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C Bebear

Publications and source records attributed to C Bebear.

At least 19 recordsLinked to original sources
PubMed1997

Characterization of Mycoplasma hominis mutations involved in resistance to fluoroquinolones.

Fluoroquinolone-resistant mutants of Mycoplasma hominis were selected in vitro from the PG21 susceptible reference strain either by multistep selection on increasing concentrations of various fluoroquinolones or by one-step selection on agar medium with ofloxacin. The quinolone resistance-determining regions (QRDR) of the structural genes encoding the A and b subunits of DNA gyrase were amplified by PCR, and the nucleotide sequences of eight multistep-selected resistant strains were compared to those of susceptible strain PG21. Four high-level resistant mutants that were selected on norfloxacin or ofloxacin contained a C-to-T transition in the gyrA QRDR, leading to substitution of Ser-83 by Leu in the GyrA protein. Analysis of the sequence of the gyrB QRDR of the eight multistep-selected mutants did not reveal any difference compared to that of the gyrB QRDR of the reference strain M. hominis PG21. Similar analyses of eight one-step-selected mutants did not reveal any base change in the gyrA and gyrB QRDRs. These results suggest that in M. hominis, like in other bacterial species, a gyrA mutation at Ser-83 is associated with fluoroquinolone resistance.

Amino Acid Sequence↗
PubMed1997

[Urogenital infections linked to Chlamydia and mycoplasmas].

Chlamydia trachomatis is responsible for urogenital infections, often minimally symptomatic, revealed by their complications. Mycoplasmas, mainly Ureaplasma urealyticum and Mycoplasma hominis, are normal commensal organisms of the genital tract, which sometimes makes it difficult to determine their pathogenicity. However, they are responsible for urogenital infections, and U. urealyticum is a pathogen in male urethris. The laboratory diagnosis is based on specific techniques adapted to these microorganisms. In the case of C. trachomatis, it has benefited from the recent progress in molecular biology techniques. The therapeutic approach is common to both types of organisms: tetracyclines and macrolides are the major antibiotics used in the treatment of these urogenital infections.

Anti-Bacterial Agents↗
PubMed1997

[Comparative in vitro activity of cefepime: multicenter study in Aquitaine].

Over a 6 month-period (1st January to 30th June 1995), the results of antibiotic susceptibility testing routinely performed for beta-lactams against enterobacteria, Pseudomonas aeruginosa, and Acinetobacter in 7 laboratory hospitals of Aquitaine, have been collected and divided in susceptibility profiles. A total of 9269 strains (7323 enterobacteria, 1667 P. aeruginosa, 279 Acinetobacter) have been examined. On the whole, cefepime (91,5%) and ceftazidime (91,7%) were the most active cephalosporins, followed by cefpirome (87,9%) and cefotaxime (80,4%); imipenem was the most active beta-lactam agent (97,4%). When the strains were divided according to their susceptibility profiles, the advantage of cefepime was shown to be related to its excellent activity against enterobacteria: all strains susceptible to cefotaxime and ceftazidime (CTX/CAZ-S) were susceptible to cefepime, as were most of the strains with an intermediate susceptibility or resistant to these drugs (CTX/CAZ-I/R, approximately 5% of the enterobacteria). The latter strains exhibited a phenotype corresponding either to the overproduction of their chromosomal cephalosporinase (approximately 20% of the species belonging to group 3) or to the synthesis of an extended spectrum beta-lactamase (19% of the strains of Klebsiella pneumoniae). Cefepime was active against 93% of the derepressed mutants of enterobacteria, including 3 imipenem resistant isolates of Enterobacter. CAZ-S strains of P. aeruginosa (84%) were usually susceptible to cefepime (80%), as were 6% of the CAZ-I/R strains. CAZ-S strains of A. baumannii (16.3%) were generally susceptible to cefepime (83%), as were 3.2% of the CAZ-I/R strains.

Acinetobacter↗
PubMed1996

Epidemiological study of an outbreak of infection with Staphylococcus aureus resistant to lincosamides and streptogramin A in a French hospital.

