Human infections caused by Brevibacterium casei, formerly CDC groups B-1 and B-3

Dietary resistant starch supplementation increases gut luminal deoxycholic acid abundance in mice

Bile acids (BA) are among the most abundant metabolites produced by the gut microbiome. Primary BAs produced in the liver are converted by gut bacterial 7-α-dehydroxylation into secondary BAs, which can differentially regulate host health via signaling based on their varying affinity for BA receptors. Despite the importance of secondary BAs in host health, the regulation of 7-α-dehydroxylation and the role of diet in modulating this process is incompletely defined. Understanding this process could lead to dietary guidelines that beneficially shift BA metabolism. Dietary fiber regulates gut microbial composition and metabolite production. We tested the hypothesis that feeding mice a diet rich in a fermentable dietary fiber, resistant starch (RS), would alter gut bacterial BA metabolism. Male and female wild-type mice were fed a diet supplemented with RS or an isocaloric control diet (IC). Metabolic parameters were similar between groups. RS supplementation increased gut luminal deoxycholic acid (DCA) abundance. However, gut luminal cholic acid (CA) abundance, the substrate for 7-α-dehydroxylation in DCA production, was unaltered by RS. Further, RS supplementation did not change the mRNA expression of hepatic BA producing enzymes or ileal BA transporters. Metagenomic assessment of gut bacterial composition revealed no change in the relative abundance of bacteria known to perform 7-α-dehydroxylation. P. ginsenosidimutans and P. multiformis were positively correlated with gut luminal DCA abundance and increased in response to RS supplementation. These data demonstrate that RS supplementation enriches gut luminal DCA abundance without increasing the relative abundance of bacteria known to perform 7-α-dehydroxylation.

Brevibacterium Bacteremia in the Setting of Pyogenic Liver Abscess: A Case Report with Accompanying Literature Review

A 71-year-old Pakistani man with poorly controlled type 2 diabetes mellitus presenting with worsening mental status, abdominal pain, and oral intake for the past seven days was found to have pyogenic hepatic abscess with unculturable bacteria and subsequently found to have rare Brevibacterium bacteremia.

Sources and prevention of graft infection during long-term ex situ liver perfusion

INTRODUCTION

The use of normothermic liver machine perfusion to repair injured grafts ex situ is an emerging topic of clinical importance. However, a major concern is the possibility of microbial contamination in the absence of a fully functional immune system. Here, we report a standardized approach to maintain sterility during normothermic liver machine perfusion of porcine livers for one week.

METHODS

Porcine livers (n = 42) were procured and perfused with blood at 34°C following aseptic technique and standard operating procedures. The antimicrobial prophylaxis was adapted and improved in a step-wise manner taking into account the pathogens that were detected during the development phase. Piperacillin-Tazobactam was applied as a single dose initially and modified to continuous application in the final protocol. In addition, the perfusion machine was improved to recapitulate partially the host's defense system. The final protocol was tested for infection prevention during one week of perfusion.

RESULTS

During the development phase, microbial contamination occurred in 27 out of 39 (69%) livers with a mean occurrence of growth on 4 ± 1.6 perfusion days. The recovered microorganisms suggested an exogenous source of microbial contamination. The antimicrobial agents (piperacillin/tazobactam) could be maintained above the targeted minimal inhibitory concentration (8-16 mg/L) only with continuous application. In addition to continuous application of piperacillin/tazobactam, partial recapitulation of the host immune system ex situ accompanied by strict preventive measures for contact and air contamination maintained sterility during one week of perfusion.

CONCLUSION

The work demonstrates feasibility of sterility maintenance for one week during ex situ normothermic liver perfusion.

