NORMAL FLORA OFTHENOSE,THROAT, ANDLOWER INTESTINE OFDOGS [623278]

NORMAL FLORA OFTHENOSE,THROAT, ANDLOWER INTESTINE OFDOGS
W.E.CLAPPER ANDG.H.MEADE
Department ofMicrobiology, TheLovelace Foundation forMedical Education andResearch,
Albuquerque, NewMexico
Received forpublication 18October1962
ABSTRACT
CLAPPER, W.E.(TheLovelace Foundation
forMedical Education andResearch, Albu-
querque, N.M.)ANDG.H.MEADE. Normal
floraofthenose,throat,andlowerintestine of
dogs.J.Bacteriol. 85:643-648. 1963.-An at-
temptwasmadetoisolateandidentifythecom-
pletenormalfloraoftherectum,nose,andthroat
ofbeagles. Forprimary isolation, 12different
kindsofmediawereused.Incubation ofblood
agarplatesandslantsanaerobically, andof
thioglycolate brothaerobically, allowed the
growthofobligate anaerobes. Fromtherectal
specimens, 20speciesofbacteriaand10speciesof
fungiwereisolatedandidentified. Theorganisms
weresimilartothosefoundinthehumanintes-
tine.Escher',chia coli,Streptococcus mitis,entero-
cocci,S.lactis,Bacillus species,andcoliforms
otherthanE.coliweremostfrequently encoun-
tered.Thefrequency ofoccurrence wasapproxi-
matelythesameatbothsamplings inmore
commonly cultured bacteria. Pathogenic E.coli
wereisolated fromnearlyone-third ofthefirst
specimens. Theseweretheonlyhumanpathogens
observed. Inthethroatcultures, 29speciesof
bacteria and2speciesofyeastswereidentified,
and27speciesofbacteria wereidentified from
thenasalcultures. S.mitis,Neisseria, andcoagu-
lase-negative Staphylococcus weremostoften
isolated. Theflorawassimilartothatfoundin
humannoseandthroatcultures, exceptthat
moreHaemophilus andpneumococcus andfewer
coliforms aregenerally foundinhumanthroats.
Organisms resembling humanpathogens were
groupAstreptococci andcoagulase-positive
staphylococci. Thesewereisolatedinfrequently.
Itappearsthatthiskindofexamination would
revealanysignificant changes innormalflora
thatmightberelatedtothe health oftheanimal.
Itiswellknownthatanimalsexposed tolarge
dosesofXirradiation oftensuccumb toanover-
whelming septicemia duetoorganisms commonlyfoundintheintestinal tract(Benacerraf, 1960),
andorgansnormally sterileinhealthyanimals
arefoundtobeinfectedwiththesebacteria when
examined atautopsy (Bradner, Bernstein, and
McCarthy, 1955).Generalized infection after
irradiation hasbeenobserved inman(Benacerraf,
1960).Anincrease incoliform bacilliinthe
intestines ofX-irradiated dogswasreported by
Furth,Coulter, andHowland (1952),andan
increase incoliforms, accompanied byadecrease
inlactobacilli, intheintestines ofirradiated
ratswasobserved byBell,Coneglio, andHudson
(1955).
Asanaidinestablishing thecauseofdisease
anddeathindogsexposed toionizing radiation,
experiments wereinitiated toidentify thebac-
terialandfungalfloraofthoseareasmostlikely
tocontribute causative organisms. Although
studiesofbacteria foundincertainareasofthe
dog'sintestinal tract(Meleney, Berg,and
Jobling, 1927;Smith,1931;Haeren, Dack,and
Wilson,1938;Schweinburg andSylvester, 1953;
Skazaki, Namioka, andMura,1956;Bornside
andCohn,1961)havebeenmade,andlarge
numbers ofdogshavebeeninvestigated to
determine theincidence ofspecific organisms
(Galton, Scatterday, andHardy,1952),reports
ofattempts toisolateallthebacteria andfungi
presentinthelowerintestine, nose,andthroat
ofdogsareeitherrareorhavenotbeenpublished.
