Longitudinal survey of Clostridium difficile presence and gut microbiota composition in a Belgian nursing home

BACKGROUND

Increasing age, several co-morbidities, environmental contamination, antibiotic exposure and other intestinal perturbations appear to be the greatest risk factors for C. difficile infection (CDI). Therefore, elderly care home residents are considered particularly vulnerable to the infection. The main objective of this study was to evaluate and follow the prevalence of C. difficile in 23 elderly care home residents weekly during a 4-month period. A C. difficile microbiological detection scheme was performed along with an overall microbial biodiversity study of the faeces content by 16S rRNA gene analysis.

RESULTS

Seven out of 23 (30.4 %) residents were (at least one week) positive for C. difficile. C. difficile was detected in 14 out of 30 diarrhoeal samples (43.7 %). The most common PCR-ribotype identified was 027. MLVA showed that there was a clonal dissemination of C. difficile strains within the nursing home residents. 16S-profiling analyses revealed that each resident has his own bacterial imprint, which was stable during the entire study. Significant changes were observed in C. difficile positive individuals in the relative abundance of a few bacterial populations, including Lachnospiraceae and Verrucomicrobiaceae. A decrease of Akkermansia in positive subjects to the bacterium was repeatedly found.

CONCLUSIONS

A high C. difficile colonisation in nursing home residents was found, with a predominance of the hypervirulent PCR-ribotype 027. Positive C. difficile status is not associated with microbiota richness or biodiversity reduction in this study. The link between Akkermansia, gut inflammation and C. difficile colonisation merits further investigations.

Clostridium difficile presence in Spanish and Belgian hospitals

Clostridium difficile is recognised worldwide as the main cause of infectious bacterial antibiotic-associated diarrhoea in hospitals and other healthcare settings. The aim of this study was to first survey C. difficile prevalence during the summer of 2014 at the Central University Hospital of Asturias (Spain). By typing the isolates obtained, it was then possible to compare the ribotype distribution at the Spanish hospital with results from the St Luc University Hospital in Belgium over the same period. The prevalence of positive cases reported in Spain and Belgium was 12.3% and 9.3% respectively. The main PCR-ribotypes previously described in Europe were found in both hospitals, including 078, 014, 012, 020 and 002. In the Spanish hospital, most of the C. difficile-positive samples were referred from oncology, acute care and general medicine services. In the Belgian hospital the majority of positive samples were referred from the paediatric service. However, a high percentage of isolates from this service were non-toxigenic. This study finds that the presence and detection of C. difficile in paediatric and oncology services requires further investigation.

Faecal microbiota characterisation of horses using 16 rdna barcoded pyrosequencing, and carriage rate of clostridium difficile at hospital admission

Background

The equine faecal microbiota is very complex and remains largely unknown, while interspecies interactions have an important contribution to animal health. Clostridium difficile has been identified as an important cause of diarrhoea in horses. This study provides further information on the nature of the bacterial communities present in horses developing an episode of diarrhoea. The prevalence of C. difficile in hospitalised horses at the time of admission is also reported.

Results

Bacterial diversity of the gut microbiota in diarrhoea is lower than that in non-diarrhoeic horses in terms of species richness (p-value <0.002) and in population evenness (p-value: 0.02). Statistical differences for Actinobacillus, Porphyromonas, RC9 group, Roseburia and Ruminococcaceae were revealed. Fusobacteria was found in horses with diarrhoea but not in any of the horses with non-diarrheic faeces. In contrast, Akkermansia was among the three predominant taxa in all of the horses studied. The overall prevalence of C. difficile in the total samples of hospitalised horses at admission was 3.7 % (5/134), with five different PCR-ribotypes identified, including PCR-ribotype 014. Two colonised horses displayed a decreased bacterial species richness compared to the remaining subjects studied, which shared the same Bacteroides genus. However, none of the positive animals had diarrhoea at the moment of sampling.

Conclusions

The abundance of some taxa in the faecal microbiota of diarrhoeic horses can be a result of microbiome dysbiosis, and therefore a cause of intestinal disease, or some of these taxa may act as equine enteric pathogens. Clostridium difficile colonisation seems to be transient in all of the horses studied, without overgrowth to trigger infection. A large proportion of the sequences were unclassified, showing the complexity of horses’ faecal microbiota.

Electronic supplementary material

The online version of this article (doi:10.1186/s12866-015-0514-5) contains supplementary material, which is available to authorized users.

Investigation of Clostridium difficile interspecies relatedness using multilocus sequence typing, multilocus variable-number tandem-repeat analysis and antimicrobial susceptibility testing

Multilocus sequence typing (MLST), multilocus variable-number tandem-repeat analysis (MLVA) and antimicrobial susceptibility were performed on 37 animal and human C. difficile isolates belonging to 15 different PCR-ribotypes in order to investigate the relatedness of human and animal isolates and to identify possible transmission routes. MLVA identified a total of 21 different types while MLST only distinguished 12 types. Identical C. difficile strains were detected in the same animal species for PCR-ribotypes 014, 078, UCL 16U and UCL 36, irrespective of their origin or the isolation date. Non clonal strains were found among different hosts; however, a high genetic association between pig and cattle isolates belonging to PCR-ribotype 078 was revealed. MLVA also showed genetic differences that clearly distinguished human from animal strains. For a given PCR-ribotype, human and animal strains presented a similar susceptibility to the antimicrobials tested. All strains were susceptible to vancomycin, metronidazole, chloramphenicol and rifampicin, while PCR-ribotypes 078, UCL 5a, UCL 36 and UCL 103 were associated with erythromycin resistance. The data suggest a wide dissemination of clones at hospitals and breeding-farms or a contamination at the slaughterhouse, but less probability of interspecies transmission. However, further highly discriminatory genotyping methods are necessary to elucidate interspecies and zoonotic transmission of C. difficile.