A Catheter-Related Bloodstream Infection by Brevibacterium casei in a Child with Acute Myeloid Leukemia: Case Report and Literature Review

The most common organisms isolated from pediatric catheter-related bloodstream infections (CRBSIs) are Gram-positive cocci, such as coagulase-negative staphylococci and Staphylococcus aureus. There are few formal reports of Brevibacterium casei infection and even fewer reports of CRBSI due to this Gram-positive rod. Here we report the first case of CRBSI due to B. casei in an 8-year-old girl with acute myeloid leukemia in Japan. The isolate exhibited decreased susceptibility to ß-lactam antibiotics. Antimicrobial therapy with meropenem and vancomycin, in addition to the removal of central venous catheter line, consequently led to a significant clinical improvement of the patient's symptoms. A literature review found available clinical courses in 16 cases (4 pediatric cases including our case) of B. casei infection. Our case and those in literature suggested that B. casei infection often occurs in patients with indwelling central venous catheters; the literature review further suggested that removal of central venous catheters is required in most cases. Special attention should be paid to the detection of opportunistic infections due to Brevibacterium spp. in immunocompromized children who are using a central venous catheter.

Identification and Control of Latent Bacteria in in vitro Cultures of Sweetpotato [Ipomoea batatas (L.) Lam]

Bacterial microorganisms which are latent in in vitro cultures can limit the efficiency of in vitro methods for the conservation of genetic resources. In this study we screened 2,373 accessions from the in vitro sweetpotato germplasm collection of the International Potato Center in Lima, Peru for bacteria associated with plantlets in tissue culture through a combination of morphological methods and partial 16S rDNA sequencing. Bacteria were detected in 240 accessions (10% of the accessions screened) and we were able to isolate 184 different bacterial isolates from 177 different accessions. These corresponded to at least nineteen Operational Taxonomic Units (OTUs) of bacteria, belonging to the genera Sphingomonas, Bacillus, Paenibacillus, Methylobacterium, Brevibacterium, Acinetobacter, Microbacterium, Streptomyces, Staphylococcus, and Janibacter. Specific primers were developed for PCR based diagnostic tests that were able to rapidly detect these bacteria directly from tissue culture plants, without the need of microbial sub-culturing. Based on PCR screening the largest bacterial OTUs corresponded to a Paenibacillus sp. closely related to Paenibacillus taichungensis (41.67%), and Bacillus sp. closely related to Bacillus cereus (22.22%), and Bacillus pumilus (16.67%). Since in vitro plant genetic resources must be microbe-free for international distribution and use, any microbial presence is considered a contamination and therefore it is critical to clean all cultures of these latent-appearing bacteria. To accomplish this, plantlets from in vitro were transferred to soil, watered with Dimanin^® (2 ml/l) weekly and then reintroduced into in vitro. Of the 191 accessions processed for bacterial elimination, 100% tested bacteria-free after treatment. It is suspected that these bacteria may be endosymbionts and some may be beneficial for the plants.

Brevibacterium from Austrian hard cheese harbor a putative histamine catabolism pathway and a plasmid for adaptation to the cheese environment

The genus Brevibacterium harbors many members important for cheese ripening. We performed real-time quantitative PCR (qPCR) to determine the abundance of Brevibacterium on rinds of Vorarlberger Bergkäse, an Austrian artisanal washed-rind hard cheese, over 160 days of ripening. Our results show that Brevibacterium are abundant on Vorarlberger Bergkäse rinds throughout the ripening time. To elucidate the impact of Brevibacterium on cheese production, we analysed the genomes of three cheese rind isolates, L261, S111, and S22. L261 belongs to Brevibacterium aurantiacum, whereas S111 and S22 represent novel species within the genus Brevibacterium based on 16S rRNA gene similarity and average nucleotide identity. Our comparative genomic analysis showed that important cheese ripening enzymes are conserved among the genus Brevibacterium. Strain S22 harbors a 22 kb circular plasmid which encodes putative iron and hydroxymethylpyrimidine/thiamine transporters. Histamine formation in fermented foods can cause histamine intoxication. We revealed the presence of a putative metabolic pathway for histamine degradation. Growth experiments showed that the three Brevibacterium strains can utilize histamine as the sole carbon source. The capability to utilize histamine, possibly encoded by the putative histamine degradation pathway, highlights the importance of Brevibacterium as key cheese ripening cultures beyond their contribution to cheese flavor production.