Thispaperreportstheorganisms isolatedfrom
swabsofthenose,throat,andrectum of25
healthydogs,andcompares therelativefrequency
ofthevariousspecies.
MATERIALS ANDMETHODS
Specimens: rectalswabs.Incollaboration with
personnel oftheSectionofVeterinary Medicine,
rectalswabsof22beaglesweretakenduringthe
periodfrom7September to9October 1961.
Ofthesedogs,3werenotavailable forthesecond
studyduringtheperiodfrom9October to20
November 1961,butanadditional 3wereadded
tothegroup,making atotalof25.Theswabs
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CLAPPER ANDMEADE
TABLE1.Mediausedfortheprimary isolation ofmicroorganisms fromthenose,throat,and
intestine ofthedoga
Medium Use RbN&TO
AerobicTrypticase (BBL)soybloodagard ……… Totalflora XX
Phenylethyl alcohol agar……………… Gram-positive cocci XX
Tomato-juice agar…………………… Lactobacilli, staphylococci, yeasts XX
Desoxycholate agar………………….. Enteric bacteria XX
Salmonella-Shigella agar……………… Entericpathogens X
Selenite broth ………………………. Entericpathogens X
Chocolate agar……………………… Fastidious organisms, Neisseria, X
Haemophilus
Staphyloccus Medium No.110(Difco)
agar…………………………. Staphylococci X
CystineTrypticase agar……………… Fastidious organisms, Neisseria, X
Haemophilus
Anaerobic
Trypticase soybloodagar……………. Anaerobes XX
Thioglycolate medium ……………….. Anaerobes XX
Fungus
Sabaraud's dextrose agar…………….. Aerobicfungi X
Mycosel agar……………………….. Aerobicfungi,pathogens X
Anaerobic bloodagarslant……………. Actinomyces XX
aSwabswereplacedinProteose Peptone No.3broth,andmediawereinoculated fromthis.
6Rectalswab.
cNoseandthroatswab.
dOutdated blood-bank blood.
wereplastic-enclosed rectalswabs(Falcon) de-
signedtopreventcontamination fromtheouter
areasoftheanus.Thesewereimmediately placed
in2mlofProteose PeptoneNo.3(Difco)broth.
Gramstainsweremadefromasecondspecimen
onthefirsteightdogsstudied.Themedialisted
inTable1wereinoculated fromthebroth.
Chocolate andbloodagarplateswereincubated
in10%CO2.Abloodagarplateandslantin-
cubated anaerobically andthioglycolate broth
incubated aerobically wereusedfortheinitial
isolation ofanaerobes. Thegeneralschemeem-
ployedforprimary isolation ofallorganisms is
alsopresented inTable1.Allcolonies oneach
plate(asmanyas25perspecimen) whichap-
pearedmorphologically different weresubcul-
turedtoappropriate mediatoobtainpurecul-
tures.Theywereidentified byGramstainsand
bytheusualbiochemical andserological studies
employed inclinicallaboratories.
Noseandthroatswabs.Thetonsillar areasand
theanterior naresof25dogswereswabbed and
theswabsplacedinbroth.Primary isolation was
madeinthemedialistedinTable1.Individualcolonies werepickedfromeachmedium foriso-
lationinpurecultureandwerethenidentified
byfurtherstudies, asindicated above.
RESULTS
Theindividual speciesisolated fromeach
areaarelistedinTable2.Thedataaredis-
cussedaccording totheoriginoftheorganisms.
Rectalswabs.Gramstainsoftenrevealed anon-
culturable spirillum orspirochete, afinding
whichhasbeenobserved byothers(Smith,
1931;Craige,1948).
Thepercentage ofdogsinwhichthevarious
kindsofbacteria werefoundisshowninFig.1
forthetwoseriesofexperiments performed.
