A Probabilistic Transmission Model for the Spread of Extended-Spectrum-β-Lactamase and AmpC-β-Lactamase-Producing Escherichia Coli in the Broiler Production Chain

Direct contact between humans and live broilers, as well as the consumption of chicken meat, have been suggested as pathways for transmission of extended-spectrum-β-lactamase (ESBL) and AmpC-β-lactamase (AmpC)-producing Escherichia coli. One approach to design intervention strategies to control the transmission of such bacteria between animals and humans is to study the transmission pathways of such bacteria between the animals themselves. The rationale is that controlling the process of the underlying source, here transmission between animals, can provide hints on how to control a higher-level process, here the transmission between animals and humans. The focus of this article is the transmission of the above-mentioned bacteria between broilers and broiler flocks in meat production with regards to the establishment of possible intervention strategies to reduce the transfer of these bacteria between animals. The objective of this work is to design a mathematical transmission model describing the effects of vertical and horizontal bacterial transmission in the broiler production chain, from the parent generation to the slaughterhouse level. To achieve this objective, an existing transmission model for Campylobacter was adapted for the case of E. coli. The model keeps track of prevalence among flocks (flock prevalence) and of prevalence among animals within one flock (animal prevalence). Flock and animal prevalences show different dynamics in the model. While flock prevalence increases mainly through horizontal transmission in hatcheries, animal prevalence increases mainly at the broiler-fattening farm. Transports have rather small effects just as the vertical transmission from parents to chicks.

Rapid urease test (RUT) for evaluation of urease activity in oral bacteria in vitro and in supragingival dental plaque ex vivo

BACKGROUND

Urease is an enzyme produced by plaque bacteria hydrolysing urea from saliva and gingival exudate into ammonia in order to regulate the pH in the dental biofilm. The aim of this study was to assess the urease activity among oral bacterial species by using the rapid urease test (RUT) in a micro-plate format and to examine whether this test could be used for measuring the urease activity in site-specific supragingival dental plaque samples ex vivo.

METHODS

The RUT test is based on 2% urea in peptone broth solution and with phenol red at pH 6.0. Oral bacterial species were tested for their urease activity using 100 μl of RUT test solution in the well of a micro-plate to which a 1 μl amount of cells collected after growth on blood agar plates or in broth, were added. The color change was determined after 15, 30 min, and 1 and 2 h. The reaction was graded in a 4-graded scale (none, weak, medium, strong). Ex vivo evaluation of dental plaque urease activity was tested in supragingival 1 μl plaque samples collected from 4 interproximal sites of front teeth and molars in 18 adult volunteers. The color reaction was read after 1 h in room temperature and scored as in the in vitro test.

RESULTS

The strongest activity was registered for Staphylococcus epidermidis, Helicobacter pylori, Campylobacter ureolyticus and some strains of Haemophilus parainfluenzae, while known ureolytic species such as Streptococcus salivarius and Actinomyces naeslundii showed a weaker, variable and strain-dependent activity. Temperature had minor influence on the RUT reaction. The interproximal supragingival dental plaque between the lower central incisors (site 31/41) showed significantly higher scores compared to between the upper central incisors (site 11/21), between the upper left first molar and second premolar (site 26/25) and between the lower right second premolar and molar (site 45/46).

CONCLUSION

The rapid urease test (RUT) in a micro-plate format can be used as a simple and rapid method to test urease activity in bacterial strains in vitro and as a chair-side method for testing urease activity in site-specific supragingival plaque samples ex vivo.

Glycocodon theory--the first table of glycocodons

Hydrophobic cellular membranes separate cells from an environment that is generally based on water. Therefore, it is not surprising that hydrophilic glycans and glycoproteins are exposed on the lipidic surface of membranes and that the glycocalyx has evolved in all basic cell types. During the evolution of multicellular life, the surface exposed protein-glycan interactions were taken as the origin of the language of cell-cell communication. The bioinformatics analysis presented here reveals that the amino acid triplets, the glycocodons, can be deduced for each glycan letter (monosaccharide). This theory proposes to distinguish between the "sugar code" (the sugar sequence) and the "glycocode" (evolutionary selected amino acids recognising the mono-sugar). Similarly to genetic code, original glycocodons are related to G, A, V, and D amino acids. Modern glycocodons can be deduced from GAVD-glycocodons using hydropathic similarity. In general, the amino acid triplets can be assembled from one dipeptide that is specific to a monosaccharide plus a polar amino acid. This theory may shed a different light on the reason for WWD conservation in the active sites of oligosaccharyltransferases and for GGQ in the active sites of ribosomes.

Cloning, sequencing and characterization of a urease gene operon from urease-positive thermophilic Campylobacter (UPTC)

AIMS

To clone, sequence and characterize the genetic organization of urease genes within urease-positive thermophilic Campylobacter (UPTC).

METHODS AND RESULTS

An approx. 5.1-kbp region encoding a urease gene operon was identified, when recombinant plasmid DNAs from a genomic DNA library of a Japanese isolate (CF89-12) of UPTC were analysed.

CONCLUSIONS

Six closely spaced and putative open reading frames (ORFs) for ureA, ureB, ureE, ureF, ureG and ureH were detected. ATG codons initiated each ORF of the UPTC urease operon except for ureB and ureH, which commenced with the most probable TTG codon. Overlaps were detected between ureA and ureB and also between ureB and ureE. Probable ribosome-binding sites and a putative rho-independent transcriptional termination region were identified. Two putative promoter structures, consisting of consensus sequences at the -35 like and -10 regions were also identified.

SIGNIFICANCE AND IMPACT OF THE STUDY

Construction of a neighbour-joining tree based on the nucleotide sequence data of urease genes indicated that UPTC formed a cluster with some Helicobacter organisms separate from the other urease-producing bacteria, suggesting a commonly shared ancestry between UPTC and Helicobacter urease genes.

Purification, crystallization and preliminary X-ray diffraction studies of the soluble domain of the oligosaccharyltransferase STT3 subunit from the thermophilic archaeon Pyrococcus furiosus

Oligosaccharyltransferase catalyzes the transfer of preassembled oligosaccharides onto asparagine residues in nascent polypeptide chains. The STT3 subunit is thought to bear the catalytic site. The C-terminal domain of the STT3 protein of Pyrococcus furiosus was expressed in Escherichia coli cells. STT3 protein prepared from two different sources, the soluble fraction and the inclusion bodies, produced crystals that diffracted to 2.7 A. During crystallization screening, cocrystals of P. furiosus STT3 with an E. coli 50S ribosomal protein, L7/L12, were accidentally obtained. This cross-species interaction is not biologically relevant, but may be used to design a built-in polypeptide substrate for the STT3 crystals.

