No abstract

Serologic testing for the presence of antibodies toBartonella henselae is a widely accepted diagnostic procedure for laboratory confirmation of the diagnosis of cat scratch disease (CSD). In this study a commercially available indirect immunofluorescence assay (IFA) based on B. henselae-infected human larynx carcinoma cells (test A) was evaluated. Sera from 42 patients with CSD (20 confirmed by PCR) and 270 sera from healthy controls (consisting of 63 cat owners, 65 individuals whose last close contact with cats was >6 months previously, and 142 persons who had never been exposed to cats) were investigated for antibodies to B. henselae. All patients with CSD had titers of immunoglobulin G (IgG) to B. henselae of 128 or higher (test A; sensitivity, 100%). Of the 270 controls 189 (70%) were seronegative (titer, <64), 38 (14.1%) had titers of 64, 30 (11.1%) had titers of 128, 9 (3.3%) had titers of 256, and 4 (1.5%) had high titers, 512 (test A; specificity, 70%). Of the cat owners and individuals who had never had close contact with cats, 71.4 and 71.12%, respectively, were seronegative, and titers of 64, 128, 256, and 512 were found in 14.3 and 16.2%, 1.6 and 10.5%, 9.5 and 0.7%, and 3.2 and 1.4%, respectively. The sera from the patients and from the first 100 healthy adults without a history of close contact with cats were additionally tested with a second commercially available IFA, based on Vero cells infected withB. henselae and Bartonella quintana (test B). The sensitivity and specificity of test B were 93 and 73%, respectively. For patients with CSD the cross-reactivity betweenB. henselae and B. quintana in this test was 95%. Both systems are highly sensitive but less specific for detection of IgG antibodies to B. henselae in samples from patients with clinically apparent CSD. For detection of IgM antibodies, test A seems to be more sensitive (88%) and more specific (95%) than test B (sensitivity and specificity of 64 and 86%, respectively). The data show that the seroprevalence of antibodies toB. henselae in German individuals is high (30%). Low antibody levels are not sufficient evidence of active or prior infection.

Mycoplasma pneumoniae cells adhering to glass or Parlodion-coated grids were extracted with Triton X-100. The extracted cells showed a cytoskeleton consisting of a rodlike tip structure and a filamentous network in the cytoplasm. The tip structure was up to 300 nm long and -40 nm wide ending at the distal end in a bleb-like structure, and seemed to consist of filaments arranged in parallel, 4.8 ± 0.5 nm wide . In the cytoplasm the filaments formed an irregular lattice. Similar filaments were found in platinum replicated critical-point dried extracted cells. An actinlike nature of the filaments is suggested by some of their properties, but the degree of homology with respect to eucaryotic actin is still unknown . The filaments were sensitive to protease treatment but stable in high molar KCI solutions . They were apparently destroyed by incubation in high molar KI solution, leaving only some parts of the tip structure. Formaldehyde-fixed M. pneumoniae cells treated with Triton X-100 bound rhodamine-labeled phalloidin specifically . Furthermore, they could be stained with antiactin antibodies . Binding of myosin subfragment 1 to the filaments was not observed .In animal and plant cells, microfilaments are involved in motile processes such as cell contraction, cytoplasmic streaming, and pseudopod or filopod formation during amoeboid movement, Information about the arrangement of microfilaments within the cell, their biochemical characteristics, and their role in maintenance of cell shape and cell motility is accumulating (1,25,26) .In contrast to eucaryotic cells, the molecular basis of motility in procaryotic cells is only poorly understood . In the mycoplasmas, the smallest procaryotes known to grow in a cell-free medium, several observations suggest the presence of contractile elements : (a) specialized tip structures and gliding movement in the species M. gallisepticum, M. pneumoniae, and M. pulmonis (7, 9, 27), (b) contractile processes in M . hominis and M. orale, as revealed in microcinematographic studies (7, 8), (c) the possible presence of actin-like proteins in several species including Spiroplasma citri (6,21,24,32).In the present study we use M. pneumoniae to demonstrate the presence and the in situ arrangement of actin-like microfilaments. MATERIALS AND METHODS MycoplasmasU . GOBEL, V. SPETH, and W. BREDT Institute for General Hygiene and Bacteriology, Center for Hygiene, University of Freiburg, and MaxPlanck-Institute for Immunobiology, Freiburg, Federal Republic of Germany M. pneumoniae strain FH was grown in a modified Hayflick medium containing 20% inactivated horse serum, 0.1% glucose, 0.05% thallium acetate and 1000 U/ml penicillin (27) .

To determine the prevalence of bacteremia caused by Bartonella henselae in domestic cats in the region of Freiburg, Germany, we investigated cultures of blood from 100 cats from 89 different households over a 12-month period. B. henselae could be isolated from 13% (13 of 100) of these cats. In eight households with two cats each and in one household with three cats, B. henselae bacteremia was found either in all of the animals or in none of the animals. Positive cultures were more likely to be found for female, young (24 months of age or younger) cats than for male or older cats. Identification of the Bartonella isolates was made by colony morphology, by Gram staining, biochemically by RapID ANA II or Rapid ID 32 A systems, and by whole-cell fatty acid analysis. Differentiation between B. henselae and Bartonella quintana was only possible by 16S rRNA sequencing, enterobacterial repetitive intergenic consensus (ERIC)-PCR, and sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Genomic fingerprinting of the B. henselae isolates by ERIC-PCR yielded two different patterns based on three distinct bands.