Escherichia coliandgram-positive cocci(Strep-
tococcusmitis,enterococci, andS.lactis)were
mostprevalent. Withtheexception ofS.lactis,
therewaslittledifference inthefrequency of
theseorganisms inthetwosamplestakenfrom
thesamedogsatdifferent times.Thisistrue
alsofortheentericbacilli:Paracolobactrum,
Aerobacter, Proteus, andPseudomonas. Patho-
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NORMAL MICROBIAL FLORA OFDOGS
moreofthedogsduringthefirstperiodoftesting
thanatthelaterperiod.Therewasalargediffer.
enceinBacillusspecieswhichprobably haslittle
significance inrelationtothehealthoftheanimal
andismostlikelyrelatedtothefloraofthe
environment. Proteusorganisms werepresentin
approximately one-third ofthespecimens at
bothtimes.P.mirabilis wasthespeciesmost
oftenisolated. Coagulase-negative staphylococci
andPseudomonas wereseeninonlyasmallper-
centageandinthesamenumber atbothtest
periods.Nocoagulase-positive staphylococci were
isolated. Clostridium andLactobacillus specieswereoflowprevalence, andbothwerefoundless
ofteninthefirstspecimens thaninthesecond.A
varietyofnonpathogenic fungiwereisolated;
Mucorspeciesweremostprevalent, beingnoted
ineightspecimens.
Throatswabs.Thepercentage ofdogsinwhich
thevariouskindsofbacteria wereisolatedfrom
throatswabsisshowninFig.2.S.mitisand
Neisseria speciespredominated inallofthe
animals. Thenextmostfrequently observed
bacteria werethecoagulase-negative staphylo-
cocci.Coagulase-positive staphylococci were
isolatedfromonlytwoanimals, andsowerenot
TABLE2.Microorganisms isolatedfrom25beagles(listedinorderoffrequency)
Nose Throat Rectum
Staphylococcus, coagulase-
negative
Streptococcus mitis
Streptococcus lactis
Neisseria flavescens
Bacillus sp.
Corynebacteriuim sp.
Neisseria catarrhalis
Mimapolymorpha
Enterococcus
Pseudomonas aeruginosa
Aerobacter aerogenes
Neisseria sicca
Lactobacillus sp.
Clostridium perfringens
Escherichia coli
Paracolobactrum intermedium
Bacillus subtilis
Alcaligenes metalcaligenes
Staphylococcus, coagulase-
positive
Alcaligenes faecalis
Intermediate coliform
Clostridium septicunm
Haemophilus haemolyticus
Paracolobactrum sp.Streptococcus mitis
Staphylococcus, coagulase-
negative
Neisseria flavescens
Neisseria sicca
Escherichia coli
Streptococcus lactis
Bacillus sp.
Alcaligenes faecalis
Mimapolymorpha
Corynebacterium sp.
Neisseria catarrhalis
Pseudomonas aeruginosa
Aerobacter aerogenes
Lactobacillus sp.
Streptococcus (,B-hemolytic,
notgroupA)
Intermediate coliform
Paracolobactrum intermedium
Streptococcus, groupA
Enterococcus
Clostridium perfringens
Staphylococcus, coagulase-
positive
Pasteurella multocida
Achromobacter sp.
Paracolobactrum sp.
Proteus mirabilis
Yeast
Candida albicansEscherichia coli
Streptococcus mitis
Enterococci
Streptococcus lactis
Aerobacter aerogenes
Bacillus sp.
Paracolobactrum sp.
Intermediate coliform
Proteus mirabilis
Escherichia coli,pathogenic
Escherichia freundii
Clostridium perfringens
Bacillus subtilis
Staphylococcus, coagulase-neg-
ative
Pseudomonas aeruginosa
Lactobacillus sp.
Proteus vulgaris
Proteusmorganii
Pseudomonas sp.
