Biomedical subjects
Publications and source records attributed to A von Graevenitz.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
The new VITEK 2 system (bioMérieux) was evaluated at two independent sites with the identification card for gram-negative bacilli (ID-GNB card). Of the 845 strains tested, which represented 70 different taxa belonging to either the family Enterobacteriaceae or the nonenteric bacilli, 716 (84.7%) were correctly identified at the species level. Thirty-two (3.8%) additional strains were identified to the species level after the performance of simple, rapid manual tests (oxidase, hemolysis, indole reaction, motility, and pigmentation). For 80 (9.5%) strains, these additional tests did not lead to an identification at the species level but the correct species identification was given among the organisms listed. Only 7 (0.8%) strains were misidentified, and 10 (1.2%) were not identified. Mistakes were randomly distributed over different taxa. Due to the new, more sensitive fluorescence-based technology of the VITEK 2 system, final results were available after 3 h. Since our evaluation was mainly a stress test, it is predicted that the VITEK 2 system in conjunction with the ID-GNB card would perform well under conditions of a routine clinical laboratory in identifying members of the family Enterobacteriaceae and selected species of nonenteric bacteria. This system is a promising, highly automated new tool for the rapid identification of gram-negative bacilli from human clinical specimens.
Throat swabs from 113 healthy individuals from Hamburg, Germany, and Zurich, Switzerland, were investigated for coryneform bacteria with nonselective and selective media. Ninety specimens contained 123 strains. Surprisingly, 76% of them were strains of Corynebacterium durum (47%) and Rothia dentocariosa (29%). Only two were strains of Corynebacterium pseudodiphtheriticum, and none were strains of C. striatum, C. amycolatum, or C. diphtheriae.
Four commercial slides were compared with in-house slides for the detection of immunoglobulin G (IgG) against Bartonella henselae in 58 healthy persons from a rural region by an indirect immunofluorescence assay. MRL-BA slides (MRL Diagnostics, USA) and Virion slides (Virion, Switzerland) with agar-derived Bartonella henselae showed IgG titers of > or = 1:256 in 44.8% and 51.7%, respectively, whereas Bion slides (Bios, Germany), MRL-Vero slides (MRL Diagnostics), and in-house slides with cell-associated Bartonella henselae showed such titers in 3.4%, 5.1% and 3.4%, respectively. The MRL-Vero slides (Bartonella IgG substrate slides, MRL Diagnostics) were further evaluated with 26 patients with cat scratch disease, 20 patients with lymphadenopathy not due to cat scratch disease, 100 blood donors from an urban area, and 120 blood donors from a mixed urban/rural area. In our mixed urban/rural population the IgG titer of 1:256 had a sensitivity of 84.6% and a specificity of 93.4% for the serodiagnosis of cat scratch disease. Seroprevalence was higher in blood donors from the mixed area (50.8%) than from the urban area (37%). MRL-Vero slides were considered useful for the serodiagnosis of cat scratch disease by indirect immunofluorescence and have replaced our in-house system. However, patients with low IgG titers should be retested three to four weeks after initial sampling to demonstrate a possible rise of IgG titers in paired sera.
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.
A total of 678 stool specimens were cultured on four different agars: on xylose-lysine-desoxycholate agar (XLD), MacConkey agar (Mac), MacConkey agar supplemented with xylose (Mac-X), and Hektoen enteric agar (HE). Isolation rates for shigellae were 77% on HE, 86% on Mac and Mac-X, and 91% on XLD. The specificities of the media were 61% for Mac, 75% for HE, and 78% for XLD and Mac-X. After overnight incubation, Mac-X is much easier to read than XLD, which requires incubation for at least 22 hours. Based on these results and also on the practical aspect that incubation for 22-21 hours does not fit well in our schedule, we now use Mac-X whenever shigellae need to be looked for (i.e. mainly patients with recent travel to tropical countries). As compared to our previous procedure the workload in the laboratory could be reduced by about 20%.
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.
Forty-eight clinical strains that were tentatively identified as Corynebacterium minutissimum on the basis of standard biochemical reactions (Hollis-Weaver tables) as well as by the use of the API (RAPID) Coryne system were examined further. Two different groups of strains were observed. The first group (including the type strain of C minutissimum) contained 27 strains showing creamy colonies. These strains grew homogeneously in 6.5% NaCl broth, exhibited DNase activity, were susceptible to the vibriocidal compound O/129, produced succinic acid, and contained mycolic acids. The second group comprised 21 strains with dry colonies. They grew in clumps at the surface of 6.5% NaCl broth, DNase activity was not detected, they were resistant against O/129, produced large amounts of propionic acid, and mycolic acids were not detected. In combination with quantitative DNA-DNA hybridizations, it was demonstrated that strains of the second cluster belonged, in fact, to C amycolatum. Furthermore, it was observed that a few C minutissimum strains may also ferment mannitol. These data indicate that the clinical microbiologist must be careful not to misidentify C amycolatum strains as C minutissimum.