Clostridium difficile infection in elderly nursing home residents

Age-related changes in intestinal flora and host defences, the receipt of antibiotic treatment, and the presence of underlying diseases are some of the most common risk factors associated with Clostridium difficile infection. Therefore, retirement care facilities for elderly people have been pinpointed as frequent sources of contamination. There is only limited data regarding the presence and epidemiology of C. difficile in nursing homes, and this gap in the current literature emphasises the need to gain a better understanding of the situation in order to prevent the emergence of new outbreaks among this population group.

Description of Acidovorax wautersii sp. nov. to accommodate clinical isolates and an environmental isolate, most closely related to Acidovorax avenae

Three Gram-negative strains, NF 1078(T), NF 1598 and NF 1715, were isolated from clinical (two) and environmental (one) samples, respectively. Sequence analysis of the 16S rRNA genes revealed similarity of 100% among the three strains and next highest similarity to the type strain of Acidovorax avenae (98.16%). The three strains were able to acidify lactose and rhamnose on low peptone phenol red agar and to alkalinize citrate on Simmons' agar and were negative for nitrate reduction. The DNA G+C content of strain NF 1078(T) was 67.1 mol%. The level of DNA-DNA relatedness between this strain and the type strains of A. avenae (ATCC 19860(T), LMG 2117(T)) was 29%. Based on these phylogenetic, phenotypic and genotypic analyses, the three strains could be distinguished clearly from all other recognized Acidovorax species and should be classified as representatives of a novel species of the genus Acidovorax, for which the name Acidovorax wautersii sp. nov. is proposed. The type strain is NF 1078(T) (=LMG 26971(T)=CCUG 62584(T)).

Clostridium difficile in young farm animals and slaughter animals in Belgium

Faecal carriage of Clostridium difficile in healthy animals has been reported recently, especially in piglets and calves. However there is limited data about carriage in animals just prior to slaughter in Europe. The main objective of this study was to determine the presence of C. difficile in pigs and cattle at the slaughterhouse. C. difficile was isolated in 6.9% of the cattle at the slaughterhouse. None of the pig slaughter samples were positive for C. difficile after an enrichment time of 72 h. For complementary data, a short study was conducted in piglets and calves at farms. C. difficile was more prevalent in piglets (78.3%) than in calves (22.2%) on the farms. Regarding the piglet samples, 27.8% of the positive samples were detected without enrichment of stools. The PCR ribotype 078 was predominant in farm animals. Samples isolated from slaughter cattle presented the widest range in PCR-ribotype variety, and the most prevalent PCR ribotype was 118a UCL. The results of this study confirm that C. difficile is present in slaughter animals in Belgium with a large percentage of toxigenic strains also commonly found in humans.

Prevalence and genetic heterogeneity of Borrelia burgdorferi sensu lato in Ixodes ticks in Belgium

Borrelia burgdorferi sensu lato is a genetically diverse group of spirochetes that includes the agent of Lyme borreliosis in which genospecies tend to be associated with specific clinical features. The aim of the study was to determine the prevalence and genetic diversity of Borrelia burgdorferi sensu lato in 524 ticks collected in woods of a western province of Belgium. Presence of spirochetes in ticks was determined by phase contrast microscopy. The mean infection rate of ticks was 12.0%. Variability was observed in the prevalence of infection among the five sites examined, ranging from 2.8 to 21.6%. Identification to genospecies was determined by PCR and sequencing. The most common genomospecies were Borrelia afzelii (55%) and Borrelia garinii (21%). For the first time in Belgium, we detected Borrelia valaisiana and Borrelia spielmanii, representing 14% and 2%, respectively. Borrelia burgdorferisensu stricto counted only for 2%. Co-infections were present in 8% of ticks. We emphasize the need for clinical studies to assess the prevalence of specific genospecies-related clinical manifestations of Lyme borreliosis in Belgium.

Chryseobacterium hominis sp. nov., to accommodate clinical isolates biochemically similar to CDC groups II-h and II-c

A collection of eight clinical strains from Belgian hospitals and three clinical strains of the CCUG collection were characterized biochemically as being similar to CDC groups II-h and II-c; the latter differs from group II-h only by positivity for sucrose acidification. These 11 strains were found to cluster according to 16S rRNA gene sequence similarity at a level of ≥99.5 %, and on the basis of their tDNA-PCR profile. Based on 16S rRNA gene sequence analysis, this collection of strains was related most closely to Chryseobacterium hispanicum (97.2 %), but they differed from the type strain of this species by the following phenotypic characteristics: growth at 37 °C, negativity for xylose acidification, positivity for acetate assimilation–alkalinization on Simmons’ agar base and absence of flexirubin pigments, and by their tDNA-PCR profile. Strain NF802T showed only 57.8 % DNA–DNA relatedness to the type strain of C. hispanicum. Fatty acid composition did not enable differentiation from C. hispanicum. The DNA G+C content of strain NF802T is 36.5 mol%. The name Chryseobacterium hominis sp. nov. is proposed for this taxon, with type strain NF802T (=CCUG 52711T=CIP 109415T).

Description of Wautersiella falsenii gen. nov., sp. nov., to accommodate clinical isolates phenotypically resembling members of the genera Chryseobacterium and Empedobacter

A total of 26 isolates of non-fermenting, Gram-negative rods, obtained between 1980 and 2004 by various clinical laboratories in Belgium, with phenotypic characteristics resembling those of members of the genera Chryseobacterium and Empedobacter (indole-positive) and a biochemical profile resembling that of CDC group II-h, but urease-positive, were collected at the Université Catholique de Louvain Microbiology Laboratory, Belgium. The 16S rRNA gene sequences were determined for most of the isolates and showed 94–95 % similarity with the type strain of Empedobacter brevis as the closest relative, indicating that these isolates might belong to a separate genus. Furthermore, the 16S rRNA gene sequences of the isolates were similar, but two clusters (genomovars) could be distinguished. The sequence similarities were 99.5–100 % for the 14 isolates of genomovar 1 and 99.4–100 % for the 12 isolates of genomovar 2. The similarity between the two clusters was 98.3–99.5 %. The presence of two clearly different groups was corroborated by using tRNA intergenic length polymorphism analysis, which also enabled differentiation of the novel species from all other species studied thus far using this technique. DNA–DNA hybridization results excluded a close relatedness to Empedobacter brevis. The DNA G+C contents of the reference strains of genomovars 1 and 2 were 33.8±0.4 and 34.4±0.2 mol%, respectively. The name Wautersiella falsenii gen. nov., sp. nov., is proposed for this group, comprising two closely related genomovars. The type strain of the species and reference strain for genomovar 1 is NF 993T (=CCUG 51536T=CIP 108861T), which was isolated from a surgical wound. The reference strain for genomovar 2 is NF 770 (=CCUG 51537=CIP 108860), which was isolated from blood.

