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Veillonella parvula is a non-motile gram-negative coccus that forms part of the normal microbiota in several body sites and which has been rarely isolated as cause of infections in human population, particularly in bacteremias. Here we give the overview of characteristics of genus Veillonella and the summary of its role in infections, particularly in bacteremia. We additionally report two patients with bacteremia due to V. parvula. Two sets of blood cultures of each patient yielded a pure culture of an anaerobic microorganism identified as V. parvula by MALDI-TOF MS, and confirmed by 16S rRNA gene sequencing. The two patients were male and one of them had risk factors for anaerobic bacteremia. The isolates were susceptible to most antibiotics and the outcome was successful in both patients. Bacteremia due to V. parvula is still rare. MALDI-TOF MS appear to be an excellent tool for the correct identification of these species. • Veillonella spp are uncommon causes of bacteremia. • Veillonellaceae plays a key role in oral biofilm development. • MALDI-TOF MS is a good diagnostic tool for these bacteria. • Antimicrobial susceptibility testing should be performed in cases of bacteremia. [ABSTRACT FROM AUTHOR]

Murdochiella asaccharolytica is a Gram-positive anaerobic coccus firstly isolated from wound specimens, since then, it was very rarely isolated from human infections. We report the first case of bloodstream infection due to this bacterium in a 90 years-old-man. The patient had a history of B-cell lymphoma and presented with pain and induration of the base of penis along with fever. A blood culture was obtained yielding M. asaccharolytica in pure culture. Only resistance to clindamycin was demonstrated. Treatment with metronidazole was started and the clinical evolution improved with antimicrobial treatment, being discharged after 6 days. • Murdochiella was firstly associated with a wound infection. • This is the first case of bacteremia caused by M. asaccharolytica. • MALDI-TOF MS is useful in the diagnosis of new anaerobic pathogens. • It is strongly recommended to report these new infections. [ABSTRACT FROM AUTHOR]

Abstract Bacteroides pyogenes can cause infections in humans. We describe a case of bloodstream infection caused by Bacteroides denticanum that probably originated from a dog bite. MALDI-TOF MS misidentified this new species as B. pyogenes. Subsequent analysis using the 16S rRNA sequencing approach identified the species as B. denticanum. Highlights • Bacteroides denticanum bloodstream infection was described. • MALDI TOF MS misidentified Bacteroides denticanum as Bacteroides pyogenes. • 16S rRNA sequencing is needed for distinguishing between these related species. [ABSTRACT FROM AUTHOR]

We report an uncommon case of bacteremia due to Lancefieldella parvula isolated in pure culture. We present a 72 year-old-man affected with cancer admitted with abdominal pain due to a parietal rupture of the urinary bladder. After surgical treatment, the patient developed fever and two sets of blood cultures yielded a pure culture of an anaerobic microorganism identified as L. parvula (formerly Atopobium parvulum) by MALDI-TOF MS, and confirmed by 16S rRNA gene sequencing. The isolate was susceptible to all antibiotics and the outcome was finally successful. Bacteremia due to L. parvula is an uncommon disease and, in that case, MALDI-TOF MS was an useful tool for the initial identification. • Lancefieldella parvula has been rarely associated with bacteremia. • The patient had some risk factors for anaerobic bacteremia. • MALDI-TOF MS provided a correct species identification. • The isolate showed susceptibility to all antimicrobials. [ABSTRACT FROM AUTHOR]

To report a series of four uncommon cases of bacteremia due to Parabacteroides distasonis. We have analyzed the epidemiological characteristics, clinical features, diagnostic methods, treatment and outcome of these patients. Two sets of blood cultures of each patient yielded a pure culture of an anaerobic microorganism identified as P. distasonis by MALDI-TOF MS, and confirmed by 16S rRNA gene sequencing. All patients were male and they had risk factors for anaerobic bacteremia. All isolates were susceptible to metronidazole and the outcome was successful in three patients. Bloodstream infections due to P. distasonis are still rare. MALDI-TOF MS appear to be an excellent tool for the correct identification. • Parabacteroides distasonis has been rarely associated with bacteremia. • All patients had risk factors for anaerobic bacteremia. • MALDI-TOF MS provided a correct species identification. • All isolates showed resistance to benzylpenicillin. [ABSTRACT FROM AUTHOR]

