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Clostridium bacteraemia characterised by 16S ribosomal RNA gene sequencing.

ABSTRACT: BACKGROUND: Owing to problems in accurate species identification of the diverse genus clostridium, the epidemiology and pathogenicity of many species are not fully understood. Moreover, previous studies on clostridium bacteraemia have been limited and relied only on phenotypic species identification. AIMS: To characterise the epidemiology, disease spectrum, and outcome of clostridium bacteraemia using 16S ribosomal RNA (rRNA) gene sequencing. METHOD: During a four year period (1998-2001), all cases of clostridium bacteraemia were prospectively studied and all "non-perfringens" clostridium isolates identified to the species level by 16S rRNA gene sequencing. RESULTS: Fifty one blood culture isolates were identified as Clostridium perfringens and 17 belonged to 11 other clostridium species. The first case of C disporicum infection and two cases of clostridium bacteraemia in children with intussusception were also described. Of the 68 clostridium isolates from 68 different patients, 38 were associated with clinically relevant bacteraemia. The gastrointestinal and hepatobiliary tracts were common sites of both underlying disease and portal of entry in these patients. Clostridium perfringens accounted for 79% of all clinically relevant bacteraemia, with the remainder caused by a diversity of species. The attributable mortality rate of clinically relevant clostridium bacteraemia was 29%. Younger age and underlying gastrointestinal/hepatobiliary tract disease were associated with mortality (p < 0.05). CONCLUSIONS: Patients with clinically relevant clostridium bacteraemia should be investigated for the presence of underlying disease processes in the gastrointestinal or hepatobiliary tracts. 16S rRNA gene analysis will continue to be useful in further understanding the pathogenicity of various clostridium species.

SUBMITTER: Woo PC

PROVIDER: S-EPMC1770585 | biostudies-literature | 2005 Mar

REPOSITORIES: biostudies-literature

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Clostridium bacteraemia characterised by 16S ribosomal RNA gene sequencing.

Woo P C Y PC Lau S K P SK Chan K-M KM Fung A M Y AM Tang B S F BS Yuen K-Y KY

Journal of clinical pathology 20050301 3

<h4>Background</h4>Owing to problems in accurate species identification of the diverse genus clostridium, the epidemiology and pathogenicity of many species are not fully understood. Moreover, previous studies on clostridium bacteraemia have been limited and relied only on phenotypic species identification.<h4>Aims</h4>To characterise the epidemiology, disease spectrum, and outcome of clostridium bacteraemia using 16S ribosomal RNA (rRNA) gene sequencing.<h4>Method</h4>During a four year period ...[more]

PMID: 15735165

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Project description:AIMS:To identify a strain of Gram negative facultative anaerobic curved bacillus, concomitantly isolated with Escherichia coli and Streptococcus milleri, from the blood culture of a 69 year old woman with acute gangrenous appendicitis. The literature on arcobacter bacteraemia and arcobacter infections associated with appendicitis was reviewed. METHODS:The isolate was phenotypically investigated by standard biochemical methods using conventional biochemical tests. Genotypically, the 16S ribosomal RNA (rRNA) gene of the bacterium was amplified by the polymerase chain reaction (PCR) and sequenced. The sequence of the PCR product was compared with known 16S rRNA gene sequences in the GenBank by multiple sequence alignment. Literature review was performed by MEDLINE search (1966-2000). RESULTS:The bacterium grew on blood agar, chocolate agar, and MacConkey agar to sizes of 1 mm in diameter after 24 hours of incubation at 37 degrees C in 5% CO2. It grew at 15 degrees C, 25 degrees C, and 37 degrees C; it also grew in a microaerophilic environment, and was cytochrome oxidase positive and motile, typically a member of the genus arcobacter. Furthermore, phenotypic testing showed that the biochemical profile of the isolate did not fit into the pattern of any of the known arcobacter species. 16S rRNA gene sequencing showed one to two base differences between the isolate and A butzleri, but 35 to 39 base differences between the isolate and A cryaerophilus, indicating that the isolate was a strain of A butzleri. Only three cases of arcobacter bacteraemia with detailed clinical characteristics were found in the English literature. The sources of the arcobacter species in the three cases were largely unknown, although the gastrointestinal tract is probably the portal of entry of the A butzleri isolated from the present case because the two concomitant isolates (E coli and S milleri) in the blood culture were common flora of the gastrointestinal tract. In addition, A butzleri has previously been isolated from the abdominal contents or peritoneal fluid of three patients with acute appendicitis. CONCLUSIONS:16S rRNA gene sequencing was useful in the identification of the strain of A butzleri isolated from the blood culture of a patient with acute gangrenous appendicitis. Arcobacter bacteraemia is rare. Further studies using selective medium for the delineation of the association between A butzleri and acute appendicitis are warranted.

Project description:Little is known about the relative importance of the four species of Lancefield group G beta-hemolytic streptococci in causing bacteremia and the factors that determine the outcome for patients with group G beta-hemolytic streptococcal bacteremia. From 1997 to 2000, 75 group G beta-hemolytic streptococcal strains were isolated from the blood cultures of 66 patients. Sequencing of the 16S rRNA genes of the group G beta-hemolytic streptococci showed that all 75 isolates were Streptococcus dysgalactiae subspecies equisimilis. The API system (20 STREP) and Vitek system (GPI) successfully identified 65 (98.5%) and 62 (93.9%) isolates, respectively, as S. dysgalactiae subspecies equisimilis with >95% confidence, whereas the ATB Expression system (ID32 STREP) only successfully identified 49 isolates (74.2%) as S. dysgalactiae subspecies equisimilis with >95% confidence. The median age of the patients was 76 years (range, 33 to 99 years). Fifty-six patients (85%) were over 60 years old. All patients had underlying diseases. No source of the bacteremia was identified (primary bacteremia) in 34 patients (52%), whereas 17 (26%) had cellulitis and 8 (12%) had bed sore or wound infections. Fifty-eight patients (88%) had community-acquired group G streptococcal bacteremia. Sixty-two patients (94%) had group G Streptococcus recovered in one blood culture, whereas 4 patients (6%) had it recovered in multiple blood cultures. Fifty-nine patients (89%) had group G Streptococcus as the only bacterium recovered in their blood cultures, whereas in 7 patients other bacteria were recovered concomitantly with the group G Streptococcus in the blood cultures (Staphylococcus aureus in 3, Clostridium perfringens in 2, Citrobacter freundii in 1, and Bacteroides fragilis in 1). Overall, 10 patients (15%) died. Male sex, diagnosis other than cellulitis, hospital-acquired bacteremia, and multiple positive blood cultures were associated with mortality [P < 0.005 (relative risk [RR] = 7.6), P < 0.05 (RR = 3.7), P < 0.005 (RR = 5.6), and P < 0.05 (RR = 5.6), respectively]. Unlike group C beta-hemolytic streptococcal bacteremia, group G beta-hemolytic streptococcal bacteremia is not a zoonotic infection in Hong Kong.

Dataset Information

Clostridium bacteraemia characterised by 16S ribosomal RNA gene sequencing.

Publications

Clostridium bacteraemia characterised by 16S ribosomal RNA gene sequencing.

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