Mycobacterium mucogenicum sepsis in an immunocompetent patient

We report a case of Mycobacterium mucogenicum sepsis in an immunocompetent woman with Münchausen syndrome presenting with multiple abscesses.

Septicemia due to Solobacterium moorei in a patient with multiple myeloma

We report a case of bacteremia caused by Solobacterium moorei, an anaerobic, non-sporulated Gram-positive bacillus in a patient with a multiple myeloma. The source of infection was presumably related to multiple dento-alveolar abscesses. This is the first recovery of S. moorei from blood cultures.

Distribution of nocardia species in clinical samples and their routine rapid identification in the laboratory

Eighty-six Nocardia strains isolated from clinical samples in Belgium were identified by 16S rRNA gene sequencing. Eighty-three (96%) strains belonged to only six Nocardia species: N. farcinica (38 [44%]), N. nova (19 [22%]), N. cyriacigeorgica (13 [15%]), N. brasiliensis (6 [6.9%]), N. abscessus (5 [5.8%]), and N. paucivorans (2 [2.3%]). A gallery of nine conventional and enzymatic tests was developed for the rapid identification of the most common species isolated during this survey. Pyrrolidonyl aminopeptidase, gamma-glutamyl aminopeptidase, alpha-mannosidase, and alpha-glucosidase were found to be highly discriminating and could be used to develop an identification scheme.

Laboratory diagnosis of Clostridium difficile-associated diarrhoea: a plea for culture

A routine protocol for diagnosing Clostridium difficile-associated diarrhoea (CDAD) based on both faecal-cytotoxin detection and toxigenic culture was adopted by the microbiology laboratory of the St Luc-UCL University Hospital in Brussels in 1997. A toxigenic culture is a faecal culture followed, in the case of positivity, by a direct immunoassay on colonies to detect toxin A production. The results obtained over the past 7 years in the hospital are reviewed here. A total of 10,552 diarrhoeal stools from 7042 patients were analysed, of which 9494 were negative for all tests. A total of 1058 samples (10 %) from 794 patients were culture-positive, of which 460 (4.4 %) were positive for a faecal cytotoxin. The remaining 598 cultures were tested for toxin A on colonies; 355 of them were positive, which is 3.4 % of the total, and the remaining 243 (2.3 %) were negative. The positivity of the faecal-cytotoxin assay was statistically linked to the number of colonies observed on the culture plate. In conclusion, over a 7 year period, toxigenic culture allowed the diagnosis of 355 cases of CDAD that would have been missed by a protocol using a faecal-cytotoxin assay alone. In terms of both patient care, prevention of environmental contamination and prevention of risk of a hospital outbreak, it is proposed that these results justify the recommendation to perform both faecal-toxin assay and culture in routine medical practice.

Histidine decarboxylase in Enterobacteriaceae revisited

With a modification of Taylor's decarboxylation broth, histidine decarboxylase was detected in Enterobacter aerogenes, Morganella morganii, Raoultella ornithinolytica, and some strains of Citrobacter youngae and Raoultella planticola. This method provides a useful confirmatory test for identification of E. aerogenes strains.

Identification of a novel Brevibacterium species isolated from humans and description of Brevibacterium sanguinis sp. nov

Six coryneforms isolated from blood and dialysate fluid were phenotypically similar to Brevibacterium casei, but 16S rRNA gene sequencing and DNA-DNA hybridization indicate that they belong to a new species for which the name Brevibacterium sanguinis is proposed.

Study of genotypes and virB4 secretion gene of Bartonella henselae strains from patients with clinically defined cat scratch disease

Bartonella henselae is the causative agent of cat scratch disease (CSD), which usually presents as a self-limiting lymphadenopathy. Occasionally, the bacteria will spread and be responsible for tissue and visceral involvement. Two B. henselae genotypes (genotypes I and II) have been described to be responsible for uncomplicated CSD on the basis of 16S rRNA sequence analysis. A type IV secretion system (T4SS) similar to the virulence-associated VirB system of Agrobacterium tumefaciens was recently identified in the B. henselae Houston-1 genotype I strain. We studied the correlations of the B. henselae genotypes with the clinical presentations and with the presence of T4SS. Isolates originated from CSD patients whose lymph nodes were prospectively analyzed. B. henselae genotype I was identified in 13 of 42 patients (30%). Among these, two teenage twins presented with hepatosplenic CSD and one immunocompetent adult presented with osteomyelitis. Genotype II was detected in 28 of 42 patients (67%), all of whom presented with uncomplicated CSD. The last patient was infected with both genotypes. T4SS was studied by PCR amplification of the virB4 gene. Amplification of virB4 codons 146 to 256, 273 to 357, and 480 to 537 enabled us to detect 66, 90, and 100% of the B. henselae isolates, respectively. Sequence analysis revealed sequence variations that correlated with genotype distribution. Our studies suggest that B. henselae genotype I strains harbor virB4 genes that are different from those harbored by genotype II strains and that genotype I strains might be more pathogenic.

Evaluation of Oxoid combination discs for detection of extended-spectrum beta-lactamases

OBJECTIVES

We evaluated the reliability of cefpirome/clavulanate (CD04) compared with ceftazidime/clavulanate (CD02) and cefotaxime/clavulanate (CD03) Oxoid combination discs for the detection of extended-spectrum beta-lactamases (ESBL) in several Enterobacteriaceae isolates, including Enterobacter spp.

