T he newly emerging multidrug-resistant yeast Candida auris can cause serious infections and may be underrepresented, as it can be misidentified as other species (e.g., Candida haemulonii, Candida duobushaemulonii, or Saccharomyces cerevisiae) by some biochemical-based testing systems (1-4). Candida auris can be identified using research use only (RUO) libraries on matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) platforms, such as the Biotyper platform (Bruker, Billerica, MA), but may need labor-intensive full-tube extraction procedures (3-5). Our laboratory uses the Biotyper equipped with both FDA-approved and RUO libraries. The RUO library contains three C. auris entries, but the identification of C. auris remains a challenge, and some isolates are never identified by the system. To improve the identification, a novel database, "CMdb," was developed and evaluated on our two Biotyper systems. The CMdb was created using internationally collected yeasts from the CDC (6) and one in-house clinical C. auris isolate. Bruker's protocol was used for database creation, and the direct on-plate extraction method was used for target preparation (7). The CMdb was evaluated on 23 clinical C. auris isolates, 20 CDC strains, 52 isolates of 10 other yeast species, and 28 isolates of 16 bacterial species.

Lactobacilli are normal colonizers of the oropharynx, gastrointestinal tract, and vagina. Infection is rare, but has been reported in individuals with predisposing conditions. Here we describe the case of a woman with pyelonephritis and bacteremia in which Lactobacillus delbrueckii was determined to be the causative agent.

Pseudomonas aeruginosa PAO1 was shown to contain three pyrC sequences. Two of these genes, designated pyrC (PA3527) and pyrC2 (PA5541), encode polypeptides with dihydroorotase (DHOase) activity, while the third, pyrC' (PA0401), encodes a DHOase-like polypeptide that lacks DHOase activity, but is necessary for the structure and function of ATCase. Both pyrC and pyrC2 were cloned and complemented an Escherichia coli pyrC mutant. In addition, pyrC and pyrC2 were individually inactivated in P. aeruginosa by homologous exchange with a mutated allele of each. The resulting mutant strains were prototrophic. A pyrC, pyrC2 double mutant was also constructed, and this strain had an absolute requirement for pyrimidines. The transcriptional activity of pyrC and pyrC2 was measured using lacZ promoter fusions. While pyrC was found to be constitutively expressed, pyrC2 was expressed only in the pyrC mutant background. An in vitro transcriptional/translational system was used to estimate the size of the pyrC2 gene product. The expressed polypeptide was approximately 47 kDa, which is in keeping with the theoretical molecular mass of 48 kDa, making it the largest prokaryotic DHOase polypeptide identified to date. To our knowledge, this is the first report of a true DHOase mutant in P. aeruginosa and also the first confirmation that pyrC2 encodes a polypeptide with DHOase activity.

Paenibacillus infections can be life threatening and are being reported with increasing incidence. There are only a few case reports of infections and are mainly described in patients who are immunocompromised, injection drug users, or those with prosthetic devices. Due to improved testing and identification, it appears that these infections may not be as rare as once perceived. We present a case of a 16-day-old term neonate who presented with status epilepticus and was found to have Paenibacillus thiaminolyticus meningoencephalitis. The patient was successfully treated with a combination of ampicillin and ceftazidime then meropenem. To our knowledge, this is the first reported case of an infant in the United States who survived this serious invasive infection. We also present an option for therapy given the difficulty treating invasive intracranial infections.

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