Flagellin gene structure offlaA andflaB and adjacent gene loci in urease-positive thermophilicCampylobacter (UPTC)

Two flagellin gene (flaA and flaB) sequences and the adjacent gene loci of urease-positive thermophilic Campylobacter (UPTC)(1) were examined. The flagellin gene sequences (1.7 kb) and adjacent gene loci of the two UPTC isolates (89049 and A3), obtained from animal hosts, were very similar to those of C. lari RM2100, C. jejuni, and C. coli. However, the structure and loci of the two flagellin genes (1.46-1.47 kb) and the adjacent gene loci of a UPTC strain obtained from the natural environment (NCTC12892) clearly differed from those of C. lari RM2100 and UPTC obtained from animal hosts. The two flagellin genes of UPTC 89049 and A3 were located between topA /CLA0518 and CLA0521, whereas those of NCTC12892 were located between topA and CLA0521. The sequences involved in regulation of flagellin expression, like sigma(28), sigma(54) and transcription termination signals, were conserved in all isolates. The characteristic direct repeat sequences containing a complete repeat unit of 5'-TCTTTAAAACAAC-3' were located in the intergenic regions between flaA and flaB in UPTC89049 and A3, but not in NCTC12892. The deduced amino acid sequence alignment revealed that the two flagellin genes in NCTC12892 had a deletion of the variable region of flagellin, which was reported previously to be modified by pseudaminic acid in C. jejuni and C. coli.Consequently, these results may possibly suggest that the length of the flagellin is related to pathogenicity and colonization of Campylobacter.

Low Level Nitrate or Nitroethane Preconditioning Enhances the Bactericidal Effect of Suboptimal Experimental Chlorate Treatment AgainstEscherichia coliandSalmonellaTyphimurium but NotCampylobacterin Swine

An experimental chlorate product that targets the respiratory nitrate reductase enzyme of bacteria such as Salmonella and Escherichia coli has shown promising results in reducing concentrations of these bacteria in the gut of food animals. Because expression of the target enzyme is induced by nitrate, we administered short-duration, low level nitrate or nitroethane preconditioning treatments to finishing swine to see if these would enhance the ability of an experimental chlorate product to kill these bacteria. Results from these studies showed that preconditioning the gut microflora of swine with low levels of nitrate or nitrocompounds enhanced (more than tenfold) the ability of the chlorate product to kill Salmonella and E. coli, but not Campylobacter. Further studies are needed before these compounds can be fed as feed additives to animals, although it is likely that nitrate preconditioning may be more near to market than the nitrocompounds, which may require more comprehensive review by regulatory authorities.

Genetic heterogeneity of urease gene loci in urease-positive thermophilic Campylobacter (UPTC)

Degenerate PCR primers in silico based on the two urease structural genes, ureA and ureB, were designed for urease-positive thermophilic Campylobacter (UPTC). Resultant PCR amplification employing these primers generated an amplicon of approximately 2kb, which was cloned and sequenced in UPTC (n=12) isolated from various parts of Europe and Japan. Overall, sequence similarities were shown to be 96.7 to 99.9%. Following sequence alignment analysis, the approximate 1.96kb regions were deduced to consist of parts of ureA (about 570bps) and ureB (about 1390bps) with an overlapping region between the ureA and ureB gene loci. Although a total of 144 heterogeneous sites of all substitutions were located throughout this region, the substitution ratio was higher in the ureA region (1/Omega10bases) than in the ureB region (1/Omega15bases). A resulting dendrogram was constructed, which was based on the nucleotide sequence data of 12 UPTC isolates and demonstrated that the UPTC were genetically variable. They formed a major cluster with Helicobacter, separate from the other urease-producing bacteria examined, suggesting a shared ancestry between UPTC and Helicobacter.

Phenotypic characterisation of flagellin and flagella of urease-positive thermophilic campylobacters

In this study, flagellin is purified biochemically from eight urease-positive thermophilic camplylobacters (UPTC) isolated from river water, sea water and mussels, and purified also from two isolates of Campylobacter jejuni and C. coli and fractionated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE). Results showed that no flagellin components were detected in the two Japanese UPTC isolates (CF89-12 and CF89-14) and the two UPTC NCTC strains (NCTC12893 and NCTC12894). Flagellin components, each consisting of a single peptide, with a heterogeneous molecular mass of approximately 52-63 kDa were demonstrated in the other four UPTC isolates (NCTC12892, NCTC12895, NCTC12896 and NI15F [from Northern Ireland]) and the two Japanese isolates of C. jejuni (JCM2013 and C. coli 27). The approximate molecular mass of flagellin from the flagellin-positive UPTC isolates was smaller than those of C. jejuni and C. coli. Flagella were not detected by electron microscopy in the four flagellin-negative UPTC isolates but they were detected in the four flagellin-positive UPTC isolates and the two isolates of C. jejuni and C. coli. Thus, significant phenotypic diversity for flagellin, which must be due to genotypic variations, was demonstrated among the UPTC isolates.

Fluoroquinolone-resistant Campylobacter in animal reservoirs: dynamics of development, resistance mechanisms and ecological fitness

Thermophilic Campylobacter species, including Campylobacter jejuni and Campylobacter coli, are responsible for foodborne campylobacteriosis in humans and are increasingly resistant to fluoroquinolone (FQ) antimicrobials. The therapeutic use of FQ antimicrobial agents in food animal production, particularly in poultry, has become a concern for public health, because the practice may promote the emergence of FQ-resistant Campylobacter that can be transmitted to humans through the food chain. Recent studies have indicated that Campylobacter displays a hypermutable phenotype in response to in vivo treatment with FQ antimicrobials, resulting in the rapid emergence of resistant mutants. Distinct from other Gram-negative bacteria, the acquisition of FQ resistance in Campylobacter does not require stepwise accumulation of gyrA mutations and overexpression of efflux pumps, and is mainly mediated by single-step point mutations in gyrA in the presence of a constitutively expressed multidrug efflux pump, CmeABC. The simplicity of the resistance mechanisms may facilitate the rapid adaptation of Campylobacter to FQ treatment. The FQ-resistant Campylobacter mutants derived from chickens do not show a fitness cost in vivo and are ecologically competitive in the colonization of chickens even in the absence of antimicrobial selection pressure. These findings suggest that FQ-resistant Campylobacter may continue to persist regardless of antimicrobial usage, and highlight the need for extra effort to prevent the occurrence and spread of FQ-resistant Campylobacter in animal reservoirs.