Brevibacterium otitidis: an elusive cause of neurosurgical infection

Coryneform bacteria are usually considered as non-pathogenic when isolated from clinical specimens. We present a case of Brevibacterium otitidis neurosurgical infection in an immunocompetent patient, and highlight the difficulty with identification and interpretation of antimicrobial susceptibility results for this unusual pathogen.

Brevibacterium casei as a cause of brain abscess in an immunocompetent patient

Coryneform bacteria belonging to the genus Brevibacterium have emerged as opportunistic pathogens. Of the nine known species of Brevibacterium isolated from human clinical samples, Brevibacterium casei is the most frequently reported species from clinical specimens. We report the first case of B. casei brain abscess in an immunocompetent patient successfully treated by surgery and antimicrobial therapy.

Assignment of Brevibacterium stationis (ZoBell and Upham 1944) Breed 1953 to the genus Corynebacterium, as Corynebacterium stationis comb. nov., and emended description of the genus Corynebacterium to include isolates that can alkalinize citrate

Brevibacterium stationis ATCC 14403T, Corynebacterium ammoniagenes ATCC 6872 and two clinical isolates were found to form a single taxon group consistent with the genus Corynebacterium, designated here as Corynebacterium stationis comb. nov. The type strain of Corynebacterium stationis is ATCC 14403T =CCUG 43497T =CIP 104228T =DSM 20302T =NBRC 12144T =JCM 11611T =VKM B-1228T. These strains can utilize citrate; therefore, inclusion of C. stationis requires that the description of the genus Corynebacterium be amended to include citrate-positive strains.

Brevibacterium pityocampae sp. nov., isolated from caterpillars of Thaumetopoea pityocampa (Lepidoptera, Thaumetopoeidae)

This work deals with the taxonomic study of a bacterium, strain Tp12T, isolated from caterpillars of the pine processionary moth (Thaumetopoea pityocampaDenis & Schiffermüller, 1775; Lepidoptera, Thaumetopoeidae). The isolate was assigned to the genusBrevibacteriumon the basis of a polyphasic taxonomic study, including morphological and biochemical characteristics, 16S rRNA gene sequence analysis, fatty acid analysis and DNA G+C content. The highest 16S rRNA gene sequence similarity to this isolate was approximately 96 %, with the type strains ofBrevibacterium albumandBrevibacterium samyangense. Cellular fatty acids of the isolate are of the branched type, with the major components being anteiso-C15 : 0and anteiso-C17 : 0. The DNA G+C content was 69.8 mol%. Although the strain was related toB. albumandB. samyangenseaccording to 16S rRNA gene sequence analysis, it differed from any known species ofBrevibacterium. Based on this evidence, the novel speciesBrevibacterium pityocampaesp. nov. is proposed, with strain Tp12T(=DSM 21720T=NCCB 100255T) as the type strain.

Blockade of neutrophil responses in aspiration pneumonia via ELR-CXC chemokine antagonism does not predispose to airway bacterial outgrowth