METHODS

Overall, a total of 105 ESBL-positive [positive double-disc synergy test (DDST)] and 94 ESBL-negative (negative DDST) Gram-negative isolates were evaluated. Ninety-eight isolates were confirmed as ESBL-positive on the basis of the sequence alignments of the blaTEM and/or blaSHV gene amplification products, which matched with previously identified ESBLs. The phenotypic detection of ESBLs was performed by the three combination discs according to the NCCLS and BSAC methods. The CD04 disc was evaluated with the manufacturer's recommended zone size difference breakpoint of > or =4 mm.

RESULTS

In Escherichia coli and Klebsiella spp., the sensitivities (%)/specificities (%) of CD02, CD03 and CD04 discs, and the combination of CD02 or CD04 discs, were, respectively, 88/92, 90/92, 95/84 and 100/82, while the corresponding figures were 94/100, 4/100, 94/100 and 100/100 in Enterobacter aerogenes. NCCLS and BSAC methods yielded concordant results in 99% of the isolates.

CONCLUSIONS

CD04 and CD02 discs were the best combination for detection of ESBLs in our collection of Enterobacteriaceae isolates, including E. aerogenes.

Brevibacterium lutescens sp. nov., from human and environmental samples

Three strains of coryneform rods isolated from clinical samples and one of environmental origin exhibited phenotypic and chemotaxonomic properties characteristic of the genus Brevibacterium and their 16S rRNA gene sequences were closely related (98.5-99.0 %) to that of Brevibacterium otitidis. However, DNA-DNA hybridization of one strain (CF87(T)) showed only 59.6 % relatedness to the type strain of B. otitidis, DSM 10718(T), and 75-82 % relatedness to the three other strains. The four strains could be differentiated from B. otitidis by cellular fatty acid composition and some phenotypic characteristics. These findings suggest that the four strains belong to a novel species, for which the name Brevibacterium lutescens sp. nov. is proposed. The type strain of B. lutescens is CF87(T) (=DSM 15022(T)=CCUG 46604(T)).

Bacteremia due to a novel Microbacterium species in a patient with leukemia and description of Microbacterium paraoxydans sp. nov

A yellow-pigmented coryneform rod was isolated from the blood of a child with acute lymphoblastic leukemia who was perfused with a central venous catheter. The culture bottles were positive twice, at a 2-month interval. The isolate was identified as a Microbacterium sp. and studied along with five other similar strains. Phenotypic, chemotaxonomic, and genetic characteristics indicated that they are closely related to Microbacterium oxydans but that they belong to a distinct species, for which the name Microbacterium paraoxydans sp. nov. is proposed. The type strain of M. paraoxydans is CF36(T) = DSM 15019(T). The G+C content of its DNA is 69.9 mol%.

International typing study of toxin A-negative, toxin B-positive Clostridium difficile variants

Clinically important strains of Clostridium difficile that do not produce toxin A but produce toxin B and are cytotoxic (A(-)/B(+)) have been reported from multiple countries. In order to compare the relatedness of these strains, we typed 23 A(-)/B(+) C. difficile isolates from the United Kingdom (6 isolates), Belgium (11 isolates), and the United States (6 isolates) by three well-described typing methods. Restriction endonuclease analysis (REA), PCR ribotyping, and serogrouping differentiated 11, 4, and 3 different strain types, respectively. Twenty-one of the 23 A(-)/B(+) variants had a 1.8-kb truncation of the toxin A gene characteristic of toxinotype VIII strains; 20 of the 21 toxinotype VIII-like strains were PCR type 17. PCR type 17 isolates could be differentiated into two separate strain groups by serogrouping and by REA. REA further discriminated these isolates into eight subgroups (REA types). PCR type 17-serogroup F-REA group CF isolates were recovered from all three countries, and one specific REA type, CF4, was recovered from patients with C. difficile disease in the United Kingdom and the United States. C. difficile A(-)/B(+) variants of apparent clonal origin are widely distributed in Europe and North America.

Pasteurella multocida in peritoneal dialysis: a rare cause of peritonitis associated with exposure to domestic cats

Pasteurella multocida is a rare cause of peritonitis in peritoneal dialysis patients with only 10 cases reported in the literature so far. All cases were observed in patients with close contact with cats, usually with a direct puncture of the dialysis tubing. We report a case of Pasteurella multocida peritonitis in a patient maintained under continuous cycling peritoneal dialysis (CCPD), who had frequent and close contact with cats. Patients should be made aware of this potential complication and advised to keep domestic animals away from the location of their peritoneal exchanges.

Biochemical and susceptibility tests useful for identification of nonfermenting gram-negative rods

Six hundred nineteen strains of nonfermenting gram-negative rods were tested for alkaline phosphatase, benzyl-arginine arylamidase, pyrrolidonyl arylamidase, ethylene glycol acidification, and susceptibility to desferrioxamine and colistin. The results were highly discriminant. Therefore, the proposed tests may be helpful for the identification of this group of organisms.

Molecular characterization of fliD gene encoding flagellar cap and its expression among Clostridium difficile isolates from different serogroups

The fliD gene encoding the flagellar cap protein (FliD) of Clostridium difficile was studied in 46 isolates belonging to serogroups A, B, C, D, F, G, H, I, K, X, and S3, including 30 flagellated strains and 16 nonflagellated strains. In all but three isolates, amplification by PCR and reverse transcription-PCR demonstrated that the fliD gene is present and transcribed in both flagellated and nonflagellated strains. PCR-restriction fragment length polymorphism (RFLP) analysis of amplified fliD gene products revealed interstrain homogeneity, with one of two major patterns (a and b) found in all but one of the strains, which had pattern c. A polyclonal monospecific antiserum raised to the recombinant FliD protein reacted in immunoblots with crude flagellar preparations from 28 of 30 flagellated strains but did not recognize FliD from nonflagellated strains. The fliD genes from five strains representative of the three different RFLP groups were sequenced, and sequencing revealed 100% identity between the strains with the same pattern and 88% identity among strains with different patterns. Our results show that even though FliD is a structure exposed to the outer environment, the flagellar cap protein is very well conserved, and this high degree of conservation suggests that it has a very specific function in attachment to cell or mucus receptors.

