Performance of mass spectrometric identification of clinical Prevotella species using the VITEK MS system: A prospective multi-center study

Prevotella species, members of the human microbiota, can cause opportunistic infections. Rapid and accurate identification of Prevotella isolates plays a critical role in successful treatment, especially since the antibiotic susceptibility profile differs between species. Studies, mostly carried out using the Matrix Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry (MALDI-TOF MS) Biotyper system, showed that MALDI-TOF MS is an accurate, rapid and satisfactory method for the identification of clinically important anaerobes. In this multi-center study, we assessed the performance of the MALDI-TOF MS VITEK MS system for the identification of clinical Prevotella isolates. A total of 508 Prevotella isolates, representing 19 different species, collected from 11 European countries, Kuwait and Turkey between January 2014 and April 2016, were identified using VITEK MS (v3.0). The reliability of the identification was assessed by 16S rRNA gene sequencing. Using VITEK MS, 422 (83.1%) of the 508 isolates were identified on the species level, 459 (90.4%) on the genus level. A total of 49 (9.6%) isolates were not identified correctly. 16S rRNA gene sequencing results showed that this was partly due to the fact that several species were not represented in the database. However, some species that were represented in the database were also not identified. Five Prevotella strains were misidentified at the genus level, 2 of these strains belonged to a species not represented in the database. In general, the VITEK MS offers a reliable and rapid identification of Prevotella species, however the databases needs to be expanded. (C) 2018 Published by Elsevier Ltd

Murdochiella asaccharolytica gen. nov., sp nov., a Gram-stain-positive, anaerobic coccus isolated from human wound specimens

Two strains of previously unknown Gram-stain-positive, anaerobic, coccus-shaped bacteria from human wound specimens were characterized using phenotypic and molecular taxonomic methods. Comparative 16S rRNA gene sequencing studies and distinguishable biochemical characteristics demonstrated that these two unknown strains, WAL 1855C(T) and WAL 2038E, are genotypically homogeneous and constitute a novel lineage within Clostridium cluster XIII. There was 13-14% 16S rRNA gene sequence divergence between the novel strains and the most closely related species, Parvimonas micra, Finegoldia magna and species of Helcococcus. Based on the phenotypic and phylogenetic findings, a novel genus and species, Murdochiella asaccharolytica gen. nov., sp. nov., are proposed. Strain WAL 1855C(T) (=ATCC BAA-1631(T) =CCUG 55976(T)) is the type strain of Murdochiella asaccharolytica

Comparing identification of clinically relevant Prevotella species by VITEK MS and MALDI biotyper

In this multicenter study, we aimed to evaluate the performance of MALDI Biotyper and VITEK MS, for identification of Prevotella species. Three hundred and fourteen clinical isolates, collected in eight European countries between January 2014 and April 2016, were identified at the collecting sites by MALDI Biotyper (versions 3.0 and 3.1) and then reidentified by VITEK MS (version 3.0) in the central laboratory. 16S rRNA gene sequencing was used as a standard method. According to sequence analysis, the 314 Prevotella strains belonged to 19 species. MALDI Biotyper correctly identified 281 (89.5%) isolates to the species level and 33 (10.5%) only at the genus level. VITEK MS correctly identified 253 (80.6%) isolates at the species level and 276 (87.9%) isolates at the genus level. Thirty-three isolates belonging to P. bergensis, P. conceptionensis, P. corporis, P. histicola, and P. nanciensis, unavailable in the VITEK MS 3.0 database, were resulted in genus level or no identification. Six Prevotella strains, belonged to P. veroralis, P. timonensis, and P. conceptionensis not represented in the MALDI Biotyper system database, were misidentified at the genus level. In conclusion, both VITEK MS and MALD1 Biotyper provided reliable and rapid identification. However, the permanent extension of the databases is needed

Antimicrobial susceptibilities of Bacteroides fragilis and Bacteroides thetaiotaomicron strains isolated from clinical specimens and human intestinal microbiota

Species of Bacteroides fragilis group bacteria are the most prevalent pathogens and have the highest resistance rates to antimicrobial agents among anaerobic bacteria. Infections due to these micro-organisms often originate from patient's own intestinal microbiota. The objective of the study was to determine and compare the susceptibility profiles of clinical and intestinal B. fragilis and B. thetaiotaomicron strains against certain antimicrobials. Isolates were identified by conventional methods and API-20 A. Susceptibility tests were performed according to recommendations of NCCLS (M 11-A4) agar dilution methods. Beta-lactamase production was determined with nitrocefin discs. Forty-five clinical isolates (33 B. fragilis and 12 B. thetaiotaomicron) were from following sites: blood (n:8), intra-abdominal abscess (n:7), soft tissue (n:26), and miscellaneous foci of infection (n:4). Fifty B. fragilis and 60 B. thetaiotaomicron isolates from intestinal microbiota of individuals with no history of antimicrobial treatment within last 30 days were also examined. Beta-lactamase production was detected in 93% of clinical and 99% of intestinal isolates. The organisms including intestinal isolates were uniformly susceptible to metronidazole. The MIC90s of other antibiotics and resistance rates of all clinical isolates to those antibiotics were as follows: 256 mug/mL (93%) for ampicillin, 128 mug/mL (13%) for piperacillin, 64 mug/mL (11%) for cefoxitin, 1 mug/mL (2%) for amoxicillin-clavulanate, 0.5 mug/mL (2%) for imipenem, > 256 mug/mL (36%) for clindamycin, 8 mug/mL (2%) for chloramphenicol. Intestinal isolates demonstrated similar resistance rates and MIC90s. Metronidazole, imipenem, amoxicillin-clavulanate seem to be effective drugs against these bacteria in Turkey. (C) 2004 Elsevier Ltd. All rights reserved