Molecular cloning, nucleotide sequencing and characterization of the flagellin gene from isolates of urease-positive thermophilic Campylobacter

A primer pair which was expected to generate an amplicon of the estimated size (approximately 1700 base pair (bp)) of the flaA gene for Campylobacter jejuni amplified products of approximately 1450 bp for 33 of the 44 isolates of urease-positive thermophilic Campylobacter (UPTC). The primer pair, however, failed to amplify fragments for 11 isolates of UPTC, for all of the 12 isolates of urease-negative C. lari and for one isolate of C. coli. Nevertheless, it successfully amplified fragments of approximately 1700 bp for five isolates of C. jejuni and for nine isolates of C. coli. Thus, the fragments of the flaA gene of UPTC were shorter than those of C. jejuni and C. coli. After PCR amplification and nucleotide sequencing of the flaA genes from five UPTC NCTC isolates, the putative open reading frames (ORFs) were found to range from 1461 to 1479 bp. The amino acid and nucleotide sequence alignments demonstrated that the PCR clones contained the flaA gene; however, our data indicated that this locus was markedly shorter in the UPTC organisms examined, as they were approximately 85 amino acid residues shorter, mainly corresponding to approximate residue numbers 390-470 of the large variable region of C. jejuni 81116. Heterogeneity was indicated in the molecular mass of the flagellin purified from the isolates examined. Flagellin of UPTC was demonstrated to be genotypically and phenotypically smaller than those of C. jejuni.

Characterization of a haemolytic phospholipase A2 activity in clinical isolates of Campylobacter concisus

A membrane-bound, haemolytic phospholipase A(2) (PLA(2)) activity was detected in clinical strains of Campylobacter concisus isolated from children with gastroenteritis. The clinical strains were assigned into two molecular groups (genomospecies) based on PCR amplification of their 23S rDNA. This calcium-dependent, heat-stable, haemolytic PLA(2) activity was detected in strains from both genomospecies. A crude haemolysin extract (CHE) was initially prepared from cellular outer-membrane proteins of these isolates and was further fractionated by ultrafiltration. The haemolytic activity of the extracted fraction (R30) was retained by ultrafiltration using a 30 kDa molecular mass cut-off filter, and was designated haemolysin extract (HE). Both CHE and HE had PLA(2) activity and caused stable vacuolating and cytolytic effects on Chinese hamster ovary cells in tissue culture. Primers for the conserved region of pldA gene (phospholipase A gene) from Campylobacter coli amplified a gene region of 460 bp in all tested isolates, confirming the presence of a homologous PLA gene sequence in C. concisus. The detection of haemolytic PLA(2) activity in C. concisus indicates the presence of a potential virulence factor in this species and supports the hypothesis that C. concisus is a possible opportunistic pathogen.

Nucleotide sequence analysis of the recA gene and discrimination of the three isolates of urease-positive thermophilic Campylobacter (UPTC) isolated from seagulls (Larus spp.) in Northern Ireland

Nucleotide sequencing after TA cloning of the amplicon of the almost-full length recA gene from three strains of UPTC (A1, A2, and A3) isolated from seagulls in Northern Ireland, the phenotypical and genotypical characteristics of which have been demonstrated to be indistinguishable, clarified nucleotide differences at three nucleotide positions among the three strains. In conclusion, the nucleotide sequences of the recA gene were found to discriminate among the three strains of UPTC, A1, A2, and A3, which are indistinguishable phenotypically and genotypically. Thus, the present study strongly suggests that nucleotide sequence data of the amplicon of a suitable gene or region could aid in discriminating among isolates of the UPTC group, which are indistinguishable phenotypically and genotypically.

Characterization of urease-positive thermophilic Campylobacter subspecies by multilocus enzyme electrophoresis typing

Thirty-one urease-positive thermophilic Campylobacter (UPTC) isolates, including three reference strains (NCTC12892, NCTC12895 and NCTC12896), and three Campylobacter lari isolates, which were isolated from several countries and sources, were compared genotypically by using multilocus enzyme electrophoresis (MLEE). We examined allelic variation around seven enzyme loci, including the adenylate kinase, alkaline phosphatase, catalase, fumarase, malic enzyme, malate dehydrogenase, and L-phenylalanyl-L-leucine peptidase loci. MLEE typing revealed the presence of 23 different electrophoretic types (ETs) among the 31 UPTC isolates, and 14 isolates shared six electrophoretic profiles. Three different ETs were identified for the three C. lari isolates examined, and no ETs were shared by UPTC and C. lari isolates. Quantitative analyses were subsequently performed by using allelic variation data, and the results demonstrated that the mean genetic diversity was 0.655. In conclusion, MLEE demonstrated that the UPTC isolates examined are genetically hypervariable and form a cluster separate from the C. lari cluster.

Multilocus enzyme electrophoresis: a practical guide

Multilocus enzyme electrophoresis (MEE) uses the relative electrophoretic mobilities of intracellular enzymes to characterize and differentiate organisms by generating an electromorph type (ET). This article presents the chemical conditions that may be useful, a guide to the successful practice of the electrophoretic technique, and analysis of the results.

Fluoroquinolone resistance in Campylobacter species from man and animals: detection of mutations in topoisomerase genes

Consecutive isolates of quinolone-resistant campylobacter isolated over a 5 year period (1990-1995) from the faeces of patients with enteritis in Plymouth, UK, were examined for the epidemiology of mutations in gyrA (n = 127). In addition, clinical isolates and poultry isolates from Germany, The Netherlands and other regions of the UK collected before 1995 were examined for mutations in the quinolone resistance-determining region of gyrA by single-stranded conformational polymorphism analysis and direct sequencing of a 270 bp fragment of PCR-generated DNA. The majority of isolates (173/208) carried a mutation at codon 86 in gyrA resulting in substitution of Ile for Thr; all of these were resistant to ciprofloxacin (MIC > or = 2 mg/L). One isolate of Campylobacter jejuni had a mutation at Asp-90, and another had a double mutation at Thr-86 and Pro-104. Only two resistant isolates showed no mutation in gyrA. A novel gyrA sequence was amplified from two Campylobacter lari and one C. jejuni, which exhibited a valine at codon 86. Only 8/192 isolates had changes in gyrB; all were shown to relate to silent mutations in gyrB and presumably reflect natural polymorphisms in the gene.

flaA-like sequences containing internal termination codons (TAG) in urease-positive thermophilic Campylobacter isolated in Japan

AIMS

To demonstrate two flaA-like sequences containing two internal termination codons (TAG) in two Japanese strains of urease-positive thermophilic Campylobacter (UPTC).

