Evaluation of the Sceptor system for identification of bacteria of veterinary origin

CopyrightC) 1991, AmericanSociety for Microbiology

Evaluation of the

Sceptor System for

Identification

of Bacteria

of

Veterinary

Origin

JOHN R. PAPPAND C. ANNEMUCKLE*

Department of Veterinary Microbiology and Immunology, Ontario Veterinary College, University of Guelph, Guelph, Ontario, Canada NIG2W1

Received 13 July 1990/Accepted 9 October 1990

The Sceptor system (BectonDickinson Diagnostic Instrument Systems, Towson, Md.)was assessed forits ability to identify veterinary clinical isolates. A total of 605 bacteria, including 315 isolates of the family

Enterobacteriaceae,

191 gram-negative nonenteric bacteria, and 99 gram-positive bacteria, were tested. Overall, 534 (88.3%) were correctly identified, 28 (4.6%) were not identified, 12 (2.0%) were incorrectly identifiedatthegenuslevel, and32 (5.3%)wereincorrectlyidentifiedatthespecieslevel.The Sceptorsystem correctly identified 292 (92.7%) isolates ofEnterobacteriaceae, 165 (86.4%) gram-negative nonenteric bacteria, and77 (77.8%) gram-positive bacteria. One hundred thirty organismsnot contained inthe data base were tested with theSceptorsystem toassessthepossibility ofexpandingthe data base. TheSceptorsystemwasan acceptablemethod fortheidentification of isolates ofEnterobacteriaceae butnotgram-negative nonentericand gram-positivebacteria of animal origin. Development ofaveterinaryisolate-specific data base would improve the utility oftheSceptor systemin veterinary diagnostic bacteriology.

Numerous commercial microbiological identification sys-tems that have been developed on the basis of numerical taxonomy depend on the metabolic activityof microorgan-isms (7). The biochemical profile of an isolate is converted

into a numerical code, which is compared with taxonomic

guides listing the possible codes derived in the system.

Computer programs that automatically analyze the profile

number and recalculate the originaldatafacilitate identifica-tion by removing the need to manually compare the

num-bers. Theadvantage ofusing commercial identification sys-temsisthatthey allowmicrobiology laboratoriesto assess a greater number of biochemical parameters without signifi-cantlyincreasing labor. However, oneserious limitation of

these systems is that they may not contain theappropriate tests required to identify an organism which is outside the data base. Also, rare species or biochemically atypical

strains may beincorrectly identified.

TheSceptor system(BectonDickinson Diagnostic Instru-ment Systems, Towson, Md.) data base was designed to

identify bacteria of medical importance. It has accurately

identified 93.8% of 678 isolates of the family Enterobac-teriaceaefromhumanclinical specimens (31) but only68.7%

of80 Providencia stuartii isolates (5). There have been no

evaluations involving the Sceptorsystem andgram-negative

nonenteric bacteriaorgram-positive bacteria, and there has been no determination of Sceptor system accuracy with

veterinary bacterial isolates. Since biochemical profiles of

bacteria isolated from veterinary clinical specimens vary

slightlyfromthose ofbacteria of human origin (4, 25), it is

difficult to base the accuracy of the Sceptor system in a

veterinary setting on previous evaluations. The purpose of this study was to evaluate the accuracy of the Sceptor system for the identification of negative and

gram-positive bacteria isolated from veterinary sources.

*Correspondingauthor.

MATERIALSANDMETHODS

Test organisms. The organisms collected were obtained fromveterinary clinical specimenssubmittedtothe Clinical

Microbiology Laboratory (CML), Veterinary Teaching

Hos-pital,OntarioVeterinary College,ortheVeterinary Labora-toryServices Branch(VLS),OntarioMinistryof Agriculture and Food. The selection of organisms included species which were contained in the Sceptor system database and those whichwere notcontained in the data base but which wereconsidered importantinveterinary medicine.Atotalof 605 bacteria, including 315 isolates of Enterobacteriaceae, 191gram-negativenonentericbacteria, and99gram-positive bacteria, representing organisms contained in the data base weretested. Organismsnotcontained inthe databasewere 10Actinobacillus equuli, 5 Actinomyces pyogenes, 10 Aero-monas salmonicida subsp. salmonicida, 10Bacillus cereus, 10 Bacillus licheniformis, 10 Corynebacterium pseudo-tuberculosis, 10 Corynebacterium renale, 4 Erysipelothrix rhusiopathiae, 9 Rhodococcus equi, 10 Staphylococcus

intermedius, 10 Staphylococcus hyicus subsp. hyicus, 10

Streptococcus dysgalactiae, 4 Streptococcus equisimilis,

and 10 Streptococcus suis isolates. The majority of the isolates were obtained from domestic food-producing and

companion animals, but occasionally isolates were recov-ered fromamphibians, fish, andreptiles.