A significant increase in the incidence of isolates of methicillin-resistant Staphylococcus aureus (MRSA), that were also resistant to lincosamides and streptogramin A (LSA-MRSA), was observed in a French university hospital. Twenty-seven isolates from the outbreak were characterised, including 17 isolates from a plastic surgery ward and six control strains of MRSA. The strains were examined by antibiotyping and biotyping, and by three molecular methods: plasmid analysis, ribotyping and insertion sequence (IS) typing with IS256 sequence as a probe. Antibiotyping (five antibiotypes) was discriminatory because of the uncommon resistance phenotype of the epidemic strain. Biotyping (three biotypes), DNA plasmid analysis (four profiles) and ribotyping (two profiles) were poorly sensitive, in contrast to IS-typing (12 profiles). By the latter method, a coefficient of similarity (percentage similarity) compared to the predominant IS profile was calculated. Strains with a coefficient of similarity > or = to 82% were considered as highly related to the epidemic strain, while those with a coefficient of similarity < or = to 40% were regarded as distant. Results obtained with the five markers confirmed that an outbreak of hospital infection had occurred in the plastic surgery ward, with spread of the epidemic strain throughout the hospital.

Adult↗
PubMed1996

Epidemiological study of an outbreak due to multidrug-resistant Enterobacter aerogenes in a medical intensive care unit.

In 1993, 63 isolates of Enterobacter aerogenes were collected from 41 patients in a medical intensive care unit (ICU). During the same period, only 46 isolates from 32 patients were collected in the rest of the hospital. All isolates were analyzed by antibiotic resistance phenotype, and 77 representative isolates were differentiated by plasmid restriction analysis, ribotyping, and arbitrarily primed (AP)-PCR. The extended-spectrum beta-lactamases produced by 22 strains were characterized by determination of their isoelectric points and by hybridization of plasmid DNA with specific probes. The isolates were divided into 25 antibiotic resistance phenotypes, either susceptible (group I) or resistant (group II) to aminoglycosides, and exhibited three phenotypes of resistance to beta-lactams: chromosomally derepressed cephalosporinase alone or associated with either extended-spectrum beta-lactamases (mainly of the SHV-4 type) or imipenem resistance. The results of the tests divided the 77 representative isolates (group I, n = 21; group II, n = 56) into 15 plasmid profiles, 14 ribotypes, and 15 AP-PCR patterns. Although the resistant isolates (group II) exhibited different plasmid profiles, ribotyping and AP-PCR analysis demonstrated an identical chromosomal pattern, indicating an epidemiological relatedness. They were mainly found in the medical ICU and occasionally in other units. The susceptible strains (group I) had various and distinct markers and were mainly isolated in units other than the medical ICU. In conclusion, the presence of a nosocomial outbreak in an ICU and the spread of a multidrug-resistant epidemic strain throughout the hospital was confirmed. Ribotyping and AP-PCR represent discriminatory tools for the investigation of nosocomial outbreaks caused by E. aerogenes.

Disease Outbreaks↗
PubMed1996

[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↗
PubMed1996

[Molecular typing by pulsed field gel electrophoresis of Stenotrophomonas maltophilia isolated in a department of hematology].

Stenotrophomonas maltophilia is an important nosocomial pathogen. The increased isolates of S. maltophilia among hematology unit patients led to an epidemiological survey. Over 26 months, 24 strains isolated from 23 patients and an environmental isolate from blood pressure armband have been identified. The isolated were first analysed by the use of phenotypical markers: biotype, antibiotic susceptibility, but the minor differences observed justified a genotypic analysis. Pulsed field gel electrophoresis of genomic DNA was carried with XbaI and DraI restriction endonucleases by contour-clamped homogeneous electric field method (CHEF). The data obtained showed a great genomic diversity within the species S. maltophilia. Nevertheless, the same restriction profile was found for 3 patients and 3 other profiles were obtained for 3 couples of patients hospitalized at the same time. All the other strains isolated from subjects hospitalized during the same period exhibited pulsotypes independent from each other. Compared to biotypes and antibiotic susceptibility, these results indicate field only with non modified primers, and the absence of 460 mutations was confirmed by sequencing. Two isolates P1 and P2, from a transplanted patient were amplified with both primers MCMM and MCMW: sequencing analysis shown the presence of a mixture of strains, one of them harbouring A- > G 1378 mutation. One resistant strain was amplified neither with MCMM nor with MCMW: a C- > T silent mutation at nt 1368 was present. As sequencing analysis confirmed PCR results, discriminative PCR enables isolates to be rapidly assessed for the presence or absence of 460 mutations. Moreover, it can distinguish Met to Val from Met to Ile mutations, and allows the analysis of mixtures of sensitive and resistant strains.