Peritonitis due to Brevibacterium otitidis in a patient undergoing continuous ambulatory peritoneal dialysis

Brevibacterium otitidis is a coryneform rod and, as far as is known, is isolated only from infected ears. We report the first known case of peritonitis caused by B. otitidis in a patient undergoing continuous ambulatory peritoneal dialysis.

Phenotypic and genotypic diversity of the flagellin gene (fliC) among Clostridium difficile isolates from different serogroups

Phenotypic and genotypic diversity of the flagellin gene (fliC) of Clostridium difficile was studied in 47 isolates from various origins belonging to the serogroups A, B, C, D, F, G, H, I, K, X, and S3. Electron microscopy revealed 17 nonflagellated strains and 30 flagellated strains. PCR and reverse transcription-PCR demonstrated that the flagellin gene was present in all strains and that the fliC gene was expressed in both flagellated and nonflagellated strains. Southern blotting showed the presence of only one copy of the gene and three different hybridization patterns. DNA sequence analysis of fliC from the strains belonging to serogroups C, D, and X, representative of each profile, disclosed great variability in the central domain, whereas the N- and C-terminal domains were conserved. The variability of the flagellin gene fliC was further studied in the isolates by PCR-restriction fragment length polymorphism (RFLP) analysis. Nine different RFLP groups were identified (I to IX), among which three (I, VII, and VIII) corresponded to numerous serogroups whereas the six others (II, III, IV, V, VI, and IX) belonged to a single serogroup. Flagellin gene RFLP analysis could constitute an additional typing method employable in conjunction with other typing methods currently available.

Comparison of PCR-ribotyping, arbitrarily primed PCR, and pulsed-field gel electrophoresis for typing Clostridium difficile

Clostridium difficile is now recognized as the major agent responsible for nosocomial diarrhea in adults. Among the genotyping methods available, arbitrarily primed PCR (AP-PCR), PCR-ribotyping, and pulsed-field gel electrophoresis (PFGE) have been widely used for investigating outbreaks of C. difficile infections. However, the comparative typing ability, reproducibility, discriminatory power, and efficiency of these methods have not been fully investigated. We compared the results of three methods-AP-PCR with three different primers (AP3, AP4, and AP5), PCR-ribotyping, and PFGE (with SmaI endonuclease)-to differentiate 99 strains of C. difficile that had been previously serogrouped. Typing abilities were 100% for PCR-ribotyping and AP-PCR with AP3 and 90% for PFGE, due to early DNA degradation in strains from serogroup G. Reproducibilities were 100% for PCR-ribotyping and PFGE but only 88% for AP-PCR with AP3, 67% for AP-PCR with AP4, and 33% for AP-PCR with AP5. Discriminatory power for unrelated strains was >0.95 for all the methods but was lower for PCR-ribotyping among serogroups D and C. PCR-based methods were easier and quicker to perform, but their fingerprints were more difficult to interpret than those of PFGE. We conclude that PCR-ribotyping offers the best combination of advantages as an initial typing tool for C. difficile.

Antimicrobial susceptibilities and serogroups of clinical strains of Clostridium difficile isolated in France in 1991 and 1997

Glycopeptides (vancomycin and teicoplanin) and metronidazole are the drugs of choice for the treatment of Clostridium difficile infections, but trends in susceptibility patterns have not been assessed in the past few years. The objective was to study the MICs of glycopeptides and metronidazole for unrelated C. difficile strains isolated in 1991 (n = 100) and in 1997 (n = 98) by the agar macrodilution, the E-test, and the disk diffusion methods. Strain susceptibilities to erythromycin, clindamycin, tetracycline, rifampin, and chloramphenicol were also determined by the ATB ANA gallery (bioMérieux, La Balme-les-Grottes, France). The MICs at which 50% of isolates are inhibited (MIC(50)s) and MIC(90)s of glycopeptides and metronidazole remained stable between 1991 and 1997. All the strains were inhibited by concentrations that did not exceed 2 microgram/ml for vancomycin and 1 microg/ml for teicoplanin. Comparison of MICs determined by the agar dilution method recommended by the National Committee for Clinical Laboratory Standards and the E test showed correlations (+/-2 dilutions) of 86. 6, 95.9, and 99% for metronidazole, vancomycin, and teicoplanin, respectively. The E test always underestimated the MICs. Strains with decreased susceptibility to metronidazole (MICs, >/=8 microgram/ml) were isolated from six patients (n = 4 in 1991 and n = 2 in 1997). These strains were also detected by the disk diffusion method (zone inhibition diameter, </=21 mm); they belonged to nontoxigenic serogroup D (n = 5) and toxigenic serogroup H (n = 1). Decreased susceptibility to erythromycin (MICs, >/=1 microgram/ml), clindamycin (MICs, >/=2 microgram/ml), tetracycline (MICs, >/=8 microgram/ml), rifampin (MICs, >/=4 microgram/ml), and chloramphenicol (MICs, >/=16 microgram/ml) was observed in 64.2, 80.3, 23.7, 22.7, and 14.6% of strains, respectively. Strains isolated in 1997 were more susceptible than those isolated in 1991, and this trend was correlated to a major change in serogroup distribution. Periodic studies are needed in order to detect changes in serogroups and the emergence of strains with decreased susceptibility to therapeutic drugs.