The CML identified clinicalisolatesby conventional bio-chemical methodologies (3) as well as the Enterotube II (Roche Diagnostics, Nutley, N.J.) and Micro-ID system

(General Diagnostics, Morris Plains, N.J.). The VLS used similar procedures, except that the isolates of Enterobac-teriaceae were identified by the Replianalyzer system

(CathraSystems,St. Paul, Minn.). Serologicalconfirmation of Salmonella specieswasperformed bytheClinical Refer-ence Bacteriology Laboratory, Ontario Ministry of Health,

Toronto, Ontario,Canada. Theidentification ofanunknown isolatewasconsidered final if theSceptor system identifica-tion agreed with the diagnostic bacteriology laboratory re-sults. If therewas adiscrepancyin theidentificationorif the

Sceptor system gave no identification, the organism was identifiedbyamoreextensivebiochemical scheme than that 10

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TABLE 1. Identification of Enterobacteriaceae contained in the Sceptor data base No.ofisolates

Organism _testedNo. _{Correctly Not Identified}

to Identifiedto

identified identified incorrectgenus incorrectspecies

Citrobacter amalonaticus 3 3 0 0 0

Citrobacter diversus 14 13 0 0 1

Citrobacterfreundii 20 17 3 0 0

Enterobacter aerogenes 13 10 1 0 2

Enterobacter agglomerans 20 17 3 0 0

Enterobacter cloacae 32 32 0 0 0

Escherichia coli 30 29 1 0 0

Escherichia vulneris 2 2 0 0 0

Hafnia alvei 4 3 1 0 0

Klebsiella oxytoca 21 20 0 0 1

Klebsiella ozaenae 3 0 2 1 0

Klebsiella pneumoniae 33 33 0 0 0

Morganella morganii 13 13 0 0 0

Proteusmirabilis 23 23 0 0 0

Proteus vulgaris 14 14 0 0 0

Providencia alcalifaciens 1 1 0 0 0

Providencia rettgeri 2 2 0 0 0

Providencia stuartii 4 4 0 0 0

Salmonella arizonae 3 2 0 0 1

Salmonella choleraesuis 5 5 0 0 0

Salmonella enteritidis 25 23 0 0 2

Serratia liquefaciens 6 5 0 1 0

Serratia marcescens 14 14 0 0 0

Serratiarubidaea 1 0 1 0 0

Yersiniaenterocolitica 5 4 0 1 0

Yersinia pseudotuberculosis 4 3 1 0 0

Totalno. 315 292 13 3 7

Total% 92.7 4.1 1.0 2.2

usedbythediagnostic laboratories (2, 3, 11, 12, 18, 19, 22, 27, 30), and these results were considered correct. All

organisms

notcontained withinthedata basewereidentified

conventionally

(2, 3, 6,9, 11, 19, 30).

Sceptor system testing. Isolates were cultured on 5% citrated calf bloodagarplates and incubated for24h at37°C in anambientoxygen atmosphere before being testedwith

the

Sceptor

system. TheSceptorsystem wasusedin

accord-ance with the manufacturer's instructions. Sceptor

gram-negative broth did not support thegrowth of Actinobacillus

andPasteurellaspecies. The manufacturer therefore

recom-mended inoculating these organisms into Sceptor anaerobe

broth,

which supported their growth. The Sceptor system

identification was considered final when the confidence value was greater than 85% or when supplemental tests

suggestedby the computerwerecompleted.

The quality ofthe Sceptorgram-negative and

gram-posi-tive panels was assessed by testing the following strains:

Escherichia coli ATCC25922,EnterococcusfaecalisATCC

29212, Klebsiella pneumoniae ATCC 13883, Proteus

vul-garis ATCC 33420, Pseudomonas aeruginosa ATCC 27853,

and Staphylococcus aureus ATCC 29213. This procedure

wasperformedonce amonth and uponreceipt ofnewpanels

with adifferentlot number.