Staphylococcus, coagulase-pos-
itive
Mucor
Fusariuni
Hormodendrum
Diplosporium
GeotrichumPenicilliunm
Cynecephalastrum
Oospora
Candida albicans
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CLAPPER ANDMEADE
included inthegraph.About50%ofthedogs
werenotedtohaveE.coliinthethroat,with
otherentericbacilli seenlessfrequently; 36%
carried,B-hemolytic streptococci, nearlyone-half
ofwhich weregroupA.Lactobacillus andCoryne-
bacterium speciesandenterococci werepresent,
butinsmallnumbers.
Thisfloraisverysimilartothatwhichthe
seniorauthorhasobserved overaperiodof10
yearsinaclinicdiagnostic laboratory where
several throatswabsfromhumans ofallages
arecultured daily.Thegreatest difference was
inthelackofHaemophilus speciesandpneu-
mococci indogs,which arecommonly encoun-
Bacteria Isolated FromRectalSwabsFromDogs
Totalno.examined %ofDogsinwhichOrganism wasfound
ineachgroup=220 25 5 7S 10,0
E.coli _. 9%
S.viridons 40.9%~~~*~~~45.2%S.lactis _6 3
Bacillus sp. _ 68 1
Enterococ 177.2%
Prterccus _3 S4.5Paracolons and 59%IntermediatesS45
A.aerogenes _40.9%409
Proteus ^ 331.5%31.5%Clostridium 18.1%
Coag.neg.staph. 13.6%13.6%
Lactobocilli 4.5i13.6%
Pseudomonas sp..',9.0%
Path.E.coli % 31.5%
E Swabstaken9-7-61to10-9-61Swabstaken10-9-61to10-20-61 somedogswithexception of3
FIG.1.Bacteria isolatedfromrectalswabsfrom
dogs.
FIG.2.Bacteria isolated fromthroatswabsfrom
dogs.LClostridium 6%16
FIG.3.Bacteria isolated fromnasalswabsfromdogs.
teredinhumans, andthegreater numberof enteric
bacteria foundinthedogs.Proteusspecies are
notoftencultured fromthroatsofhumans; they
werefrequently isolated fromthethroatsofthe
dogs.
Nasalswabs.Figure3showstheresultsofthe
studycarriedoutonnasalswabs.Theorganisms
mostfrequently isolated werethesameasthose
notedinthethroat, exceptthatcoagulase-
negative staphylococci werefoundineverydog;
coagulase-positive staphylococci werenoten-
countered. Corynebacterium species were seen
frequently. Thecoliform bacilli weremuchless
inevidence inthenasalswabsthaninthethroat
swabs.13-Hemolytic streptococci andpneumo-
cocciwerenotobserved. B.subtilis orrelated
organisms wereapparent inaboutone-half of
thecultures; thiswasalsotrueofboththroat
andrectalswabs.
DISCUSSION
Bacterial counts werenotattempted, sinceit
wasfeltthatthiswouldcomplicate studiesin-
volving alargenumberofanimalsforanextended
periodoftimetothepointofdiminishing produc-
tivityinresults. Furthermore, Smith(1931)
abandoned suchcountsbecause theyvaried
greatlyinthesamedogandhadnoapparent
relation tothehealthoftheanimal.SinceBorn-
sideandCohn(1961)statedthatthemostcom-
monlyfoundbacteria werealsothemostnumer-
ousinbothcontrol groupsanddogswithclosed
loopsintheintestine, itseemedjustifiable inthe
presentstudytousethepercentage occurrence asBacteria Isolated FromNasalSwabsFromDogs
Totalnumber %ofDogsinwhichOrganism wasfound
examined -25D 25 50 75 100
Coog.neg.stph. _ __ _ _100%Strep.virident _92%
Neisseria 92%
Strep.lactis 556 % .