A novel toxinotyping scheme and correlation of toxinotypes with serogroups of Clostridium difficile isolates

Two hundred nineteen Clostridium difficile isolates from 22 serogroups were screened for changes in the genes coding for toxin B (tcdB) and toxin A (tcdA). Parts of the toxin genes were amplified, and the PCR fragments were checked for length polymorphisms and cut with several restriction enzymes to monitor restriction fragment length polymorphisms (RFLPs). For 47 strains (21%), differences in the toxin genes were found compared to the toxin genes of reference strain VPI 10,463. Polymorphisms were usually observed in both toxin genes. RFLPs were more commonly found in the tcdB gene, in which a single restriction enzyme could give up to five different patterns. Restriction sites seemed to be less heterogeneous in the tcdA gene, in which for most enzymes only two different RFLPs were recognized. However, deletions were observed in tcdA, and four new types of shortened tcdA genes are described. According to the changes in their toxin genes, variant strains could be divided into 10 groups (toxinotypes I to X). A toxinotype was characterized by similar patterns of changes in the toxin genes and in other regions of the pathogenicity locus and also similar pulsed-field gel electrophoresis patterns. Variant toxinotypes were found in 9 of the 22 serogroups studied, and some toxinotypes were clearly associated with specific serogroups. Toxinotype VIII is characteristic for all strains of serogroup F. Other serogroups in which variant toxinotypes were commonly found are A1, A15, E, and X. Testing of variability in C. difficile toxin genes not only might be useful as a molecular typing system but also could have implications in diagnostics and pathogenesis.

Clostridium difficile-associated diarrhea in HIV-infected patients: epidemiology and risk factors

A retrospective analysis of all the cases of Clostridium difficile-associated diarrhea (CDAD) in hospitalized patients infected with HIV was performed over a 52-month period to assess the incidence, epidemiology, and risk factors of CDAD. A case of CDAD was defined as a patient with diarrhea and a positive stool cytotoxin B assay. Sixty-seven cases of CDAD were recorded in HIV-infected patients between January 1991 and April 1995. The annual incidence of CDAD ranged from 1.7 to 6.4 per 100 HIV-infected patients discharged from hospital. The 67 CDAD cases included 48 (72%) first episodes and 19 (28%) relapses. Serogroup C accounted for 69% of strains from initial episodes of CDAD. To identify risk factors for CDAD, 34 HIV-infected patients with a first episode were compared with 66 HIV-infected controls matched for the length of hospital stay. Three independent factors remained significantly associated with CDAD among HIV-infected patients: CD4+ cell counts <50/mm3 (OR = 5.2; 95% CI = 1.4-19.3; p = 0.01), clindamycin use (OR = 5.0; 95% CI = 1.3-18.3; p = 0.02) and penicillin use (OR = 4.6; 95% CI = 1.1-18.8; p = 0.03). C. difficile is a common enteric pathogen responsible for nosocomial diarrhea in HIV-infected patients. Clinicians should keep this pathogen in mind when searching for the cause of diarrhea in these patients, especially those who are severely immunocompromised or have received clindamycin or penicillin.

Genotyping of outbreak-related and sporadic isolates of Clostridium difficile belonging to serogroup C

Serogroup C of Clostridium difficile is the serogroup most frequently related to outbreaks. Fifty-six toxigenic serogroup C isolates of C. difficile were genotyped by ribotyping PCR (ribo-PCR), random amplified polymorphic DNA (RAPD) assay, and pulsed-field gel electrophoresis (PFGE). Thirty-five of the 56 isolates were recovered from four unrelated outbreaks (Belgium, 1987, 1992, and 1995; France, 1992 to 1993) 7 derived from a spatiotemporal cluster in Cotonou, Benin (1992), and 14 were sporadic isolates. The serogroup C reference strain, also isolated during an outbreak (Belgium, 1983), was genotyped too. Ribo-PCR, the RAPD assay, and PFGE generated 2, 5, and 11 major genotypes, respectively. Combination of the three methods finally yielded 13 general types, although ribo-PCR did not play any role in enhancing resolution. Three general types were recovered from all the isolates from the five outbreaks and the cluster, with two types being predominant. The 14 sporadic serogroup C isolates were divided into 11 overall genotypes. These results indicate that genotyping methods, and more particularly the combination of the RAPD assay and PFGE, can resolve genetic diversity within toxigenic, serogroup C C. difficile strains. Also, this study suggests that outbreak-related serogroup C strains are limited to a few genetically stable and apparently very widely (internationally and intercontinentally) distributed genotypes.

Toxin A detection on Clostridium difficile colonies from 24-h cultures

OBJECTIVE: Performance of a combined approach for the detection of toxigenic strains in patients suspected of having Clostridium difficile-associated disease was evaluated. METHODS: In this approach, stools were cultured for 24 h on a selective medium supplemented with sodium taurocholate (TCCFA), in anaerobic conditions created with the Martreg Anoxomat system, and toxin A detection was performed directly on C. difficile colonies, by enzyme immunoassay (EIA). This method was compared with three others: cytotoxigenic culture consisting of a 48-h culture on selective medium followed by detection of in vitro cytotoxin production on cell monolayers, fecal cytotoxin detection and fecal toxin A detection by EIA. RESULTS: From 548 stools, 108 yielded a positive culture by at least one of the methods, and 81 isolates were cytotoxin producers. Cultures for 24 h on TCCFA were positive in 106 cases and EIA performed on colonies gave 73 positive results, giving a sensitivity of 90.1% and a specificity of 100%. By comparison, the sensitivity and specificity of cytotoxigenic culture, stool cytotoxin and stool toxin A were respectively 96.2% and 100%, 61.7% and 100%, and 66.7% and 95.9%. CONCLUSIONS: Performing EIA on colonies recovered after 24 h culture allows us to improve the detection of toxigenic strains in patients suspected of having C. difficile-associated disease.

Enzyme electrophoresis combined with serogrouping for improved differentiation of Clostridium difficile strains

We used enzyme electrophoresis to study a set of epidemiologically related and unrelated isolates of Clostridium difficile. The 53 strains belonged to the most frequent serogroups (A1, C, G, H and K). Nine electrophoretic profiles were defined on the basis of five enzymes, and two were characteristic of a single strain. Each serogroup was resolved into two or three different enzyme patterns. By combining the two methods we were able to resolve the strains into 12 types. There was an excellent correlation between enzyme electrophoresis and serogrouping data. This method may be of use in investigating nosocomial transmission.