Interpretation of results. TheSceptorsystem identification results fororganisms contained in the data base were

clas-sified as follows: (i) correct to the species level,

(ii)

not

identified, (iii) incorrectly identified to the genuslevel, and

(iv) incorrectly identifiedtothespecieslevel. Identifications tabulated asincorrectatthegenuslevelwere notincludedin

identifications tabulated as incorrectatthe species level. A test of significance was used to determine whether the Sceptor system was more accurate at bacterial identification than was the CML or the VLS (13). The Sceptor system biochemical profile numbers of organisms not contained in thedata base wererecorded with theresulting identification.

RESULTS

Organisms containedintheSceptordata base.

Overall,

the Sceptor system correctly identified 534 of 605 isolates

(88.3%). Twenty-eight(4.6%) were notidentified, 12 (2.0%)

were incorrectly identified atthegenus level,and 32(5.3%)

were incorrectly identified at the species level. Of the 315

isolates of Enterobacteriaceae tested, 292 (92.7%) were

correctly identified (Table 1). Culturesthat were most com-monly misidentified or notidentified by the Sceptor system were Citrobacter freundii, Enterobacter aerogenes, and Enterobacter agglomerans.

Table 2 lists thegram-negative nonenteric bacteria

exam-ined and summarizesthe correctidentifications madebythe Sceptor system. The systemcorrectly identified 165 of 191 strains(86.4%), did not identify9(4.7%), identified 7(3.6%)

to anincorrect genus, and identified 10

(5.2%)

toanincorrect species. Errors in identification were commonly encoun-tered when Aeromonas species weretested; only 56%were identified (14 of 25 strains). One supplemental test result,

positive nitrate reduction,wasrequired tocorrectly

identify

the 20Bordetella bronchiseptica isolates.

Seventy sevenofthegram-positive bacteria

(77.8%)

were

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TABLE 2. Identificationofgram-negative nonenteric bacteria containedintheSceptordatabase

No. of isolates

Organism _testedNo. _{Correctly Not Identifiedto Identifiedto}

identified identified incorrect genus incorrectspecies

Acinetobacter anitratus 13 12 1 0 0

Acinetobacteriwoffii 14 14 0 0 0

Actinobacillus lignieresii 5 4 0 0 1

Actinobacillus suis 10 8 0 2 0

Alcaligenes species 3 3 0 0 0

Aeromonas hydrophila 11 4 0 3 4

Aeromonas sobria 14 10 1 1 2

Bordetella bronchiseptica 22 20 1 1 0

CDCgroupEF-4 3 2 1 0 0

Flavobacterium multivorum 1 1 0 0 0

Moraxella species 5 4 1 0 0

Pasteurellahaemolytica 21 20 1 0 0

Pasteurella multocida 22 17 2 0 3

Plesiomonas shigelloides 1 1 0 0 0

Pseudomonas aeruginosa 41 40 1 0 0

Pseudomonasfluorescens 3 3 0 0 0

Pseudomonasmaltophilia 2 2 0 0 0

Totalno. 191 165 9 7 10

Total% 86.4 4.7 3.6 5.2

correctly identified by the Sceptor system (Table 3). Six one strain ofStreptococcus equi and three strains of group G

(6.1%) were not identified, 1 (1.0%) was incorrectlyidenti- streptococci as Streptococcus agalactiae.

fied at the genus level, and 15 (15.2%) were incorrectly The resultsforwhich conventional testing agreed withthe

identifiedat thespecies level. Of 31 S. aureusisolates,1 was identifications made by either the Sceptor system or a

incorrectly identified at the genus level and 6 were incor- diagnostic laboratory are given in Table 5. The Sceptor rectly identifiedatthe species level. system was significantly better at identifying isolates of

Significant misidentifications were noted with 2 of 22 Enterobacteriaceaethan were themethodsemployedbythe

strains of Salmonella enteritidis identified as Salmonella CML. There was no significant difference between the

typhi. One of three strains of Salmonella arizonae was Sceptor system and the CML in the identification of

gram-identified as S. enteritidis (Table 4). Onestrain of Yersinia negative nonenteric bacteria andgram-positive bacteria. In enterocolitica wasidentifiedas aShigellaspecies. Also,two comparison with theVLS, the Sceptorsystem was equally

strains of Actinobacillus suis were incorrectly identified as accurate atidentifying isolates of Enterobacteriaceae.