Pneumonia associated with aspiration of bacterial-laden gastric contents is characterized by Glu-Leu-Arg (ELR)-CXC chemokine (e.g., CXC2L1, CXCL8) expression leading to local neutrophil sequestration. This neutrophil response is designed to be protective, but overly aggressive responses can be pathogenic in themselves. Herein we assessed whether blocking neutrophil responses in a guinea pig model of aspiration pneumonia would foster airway bacterial growth. Guinea pigs (n=5) were challenged intranasally with saline, acidified saline or acidified gastric contents (35mg/kg body weight, pH 2.0) and treated subcutaneously with 250mug/kg of the human ELR-CXC chemokine antagonist CXCL8((3-72))K11R/G31P (G31P) or saline. After 20h the animals' airway inflammatory responses and bacterial burdens were assessed. A loss of vascular integrity was apparent in the lungs of the saline-treated aspiration pneumonia animals (12.07+/-1.3% of the pleural surfaces exhibited hemorrhagic consolidation, 4.6x10(6) RBC/ml bronchoalveolar lavage fluid [BALF]), as was a pulmonary neutrophilia. The BAL fluids contained gram-negative and -positive bacteria (total load, 6.3+/-3.2x10(7) CFU/ml BALF) that are associated with nosocomial infections in humans. The G31P-treatments attenuated the pulmonary vascular complications (2.27+/-0.5% pleural surface hemorrhagic consolidation, 0.46x10(6) RBC/ml BALF), and reduced the pulmonary neutrophilia by >/=86%. The G31P-treatments did not lead to significant changes in the airway bacterial loads (total load, 3.46+/-1.8x10(7) CFU/ml BALF). This data indicates that attenuation of the pulmonary neutrophil response in aspiration pneumonia reduces pathology very significantly but does not reduce the efficiency of pulmonary bacterial clearance.

Management of long-term catheter-related Brevibacterium bacteraemia

Brevibacterium has been reported as a rare cause of implanted-device infection. In two cases of recurrent Brevibacterium casei bacteraemia associated with infection of surgically implanted intravascular devices, relapse occurred 2 and 5 months, respectively, after completion of therapy with vancomycin via the infected catheter. A second intravenous antibiotic therapy course by the antibiotic-lock technique led to bacteriological cure in one patient. Molecular typing results demonstrated that the recurrent bacteraemia was caused by the same strain. Implanted-device removal may be necessary, in addition to appropriate antibiotics, for successful management of such infections.

Arthrobacter woluwensisSubacute Infective Endocarditis: Case Report and Review of the Literature

We report a case of endocarditis due to Arthrobacter woluwensis and review the published reports of Arthrobacter species isolated from human clinical samples. A 39-year-old injection drug user presented with fever and a new heart murmur. A. woluwensis was isolated from blood cultures, and a diagnosis of subacute infective endocarditis of the native mitral valve was made. The patient was successfully treated with a 6-week course of intravenous teicoplanin. From our review of the literature, we were able to retrieve data on 41 cases of Arthrobacter species isolated from human clinical samples. However, Arthrobacter species was documented as a cause of human disease on only 5 other occasions (2 cases of bacteremia, 1 case of postoperative endophthalmitis, 1 case of a Whipple disease-like syndrome, and 1 case of phlebitis). Because of the difficulty of identifying Arthrobacter strains by conventional biochemical assays, it is likely that infections with these coryneform bacteria are underreported.

Brevibacterium endocarditis: a first report

There are few case reports of infections caused by Brevibacterium species, and there have been no previously reported cases of endocarditis caused by any of the 6 known species of Brevibacterium. We report the first case of Brevibacterium endocarditis (caused by Brevibacterium otitidis) in a patient with prosthetic heart valves. The patient responded to 6 weeks of treatment with vancomycin and 2 weeks with gentamicin, and she has been receiving long-term maintenance therapy with oral azithromycin.

Brevibacterium casei sepsis in an 18-year-old female with AIDS

Brevibacterium sp. was isolated from the blood of an acutely ill 18-year-old female with AIDS. The isolate was identified as Brevibacterium casei by use of carbohydrate assimilation tests. Treatment was successful with intravenously administered ciprofloxacin. To our knowledge, this is the first report of sepsis caused by B. casei in a human immunodeficiency virus-infected patient.