Anti-Bacterial Agents↗
PubMed1995

Epidemiologic and molecular investigations of genital mycoplasmas from women and neonates at delivery.

The rates of colonization by Ureaplasma urealyticum and Mycoplasma hominis were evaluated in 208 women at delivery and in their neonates. Mycoplasmas were isolated from the cervicovaginal specimens of 100 mothers (48.1%) and from the gastric secretions of 40 neonates (19.2%). The prevalences of U. urealyticum and M. hominis were 47.6% and 11.0% in women and 19.2% and 1.0% in neonates, respectively. Premature rupture of membranes was significantly associated with colonization of women by U. urealyticum (P = 0.031), and colonization of their neonates by U. urealyticum (P = 0.002) and/or M. hominis (P = 0.023). Forty-four selected strains of mycoplasmas were further characterized by arbitrarily primed polymerase chain reaction. All strains of U. urealyticum belonged to the parvo biovar of the species. Arbitrarily primed polymerase chain reaction demonstrated the similarity of strains isolated from mother-neonate pairs, confirming the importance of vertical transmission of mycoplasmas at delivery.

Bacterial Typing Techniques↗
PubMed1995

[Molecular typing by pulsed field gel electrophoresis of Pseudomonas (Burkholderia) cepacia isolated from a nosocomial infection].

Because of the emergence of Pseudomonas (Burkholderia) cepacia, isolated among patients from an intensive care unit of the Hôpital Pellegrin (Bordeaux), strains were studied in the aim to determine the source and the mode of transmission of the bacteria. The study was performed on 44 isolates of P. cepacia from 21 patients (23 strains) or from the environment (16 isolates from ventilators and five from the distilled water used for these ventilators). Susceptibility to 23 antibiotics of these strains and endonuclease restriction polymorphism on their total DNA were determined. Pulsed field gel electrophoresis was performed after digestion of the genomic DNA, using three restriction enzymes. Results obtained by analysis of genotypic characteristics demonstrated the clonal origin of the P. cepacia epidemy in the different intensive care units, but did not localize the source of the infection.

Aminoglycosides↗
PubMed1994

Genetic variability among Chlamydia trachomatis reference and clinical strains analyzed by pulsed-field gel electrophoresis.

Pulsed-field gel electrophoresis (PFGE) was applied to Chlamydia trachomatis reference strains representing each of the 18 serovars and to 29 clinical isolates from genital specimens collected in Bordeaux, France, or Malmö, Sweden. Comparison of the fingerprint patterns of the reference strains revealed a high level of polymorphism of the total DNA when SmaI was used (14 profiles), whereas the other enzymes, Sse8387I and ApaI, showed fewer differences. Some serovars, considered to be closely related on the basis of their antigenic determinants located on the major outer membrane protein (MOMP), such as D and Da or I and Ia, were shown to be different after PFGE of their genomic DNAs. However, serovars B and Ba and serovars L2 and L2a had identical patterns after analysis with the three endonucleases. When applied to clinical isolates, which were typed by restriction fragment length polymorphism analysis of the MOMP gene, PFGE allowed the detection of intragenotype polymorphisms and showed the identity of two strains successively isolated from the same patient. This technique seems to be an efficient tool for epidemiological studies when used in addition to serotyping or genotyping by restriction fragment length polymorphism analysis of the MOMP gene.

Bacterial Outer Membrane Proteins↗
PubMed1994

[In situ hybridization of cells infected by Chlamydia trachomatis].