How-Pasteurella haemolytica. The Sceptor system categorized ever, theSceptor systemidentified significantlymore

gram-TABLE 3. Identification ofgram-positive bacteria contained in theSceptor data base

No.of isolates

Organism _testedNo. _{Correctly Not Identified to Identifiedto}

identified identified incorrect genus incorrectspecies

Enterococcusfaecium 3 3 0 0 0

Listeriamonocytogenes 11 11 0 0 0

Staphylococcusaureus 31 24 0 1 6

Streptococcus agalactiae 6 6 0 0 0

Streptococcusavium 1 0 1 0 0

Streptococcusconstellatus 3 1 0 0 2

Streptococcus equi 5 3 1 0 1

Streptococcus group G 7 3 1 0 3

Streptococcus intermedius 1 0 0 0 1

Streptococcusmutans 1 1 0 0 0

Streptococcus salivarius 1 0 0 0 1

Streptococcus sanguis I 3 2 1 0 0

Streptococcus uberis 1 1 0 0 0

Streptococcus zooepidemicus 25 22 2 0 1

Totalno. 99 77 6 1 15

Total% 77.8 6.1 1.0 15.2

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TABLE 4. Veterinary clinical isolates contained in the Sceptor data baseandincorrectly identified by the Sceptor system

No.~~~~~~~~~~~~~~~~~~~~~~of

Correct identification isolates Sceptoridentification

Actinobacilluslignieresii 1 Actinobacillus suis Actinobacillus suis 2 Pasteurellahaemolytica Aeromonas hydrophila 4 Aeromonassobria

2 Pasteurellapneumotropica 1 Vibrio vulnificus

Aeromonas sobria 2 Aeromonas hydrophila 1 Vibriovulnificus Bordetellabronchiseptica 1 Moraxella species Citrobacter diversus 1 Citrobacter freundii Enterobacter aerogenes 2 Enterobacter cloacae Klebsiella oxytoca 1 Klebsiellapneumoniae Klebsiella ozaenae 1 Enterobacter agglomerans Pasteurellamultocida 3 Pasteurellahaemolytica Salmonella arizonae 1 Salmonella enteritidis Salmonella enteritidis 2 Salmonella typhi Serratialiquefaciens 1 Enterobacter cloacae Staphylococcus aureus 1 Micrococcus varians

1 Staphylococcus sciuri 4 Staphylococcussimulans 1 Staphylococcus xylosus Streptococcus constellatus 2 Streptococcus sanguis I Streptococcus equi 1 Streptococcusagalactiae Streptococcus group G 3 Streptococcusagalactiae Streptococcus intermedius 1 Streptococcus mutans Streptococcus salivarius 1 Streptococcus sanguis I Streptococcuszooepidemicus 1 Enterococcusfaecalis

Yersiniaenterocolitica 1 Shigella species

negativenonentericbacteria andgram-positivebacteria than didthe VLS.

Organisms not contained in the Sceptor data base. The biochemical reactions for catalase-positive gram-positive

bacteriawere determined following 18to24 hofincubation at 35 to 37°C, except for C. pseudotuberculosis, which required 48 h of incubation. Bacillus species, Corynebacte-rium species, and Rhodococcus species were identified as Staphylococcus species or Listeria monocytogenes. Four strains of E. rhusiopathiae and five strains of A. pyogenes failedtogrowinSceptorgram-positive or anaerobe broth.

TheSceptorsystemidentifiedonestrain of S. intermedius asStaphylococcus epidermidis. Of the sixbiochemical

pro-file numbers generated for the S. intermedius strains, five were characteristic oflow-probability identifications (confi-dence value, less than 85%). S. hyicus subsp. hyicus was identified asS. simulansornotidentified.

Of the sevenprofile numbers generated forS.

dysgalac-tiae, fivewerenotspecific foranyorganism in the data base.

One strain was identifiedas streptococcusgroup CFG, and

another was identified as Streptococcus constellatus. The four strains of S.equisimilisgaveaconsistent profile number but were identified as S. constellatus. There were four alternateidentifications andonenonidentification of S. suis. Both A. equuli and A. salmonicida subsp. salmonicida produced three profile numbers.A. equuliwas identifiedas eitherActinobacillus lignieresiiorA. suis, andA. salmoni-cida subsp. salmonicida was identified as P. haemolytica. Fivestrains ofA. equuli and three strains ofA. salmonicida subsp. salmonicida werenotidentified.