METHODS AND RESULTS

A primer pair of A1 and A2, which ought to generate a product of approx. 1700 bp of the flaA gene for Campylobacter jejuni, was used to amplify products of approx. 1450 bp for two Japanese strains of UPTC, CF89-12 and CF89-14. After molecular cloning and sequencing, the nucleotide sequences of the amplicons from the two strains were found to be 1461 bp in length and to have nucleotide sequence differences in relation to each other at four nucleotide positions, respectively.

CONCLUSIONS

Nucleotide and amino acid sequence alignment and homology analysis demonstrated that the polymerase chain reaction (PCR) amplicons from the two Japanese strains have approx. 83% nucleotide and 80% amino acid sequence homology to the possible open reading frame of the flaA gene of UPTC NCTC 12892.

SIGNIFICANCE AND IMPACT OF THE STUDY

Surprisingly, both PCR amplicons from the Japanese UPTC have two internal termination codons (TAG) at nucleotide positions from 775 to 777 and 817 to 819, respectively.

Genetic diversity and relationships of Campylobacter species and subspecies

The existence of tremendous genetic diversity within Campylobacter species has been well documented. To analyse the population structure of Campylobacter and determine whether or not a clonal population structure could be detected, genetic diversity was assessed within the genus Campylobacter by multilocus enzyme electrophoresis of 156 isolates representing 11 species and subspecies from disparate sources. Analyses of electrophoretic mobility of 11 enzymes revealed 109 electrophoretic types (ETs) and 118 ETs when nulls were counted as an allele. Cluster analysis placed most ETs into groups that correlated with species. With nulls counted as alleles, 19 ETs were identified among 33 isolates of Campylobacter lari, 31 ETs among 34 isolates of Campylobacter coli and 43 ETs among 59 isolates of Campylobacter jejuni subsp. jejuni. Nine C. jejuni subsp. jejuni isolates, confirmed as this species by DNA-DNA hybridization, were hippuricase-negative. Reported linkage analyses were done with nulls ignored. Scores for mean genetic diversity (H) were high for the total population (mean H = 0.802). Allelic mismatch-frequency distributions and allelic tracing pointed to possible genetic exchange between subpopulations. C. lari appears to be a panmictic species. Some pairs of species shared multiple alleles of certain loci, possibly indicating genetic exchange between species. Of the species tested, C. jejuni appeared to be the most active in sharing alleles. However, there was evidence of variable involvement in recombination by the different loci. Linkage analysis of loci in C. jejuni and C. coli revealed a clonal framework, with some loci tightly linked to each other. The loci appeared to occur in linkage groups or islands. Campylobacter may have a clonal framework with other portions of the genome involved in frequent recombination. Population genetic structure among Campylobacter is inconclusive and it remains to be seen if pathogenic types can be identified.

Cloning and sequencing of 16S rDNA and 16S-23S rDNA internal spacer region (ISR) from urease-positive thermophilic Campylobacter (UPTC)

AIMS

To clone and sequence the 16S rDNA and 16S-23S rDNA internal spacer region (ISR) from urease-positive thermophilic Campylobacter (UPTC).

METHODS AND RESULTS

The primer sets for 16S rDNA and 16S-23S rDNA ISR amplified almost the full length of 16S rDNA and 16S-23S rDNA ISR. About 1500 bp for 16S rDNA and about 720 bp for 16S-23S rDNA ISR of the rrn operon of four strains of UPTC were identified after molecular cloning and sequencing.

CONCLUSIONS

The four strains and CCUG18267 of UPTC showed approximately 99% sequence homology of 16S rDNA to each other, 96-97% to Camp. coli, 97-98% to Camp. jejuni and 97-98% to Camp. lari.

SIGNIFICANCE AND IMPACT OF THE STUDY

For the first time, the nucleotide sequence of 16S-23S rDNA ISR of UPTC has been analysed. The sequence of ISR was almost identical among the four strains of UPTC. It is interesting that the UPTC intercistronic tRNAs demonstrated an order of tRNA of 5'-16S-tRNAAla-tRNAIle-23S-3' in the organisms.

Is the molecular basis of metronidazole resistance in microaerophilic organisms understood?

Metronidazole is an antibiotic that has been effective against many microaerophilic microorganisms with importance in medicine and animal husbandry. The development of increasing resistance against current treatments by many of these organisms has created an urgent need to establish the molecular bases of resistance, knowledge which will help to develop novel diagnostic methods and identify new therapeutic targets. Significant progress has been made in understanding resistance to this antibiotic in the human pathogens Helicobacter pylori and, to a lesser extent, Campylobacter spp. However, insufficient knowledge of the physiology and genetics of these and other related bacteria has led to investigations based on hypotheses that themselves must be established more thoroughly. This review presents the status of our current knowledge of metronidazole resistance and outlines reasons to explain some of the conflicting evidence and controversy in the interpretation of results in this area.

First isolation of urease-positive thermophilic Campylobacter (UPTC) from crows (Corvus levaillantii) in Japan

Two strains of urease-positive thermophilic Campylobacter (UPTC), designated YC98-1 and YC98-2, were identified by biochemical characterization after isolation from the intestinal contents of crows around Yokohama City, Japan, in 1998. The biochemical characteristics of these strains were identical to those of strains described previously. Pulsed-field gel electrophoresis (PFGE) after separate digestion with ApaI, SalI, and SmaI of the genomic DNA from the two strains indicated that respective PFGE profiles were distinctly different and distinguishable from each other. This is the first report of the isolation of UPTC from crows (Corvus levaillantii).

Identification of Campylobacter jejuni, C. coli, C. lari, C. upsaliensis, arcobacter butzleri, and A. butzleri-like species based on the glyA gene

Currently, the detection and identification of Campylobacter and Arcobacter species remains arduous, largely due to cross-species phenotypic similarities and a relatively narrow spectrum of biochemical reactivity. We have developed a PCR-hybridization strategy, wherein degenerate primers are used to amplify glyA fragments from samples, which are then subjected to species-specific oligodeoxyribonucleotide probe hybridizations, to identify and distinguish between Campylobacter jejuni, C. coli, C. lari, C. upsaliensis, Arcobacter butzleri, and an A. butzleri-like species. Evaluation of this strategy with genomic DNA from different type strains suggests that this approach is both specific and sensitive and thus may be applicable in a diagnostic assay to identify and differentiate these highly related species.