Bacillus 5656
Corynebocterium 1110%0
B.anitratum 3_3 %
Enterococcu __2 %
Pseudomoe -24%
A.aerogenes _20%
Lactobocillus _20%
Paracoldon and 20%
Alkaligene p_20%
E.coli _16%
Bacteria IsolatedFromThroatSwabsFromDogs
Totalnumber %ofDogsinwhichOrgonism wasfound
examined =250 2.5 50 75 I0o
Strept.viridons100%Neisseria
100%Coag.neg.stoph. 64%
E.coli 52%
Strept.lactis 48%
Bacillus 40%
Alkaligenes fecolis 40%
B-strept. 36%
Paracolonand32Intermediots 32
B.anitratum 24%
Pseudomonas 20%
A.aerogenes 20%
Lactobocillus 20%
Corynebacterium 16%
Enterococcus 8%
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VNORMAL MICROBIAL FLORA OFDOGS
ameasure oftheprevalence ofdifferent species
orgroups. Specimens showing anyspeciesin
nearlypureculture wouldbegiventhesame
significance aspossible causesofdiseaseasthey
areinaclinical microbiology laboratory.
Zubrzycki andSpaulding (1962)recently re-
ported astudyinwhlichtheyfoundthenormal
humanfecalfloratoberemarkably stable.Wide
fluctuations occurred onlyinthenumber and
typeoflessfrequently observed organisms. They
believed thatasignificant variation inthenormal
florawouldaffectthehealthoftheindividual. A
comparison oftheresultsoftwospecimens taken
atdifferent timesonthesamedogs(Fig.1)
showedlittlevariation inmostofthemorecom-
monlyisolated organisms, withtheexception of
S.lactis.Itseemsprobable thatthefecalfloraof
healthydogsisalsoquitestable.
Smith(1931),inherstudyofthebacterial
floraofisolated segments ofthe small intestine,
examined 307specimens from40dogs.Noat-
temptwasmadetoisolateandidentify allor-
ganisms, aswasdoneinthisstudy,butacom-
parison ofresultsisofinterest. C.perfringens
wasfoundin87%ofthespecimens, andE.coli
in85%.Nonhemolytic streptococci (45%70)and
hemolytic streptococci werenextinorder.In
thepresentstudy,Clostridiumn specieswerenoted
muchlessoften,perhaps because thesampling
wasmadefromthelowerintestine.
HaenelandMueller-l3euthow (1956)examined
thefecalfloraofseveralanimals including dog
andman.Twospecimens werecultured from
eachsubject(sixtimesin4weeks).Thefloraof
mananddogwereobserved tobequitesimilar
andtoconsistofaerobes, anaerobes, coliforms,
andenterococci inthatquantitative order.
Staphylococci wererare.Datareported inthe
presentstudyconfirm thestaphylococcal find-
ings,andcoliforms, enterococci, andlactobacilli
proved tobeamongthesixmostfrequently
culturedorganisms.
Mikhlin andGeimberg (1956)reported the
fecalfloraofdogstoconsistchieflyofacidogenic
streptococci, coliforms, andlacticacidbacilli,
andanother group(Skazaki etal.,1956)stated
thatE.coliwasthemostcommon organism. In
thesurveyreported inthispaper,E.coli,S.mitis,
S.lactis,andenterococci werethebacteria iso-
latedmostoften.SinceZubrzycki andSpaulding
(1962)foundBacteroides tobethepredominating
organism inhumanfeces,inspiteofcoliforms
beingsoconsidered byothers,itmightbeusefulinfuturestudiestomakedilutions astheydid,
toallowbetterisolation ofthesesmaller and
slower-growing colonies. Itwouldseemdoubtful,
however, thatthiswouldbeofimportance in
evaluating thehealthofananimalunlessthey
suddenly appeared asthepredominating
organism oftheculturewiththeusualflorasup-
pressed orabsent.
Proteus species, identified inone-third ofthe
specimens examined inthel)resentstudy,have
beenisolated byothers(Smith, 1931;Bornside
andCohn,1961;Galtonetal.,1952;Gorham,
1949),andProteusisgenerally considered tobe
partofthenormalflora.Gebert(1953),however,
foundnoneinhealthy dogs,butdidnoteP.
mirabilis andP.morganii in60%/oofthosewith
dysentery.