Gemella asaccharolytica sp nov., isolated from human clinical specimens

Three strains of an unidentified Gram-stain-variable, fastidious, catalase-negative, capnophilic, non-spore-forming, coccus-shaped bacterium from human wound specimens were characterized by phenotypic and molecular taxonomic methods. Initially, these strains were anaerobic; with repeated culture, they became aerotolerant. Comparative 16S rRNA gene sequencing studies demonstrated that the unknown strains were genealogically homogeneous and constituted a novel subline within the genus Gemella. The unknown bacterium was readily distinguished from other Gemella species by biochemical tests. On the basis of both phylogenetic and phenotypic evidence, it is proposed that the unknown bacterium from clinical specimens be classified as Gemella asaccharolytica sp. nov. The type strain is WAL 1945J(T) (=ATCC BAA-1630(T) =CCUG 57045(T))

Sepsis caused by Anaerococcus nagyae after transarterial- chemoembolization for hepatocellular carcinoma: Case report and literature review

Hepatocellular carcinoma (HCC) is more common in patients with chronic viral hepatitis infection and cirrhosis. Transarterial chemoembolization (TACE) is an effective treatment method for unresectable HCC. A rare complication of TACE is the development of bloodstream infection. We present a fatal case of sepsis due to Anaerococcus nagyae after TACE. (c) 2021 Elsevier Ltd. All rights reserved

Phylotyping and Determining the Antimicrobial Susceptibility of Cutibacterium acnes Isolated from Patients with Acne Vulgaris

Cutibacterium acnes (formerly known as Propionibacterium acnes), obligate anaerobic gram-positive diphtheroid, is a member of normal skin microbiota and frequently isolated from acne lesions and also in various infections as an opportunist pathogen. Within the last decade, distinct phylogroups of C.acnes have been discovered, and specific strains associated with human disease were defined. Increasing resistance to antimicrobials used in the treatment of C.acnes infections has been reported. Resistance rates vary among isolates from different geographic locations. However, knowledge about the antimicrobial susceptibility patterns of C.acnes is limited in Turkey. Determining the phylotypes of C.acnes isolates and providing antimicrobial susceptibility data will be very useful in understanding the pathogenesis of the disease, preventing the development of resistance, and applying rational and effective empirical treatment. The aim of this study was to determine the phylotypes and antimicrobial susceptibility patterns of C.acnes and to investigate the relationship among C.acnes phylotypes, the severity of acne and the antimicrobial resistance. C.acnes isolates cultivated from the acne lesions of 57 patients who admitted to the dermatology outpatient clinic of our university hospital and from the skin of 62 healthy control group in a six-month period were included in the study. The acne lesions on the face and chest/upper back were given a score according to the Global acne grading system (GAGS) for describing the severity of acne. The severity was graded as mild if the score was 1-18, moderate with scores from 19 to 30, severe with scores from 31 to 38, and as very severe if the score is more than 39. The isolates were identified by using matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Phylotype analysis was performed by polymerase chain reaction (PCR) using specific primers. The minimum inhibitory concentrations (MICs) of clindamycin, erythromycin, azithromycin, tetracycline and doxycycline were determined by agar dilution technique recommended by Clinical and Laboratory Standards Institute (CLSI) for anaerobic bacteria. The majority of the isolates (patient; n=47, control; n=47) in both of the patient and control groups were phylotype IA, followed by type IB and type II, respectively and no type III C.acnes was detected. There was no correlation between acne severity and bacterial phylotypes. The resistance rates of clindamycin, erythromycin, azithromycin, tetracycline and doxycycline were found to be 22.8%, 29.8%, 35.2%, 3.5% and 5.3% in the acne patients group, respectively, whereas in the control group the incidence of resistance to these antimicrobials was 11.3%, 21%, 38.7%, 1.6% and 1.6%, respectively. There was no significant difference in antimicrobial resistance between the patient and control groups, except erythromycin (p=0.043, Fisher's exact) as well as no relationship was found between antimicrobial resistance and phylotypes in both of the groups. The number of isolates, resistant to two or more antimicrobials, was higher in the patients with acne. C.acnes isolates were highly resistant to clindamycin, erythromycin and azithromycin. Type IA constituted the majority of the phylotypes. There was no significant relationship between C.acnes phylotype, antimicrobial resistance and acne severity