Prospective study of catalase-positive coryneform organisms in clinical specimens: identification, clinical relevance, and antibiotic susceptibility

During a 6-month period, all clinical isolates of catalase-positive coryneform organisms, which were isolated during the routine processing of clinical specimens, were characterized in the laboratory of the 1800-bed University Hospital of Leuven. The distribution of the species in the corynebacteria was: Corynebacterium amycolatum 70 (53%), Corynebacterium jeikeium 16 (12%), Corynebacterium striatum 11 (8%), Corynebacterium afermentans 10 (7%), Corynebacterium minutissimum 9 (6%), CDC coryneform group G 4 (3%), Corynebacterium urealyticum 4 (3%), Corynebacterium glucuronolyticum 1 (0.7%), and Corynebacterium xerosis 1 (0.7%). Of the 150 isolates, 37 (25%) were considered to be infection related and the remaining 113 (75%) were of questionable clinical significance. Susceptibility of the corynebacteria to 12 antibiotics active against Gram-positive organisms was evaluated. C. amycolatum, C. jeikeium, and C. urealyticum were multiresistant, but all isolates were susceptible to teicoplanin and vancomycin. Most of the C. amycolatum strains, and all strains of C. jeikeium and C. striatum, were susceptible to the vibrocidal compound O/129.

Broviac catheter-related bacteraemias due to unusual pathogens in children with cancer: case reports with literature review

Among 102 episodes of intravenous catheter related bacteraemias documented between January 1989 and July 1996 in children receiving antineoplastic chemotherapy or bone marrow transplantation at G. Gaslini Children's Hospital, Genoa, Italy, were identified seven episodes due to unusual pathogens: Bacillus circulans, Bacillus licheniformis, Brevibacterium casei, Flavimonas oryzihabitans, Porphyromonas asaccharolytica, Comamonas acidovorans and Agrobacterium radiobacter. Susceptibility to different antibiotics of all strains are reported. In all cases catheter removal was required for culture negativization. All episodes were diagnosed in absence of granulocytopenia.

Clinical microbiology of coryneform bacteria

Coryneform bacteria are aerobically growing, asporogenous, non-partially-acid-fast, gram-positive rods of irregular morphology. Within the last few years, there has been a massive increase in the number of publications related to all aspects of their clinical microbiology. Clinical microbiologists are often confronted with making identifications within this heterogeneous group as well as with considerations of the clinical significance of such isolates. This review provides comprehensive information on the identification of coryneform bacteria and outlines recent changes in taxonomy. The following genera are covered: Corynebacterium, Turicella, Arthrobacter, Brevibacterium, Dermabacter. Propionibacterium, Rothia, Exiguobacterium, Oerskovia, Cellulomonas, Sanguibacter, Microbacterium, Aureobacterium, "Corynebacterium aquaticum," Arcanobacterium, and Actinomyces. Case reports claiming disease associations of coryneform bacteria are critically reviewed. Minimal microbiological requirements for publications on disease associations of coryneform bacteria are proposed.

Isolation of Arthrobacter spp. from clinical specimens and description of Arthrobacter cumminsii sp. nov. and Arthrobacter woluwensis sp. nov

Arthrobacter spp. are very widely distributed in the environment (e.g., soil) but have not been described as causing disease in humans. Over a 6-year period, two reference laboratories isolated or received 11 strains which were eventually identified as belonging to the genus Arthrobacter. These strains had been initially identified as Centers for Disease Control and Prevention coryneform group B-1 and B-3 bacteria (whitishgrayish colonies of 2 mm or greater in diameter after 24 h of incubation, respiratory metabolism, absent or weak acid production from sugars, and hydrolysis of gelatin). However, chemotaxonomic investigations revealed lysine as the diamino acid of the cell wall and the presence of branched cellular fatty acids (with anteiso-pentadecanoic acid predominating) which was compatible with an assignment of the 11 isolates to the genus Arthrobacter only. Peptidoglycan and 16S rRNA gene sequence analyses demonstrated that three of the strains studied were representatives of a new Arthrobacter species for which the name Arthrobacter cumminsii sp. nov. is proposed and that one other strain represented a second new Arthrobacter species for which the name Arthrobacter woluwensis sp. nov. is proposed. This report is the first on the isolation of Arthrobacter spp. from clinical specimens.

