Turicella otitidis and Corynebacterium auris: 20 years on.

Turicella otitidis and Corynebacterium auris, described as new species 20 years ago, have been isolated mainly from the external ear canal and middle ear fluid. While their taxonomic position has been clearly established, their diagnosis in the routine laboratory is difficult. The question of their pathogenic potential in otitis is still open but might be elucidated better if corynebacteria are speciated more often.

The role of Aeromonas in diarrhea: a review.

The evidence for an enteropathogenic role of Aeromonas spp. is still controversial. This review examines various parameters related to a causative role of Aeromonas and concludes that infraspecific subsets of strains with a particular array of enterotoxin genes are potential enteropathogens. The consequences for stool bacteriology are discussed.

Rothia dentocariosa: taxonomy and differential diagnosis.

As recent external quality control results have shown, the diagnosis of Rothia dentocariosa infection still presents problems for clinical laboratories. This review describes the taxonomy, as well as the chemotaxonomic, morphological and biochemical characteristics, of this organism, and surveys bacteria that may be confused with Rothia dentocariosa.

Aortic homograft endocarditis caused by Rhodotorula mucilaginosa.

Serious infections caused by Rhodotorula spp. are rare and usually occur in immunocompromised people, especially in patients with tumors and long-time use of indwelling central venous catheters. We report a case of Rhodotorula mucilaginosa homograft endocarditis in an otherwise healthy man, which was successfully treated by surgery in combination with amphotericin B and subsequently intraconazole.

In vitro activities of BAL9141, a novel broad-spectrum pyrrolidinone cephalosporin, against gram-negative nonfermenters.

The activities of BAL9141 (formerly Ro 63-9141), a novel pyrrolidinone-3-ylidenemethyl cephalosporin, against 244 strains of gram-negative nonfermenters were evaluated. The overall MIC at which 50% of isolates are inhibited (MIC50) and the overall MIC90 were 2 and 64 microg/ml, respectively, which are similar to those of imipenem, lower than those of the other cephalosporins tested, amoxicillin, and the ticarcillin-clavulanic acid combination, and much higher than those of ciprofloxacin. BAL9141 shows species-dependent activity in vitro against a variety of gram-negative nonfermentative pathogens.

Antimicrobial therapy of infections with aerobic Gram-positive rods.

This review presents data on in vitro susceptibilities of aerobically growing Gram-positive rods and in vivo activities of antibiotics used against Gram-positive rods. While in some instances susceptibility and efficacy are predictable (e.g. penicillin vs. Listeria and microaerophilic coryneforms, or metronidazole vs. Gardnerella) susceptibility testing by dilution techniques seems necessary for many Gram-positive rods as long as they are deemed clinically relevant.

Natural antibiotic susceptibility of recently established coryneform bacteria.

The natural susceptibility of 20 strains each of Brevibacterium casei (formerly CDC coryneform groups B-1 and B-3), Dermabacter hominis (formerly CDC coryneform groups 3 and 5), and Turicella otitidis (formerly coryneform group ANF-1-like) isolated from clinical specimens to 71 antibiotics was investigated. Susceptibility testing was carried out with a microdilution procedure using H medium. All three species were naturally sensitive to tetracyclines, most aminoglycosides, carbapenems, macrolides, lincosamides, glycopeptides, and rifampin. Susceptibility patterns indicating natural resistance to pipemidic acid, sulfamethoxazole, and cotrimoxazole also were found for all three species. Species-dependent discrepancies in susceptibility leading to completely different categorizations (changing from sensitive to resistant or vice versa) were found for some penicillins (e.g., oxacillin and amoxicillin), a few cephalosporins (e.g., ceftibutene), aztreonam, tobramycin, norfloxacin, fleroxacin, trimethoprim, nitrofurantoin, fosfomycin, and fusidic acid. For the majority of antibiotics, Brevibacterium casei was the least susceptible species and Turicella otitidis the most susceptible taxon. The present study describes a database on the natural susceptibility of Brevibacterium casei, Dermabacter hominis, and Turicella otitidis to a wide range of antibiotics. This database can be applied for the validation of susceptibility testing results of these recently established coryneform bacteria.

The corynebacterial flora of the normal human conjunctiva is lipophilic.

Corynebacterial isolates, obtained by selective and non-selective media from conjunctival swabs, were speciated by using two recently developed systems. All 25 strains from 92 individuals, as well as 12 strains from a previous similar study, belonged to lipophilic species. The significance of this unusual finding is discussed.

