteurella multocida. The fast growth rate, high concentration of cells, genetic Isolation of aerobic bacteria.
processes of mutation and selection, and ability to exchange genesaccount for the extraordinary adaptation and evolution of bacteria.44 For these reasons bacterial resistance to antibiotics may α-hemolytic Streptococcus + E. coli take place very rapidly in evolutionary time. Risk factors α-hemolytic Streptococcus + P. multocida responsible for the emergence and spread of resistant bacteria α-hemolytic Streptococcus + E. coli include: (1) antibiotic use; (2) reservoirs for resistance; (3) α-hemolytic Streptococcus + E. coli medical advances; and (4) societal changes.45 Antibiotics make conditions favorable for overgrowth of some bacteria, including α-hemolytic Streptococcus S. intermedius + P. multocida those that possess mechanisms of drug resistance. If a resistant organism is present, antibiotics will create ‘selective pressure'favoring the growth of that organism. A number of studies havedemonstrated conclusively that the development of bacterial α-hemolytic Streptococcus resistance to antibiotics is correlated with the level of antibiotic + E. coli + P. multocida use.46-48 Antibiotic resistance of nosocomial pathogens in hospitals, α-hemolytic Streptococcus + E. coli + S. intermedius nursing homes, day-care centers, and animal facilities is increasedby the transfer of individuals already colonized by resistant + S. intermedius organisms from one location to another. Progress in the treatment of many diseases has led to an increased life span of humans andanimals. Consequently, with advanced age, chronic disease orimmunosuppression, individuals can be more susceptible tobacterial infections, resulting in greater use of antibiotics.
Worldwide spread of bacterial resistance to antibiotics hasoccurred due to the increased mobility of today's society.45 Pet animal numbers have substantially increased in modern α-hemolytic Streptococcus + P. multocida society, and attention is increasingly devoted to pet welfare.
Antibiotics are frequently used in small animal practice, withheavy use of broad-spectrum agents such as amoxicillin +clavulanic acid, cephalosporins, and fluoroquinolones. The practice of antibiotic overuse and misuse in cats and dogs hascontributed to the development of Staphylococcus spp., Antibiotic activity versus Prevotella intermedia.
Escherichia coli and various other bacteria that are resistant toantibiotics.49-53 The role of pets in the dissemination of bacterial resistance to antibiotics has been given relatively little attention when compared with that of food animals, and a marked contrast is evident between the current policies on antibiotic usage in companion and food animals. However, the possible transfer of resistant bacteria from cats and dogs to humans has recently been acknowledged as a potential threat to public health.44,54 One of the biggest problems is inappropriate prescribing of antibiotics. There are many reasons for this, including demand from patients/patient owners, time pressure on physicians/ J.VET.DENT. Vol. 23 No. 4 December 2006 221
Antibiotic activity versus Bacteroides fragilis.
Antibiotic activity versus Porphyromonas gingivalis +Peptostreptococcus.
Antibiotic activity versus α-haemolytic Streptococcus + E.
Antibiotic activity versus α-haemolytic Streptococcus + P.
humans.40-43 It is therefore imperative to review periodontaltreatment strategies and determine whether systemic antibiotics have a role to play in the management of periodontal disease.
If accumulation of plaque is prevented, periodontal disease American Veterinary Dental College (AVDC) Position does not develop.2 Although this condition is caused by bacteria, Statement on the Use of Antibiotics in Veterinary Dentistry.
antibiotic therapy is not considered the primary treatmentstrategy.38,39 Instead, treatment of periodontal disease should be The AVDC endorses the use of systemic antibiotics in directed at mechanical removal or reduction of plaque and veterinary dentistry for treatment of some infectious calculus accumulation, suppression of the tissue-destructive conditions of the oral cavity. Although culture andsusceptibility testing is rarely performed on individual effects of the inflammatory response, surgical management of patients that have an infection extending from/to the oral periodontal pockets, extraction of more severely affected teeth, cavity, the selection of an appropriate antibiotic should be and thorough debridement of extraction sites.1 A controlled- based on published data regarding susceptibility testing release local antibiotic delivery system, reaching of the spectra of known oral pathogens. Patients that are periodontopathogens deep within periodontal pockets, has been scheduled for an oral procedure may benefit from pre-treatment with an appropriate antibiotic to improve the described in dogs.59 Professional supra- and subgingival scaling, health of infected oral tissues. Bacteremia is a recognized followed by daily tooth brushing, is the ‘gold standard' for sequela to dental scaling and other oral procedures.
prevention of periodontal disease.1 Home oral hygiene may be Healthy animals are able to overcome this bacteremia enhanced by offering products that support dietary abrasion or without the use of systemic antibiotics. However, use of asystemically administered antibiotic is recommended to chemically suppress plaque and calculus accumulation.60 reduce bacteremia for animals that are immune Bacteremia secondary to periodontal disease occurs daily in compromised, have underlying systemic disease (such patients with periodontal disease, and it is normally rapidly as clinically-evident cardiac, hepatic, and renal diseases) cleared by the reticulo-endothelial system in the healthy patient.61 and/or when severe oral infection is present. Antibiotics Therefore, for the great majority of otherwise healthy cats and should never be considered a monotherapy for treatmentof oral infections, and should not be used as preventive dogs presenting with periodontal disease and other oral management of oral conditions. Adopted by the Board of conditions, systemic antibiotics are not indicated.1,39 Bacteremia Directors, April 2005 can be prevented or reduced in severity by rinsing the oral cavity J.VET.DENT. Vol. 23 No. 4 December 2006 with dilute chlorhexidine gluconate (0.12 %) prior to di cani con parodontopatie e loro antibiotico-sensibilità. Tesi di laurea, Relatore Dott.ssa P.A. Martino, 2003. Facoltà di Medicina Veterinaria, Milano.
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