Georges Wauters

Yersinia enterocolitica infections and pork: the missing link

To determine the risk factors for Yersinia enterocolitica (YE) infection in Belgium, which is the country with the highest incidence of this infection, 40 persons with YE infections due to serotype O:3 (n = 36) or O:9 (n = 4) were compared with matched controls. Most patients had acute gastroenteritis; 1 had a liver abscess. 20% were admitted to hospital; the mean duration of hospital stay was 9 days. YE infection was strongly associated with eating raw pork in the 2 weeks before onset (odds ratio = 12, p = 0.00002), a factor that accounted for 58% of the YE infections studied. 14 (18%) of 79 families surveyed at a well-baby clinic fed their children raw pork from a median age of 18 months. Specific control measures to reduce contamination and consumption of raw pork may reduce the incidence of YE infections.

Evaluation of chlorhexidine and silver-sulfadiazine impregnated central venous catheters for the prevention of bloodstream infection in leukaemic patients: a randomized controlled trial

It has been suggested that central venous catheters impregnated with antiseptics such as chlohexidine and silver-sulfadiazine reduce the risk of catheter-related bacteraemia in intensive care patients. Patients suffering from haematologic malignancy treated by chemotherapy through a central venous catheter are at even greater risk of catheter-related bacteraemia. A prospective double-blind randomized controlled trial was performed in order to investigate the effectiveness of chlorhexidine and silver-sulfadiazine impregnated catheters (CH-SS) in these patients. A total of 680 catheters (13,826 catheter days) were inserted, of which 338 were antiseptic impregnated. Bloodstream infection was observed in 105 cases with an overall risk of 7.6 per 1000 catheter days. Thirty-two infections (30.5%) were catheter-related, corresponding to a risk of 2.3 per 1000 catheter days. There was no statistically significant different between the overall rates of bloodstream infection for impregnated and non-impregnated catheters (14.5 vs. 16.3%). The incidence of catheter-related infection was also similar in both groups (5 vs. 4.4%) and there was no difference in the time of the onset of bacteraemia in the two groups. It is concluded that the use of CH-SS catheters in patients with haematologic malignancy reduces neither the overall risk of bloodstream infection, nor the catheter-related infection rate, nor the delay for the occurrence of infection.

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for identification of Nocardia species.

ABSTRACT The identification of Nocardia species, usually based on biochemical tests together with phenotypic in vitro susceptibility and resistance patterns, is a difficult and lengthy process owing to the slow growth and limited reactivity of these bacteria. In this study, a panel of 153 clinical and reference strains of Nocardia spp., altogether representing 19 different species, were characterized by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). As reference methods for species identification, full-length 16S rRNA gene sequencing and phenotypical biochemical and enzymatic tests were used. In a first step, a complementary homemade reference database was established by the analysis of 110 Nocardia isolates (pretreated with 30 min of boiling and extraction) in the MALDI BioTyper software according to the manufacturers recommendations for microflex measurement (Bruker Daltonik GmbH, Leipzig, Germany), generating a dendrogram with species-specific cluster patterns. In a second step, the MALDI BioTyper database and the generated database were challenged with 43 blind-coded clinical isolates of Nocardia spp. Following addition of the homemade database in the BioTyper software, MALDI-TOF MS provided reliable identification to the species level for five species of which more than a single isolate was analyzed. Correct identification was achieved for 38 of the 43 isolates (88%), including 34 strains identified to the species level and 4 strains identified to the genus level according to the manufacturers log score specifications. These data suggest that MALDI-TOF MS has potential for use as a rapid (<1 h) and reliable method for the identification of Nocardia species without any substantial costs for consumables.