Human antibody response to Clostridium difficile toxin A in relation to clinical course of infection

This study investigated whether differences in fecal and serum antitoxin A antibody levels may account for the duration of Clostridium difficile-associated diarrhea (CDAD) and the occurrence of relapses. By an enzyme linked-immunosorbent assay, we tested 40 patients with CDAD including 25 patients without immunodeficiency and 15 patients receiving antineoplastic drugs. Two hundred eighty serum samples and 80 normal stool samples were investigated as controls. In nonimmunocompromised patients, serum immunoglobulin (IgG) and fecal IgA antitoxin A antibody titers were significantly higher in patients who suffered a single episode (n = 21) than in those with relapsing CDAD (n = 4) whose titers were at control levels. Of these 25 patients, eight suffered from diarrhea which lasted for more than 2 weeks. These patients had significantly lower serum- and feces-specific antibody levels than the others who presented symptoms of shorter duration. In cytostatic-treated patients, antitoxin A antibody levels were similar to controls, but relapses occurred in a single case. These data suggest an association between a defective humoral response to toxin A and a more severe form of C. difficile infection. They also indicate that other host-related factors control the severity of CDAD and remain to be elucidated.

Use of an enzyme-linked immunoassay for Clostridium difficile serogrouping

An enzyme-linked immunoassay (ELISA) with 11 Clostridium difficile serogroup-specific antisera was applied for serogrouping of C. difficile colonies from 314 consecutive positive fecal samples. Two hundred forty-nine strains (79%) were correctly serogrouped, 57 (18%) belonged to serogroups other than the 11 which were evaluated and gave a negative reaction with all antisera, and 8 isolates (2.5%) did not react with their corresponding antisera. ELISA is a rapid and reliable method for serogrouping C. difficile and should allow for the automation of this procedure.

Serogroup F strains of Clostridium difficile produce toxin B but not toxin A

Most toxigenic strains of Clostridium difficile produce two toxins: an enterotoxin (toxin A) and a cytotoxin (toxin B). Only one strain (strain 8864) has been reported to produce toxin B but no toxin A. Serogroup F strains (44) of C. difficile, often isolated from asymptomatic infants, have been examined for toxin production. These strains, which were from distinct geographical and clinical sources, did not produce any detectable toxin A in vitro when examined in three distinct immunoassays. Nevertheless, all the strain produced a cytotoxin. Immunological differences between the cytotoxin of the serogroup F strains and that produced by C. difficile strain VPI 10463 (serogroup G) were demonstrated with monoclonal antibodies specific for either the toxin B produced by C. difficile strain VPI 10463 or C. sordellii lethal toxin (LT). Polymerase chain reaction amplification with primers derived from C. difficile strain VPI 10463 toxin A and B genes showed that serogroup F strains seem to possess a toxin B gene homologous with that of strain VPI 10463 and at least fragments of the toxin A gene. When axenic mice were inoculated with serogroup F strains, the animals survived; they did not develop diarrhoea and no toxin A could be detected in their faeces. However, cytotoxin was detected. Furthermore, these mice were protected against subsequent challenge with the otherwise lethally toxigenic C. difficile strain VPI 10463. The serogroup F strains appeared to be homogeneous and distinct from other C. difficile strains with regard to toxin production.

Virulence of ten serogroups of Clostridium difficile in hamsters

A slide agglutination technique identifying 10 serogroups of Clostridium difficile (A,B,C,D,F,G,H,I,K and X) has been described previously. In this study, we have used the hamster to compare the ability of the 10 serogroup reference strains to colonise and produce disease. Groups of four hamsters were each given a single intraperitoneal injection of either clindamycin or cefoxitin, and an oral challenge dose of C. difficile. The time taken to establish faecal colonisation and the length of survival after colonisation were monitored. All hamsters treated with cefoxitin became colonised by day 3 and those challenged with the cytotoxigenic strains of serogroups A,C,H and K developed colitis and died. Among those challenged with the non-toxigenic strains of groups B,D,I and X and the toxigenic strains of groups F and G, faecal colonisation was established without signs of disease. This demonstrates that there are differences in virulence even among toxigenic strains of C. difficile. The same phenomenon was observed after treatment with clindamycin but the pattern of colonisation was quite different with some strains. In the hamsters challenged with toxigenic strains of groups C and K and non-toxigenic strains of groups D and I, which are highly resistant to clindamycin, the response was the same as with cefoxitin. The results were different with strains which were susceptible to clindamycin. Some animals became colonised much later than those treated with cefoxitin but the mortality was similar.(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of flagella of Clostridium difficile and their role in serogrouping reactions

Slide agglutination with rabbit antisera allows the differentiation of 10 serogroups of Clostridium difficile, namely, A, B, C, D, F, G, H, I, K, and X. Each serogroup displays a specific protein profile in sodium dodecyl sulfate-polyacrylamide gel electrophoresis, except for A, which displays 12 different protein profiles (A1 to A12). In the present work, electron microscopy revealed the presence of uniformly distributed flagella in the reference strains of serogroups G and K and in all strains representative of the 12 subgroups within serogroup purified by differential centrifugation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of these preparations revealed one distinct band with an apparent molecular mass of approximately 39 kilodaltons. Antiserum was prepared by immunizing a rabbit with the serogroup A flagellin, which had been eluted from the gel. In immunoblotting, this antiserum cross-reacted with the flagellin of the other strains. When the cells were deflagellated by a short sonication, the cross-reactions observed by slide agglutination with A, G, and K antisera were suppressed. Similarly, shearing of flagella allowed specific slide agglutination of the 12 subgroups of serogroup A.