Prevotella species are Gram-negative anaerobic bacilli mainly involved in oral cavity infections. We report a rare case of bacteremia due to P. oris of probable hepatic origin. A 70-year-old man with a history of diabetes mellitus was admitted for general malaise, fever and dyspnea. The patient was admitted to the ICU due to septic shock. Two sets of blood cultures yielded a pure culture of an anaerobic microorganism identified as P. oris by MALDI-TOF MS. The same microorganism was isolated from a hepatic abscess drainage. Only resistance to penicillin was documented. Treatment with piperacillin-tazobactam and levofloxacin was administered, and the patient was discharged following his recovery. • Prevotella oris has been rarely associated with bacteremia. • The probable source of infection was a hepatic abscess. • 16S rRNA gene sequencing provided the definitive species identification. • This isolate only showed resistance to penicillin. [ABSTRACT FROM AUTHOR]

Porphyromonas species are Gram-negative anaerobic bacilli mainly involved in human periodontal diseases. We report an uncommon case of bacteremia due to P. asaccharolytica in a patient with necrotizing fasciitis. A 52-year-old woman with a history of diabetes mellitus was admitted for an extensive necrotizing lesion on the left lower limb. After she developed septic shock, two sets of blood cultures were taken. Anaerobic bottles yielded a pure culture of a microorganism initially identified as P. uenonis by MALDI-TOF MS but with a low log score, and a gene sequencing technique was therefore applied, identifying the isolate as P. asaccharolytica. Only resistance to penicillin and clindamycin was documented. Treatment with meropenem was administered, and the patient was discharged following her recovery. • Porphyromonas asaccharolytica has been rarely associated with bacteremia. • The probable source of infection was a necrotizing fasciitis. • MALDI-TOF MS is sometimes unable to provide definitive species differentiation. • This isolate only showed resistance to penicillin and clindamycin. [ABSTRACT FROM AUTHOR]

Bacteroides fluxus is a Gram-negative anaerobic bacillus isolated from human faeces in healthy individuals. Until now, this bacterium had not been involved in human diseases. We report the first case of abdominal infection due to this microorganism in an elderly patient. A 76-year-old man with a history of chronic pulmonary obstructive disease presented with dyspnea, orthopnea and cough. The clinical evolution worsened with both a colonic ischemia and further diffuse peritonitis of pancreatic origin. Peritoneal fluid was obtained and the culture yielded B. fluxus in pure culture. Resistance to penicillin, amoxicillin-clavulanate, clindamycin and moxifloxacin was documented. Treatment with meropenem + linezolid was started, but the patient finally died due to a multiorganic failure. • Bacteroides fluxus has never been associated with human infections until now. • This is the first case of abdominal infection caused by this anaerobe in pure culture. • Mass spectrometry and molecular techniques are useful in the diagnosis of anaerobes. • The antimicrobial susceptibility pattern was similar to other Bacteroides strains. [ABSTRACT FROM AUTHOR]

Veillonella dispar is a Gram-negative anaerobic coccus involved in only a few human diseases. We report the second case of bacteremia due to this microorganism in an elderly patient. A 72-year-old man with a history of bladder cancer presented with diarrhea, vomiting, and fever for 48 hours. After the diagnosis of septic shock, four sets of blood cultures were taken, and three of them yielded V. dispar. Resistance to metronidazole, penicillin, and piperacillin-tazobactam was documented. Treatment with clindamycin was started, and the patient was discharged after improvement in his general condition. • Veillonella dispar is rarely associated with bloodstream infections. • This is the second case of bacteraemia caused by this pathogen in pure culture. • Caution should be taken with anaerobes and mass spectrometry. • The strain, as in other published cases, was resistant to metronidazole. [ABSTRACT FROM AUTHOR]

Alistipes spp is a genus of Gram-negative anaerobic rods involved in very few human diseases. We report the first case of abdominal infection due to Alistipes onderdonkii in a 58-year-old man with a history of chronic obstructive pulmonary disease. He presented with abdominal pain and general malaise after retrogastric drainage for a pancreatitis episode a few days earlier. After the diagnosis of diffuse peritonitis with perforation and necrotizing pancreatic collection, abundant pancreatic fluid was drained and yielded the isolation of A. onderdonkii in pure culture. Resistance to penicillin and moxifloxacin was documented for this strain. Treatment with metronidazole was prescribed, and the patient was discharged after improvement of his general condition. • Alistipes genus is rarely associated with human infections. • This is the first case of infection caused by A. onderdonkii in pure culture. • Caution should be taken with anaerobes and MALDI TOF MS. • The strain was only resistant to penicillin and moxifloxacin. [ABSTRACT FROM AUTHOR]