[Detection of pyrazinamidase activity for differentiation of Campylobacter, Arcobacter, and Helicobacter spp. by using a high-performance liquid chromatography method]

A high-performance liquid chromatography method was investigated for the detection pyrazinamidase activity by Campylobacter, Arcobacter, and Helicobacter spp. Pyrazine carboxilic acid, one of the end products of pyrazinamide hydrolysis by microorganisms, was detected by using a high-performance liquid chromatography (HPLC). A loopful of organism colonies was emulsified in 0.5 ml of a 0.5% pyrazinamide solution. The suspens on was incubated in a 37 degrees C water bath for 18-20 hr. After centrifugation, the supernatant was analyzed by HPLC. This HPLC method does not require microaerobic incubation and was easy to interpret for strains with weak enzymatic activity. By this method, we tested 111 clinical isolates, type and reference strains of Campylobacter spp., Arcobacter spp., and Helicobacter spp. , C. jejuni, C. jejuni subsp. doylei, C. coli, C. upsaliensis, C. lari, C. lari (urease+), C. helveticus, C. hyolei, C. sputorum subsp. fecalis, C. gracilis, C. concisus, C. curvus were positive for pyrazinamidase. C. fetus subsp. fetus, C. hyointestinalis, C. sputorum subsp. sputorum, C. sputorum subsp. bubulus, C. mucosalis, A. butzleri, A. skirrowii, A. cryaerophilus, H. pylori, H. cinaedi, H. fennelliae, H. mustelae, H. felis, H. muridarum, H. canis, H. nemestrinae, H. pamentensis, H. pullourum were negative.

Antibiotic susceptibility patterns and beta-lactamase production of animal and human isolates of Campylobacter in Lagos, Nigeria

Forty-three stool samples and rectal swabs were collected from diarrhoeic and 20 non-diarrhoeic patients under 5 years of age at various general hospitals in Lagos. A total of 110 faecal samples from animals (101 from chickens and 9 from pigs) were obtained from Mitchel farm, Agege and Oshodi--Isolo Local Government farms at Ejigbo. Campylobacter species were isolated from 6 (13.9%) of 43 children with gastroenteritis and none from 20 asymptomatic subjects. Forty-nine (48.5%) isolates from the hundred and one faecal specimen were isolated from chicken, while 3 (33.33%) out of 9 were from pigs. Campylobacter jejuni was the most prevalent accounting for 79% of the total isolates and C. coli accounted for 25%. All the human strains were gentamicin sensitive, while streptomicin and cloxacillin were resistant. Erythromycin had a high activity (83.3%) on human strains and only 59.6% activity on animal strains. About ten percent (9.6%) of the strains produced beta-lactamase.

Isolation and purification of a Campylobacter upsaliensis autolysin

Autolytic activity in the soluble and sediment fractions of sonicates of the spiral and the coccoid form of Campylobacter upsaliensis could not be demonstrated by native (nondenaturing) polyacrylamide gel electrophoresis (PAGE). Autolysins were detected, however, by using denaturing sodium dodecyl sulfate (SDS)-PAGE gels containing either purified Escherichia coli peptidoglycan or whole cells of Micrococcus luteus (Micrococcus lysodeikticus) as the turbid substrate, with subsequent renaturation by treatment with Triton X-100 buffer. In renaturing gels that contained Escherichia coli peptidoglycan, 14 putative autolytic bands ranging from 200 to 12 kDa were detected. In similar gels containing whole cells of M. luteus, only a single band appeared with a molecular mass of 34 kDa. This band corresponded to one of the bands present in the gels containing Escherichia coli peptidoglycan. This common autolysin was isolated by adsorbing it from Campylobacter upsaliensis soluble fractions onto M. luteus cells and then subjecting these cells to renaturing SDS-PAGE in gels containing Escherichia coli peptidoglycan. The 34-kDa autolysin differed from a single 51-kDa autolysin unique to the M. luteus cells, and when isolated from an SDS-PAGE gel, was pure when tested by isoelectric focusing. The N-terminal amino acid sequence analysis showed the first 15 amino acids of the 34-kDa autolysin to have 67% identity to a part of antigenic protein PEB4 of Campylobacter jejuni. The purified autolysin was used to immunize rabbits and the antibodies produced precipitated autolytic activity from cell lysates. The specificity of the antibodies was shown by Western blotting: only a single specific band occurred, with a molecular mass of 34 kDa, and thus it seems unlikely that the 34-kDa autolysin was derived from any of the other autolysins that were detected.

Metronidazole resistance and microaerophily in Campylobacter species

Metronidazole is active against most anaerobic organisms and is also used in the treatment of the microaerophilic bacterium Helicobacter pylori. Resistance to metronidazole is uncommon in most anaerobic organisms, but it is increasingly prevalent in H. pylori. Previously we have suggested that metronidazole resistance in H. pylori is inherent in the microaerophilic nature of the organism and therefore would be present in other microaerophiles such as Campylobacter. Short periods of anaerobiosis caused metronidazole-resistant (MtrR) strains of Campylobacter spp. to become sensitive to metronidazole. Under microaerophilic conditions, cultures of the MtrR mutant Campylobacter coli R1 at bacterial cell densities of greater than 10(8) cfu/ml lost viability, whereas no loss in viability was observed in cultures at cell densities of less than 10(8). The MtrS C. coli strain lost viability at all cell densities. Comparisons of NAD(P)H oxidase activity between MtrS and MtrR strains indicated that the MtrS C. coli strain contained fourfold higher NADH oxidase activity and twofold higher NADPH oxidase activity than did the MtrR Campylobacter strains. These results show that MtrR Campylobacter spp. display resistance characteristics similar to those of H. pylori, suggesting that the resistance mechanism is a phenomenon of the microaerophilic nature of these bacteria.