Can the API (RAPID) Coryne system be used for identification of rapidly growing mycobacteria?

Fifty-six strains of rapidly growing mycobacteria (RGM) and 14 strains of aerobic actinomycetes as quality controls (QC) were tested in the API (RAPID) Coryne system version 2. Both groups yielded codes with low identification scores, considerable overlaps, and similar diagnoses. No species-specific codes were observed. Thus, the system would not be useful for the identification of RGM.

Human infection with Halomonas venusta following fish bite.

Halomonas venusta, a moderately halophilic, nonfermentative gram-negative rod, is reported for the first time as a human pathogen in a wound that originated from a fish bite.

Identification of coryneform bacterial isolates by ribosomal DNA sequence analysis.

Identification of coryneform bacteria to the species level is important in certain circumstances for differentiating contamination and/or colonization from infection, which influences decisions regarding clinical intervention. However, methods currently used in clinical microbiology laboratories for the species identification of coryneform bacteria are often inadequate. We evaluated the MicroSeq 500 16S bacterial sequencing kit (Perkin-Elmer Biosystems, Foster City, Calif.), which is designed to sequence the first 527 bp of the 16S rRNA gene for bacterial identification, by using 52 coryneform gram-positive bacilli from clinical specimens isolated from January through June 1993 at the Mayo Clinic. Compared to conventional and supplemented phenotypic methods, MicroSeq provided concordant results for identification to the genus level for all isolates. At the species level, MicroSeq provided concordant results for 27 of 42 (64.3%) Corynebacterium isolates and 5 of 6 (83.3%) Corynebacterium-related isolates, respectively. Within the Corynebacterium genus, MicroSeq gave identical species-level identifications for the clinically significant Corynebacterium diphtheriae (4 of 4) and Corynebacterium jeikeium (8 of 8), but it identified only 50.0% (15 of 30) of other species (P < 0.01). Four isolates from the genera Arthrobacter, Brevibacterium, and Microbacterium, which could not be identified to the species level by conventional methods, were assigned a species-level identification by MicroSeq. The total elapsed time for running a MicroSeq identification was 15.5 to 18.5 h. These data demonstrate that the MicroSeq 500 16S bacterial sequencing kit provides a potentially powerful method for the definitive identification of clinical coryneform bacterium isolates.

Natural antibiotic susceptibility of Listeria species: L. grayi, L. innocua, L. ivanovii, L. monocytogenes, L. seeligeri and L. welshimeri strains.

OBJECTIVE: To investigate the natural susceptibility to 71 antimicrobial agents of 103 Listeria strains belonging to all known Listeria species (L. monocytogenes (N = 21), L. innocua (N = 21), L. seeligeri (N = 21), L. ivanovii (N = 19), L. welshimeri (N = 11), and L. grayi (N = 10)). METHODS: MICs were determined using a microdilution procedure in H-Medium. RESULTS: All listeriae were naturally sensitive or intermediate to tetracyclines, aminoglycosides, penicillins (except oxacillin), loracarbef, cefazoline, cefaclor, cefotiam, cefoperazone, carbapenems, macrolides, lincosamides, glycopeptides, dalfopristin/quinupristin, chloramphenicol and rifampicin (probably except L. grayi). Listeria spp. were naturally resistant or intermediate to most 'modern' cephalosporins (cefetamet, cefixime, ceftibuten, ceftazidime, cefdinir, cefpodoxime, cefotaxime, ceftriaxone, cefuroxime), aztreonam, pipemidic acid, dalfopristin quinupristin and sulfamethoxazole. Significant differences in natural susceptibility among the species were seen with the quinolones, trimethoprim, co-trimoxazole, rifampicin, fosfomycin and fusidic acid. It seems likely that L. grayi is naturally resistant to all antifolates; the species was least susceptible to rifampicin and most susceptible to quinolones, whereas L. ivanovii was naturally resistant to most quinolones. L. ivanovii was naturally sensitive to fosfomycin, whereas L. innocua and L. monocytogenes were naturally resistant. L. ivanovii was also the most susceptible species to fusidic acid. CONCLUSIONS: The present study describes a database on the natural susceptibility of Listeria spp. to a wide range of antibiotics, which can be used to validate susceptibility testing results of these microorganisms.

Streptobacillus moniliformis endocarditis in an HIV-positive patient.