An identification scheme for rapidly and aerobically growing gram-positive rods

An identification scheme for aerobically growing Gram-positive rods (genera Actinomyces, Arcanobacterium, Aureobacterium, Bacillus, Brevibacterium, Cellulomonas, Corynebacterium, Dermabacter, Erysipelothrix, Gardnerella, Lactobacillus, Listeria, Microbacterium, Oerskovia, Propionibacterium, Rhodococcus, Rothia, Turicella, as well as unnamed CDC groups, Clostridium tertium, and Mycobacterium fortuitum/chelonae) is presented. It is derived from the Hollis-Weaver scheme and uses catalase, oxidative/fermentative carbohydrate metabolism and motility as primary reactions. Tests for lipophilism, nitrate reduction, urease, esculin hydrolysis, the CAMP reaction, acid formation from five carbohydrates, as well as for some facultative reactions should lead to a correct diagnosis based on information available at the end of 1995.

Recurrent bacteremia due to Brevibacterium casei in an immunocompromised patient

A case of an immunocompromised patient who experienced two episodes of septicemia caused by a coryneform bacterium is reported. Biochemical characteristics and analysis of cellular fatty acids and of cell wall components showed two identical strains of Brevibacterium casei to be responsible for these infections. The lack of easy-to-perform methods for identification may have led, in the past, to an underestimation of the role of this bacterium, especially in immunocompromised patients.

Evaluation of the applicability of amplified rDNA-restriction analysis (ARDRA) to identification of species of the genus Corynebacterium

The 16S rRNA genes (rDNA) of 50 strains belonging to 26 different coryneform bacterial species and genomospecies and of the type strain of Rhodococcus equi were enzymatically amplified. Amplified rDNA restriction analysis (ARDRA) with the enzymes AluI, CfoI and RsaI was carried out. The combination of the ARDRA patterns obtained after restriction with these three different enzymes enabled the differentiation between the following species: Corynebacterium accolens (number of strains = 2), C. afermentans subsp. afermentans (2), C. afermentans subsp. lipophilum (2), C. amycolatum (3), CDC coryneform group ANF-1-like (1), CDC coryneform group ANF-3-like (1), C. cystitidis (1), C. diphtheriae (4), C. jeikeium (3), C. macginleyi (2), C. minutissimum (1), C. pilosum (1), C. pseudotuberculosis (2), C. renale (2), C. striatum (2), C. urealyticum (3), C. xerosis (1), CDC coryneform groups B-1 (2), B-3 (2), F-1, genomospecies 1 and 2 (6), G, genomospecies 1 (1) and G, genomospecies 2 (2). The following strains or species could not be differentiated from each other: C. pseudodiphtheriticum (2) from C. propinquum (former CDC coryneform group ANF-3) (2), CDC coryneform group F-1, genomospecies 1 (4) from genomospecies 2 (2) and C. jeikeium genomospecies A (1) from genomospecies C (2). ARDRA may represent a possible alternative for identification of coryneforms, since this technique enabled the identification of most coryneforms tested and since DNA extraction (i.e. cell lysis by boiling), amplification, restriction and electrophoresis can be carried out within 8 hours. This might allow quick identification of C. diphtheriae and other possible pathogens of the genus Corynebacterium.

Bacteremia caused by Brevibacterium species in an immunocompromised patient

A 46-year-old woman suffering from non-Hodgkin's lymphoma was admitted to the hospital because of high fever. Multiple blood cultures revealed an unusual finding, a Brevibacterium species, which was reisolated 16 days later from the tip of her long-term central venous catheter. This case indicates that Brevibacterium species isolated from normally sterile sites should be considered as a potential pathogen, especially in immunocompromised patients.