The largest subunits of RNA polymerase from gastric helicobacters are tethered

The rpoB and rpoC genes of eubacteria and archaea, coding respectively for the beta- and beta'-like subunits of DNA-dependent RNA polymerase, are organized in an operon with rpoB always preceding rpoC. The genome sequence of the gastric pathogen Helicobacter pylori (strain 26695) revealed homologs of two genes in one continuous open reading frame that potentially could encode one 2890-amino acid-long beta-beta' fusion protein. Here, we show that this open reading frame does in fact encode a fused beta-beta' polypeptide. In addition, we establish by DNA sequencing that rpoB and rpoC are also fused in each of four other unrelated strains of H. pylori, as well as in Helicobacter felis, another member of the same genus. In contrast, the rpoB and rpoC genes are separate in two members of the related genus Campylobacter (Campylobacter jejuni and Campylobacter fetus) and encode separate RNA polymerase subunits. The Campylobacter genes are also unusual in overlapping one another rather than being separated by a spacer as in other Gram-negative bacteria. We propose that the unique organization of rpoB and rpoC in H. pylori may contribute to its ability to colonize the human gastric mucosa.

Emended description of Campylobacter sputorum and revision of its infrasubspecific (biovar) divisions, including C. sputorum biovar paraureolyticus, a urease-producing variant from cattle and humans

A polyphasic taxonomic study of 15 bovine and human strains assigned to the catalase-negative, urease-positive campylobacter (CNUPC) group identified these bacteria as a novel, ureolytic biovar of Campylobacter sputorum for which we propose the name C. sputorum bv. paraureolyticus: suitable reference strains are LMG 11764 (human isolate) and LMG 17590 (= CCUG 37579, bovine isolate). The present study confirmed previous findings showing that the salient biochemical tests used to differentiate C. sputorum bv. sputorum from C. sputorum bv. bubulus are not reproducible; and that the absolute validity of source-specific biovars of the species is questionable. A correlation between the results of numerical analysis of protein profiles and the reaction of strains in certain enzyme tests was, however, noted. Therefore, it is proposed that the infrasubspecific (biovar) divisions of C. sputorum should be revised to include bv. sputorum for catalase-negative strains; bv. fecalis for catalase-positive strains; and bv. paraureolyticus for urease-positive strains. Strains classified previously as bv. bubulus should be reclassified as bv. sputorum. The species description of C. sputorum is revised accordingly.

beta-Lactamase producing bacteria in adult periodontitis

In 23 untreated adult periodontitis patients, the occurrence of beta-lactamase producing periodontal bacteria was determined. In addition to non-selective isolation media, selective isolation and growth of beta-lactamase positive subgingival bacterial species was carried out on blood agar plates supplemented with amoxicillin and plates with amoxicillin+clavulanic acid. Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Peptostreptococcus micros, Fusobacterium nucleatum, Bacteroides forsythus and Campylobacter rectus isolates from the non-selective medium were tested for beta-lactamase activity by a nitrocefin disk method (DrySlide) and by a laboratory chromogenic nitrocefin-based test. Isolates from the amoxicillin plates that were absent on the amoxicillin/clavulanic acid plates were identified and tested for beta-lactamase production. Based on the non-selective plates, six of 23 P. intermedia isolates, 2 of 19 B. forsythus isolates and 3 of 23 F. nucleatum isolates were beta-lactamase positive. The beta-lactamase positive species Prevotella loescheii, Prevotella buccae, Prevotella buccalis and Actinomyces spp were recovered from the selective amoxicillin plates. beta-Lactamase positive subgingival species were recovered from 17 of 23 patients (74%) but usually comprised low proportions of the subgingival microbiota (range < 0.01-15%). Comparison of the DrySlide test and the nitrocefin-based laboratory test revealed full agreement of test results. beta-Lactamase activity in whole subgingival plaque was detected in 12 patient samples (52%). It was concluded that beta-lactamase activity in subgingival bacteria in adult periodontitis is a common feature. However, since the majority of the samples showed only low-level enzymatic activity, the clinical relevance of this observation with regard to therapy with unprotected enzyme-susceptible beta-lactams is uncertain, though failure on the other hand, is difficult to rule out when a mechanism of resistance is present. The majority of beta-lactamase positive strains was found among species of the Prevotella genus.

[Enzymatic activities of Campylobacter jejuni, C. coli, and C. lari]

Susceptibility to nalidixic acid has been considered for a long time as an important test in the identification of the different species of the genus Campylobacter. However, due to the increasing development of resistance new laboratory tests are needed to carry out an accurate identification to the species level in combination with other typing schemes. We have evaluated the enzymatic activity of 180 Campylobacter spp. strains isolated from clinical specimens performing the Api ZYM system (bioMérieux) in order to assay whether different enzymatic patterns could help to characterize these microorganisms. Thirteen of the 19 enzymatic activities detected by the system (lipase-C14, valine arylamidase, cystine arylamidase, trypsin, chymiotrypsin, alpha-galactosidase, beta-galactosidase, beta-glucuronidase, alpha-glucosidase, beta-glucosidase, N-acetyl-beta-glucosaminidase, alpha-manosidase and alpha-fucosidase) were negative for all the strains tested, whereas 3 enzymes (alkaline phosphatase, acid phosphatase and naphtol-A-S-BI-phosphohydrolase) were detected in 96.6% of the strains. Esterase-C1, esterase lipase-C8 and leucin arylamidase showed a variable reactivity depending on isolates. Enzymatic activity patterns clearly differentiate all the C. lari strains from other Campylobacter species. No significant differences were detected among the enzymatic activities of C. jejuni and C. coli strains. Our study suggests that the Api ZYM system is easy to perform and a valuable method to be applied in the characterization of the campylobacteria as a complement to other biotyping and serotyping schemes.

Pyruvate metabolism in Campylobacter spp

The metabolism of pyruvate by Campylobacter spp. was investigated employing one- and two-dimensional 1H, 13C and 31P nuclear magnetic resonance spectroscopy. Metabolically competent cells incubated aerobically with pyruvate yielded acetate, acetolactate, alanine, formate, lactate, and succinate. The production of acetolactate, alanine and lactate indicated the presence of acetohydroxy acid synthase, alanine transaminase and lactate dehydrogenase activities, respectively. Accumulation of acetate and formate as metabolic products provided evidence for the existence of a mixed acid fermentation pathway in the microorganism. Formation of succinate suggested the incorporation of the pyruvate carbon skeleton to the Kreb's cycle, and the observation of pyruvate dehydrogenase activities in bacterial lysates supported this interpretation. Generation of pyruvate from L-serine in incubations with intact cells and lysates indicated the presence of serine dehydratase activity in the bacterium. Pyruvate was also formed in cell suspensions and lysates from phosphoenol pyruvate. The existence of anaplerotic sequences involving phosphoenol pyruvate carboxykinase and a malic enzyme were established in bacterial lysates. The activities of enzymes involved in the biosynthesis of isoleucine and valine were measured. Addition of pyruvate to different solid culture media inhibited bacterial growth, and the inhibition was attributed to the accumulation of acetate and formate. The variety of products formed using pyruvate as the sole substrate and the existence of anaplerotic sequences and anabolic pathways which employ pyruvate, showed the important role of this metabolite in the energy and biosynthesis metabolism of Campylobacter spp.