Multilocus Sequence Typing for Studying Genetic Relationships among Yersinia Species

ABSTRACT The intra- and interspecies genetic relationships of 58 strains representing all currently known species of the genus Yersinia were examined by multilocus sequence typing (MLST), using sequence data from 16S RNA, glnA, gyrB, recA, and Y-HSP60 loci. Yersiniaaldovae, Y. bercovieri, Y. intermedia, Y. pestis, Y. pseudotuberculosis, Y. rohdei, and Y. ruckeri were genetically more homogeneous than were Y. enterocolitica, Y. frederiksenii, Y. kristensenii, and Y. mollaretii. The MLST data concerning the genetic relatedness within and among various species of Yersinia support the idea that Y. pestis and Y. pseudotuberculosis are two lineages within the same species rather than two distinct species. Y. ruckeri is the genetically most distant species within the genus. There was evidence of O-antigen switching and genetic recombination within and among various species of Yersinia. The genetic relatedness data obtained by MLST of the four housekeeping genes and 16S RNA agreed in most, but not all, instances. MLST was better suited for determining genetic relatedness among yersiniae than was 16S RNA analysis. Some strains of Y. frederiksenii and Y. kristensenii are genetically less related to other strains within those species, compared to strains of all other species within the genus. The taxonomic standing of these strains should be further examined because they may represent currently unrecognized Yersinia species.

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

ABSTRACT 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, γ-glutamyl aminopeptidase, α-mannosidase, and α-glucosidase were found to be highly discriminating and could be used to develop an identification scheme.

Bacteremia Due to a Novel Microbacterium Species in a Patient with Leukemia and Description of Microbacterium paraoxydans sp. nov.

ABSTRACT 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 Microbacteriumoxydans but that they belong to a distinct species, for which the name Microbacteriumparaoxydans sp. nov. is proposed. The type strain of M. paraoxydans is CF36T = DSM 15019T. The G+C content of its DNA is 69.9 mol%.

Bacteremic Infection with Pantoea ananatis

ABSTRACT A 73-year-old man was hospitalized for dyspnea and bilateral ankle edema. During his hospital stay he presented anal hemorrhage and developed a high fever after colonoscopy. A set of aerobic and anaerobic blood culture bottles yielded a pure culture of gram-negative rods, susceptible to all antibiotics tested. The API20E code was 1005133, resulting in a very good identification as Pantoea sp. Subsequent sequencing of the 16S rRNA gene revealed a final identification as Pantoea ananatis. The patient was given intravenous and oral therapy with piperacillin-tazobactam and ofloxacin and recovered completely from his infection.

Description of Chryseobacterium anthropi sp. nov. to accommodate clinical isolates biochemically similar to Kaistella koreensis and Chryseobacterium haifense, proposal to reclassify Kaistella koreensis as Chryseobacterium koreense comb. nov. and emended description of the genus Chryseobacterium.

A collection of eight strains, NF 1366(T), NF 450, NF 1101, NF 1107, NF 1123, NF 1413, CCUG 15260 and CCUG 15624, from various clinical origins, were characterized biochemically as similar to Kaistella koreensis and Chryseobacterium haifense. They differed from K. koreensis, which is unable to alkalinize acetate, and from C. haifense, which is ONPG-positive (beta-galactosidase) and acidifies sucrose, fructose and lactose. Based on 16S rRNA gene sequence comparisons, this collection of strains was most closely related to the type strains of K. koreensis (97.3-97.5 %) and C. haifense (99.1 %). Representative strain NF 1366(T) showed only 41.8 % DNA-DNA relatedness with K. koreensis DSM 12107(T) and only 51.9 % with C. haifense DSM 19056(T). DNA-DNA hybridization of strains NF 450 and CCUG 15624 to strain NF 1366(T) was 41.7 and 74.6 %, respectively, and relatedness of these strains with C. haifense DSM 19056(T) was 72.6 and 70.2 %. With the present information, these two strains must be classified as intermediate between C. haifense and strain NF 1366(T). The fatty acid composition and polar lipid profile of strain NF 1366(T) were similar to those reported for other Chryseobacterium species. Like other chryseobacteria, strain NF 1366(T) exhibited a polyamine pattern with the predominant compound sym-homospermidine and a quinone system consisting of menaquinone MK-6 only. For this collection of clinical strains, the name Chryseobacterium anthropi sp. nov. is proposed, with NF 1366(T) (=CCUG 52764(T) =CIP 109762(T)) as the type strain. K. koreensis was shown to be very similar genotypically and phenotypically to Chryseobacterium. Its polar lipid profile exhibited the major characteristics shown for recently described Chryseobacterium species and the fatty acid profile of K. koreensis was also very similar to those of the Chryseobacterium species. Hence, no striking genotypic or phenotypic differences could be found that could justify the classification of this species into a separate genus, and we therefore propose to reclassify Kaistella koreensis in the genus Chryseobacterium as Chryseobacterium koreense comb. nov. (type strain Chj707(T) =IAM 15050(T) =JCM 21512(T) =KCTC 12107(T) =NBRC 103027(T)). An emended description of the genus Chryseobacterium is also proposed.