Although severalextensive investigations have
showndogstobecarriersofSalmonella (Skazaki
etal.,1956;Galtonetal.,1952;Wolff,Hender-
son,andMcCallum, 1948),neitherSalmonella
norShigella werefoundinthecurrentstudy.
Themostinteresting findingrelatedtothedog
asacarrierofhumanpathogens (Fig.1)wasthe
isolation ofseveralpathogenic E.coli.Mian
(1959)reported thatdogscarrypathogenic E.
coliintheirintestines andmaybeasourceof
infection toman.Ofthe22dogsfirstexamined
here,7werecarrying theseorganisms. Fivewere
type0119B14, andtwoweretype055B5. No
furtherantigendeterminations weremade.Only
onedogwasstillcarrying apathogenic E.coli
whenexamined thesecondtime.Thiswastype
055B5.
Frequent isolation ofPasteurella multocida from
thetonsilsandnoseofhealthydogshasbeen
reported (Smith,1955).Ithasbeenoccasionally
notedindogbites(AIeyer, 1948;LeaandBuan,
1960).3-Hemolytic streptococci havealsobeen
cultured fromdogtonsils, noneofwhichwere
human-type strains(Pilotetal.,1936;Laughton,
1948).Mann(1959)reported that23ofthenasal
swabsfrom100dogsyieldedcoagulase-positive
staphylococci. P.multocida wasfoundinonly
twoofthethroatandoneofthenasalswabsin
the25dogsexamined inthepresentstudy.Nine
throatswabsshowed#-hemolytic streptococci,
fourofwhichweregroupAbythebacitracin-
disctest(Maxted, 1953).Thesewerenotidenti-
fiedserologically. Nof3-hemolytic streptococci
andonlytwocoagulase-positive staphylococei
wereisolated fromthenasalswabs.
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CLAPPER ANDMEADE
foundintheintestinal andrespiratory floraof
dogs,depending uponthemethods usedforisola-
tion,themanner inwhichcultures aretaken,
detailsrelevant tohousing, and,perhaps, the
contribution ofotherfactors.However, ingeneral,
thesameorganisms havebeennotedinthevari-
ousstudiesreviewed above,andthefloradoes
notseemtodiffergreatlyfromthatofhumans.
Therefore, itappearsfeasibletodetermine major
fluctuations inavariety ofexperimental situa-
tions,including exposure toradiation. Tocor-
relatethiswiththedog'shealthundervarious
experimental conditions, itwillbenecessary to
conduct similardeterminations onacontrol as
wellasontheexperimental group.
ACKNOWLEDGMENTS
XVewishtothankJ.F.StaraandH.C.Red-
manforobtaining thespecimens fromtheani-
mals.
Thisinvestigation wassupported byfunds
fromtheDivision ofBiologyandMedicine ofthe
Atomic EnergyCommission.
LITERATURE CITED
BEI,E.J.,J.G.CONEGLIO, ANDG.W.HUDSON.
1955.Effectofx-irradiation oncecalfloraof
therat.Proc.Soc.Exptl.Biol.Med.89:404-
406.
BENACERRAF, B.1960.Influence ofirradiation on
resistance toinfection. Bacteriol. Rev.24:
35-40.
BORNSIDE, G.H.,ANDI.COHN,JR.1961.Intestinal
bacteriology ofclosedloopstrangulated ob-
struction indogs.Gastroenterology 41:245-
250.
BRADNER, W.T.,S.E.BERNSTEIN, ANDR.E.
MCCARTHY. 1955.Comparison ofbacteria iso-
latedfromblood,tissues, andfeces of x-ir-
radiated mice.Proc.Soc.Exptl.Biol.Med.
89:107-111.
CRAIGE, J.E.1948.Spirochetes associated with
dysentery indogs.J.Am.Vet.Med.Assoc.
113:247-249.
FURTH, F.W.,M.P.COULTER, ANDJ.W.
HOWLAND. 1952.Bacteriologic studies of
x-irradiated dog.Am.J.Pathol. 28:171-183.