RGFGIGS is an amino acid sequence required for acetyl coenzyme A binding and activity of human spermidine/spermine N1acetyltransferase

Polyamine catabolism is rate limited by spermidine/spermine N1-acetyltransferase (SSAT). Although the amino acid sequence of SSAT is known, the substrate binding and catalytic sites are not. The goal of this study was to define the region responsible for acetyl coenzyme A binding. Human SSAT contains a region of 20 amino acids homologous to several microbial antibiotic N-acetyltransferases. The highest homology is represented in the Campylobacter coli streptothricin acetyltransferase sat4 gene, where 16 identical or highly conserved amino acids exist in a 20-residue stretch. The most conserved residues within this region are RGFGIGS beginning at Arg-101 in the human SSAT. Site-directed mutations to Arg-101, Gly-104, and Gly-106 resulted in proteins with no measurable activity. The G102D mutation produced a partially active protein with a decreased affinity for acetyl coenzyme A and with a Km >10-fold that of the wild-type protein. Analysis using the PredictProtein program suggests a common structure among the microbial and eukaryotic N-acetyltransferases in the region corresponding to the RGFGIGS of human SSAT consisting of an alpha-helix usually preceded by a glycine loop. Our data are consistent with the hypothesis that Arg-101 and the proximal glycine loop are necessary for the activity of human SSAT.

Conservation and diversity of the Helicobacter pylori copper-transporting ATPase gene (copA) sequence among Helicobacter species and Campylobacter species detected by PCR and RFLP

BACKGROUND

Helicobacter pylori is a causative pathogen of such human stomach diseases as chronic type B gastritis, ulcer, and possibly gastric carcinoma. As a cofactor in various redox enzymes and an essential trace metal required for the synthesis of metalloproteins, copper might play a role in the pathogenesis of H. pylori. A gene, copA, associated with copper transport, has been isolated from H. pylori UA802. In this study, conservation and diversity of this gene were analyzed among some Helicobacter and Campylobacter species.

MATERIALS AND METHODS

Twenty-one clinical isolates and strains of helicobacters and campylobacters were used in this study. Methods including polymerase chain reaction (PCR) amplification, restriction fragment-length polymorphisms (RFLPs), and hybridization were employed to carry out this work.

RESULTS

The copA gene was highly conserved in all the H. pylori isolates tested (Helicobacter nemestrinae and Helicobacter felis but not in Helicobacter mustelae and the Campylobacter species), whereas the sequence downstream of the copA appears to diverge among H. pylori isolates. In addition, two restriction patterns of the PCR-amplified copA fragments from seven H. pylori isolates and H. nemestrinae were identified, and the RFLP of H. nemestrinae was identical to that of one of the H. pylori isolate group.

CONCLUSIONS

The adenosine triposphatase-derived copper-transporting mechanism is employed by various H. pylori strains, H. nemestrinae, H. felis, and perhaps by other Helicobacter species. The nucleotide mutations have risen in the copA gene. It appears that there is a genetic relatedness of the copA gene to H. pylori and H. nemestrinae.

[The comparative identification of Campylobacter strains by traditional enzymatic tests and the gene amplification reaction]

39 strains of Campylobacter isolated from 153 diarrhoeal children (0-3 years) were comparatively identified by the traditional enzymatic tests and by the Polymerase Chain reaction (PCR). The hippurate hydrolysis test appreciated 27 strains as Campylobacter jejuni (69.2%) and 12 strains as Campylobacter coli (30.8%). The P.C.R. realised in France has appreciated 29 strains as Campylobacter jejuni (74.4%) and 10 strains as Campylobacter coli (25.6%). The analysis of the results discrepancy permitted to reveal 4 strains appreciated by two methods as different ones. The supplementary examinations of dubious strains by API-Campy test systems permitted to confirm the PCR results and to explain their divergence in contrast to hippurate hydrolysis test results. Two results were appreciated as false ones for hippurate test (5.1%). Other two errors were due to two hippurate-negative Campylobacter jejuni strains. The PCR results were exact, without errors and not influenced by modified phenotypical characters of Campylobacter strains. Thus, the efficiency of the identification by the hippurate hydrolysis test was only 89.7% in comparison to 100% efficiency of PCR (p<0.05). The discrepant cases indicated the necessity of supplementary differentiation of hippurate-negative Campylobacter strains including genetical methods in order to define the species exactly and to prevent the grave consequences especially characteristic of Campylobacter jejuni.

Construction of new Campylobacter cloning vectors and a new mutational cat cassette

We have developed new Campylobacter shuttle vectors which are 6.5-6.8-kb plasmids carrying Campylobacter and Escherichia coli replicons, a multiple cloning site (MCS), the lacZ alpha gene, oriT and either a kanamycin or chloramphenicol resistance-encoding gene (KmR or CmR) from Campylobacter which functions in both hosts. These vectors can be mobilized efficiently from E. coli into C. jejuni or C. coli, and stably maintained in these hosts. Plasmids pRY107 and pRY108 carry a KmR marker and 17 unique cloning sites in two different orientations in lacZ alpha, allowing easy blue/white color selection. Plasmids pRY111 and pRY112 contain a CmR gene and 17 unique sites in both orientations. In addition, MCS are flanked by T7 and T3 late promoters and M13 forward and reverse primer sites, facilitating expression in T7 or T3 expression systems and sequence analysis. A Campylobacter CmR gene cartridge, bracketed by six restriction sites, has been developed for use in site-specific mutagenesis of Campylobacter genes.

Three supplementary diagnostic tests for Campylobacter species and related organisms

We analyzed 307 recent clinical isolates and reference strains of Campylobacter spp., Helicobacter spp., and Arcobacter spp. for arylsulfatase and pyrazinamidase activities and susceptibility to polymyxin B. All isolates studied were identified by DNA dot hybridization prior to testing. Campylobacter concisus, C. sputorum, and Helicobacter fennelliae were positive for arylsulfatase. C. jejuni, C. coli, C. lari, C. upsaliensis, and C. concisus were positive for pyrazinamidase. Only Helicobacter spp. were resistant to polymyxin B. C. fetus subsp. fetus, C. hyointestinalis, C. mucosalis, and Arcobacter spp. were negative in all three tests. The tests were simple to perform and read, and with the exception of C. sputorum biovars, all isolates within a species gave consistently positive or negative results in all the assays. These three phenotypic tests may help refine current methods for phenotypic identification of Campylobacter spp. and related organisms in a reference laboratory setting.

