In vitro activity of midecamycin diacetate against Mycoplasma pneumoniae and Chlamydia pneumoniae.
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Anti-Bacterial Agents↗
Biomedical subjects
F Poutiers
Publications and source records attributed to F Poutiers.
Antibiotic susceptibility testing for Chlamydia trachomatis using flow cytometry.
The aim of this study was to compare the effectiveness of two methods of antibiotic susceptibility testing performed on Chlamydia trachomatis-infected cells: a flow cytometric detection method and the standard method, which consists of a microscopic reading of minimal inhibitory concentration (MIC). The L2 reference strain and 13 clinical strains isolated from six patients presenting recurrent infections were tested. McCoy cells infected with an inoculum of 10(5) inclusion forming units (IFU)/ml were incubated with serial dilutions of doxycycline, ofloxacin, and erythromycin. Mean fluorescence intensity (MFI) of cells was determined by flow cytometry after staining of chlamydial inclusions with an anti-Chlamydia fluorescent monoclonal antibody. The end-point values determined by flow cytometry and microscopic reading were equivalent but presented the same imprecision. Calculation of the inhibitory concentration 50 (IC50) by flow cytometry, defined as the antibiotic concentration required to reduce the drug-free control MFI by 50%, allowed a more objective and precise evaluation of antibiotic activity than MIC. Moreover, IC50 values were reproducible, independent of the antibiotic dilution series tested, and could be used to compare the in vitro efficiency of various drugs on C. trachomatis. No resistant strain was found among the 13 clinical isolates of C. trachomatis tested.
Anti-Bacterial Agents↗
[In vitro activity of a new quinolone, NM 394, against Chlamydia trachomatis].
A study of antimicrobial susceptibility of Chlamydia trachomatis was performed with a new quinolone, NM 394 (Laboratoire Dr. Bouchara). Ten C. trachomatis strains of four different genovars (3G, 4E, 2D, IDv) were grown in confluent McCoy cells on coverslips in multidishes (24 wells). For each C. trachomatis strain, two multidishes were prepared, one for MIC, one for MBC. Three inoculum titrated from 100 to 10000 IFU/ml were inoculated into wells. After incubation 48 h at 37 degrees C, the cultures were fixed in methanol and examined for inclusions after staining with fluorescein-conjugated anti-Chlamydia antibody. The MIC was defined as the lowest antibiotic concentration at which no inclusion formation was observed. For the determination of MBC, the culture media was replaced with sucrose phosphate buffer (2SP) and the cultures were incubated without antibiotic for 48 h and stained. The MBC was the lowest antibiotic concentration at which no inclusion formation was observed after one passage without antibiotic. The increase of the inoculum from 10(3) to 10(5) IFU/ml did not affect significantly the activity of NM 394. All strains were inhibited by 16 mg/l of NM 394. The IC 50 and 90 were 2 and 8 mg/l respectively. The MIC and the MBC values were similar.
Anti-Bacterial Agents↗
Detection of mollicute contamination in cell cultures by 16S rDNA amplification.
A polymerase chain reaction (PCR) system was developed for the detection of mollicutes as contaminants of cell cultures. By using three oligonucleotides chosen in the 16S rDNA sequences, two sets of primers able to promote amplification of all Mycoplasma and Ureaplasma (molli1-molli2a) or all Acholeplasma (molli1-molli2b) species examined were determined. This PCR system, first applied to experimentally infected Vero cell lines, was then evaluated for the detection of mollicutes in 86 cell culture samples, comparatively to DNA staining, culture and ELISA. The results obtained by the four techniques were in agreement in 82 cases (36 positive, 46 negative). PCR allowed detection of contamination in one and two cases negative by ELISA and culture, respectively, and confirmed questionable results obtained by DNA staining. As described, PCR seems to be a very convenient tool for routine detection of cell culture contaminants.
Acholeplasma↗
Detection of Mycoplasma hominis antibodies by three different techniques, application to women with pelvic inflammatory disease.
Mycoplasma hominis, a mycoplasma potentially isolated from the genital tract of healthy women, seems to have some role in pelvic inflammatory diseases (PID). Three serologic techniques were developed to detect antibodies to M. hominis: ELISA (IgG, IgM), microimmunofluorescence (MIF) and Western blot. Rabbit and human control sera were used to establish the standard assay conditions. ELISA proved to be more sensitive but less specific than MIF. Cross-reactivity with antibodies to M. pneumoniae existed with ELISA but not with MIF. Twenty six and 60 kDa proteins were responsible for that cross-reactivity, as assessed by Western blot analysis. Among 33 patients with PID, 18 to 35 year old, 67% had antibodies to M. hominis by ELISA and 33% by MIF. Among 52 age comparable healthy women, 44 and 13% were positive for M. hominis by ELISA and MIF respectively. The Western blot analysis showed heterogeneity in the antibody response to M. hominis, but a 76 kDa protein reacted with half of the tested sera. Our study agrees with some role for M. hominis in PID. M. hominis was certainly the primary pathogen in one case, played a role that was probable in seven cases, and possible in three patients.
Adult↗