An outbreak of Ochrobactrum anthropi bacteraemia in five organ transplant patients

Nosocomial bacteraemia caused by Ochrobactrum anthropi occurred over a 1-month period in five organ transplant recipients, four of whom were in the same renal and pancreatic transplant unit. Bacteraemia occurred with cyclosporin A, azathioprine and steroids, and with a rabbit anti-thymocyte globulin (RATG) during the induction phase. RATG appeared to be the only common factor among the five cases. Over the period described, 71.4% of all patients receiving RATG developed O. anthropi bacteraemia. Three patients presented with fever and chills during or shortly after RATG infusion. Analysis of residues of the infusion, and the used vials of RATG, showed the presence of O. anthropi in concentrations of between 20 and 1000 cfu ml-1 in 5.3% of samples. Unused vials were found to be heavily contaminated with either O. anthropi or Microbacterium spp. in 23.5% of samples. All positive vials were of one particular lot number suggesting a malfunction in the manufacturing process. Many parenteral drugs such as the RATG used here do not contain preservatives and, although aseptically prepared, will not withstand thermal sterilization. Bacterial contamination of these small volume medications is not always easily detectable by conventional methods. This outbreak highlights the need for accurate quality control testing to detect small inocula that may occur during or after the manufacturing process.

Epidemiological investigation of a nosocomial outbreak of multidrug-resistant Corynebacterium striatum at one Belgian university hospital

During an 8-month period, 24 Corynebacterium striatum isolates recovered from lower respiratory tract specimens of 10 hospitalized patients were characterized. The organisms were identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) and by 16S rRNA gene sequencing. The cluster of C. striatum exclusively affected patients who had been admitted to an intensive care unit and/or subsequently transferred to one medium-size respiratory care unit. Prolonged duration of hospitalization, advanced stage of chronic obstructive pulmonary disease, recent administration of antibiotics and exposure to an invasive diagnostic procedure were the most commonly found risk factors in these patients. Seven patients were colonized and three infected. All strains displayed a similar broad spectrum resistance to antimicrobial agents, remaining susceptible to vancomycin only. Typing analysis by MALDI-TOF MS and by semi-automated repetitive sequence-based PCR (DiversiLab typing) showed that all outbreak-associated C. striatum isolates clustered together in one single type while they differed markedly from epidemiologically unrelated C. striatum isolates. Pulsed-field gel electrophoresis (PFGE) profiles revealed three distinct PFGE types among the C. striatum isolates associated with the outbreak while all external strains except one belonged to a distinct type. We conclude that C. striatum is an opportunistic nosocomial pathogen in long-term hospitalized patients and can be at the origin of major outbreaks. The routine use of MALDI-TOF MS greatly facilitated the recognition/identification of this organism in clinical samples and this technique could also offer the potential to be used as an easy and rapid epidemiological typing tool for outbreak investigation.