Assessment of enzyme detection tests useful in identification of campylobacteria

Twenty-one type or other reference strains, each representing a different Campylobacter, Helicobacter, or Arcobacter taxon, and a reference strain of Staphylococcus aureus were used to assess the reproducibility of nine enzyme detection tests used in the identification of campylobacters. For five of the tests (alkaline phosphatase, DNase, and H2S production, indoxyl acetate hydrolysis, and nitrate reduction), more than one procedure was employed to determine the most suitable method. Alkaline phosphatase test results were better defined and more reproducible if read after 1 h of incubation. Detection of DNase was fully reproducible with each method (except with Helicobacter pylori), but reactions were generally weaker than those of other DNase-producing organisms. Both procedures for determining H2S production were irreproducible for the same strains. The reproducibility of indoxyl acetate hydrolysis was improved by using disks impregnated with 25 microliters of substrate. Reduction of nitrate was best determined by Cook's plate method. Results for the other tests examined (catalase, oxidase, and urease production and hippurate hydrolysis) were both pertinent and fully reproducible for all strains.

Purification and characterization of Helicobacter mustelae urease

Helicobacter mustelae is a urease-rich bacterium associated with gastritis in ferrets. The ureases of H. mustelae and Helicobacter pylori, a bacterium implicated in human gastritis, share many characteristics. Helicobacter sp. ureases appear to be unique among bacterial enzymes in exhibiting submillimolar Km values and in being composed of two subunits.

Simplified method for the detection of DNA hydrolysis by enteric campylobacters

A simplified medium was developed for the detection of DNase produced by enteric campylobacters. Sensitivity and reproducibility of the test were similar to that of the improved toluidine blue DNA agar method. Logistically, the simplified DNA hydrolysis test was cheaper (5.5 times) than the earlier medium. Based on this study we recommend the routine use of the simplified medium to perform the DNase test for biotyping enteric campylobacters.

Isolation of a urease positive thermophilic variant of Campylobacter lari from a patient with urinary tract infection

An unusual campylobacter strain, a urease positive thermophilic variant of Campylobacter lari, was isolated from the urine of a patient with urinary tract infection who was hospitalized because of cirrhosis and haemorrhage. The strain was isolated from urine specimens on three separate occasions. A significant serological response to the organism was also detected. This is the first documented case of extra-intestinal infection due to this group of organisms.

Chloramphenicol resistance in Campylobacter coli: nucleotide sequence, expression, and cloning vector construction

A chloramphenicol-resistance determinant (CmR), originally cloned from Campylobacter coli plasmid pNR9589 in Japan, was isolated and the nucleotide sequence determined, which contained an open reading frame of 621 bp. The gene product was identified as Cm acetyltransferase (CAT), which had a putative amino acid sequence that showed 43% to 57% identity with other CAT proteins of both Gram+ and Gram- origin. Although expression of the cat gene was constitutive in both C. coli and Escherichia coli, results of primer extension experiments indicated that transcription was initiated at different sites in these two species. A kanamycin-resistance determinant, identified as the aphA-3 gene, was located downstream from the cat gene. The codon usage of the cat gene is very different from that used in E. coli, however, the CAT polypeptide was synthesized in large amounts in E. coli maxicells. Therefore, the codon usage bias is not one of the obstacles which affects Campylobacter spp. gene expression in E. coli. New Campylobacter cloning vectors were constructed in this study.

[Correlation between Campylobacter pylori and chronic atrophic gastritis]

The correlation between urease activity of Campylobacter pylori and atrophic gastritis was studied. On the basis of fundamental study on the optimal pH of C. pylori urease activity, urease activity of 38 biopsied specimens were measured under pH 5 condition, and compared with the positive ratio of C. pylori. In this study, sensitivity was 86.7%, and specificity was 87.0%, respectively. Mean urease activity of C. pylori positive specimens was 3.69 mIU/mg protein, and under this condition, C. pylori was likely to produce ammonia of 0.0218 mumole per minute, enough to damage the gastric mucosa. In addition, there was encountered high urease activity in the specimens which showed moderate glandular atrophy and severe mucosal inflammation. In conclusion, urea-urease-NH3 sequence is most likely to have some association with gastric glandular atrophy.

Purification and characterization of urease from Helicobacter pylori

Urease was purified 112-fold to homogeneity from the microaerophilic human gastric bacterium, Helicobacter pylori. The urease isolation procedure included a water extraction step, size exclusion chromatography, and anion exchange chromatography. The purified enzyme exhibited a Km of 0.3 +/- 0.1 mM and a Vmax of 1,100 +/- 200 mumols of urea hydrolyzed/min/mg of protein at 22 degrees C in 31 mM Tris-HCl, pH 8.0. The isoelectric point was 5.99 +/- 0.03. Molecular mass estimated for the native enzyme was 380,000 +/- 30,000 daltons, whereas subunit values of 62,000 +/- 2,000 and 30,000 +/- 1,000 were determined. The partial amino-terminal sequence (17 residues) of the large subunit of H. pylori urease (Mr = 62,000) was 76% homologous with an internal sequence of the homohexameric jack bean urease subunit (Mr = 90,770; Takashima, K., Suga, T., and Mamiya, G. (1988) Eur. J. Biochem. 175, 151-165) and was 65% homologous with amino-terminal sequences of the large subunits of heteropolymeric ureases from Proteus mirabilis (Mr = 73,000) and from Klebsiella aerogenes (Mr = 72,000; Mobley, H. L. T., and Hausinger, R. P. (1989) Microbiol. Rev. 53, 85-108). The amino-terminal sequence (20 residues) of the small subunit of H. pylori urease (Mr = 30,000) was 65 and 60% homologous with the amino-terminal sequences of the subunit of jack bean urease and with the Mr = 11,000 subunit of P. mirabilis urease (Jones, B. D., and Mobley, H. L. T. (1989) J. Bacteriol. 171, 6414-6422), respectively. Thus, the urease of H. pylori shows similarities to ureases found in plants and other bacteria. When used as antigens in an enzyme-linked immunosorbent assay, neither purified urease nor an Mr = 54,000 protein that co-purified with urease by size exclusion chromatography was as effective as crude preparations of H. pylori proteins at distinguishing sera from persons known either to be infected with H. pylori or not.