Detection of specific antigens for ten serogroups of Clostridium difficile

We previously described a serogrouping technique for Clostridium difficile based on slide agglutination with rabbit antisera raised against formol-treated cells. It allows the differentiation of ten serogroups, namely A, B, C, D, F, G, H, I, K and X. Each serogroup displays a specific profile with several distinctive bands by polyacrylamide gel electrophoresis (PAGE). In this study we investigated the common and specific antigenic determinants of the ten serogroups by immunoblotting. In a first experiment, whole cell proteins of the ten reference strains were separated by SDS-PAGE, transferred onto nitrocellulose membrane and immunoblotted against their homologous and heterologous antisera. Each serogroup was characterized by several common bands and one or two specific antigens which were proven to correspond to the lowest molecular weight distinctive band observed on PAGE profiles. New rabbit antisera were subsequently raised against the purified specific antigen obtained by electro-elution from polyacrylamide gels. Immunoblots were repeated with these new antisera: all reactions were serogroup specific except one minor cross reaction between C and F. The antisera still agglutinated the homologous strain without any cross agglutination, suggesting that the serogroup specific determinant is a surface antigen responsible for agglutination.

Correlation between serogroup and susceptibility to chloramphenicol, clindamycin, erythromycin, rifampicin and tetracycline among 308 isolates of Clostridium difficile

The susceptibility to chloramphenicol, clindamycin, erythromycin, rifampicin and tetracycline of 308 isolates of Clostridium difficile from various origins was determined by a disc diffusion susceptibility testing and the results were compared with the serogroup of the strains. For the five antimicrobials, there was a clear-cut separation between susceptible and resistant strains. Some correlation between resistance and serogroup was found. Almost all of the 161 isolates of serogroups A, F, G, H and X were susceptible to all antibiotics. The 32 toxigenic isolates of serogroup C were characterized by a typical resistance pattern which could be used for typing purposes. Other serogroups showed variable patterns. The review of 64 cases of antibiotic associated diarrhoea showed that these differences in susceptibility could have clinical implications: all seven cases due to clindamycin were caused by a clindamycin resistant strain of serogroup C, whereas cases associated with other antibiotics were distributed among various serogroups.

Susceptibility of clinical isolates of Campylobacter pylori to 24 antimicrobial and anti-ulcer agents

Forty-nine isolates of Campylobacter pylori were tested for their susceptibility to twenty antibiotics and four anti-ulcer agents by an agar dilution technique. Penicillin and amoxycillin were the most active drugs (MIC90, 0.06 microgram/ml); erythromycin, cefazolin, minocycline, ciprofloxacin, ofloxacin and gentamicin were slightly less active (MIC90, less than or equal to 1 microgram/ml). Moderate activity was found for doxycyclin, rifampin, nitrofurantoin, norfloxacin, pefloxacin, enoxacin, paromomycin, metronidazole and tinidazole. All strains were resistant to trimethoprim (MIC greater than 512 micrograms/ml). Nalidixic acid (MIC90, greater than 256 micrograms/ml) and colistin (MIC90, greater than 64 micrograms/ml) had little to no activity. Of four anti-ulcer drugs, only bismuth subcitrate showed activity (MIC90, 64 micrograms/ml). Strains resistant to all 4-quinolones were found in patients who had previously received ofloxacin as part of a clinical trial aimed at eradication of C. pylori. These isolates remained susceptible to amoxycillin, tetracyclines and to other classes of antibiotics.

Clostridium difficile in neonates: serogrouping and epidemiology

A typing scheme for Clostridium difficile based on serogrouping, toxigenicity and sorbitol fermentation was applied to 270 strains isolated in one neonatal ward during a 6-month prospective study. Two hundred and twenty-three strains were isolated from 377 faecal samples of 114 neonates and 47 from 92 environmental specimens. The isolates were distributed among five different types; 87% of the faecal and 85% of the environmental isolates belonged to two of these types (toxigenic, sorbitol negative, serogroup F and nontoxigenic, sorbitol positive, serogroup A). Nosocomial spread was clearly demonstrated and the environment appeared to be the main source of contamination: most of the neonates were colonized after admission by strains found in their environment; clusters of colonization with unusual isolates were observed following referral of patients from the intensive care unit or from other hospitals. No relation was found between the acquisition or the carriage of C. difficile and any intestinal symptoms. All the strains belonged to types different from those usually found in cases of antibiotic associated colitis (AAC) suggesting differences of pathogenicity among the different types.

Epidemiology and prevention of Clostridium difficile infections in a leukemia unit

A 29-month prospective study was carried out in a leukemia unit with the aim of investigating the epidemiology of Clostridium difficile infections and limiting their spread. Systematic cultures of stools and assays for cytotoxin were performed on patient admission and at weekly intervals, yielding 1,355 cultures and assays. The study period was divided in period A, before total unit renovation, and period B, afterwards. During period B all patient carriers of Clostridium difficile received vancomycin. A comparison of the two periods showed that the percentage of positive cultures fell from 16.6% to 3.6% and the positive toxin assays from 9.9% to 1.2%. It was concluded that colonization by Clostridium difficile can be prevented in hospital wards with generally high rates of infection by a combination of decontamination of the environment, introduction of preventive measures and treatment of Clostridium difficile carriage with vancomycin.

Comparison of serogrouping and polyacrylamide gel electrophoresis for typing Clostridium difficile

A typing scheme for Clostridium difficile based on slide agglutination with rabbit antisera was previously described. It allows the differentiation of 10 serogroups designated A, B, C, D, F, G, H, I, K, and X. We studied the correlation between serogrouping and polyacrylamide gel electrophoresis (PAGE) of whole-cell proteins. A total of 202 isolates from different sources were analyzed by PAGE after ultrasonic disintegration of cells from an 18-h liquid culture and treatment with sodium dodecyl sulfate and 2-mercaptoethanol. A total of 21 different patterns were observed. The reference strains from the 10 serogroups showed different profiles. For each serogroup except A, the patterns obtained with the clinical isolates were identical to the patterns obtained with the reference strains. For the 48 strains belonging to serogroup A, 12 different profiles were observed. Five of these involved strains isolated from patients with antibiotic-associated diarrhea. Typing by sodium dodecyl sulfate-PAGE thus correlates with serogrouping. In addition, it allows discrimination within the heterogeneous serogroup A.