GALTON, M.M.,J.E.SCATTERDAY, ANDC.V.
HARDY. 1952.Salmonellosis indogs.I.Bac-
teriological, epidemiological, andclinical
considerations. J.Infect. Diseases 91:1-18.
GEBERT, S.J.1953.Theassociation ofProteus
witlhcanine dysentery. Australian Vet.J.
29:168-170.
GORIIAM, J.R.1949.Comment onpaperbyJ.E.
Craige. J.Am.Vet.Med.Assoc.114:425-428.HAENEL, H.,ANDW.MUELLER-BEUTHOW. 1956.
Comparative quantitative investigations on
thebacterial countinfecesofmanandsome
vertebrates. Zentr.Bakteriol. Parasitenk.,
Abt.1.Orig.167:123-133.
HAEREN, S.,G.M.DACK,ANDH.WILSON. 1938.
Acuteintestinal obstruction. 1.Theroleof
bacteria inclosedjejeunal loops.Surgery
3:333-350.
LAUGHTON, N.1948.Caninebetahemolytic strep-
tococci. J.Pathol. Bacteriol. 60:471-476.
LEA,M.L.,ANDB.A.BUAN.1960.Dogbitesand
localinfection withPasteurella septica. Brit.
Med.J.1:169-171.
MANN,P.1959.Antibiotic sensitivity testingand
bacteriophage typingofstaphylococci found
inthenostrils ofdogsandcats.J.Am.Vet.
Med.Assoc.134:469-470.
MAXTED, W.R.1953.Theuseofbacitracin for
identifying groupAhaemolytic streptococci.
J.Clin.Pathol. 6:224-226.
MELENEY, F.L.,B.N.BERG,ANDJ.W.JOBLING.
1927.Experimental chronicduodenal obstruc-
tion.II.Bacteriology. Arch.Surg.14:762-771.
MEYER, K.F.1948.Theanimalkingdom, areser-
voirofhuman disease. Ann.Internal Med.
29:326-346.
MIAN,K.A.1959.Isolation ofenteropathogenic
Escherichia colifromhousehold pets.Relation
toinfantile diarrhea. J.Am.Med.Assoc.
171:1957-1961.
MIKHLIN, S.,ANDV.GEIMBERG. 1956.Excretion
ofintestinal enzymes withthefecesindogs
onsuppression ofthenormalmicroflora ofthe
intestinal tract.Vopr.Pitaniya 13:27-31.
PILOT,I.,C.BUCK,0.J.DAVIS, ANDD.A.EAST-
MAN.1936.Tonsillitis indogsduetohemolytic
streptococci. Proc.Soc.Exptl.Biol.Med.
34:499-502.
SCHWEINBERG, F.B.,ANDE.M.SYLVESTER. 1953.
Bacteriology ofthehealthy experimental ani-
mal.Proc.Soc.Exptl.Biol.Med.82:527-530.
SKAZAKI, R.,S.NAMIOKA, ANDS.MURA. 1956.
Enteric bacteria inapparently healthy ani-
mals.Japan.J.Vet.Res.4:51-56.
SMITH,J.E.1955.Studies onPasteurella septica.
1.Theoccurrence inthenoseandtonsilsof
dogs.J.Comp.Pathol. Therap. 65:239-245.
SMITH,V.1931.Thebacterial floraofisolated in-
testinal segments. J.Infect.Diseases 48:295-
303.
WOLFF, A.H.,N.D.HENDERSON, ANDG.L.
MCCALLUM. 1948.Salmonella fromdogsand
thepossible relationship tosalmonellosis in
man.Am.J.PublicHealth38:403-408.
ZUBRZYCKI, L.,ANDE.H.SPAULDING. 1962.
Studies onthestability ofthenormalhuman
fecalflora.J.Bacteriol. 83:968-974.648 J.BACTERIOL. on August 3, 2020 by guest http://jb.asm.org/ Downloaded from