Hybridization in situ of chlamydia trachomatis allows identification of the bacteria. Moreover exact chlamydia trachomatis localization at tissue level can be demonstrated. It seems to us very important to know for instance in conjunctiva were chlamydia trachomatis are located. We used DNA DIGOXIGENIN labelled plasmidic probe of 503 b.p. Detection of chlamydia trachomatis on paraffin embedded cells becomes possible. Specificity is 100% as plasmidic sequence is not found in other bacteria. Sensitivity seems to be good quality on experimental model. At present time, it is under clinical evaluation. This method could complete PCR for chlamydia detection in case of controversial diagnosis.

Chlamydia Infections↗
PubMed1993

Polymerase chain reaction using 16S rRNA gene sequences distinguishes the two biovars of Ureaplasma urealyticum.

Several fundamental phenotypic and genotypic differences have separated strains of the genital mycoplasma Ureaplasma urealyticum into two clusters or biovars. However, the lack of an easily performed and unambiguous test to discriminate between them has hampered investigation of the relationship between these biovars and disease. We determined the 16S rRNA nucleotide sequence of U. urealyticum 27, the serovar 3 standard and representative of the parvo biovar (serovars 1, 3, 6, and 14). This sequence was compared with the published sequence of U. urealyticum T960, which is the type strain and the serovar 8 standard and is representative of the T960 biovar which is composed of the 10 intervening serovars. Homology between the two sequences was 98.8%; differences were exploited to provide primers for biovar-specific polymerase chain reactions (PCRs). The results of these reactions placed all 14 serovar standard strains into the correct biovar. The PCRs were also applied to 10 cloned and 8 noncloned isolates that had been serotyped earlier. For 16 of them, we deduced their biovars from the serotyping data and then confirmed them by PCR. One unpredictable isolate and one nonserotypeable isolate were also classified as to biovar. Thus, we have developed a method for biotyping U. urealyticum that is applicable to both laboratory-adapted strains and wild-type isolates and that is appropriate for testing large numbers of clinical isolates. The amplification by the T960 biovar PCR protocol of DNAs from ureaplasmas of animals and certain Mycoplasma species suggested that the parvo biovar has diverged from the mainstream of the evolution of this clade.

Bacterial Typing Techniques↗
PubMed1993

Evaluation of molecular typing for epidemiological study of Chlamydia trachomatis genital infections.

Molecular typing and serotyping were compared for 150 Chlamydia trachomatis strains isolated from genital sources, belonging to 10 different serovars. Because of the general agreement of the two methods, molecular omp1 genotyping was applied to the epidemiological study of C. trachomatis isolates from genital infections in Bordeaux (France), during a 29-month period. The most prevalent omp1 genotypes were E (51.7%), F (17.3%), D (8.8%), and G (8.4%). Restriction enzyme analysis allowed identification of a serovar D variant (Dv), whereas serovar E strains were homogeneous.

Bacterial Outer Membrane Proteins↗
PubMed1992

In vitro susceptibilities of Mycoplasma genitalium to antibiotics.

The susceptibilities of seven clinical isolates of Mycoplasma genitalium and three strains of Mycoplasma pneumoniae to a variety of antibiotics were examined by an agar dilution method. Macrolides, pristinamycin, and tetracyclines were very active against both species. Sparfloxacin was the most active quinolone tested. None of the 21 antibiotics tested had differential activity toward the two organisms.

Anti-Bacterial Agents↗
PubMed1992

Isolation of genital mycoplasmas from blood of febrile obstetrical-gynecologic patients and neonates.

In a prospective study, 1156 blood specimens collected from hospitalized febrile obstetrical-gynecologic patients and neonates with suspected sepsis, were inoculated into a conventional biphasic culture medium, Castaneda S and cultures incubated aerobically. 15-24 h later the broth cultures were subcultured to specific media for detection of mycoplasmas. Genital mycoplasmas were isolated in 15 samples (taken from 8 women) and in 2 from 1 neonate. Mycoplasmas and members of the family Enterobacteriaceae were the most frequent significant bacteria isolated from adult specimens. Mycoplasma isolations were associated with either postpartum or postabortum febrile infections in women. Four of the neonates, whose mothers were infected, showed respiratory distress at birth; 1 of them had mycoplasmas in the blood. All febrile states in obstetrical or gynecological patients, and in neonates, should routinely lead to blood cultures for detection of mycoplasmas and ureaplasmas.

Adult↗