DISCUSSION

Guidelines for assessing the acceptability of automated and/orrapid bacterial identification systemsindicate that the level ofaccuracy should approach 95% and that species of

clinical significance should be consistently identified (24). TheSceptorsystemwasmosteffective for theidentification of isolates of Enterobacteriaceae (92.7%). Although these results were comparable to those of the previous study involving isolates of Enterobacteriaceae of human origin (93.8%) (31), they did notachieve the95% level. Similarly, the system was unable to reach the 95% level for

gram-negative nonenteric bacteria(86.4%)andgram-positive bac-teria (77.8%). Identification discrepancies were further tested with a more extensive conventional biochemical de-sign. However, it ispossible thatsome of the isolates were incorrectly identified by both the Sceptor system and the CML or the VLS. If all the bacteria tested had been

identified byareferencelaboratory, the identification values mayhavebeenslightly lower than theonespresentedinthis

study.

The Sceptorsystem's ability toidentify veterinary bacte-ria appearsto be limited toisolates ofEnterobacteriaceae. Although thesystemwaslessthan95%accurate,itwasable to consistently identify organisms of clinical significance. The most prominent errors associated with isolates of En-terobacteriaceae involved the reporting of S. typhi and Shigella species for two strains of S. enteritidis and one

strain of Y. enterocolitica, respectively. Since S. typhi is hostspecific for humans (20) and sincethese isolates were fromreptiles, the laboratory would be alertedtotheerroron

the basisof the animalspeciesinvolved.TheSceptorsystem identified Salmonella isolates to the correct genus; there-fore, routine serotyping would eliminate incorrect species identification. For Y.enterocolitica, the presenceofgrowth

oncefsulodin-Irgasan-novobiocinagar (23) would allow dif-ferentiation fromShigella species.

TABLE 5. Comparison of identifications made bytheSceptor system anddiagnostic bacteriology laboratories

Diagnosticbacteriology O No.of No. correctly identified by: 2b

laboratory Orgamsmgroup

discrepanciesa

Sceptor

LaboratoryX

CML Enterobacteriaceae 23 16 7 3.92

Gram-negative nonenteric bacteria 13 9 4 2.33

Gram-positive bacteria 20 12 8 1.01

VLS -. Enterobacteriaceae 29 19 10 3.11

Gram-negative nonenteric bacteria 24 18 6 6.51

Gram-positive bacteria 3 3 0 4.08

aNumber ofdiscrepanciesinidentification betweentheSceptor systemand thediagnosticbacteriologylaboratorywhenconventionaltestingagreedwithone

ofthe two methods.

bChi-square statisticwith 1df;thecriticalvalue at P=0.05 is 3.84.

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Only 56% of the 25 Aeromonas isolates tested were

identifiedby the Sceptor system. It has been suggestedthat humandiagnostic bacteriology laboratories accurately iden-tifythese organisms (21); inveterinary medicine,A. salmo-nicida andAeromonas hydrophila areimportant pathogens

(10, 14, 15, 17). Although other clinically significant

gram-negativenonentericbacteriawereconsistently identified,we needed to identify organismsbelongingto theActinobacillus and Pasteurella genera prior to Sceptor system testing because they required Sceptor anaerobe broth. Until

Scep-tor gram-negative broth is supplemented to support the

growth of these organisms, technical expertise beyond the abilitytosimply inoculate and read Sceptortestpanels is still required.

The poor performance associated with the gram-positive panels indicates that this arearequires extensive modifica-tions before it can be accepted as a routine method of identification. TheSceptor systemmadeanumber of signif-icant gram-positive misidentifications. For example, the

incorrectS. aureus identifications may be clinically

impor-tantbecause thisorganism isassociated withawidevariety

of disease conditions in veterinary medicine (26). With the

exception ofStreptococcuszooepidemicus, fewstreptococci

were available for the study. Therefore, a greater sample size may reflect the true ability ofthe Sceptor system to

identify Streptococcus species. Problems with veterinary gram-positive identification are, however, notuniquetothe

Sceptor system and appear to be inherent in commercial

systems(28, 29).

Currently, the Sceptor systemgram-positive data base is

separated intothree subgroups: (i) alpha-hemolytic or

non-hemolytic streptococci; (ii) beta-non-hemolytic streptococci;and

(iii) catalase-positive cocci. Bacillus species,

Corynebacte-riumspecies, and R. equi wereidentifiedasmembersofthe

catalase-positive coccidata base. Additionalsubgroups

spe-cific for gram-positive rods, with orwithout spores, would

separate these organisms from L. monocytogenes and

Staphylococcus

species without modification of the bio-chemical format of the

gram-positive

panels.