Streptobacillus moniliformis is the causative agent of rat bite fever, with endocarditis being a rare but well-documented complication. We report the case of an HIV-positive man who acquired S. moniliformis endocarditis through a rat bite. No predisposing cardiac lesion was known. He was treated with ceftriaxone 2 g/day i.v. for 3 weeks, gentamicin 120 mg/day i.v. for 2 weeks and penicillin 24x10(6) units/day for 1 week. At the end of the antibiotic therapy he suffered a generalized Candida albicans infection, which was treated with fluconazole for 1 week. He was subsequently discharged in a satisfactory condition.

False-positive beta-lactamase results with Staphylococcus lugdunensis in the Vitek AutoMicrobic system.

The Vitek AutoMicrobic system in combination with the Gram-positive susceptibility card detects beta-lactamase in staphylococci by utilizing penicillin as the substrate coupled with oxacillin as an inducer. The beta-lactamase activity of 21 clinical isolates and two reference strains of Staphylococcus lugdunensis was determined with this automated system and compared with a liquid nitrocefin assay after induction with oxacillin. Eight (38%) clinical isolates and the reference strain ATCC 49576 of S. lugdunensis showed production of beta-lactamase in both tests. Thirteen (62%) clinical isolates and the type strain ATCC 43809 were nitrocefin-negative. The Vitek AutoMicrobic system reported false-positive beta-lactamase results for 9 of those 13 isolates and for the type strain of S. lugdunensis. Results for disk diffusion (ampicillin) were concordant with the nitrocefin assay. With one exception, the MICs for penicillin of the nitrocefin-negative strains were in the equivocal range of 0.06-0.12 mg/l according to NCCLS. However, none of the nitrocefin-negative and Vitek-positive strains revealed any of the known staphylococcal genes for beta-lactamase as investigated by Southern hybridization, supporting the fact that false-positive beta-lactamase results may occur in the Vitek AutoMicrobic system. We conclude from our data that it may be justified to include S. lugdunensis in the quality control of Vitek cards containing beta-lactamase tests.

Emergence of related nontoxigenic Corynebacterium diphtheriae biotype mitis strains in Western Europe.

We report on 17 isolates of Corynebacterium diphtheriae biotype mitis with related ribotypes from Switzerland, Germany, and France. Isolates came from skin and subcutaneous infections of injecting drug users, homeless persons, prisoners, and elderly orthopedic patients with joint prostheses or primary joint infections. Such isolates had only been observed in Switzerland.

Endocarditis due to Aerococcus urinae: diagnostic tests, fatty acid composition and killing kinetics.

Two cases of Aerococcus urinae endocarditis are reported. The organism is not included in any database of commercial identification systems at this time. Formation of tetrades and positive reactions for leucine arylamidase and beta-glucuronidase pointed strongly to A. urinae. The cellular fatty acid pattern was similar to that of Aerococcus viridans, with predominantly C16:0, C18:1 omega 9c and C18:0; the presence of C18:1 omega 7t differentiated our isolates from A. viridans and can support the diagnosis of A. urinae. Furthermore, susceptibility to penicillin but resistance to cotrimoxazole represents a pattern opposite to that of A. viridans. Minimal inhibition concentrations of gentamicin and netilmicin were < or = 64 mg/l but those of tobramycin were > or = 256 mg/l. Penicillin combined with either gentamicin or netilmicin showed distinct synergy in killing kinetics. These combinations seem to be the appropriate regimen to treat A. urinae endocarditis.

Septicemia caused by dysgonic fermenter 3 in a severely immunocompromised patient and isolation of the same microorganism from a stool specimen.

Dysgonic fermenter 3 (DF-3)-associated bacteremia occurred in a febrile patient with acute myelocytic leukemia during aplasia. Another DF-3 isolate, identical by ribotyping, was grown 10 weeks later from stool collected in the absence of diarrhea. This is the first case in which DF-3 was isolated from blood and stool specimens from the same patient.

Failure to recognize rapidly growing mycobacteria in a proficiency testing sample without specific request--a wider diagnostic problem?

Fifty participants in the Swiss External Quality Control Program in Bacteriology/Mycology received a diagnostic sample containing Mycobacterium fortuitum. Only 31 used some sort of acid-fast stains, and 13 reported the diagnosis of M. fortuitum or rapidly growing mycobacteria. We conclude that the presence of 'rapid growers' in routine bacteriology samples is underestimated, and that acid-fast stains should be performed on suspicious Gram-positive rods.