TheSceptorsystem wasfoundtobemore accuratein the identification of isolates of Enterobacteriaceaethan was the

CML. Thisresult was not surprising, since the widerrange

oftestsperformedin the Sceptortestpanels better charac-terizes isolates of Enterobacteriaceae. Fewer biochemical

tests arecarried out in the CML, possibly

resulting

in less accurateidentifications. TheSceptorsystemwasnot signif-icantly betterat the identification ofgram-negative

nonen-teric bacteriaandgram-positive bacteriathan wasthe CML.

The problems noted with the identification ofAeromonas species andS. aureus may have accounted forthe

insignif-icantdifference seen.

In comparison with the VLS, the

Sceptor

system was more accuratefor theidentification ofgram-negative

nonen-teric bacteria and gram-positive bacteria. However, this

differencewas mainlydue to theSceptorsystemidentifying

theisolatetothe correct specieswhile the VLSidentifiedit to the correct genus without identifying the

species.

Obvi-ously, theseare not truediscrepancies, since the VLS may havequestionedthe need toidentifytheseorganisms tothe

species level. There was nodifferencebetween the Sceptor

system and the VLS in the identification of isolates of

Enterobacteriaceae, which are routinely identified to the

specieslevelby theVLS.

The API 20E system (Analytab Products Inc.,Plainview, N.Y.)wasreported toidentify

96%

of isolates of Enterobac-teriaceae from clinical specimens submitted to veterinary

laboratoriesacrosstheUnited States

(25). However,

Black-all

(1)

found that the API 20E was

only

86% accurate for enteric

pathogens

obtained from an Australian

veterinary

laboratory.

Therefore,

in addition to

biotype

differences

betweenbacteria of human and animal

origins,

theremay be

regional

biochemical variations inbacterial isolates. Other commercialidentificationsystemswhich have been assessedwith

veterinary

isolateshavenot

approached

a95%

accuracylevel

(4,

8, 16, 28, 29).

Therefore,

we canconclude

that,

atthe present

time,

no

commercially

available identi-fication system has been shown to be

fully

suitable for

general

veterinary

clinical

microbiology. Indeed,

most

re-portsstressthe needto

develop

adata base which

incorpo-ratesresultsfrombacteriaofanimal

origin (4, 8, 16, 28,

29).

Manufacturers havebeen reluctant to

develop

a

veterinary

isolate-specific

data base because ofthe lower market

po-tential

compared

with that for human

diagnostic

bacteriol-ogy. Until sucha systemis

developed, veterinary

laborato-ries must either

struggle

with systems which contain data

obtained

primarily

from human bacterial

pathogens

or

con-tinueto useconventionalbiochemical

methodologies.

In

conclusion,

the

Sceptor

system has been showntobea

reasonably

accurate method for

identifying

isolates of

En-terobacteriaceaewithinaroutine

veterinary diagnostic

lab-oratory.

Although

thesystem didnotreach the95%levelset

by

Sherris and

Ryan

(24),

itwas able to

identify

clinically

significant

isolates.

However,

for

veterinary

laboratories

dealing

with animal

species

such as

fish, reptiles,

and other

species

which

yield

isolatesnotcontainedin the data

base,

it may be

unacceptable.

In its present state, the

Sceptor

gram-positive

data base isnotreliablefor identification.The

development

of a

veterinary-isolate-specific

data base is

highly

desirable,

sinceitwould

recognize

the

biotype

differ-encesbetween human andanimal bacterial isolatesaswellas

species

not includedin the data base.

However,

such

mod-ificationsmay bea

costly

venture;

therefore,

itmaybemore

feasible

simply

to

develop

acomputer programwhich allows individuallaboratoriesto

personally modify

the data base. In

this way, each

microbiology laboratory

would have a data

base

specific

for its

particular region

and

patient

type.

ACKNOWLEDGMENTS

We thankJohn F. Prescott and John A. Lynchforcomments.

Bacterial strains were kindly

supplied

by Debbie Bateman, Kim

Chan,GiselaKittler,and Valerie

Longfield.

Thisworkwassupported bytheOntarioMinistryofAgriculture

and Food.

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