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Biomedical subjects

H Bianchini

Publications and source records attributed to H Bianchini.

18 recordsLinked to original sources
PubMed2001

Vaginal microflora associated with bacterial vaginosis in nonpregnant women: reliability of sialidase detection.

OBJECTIVE: To determine the prevalence of Gardnerella vaginalis, anaerobic bacteria and Mycoplasma hominis in vaginal specimens of women with and without bacterial vaginosis (BV) as well as to determine the sensitivity and specificity of the direct sialidase assay of vaginal fluid as a rapid test for diagnosing this syndrome. METHODS: Vaginal cultures were obtained from 109 nonpregnant women (mean age 33 +/- 7.1 years), 47 of them with clinical signs of BV (BV+) and 62 of them without BV (BV-). In addition, we determined the vaginal sialidase activity in both groups, which may serve as a feature of this syndrome. RESULTS: Anaerobic bacteria were isolated in 91% and 18% of the BV+ and BV- groups, respectively (p < 0.001). Peptostreptococcus spp., Prevotella bivia and Porphyromonas spp. were strongly associated with BV. P. bivia and Prevotella spp. represented 44% of all the anaerobes isolated in the BV+ group. All the isolated P. bivia strains presented sialidase activity. G. vaginalis and M. hominis were isolated in 76% and 42% of the BV+ and 1% and 0% of the BV- women, respectively (p < 0.001). Mobiluncus morphotypes were observed in 34% of the BV+ and 0% of BV- women. Sensitivity, specificity, positive predictive value and negative predictive value of sialidase activity were 81%, 94%, 90% and 86%, respectively. CONCLUSIONS: Our data demonstrate a strong association between G. vaginalis, M. hominis, and P. bivia and BV. Sialidase activity and Gram stain of vaginal fluid represent accurate methods for diagnosing BV.

Adult↗
PubMed2000

Comparison of several methods to determine methicillin-resistance in Staphylococcus aureus with focus on borderline strains.

We compared the performance of several phenotypic tests to detect methicillin-resistant Staphylococcus aureus, with special focus on borderline strains. The reliability of the agar screen oxacillin and BBL Crystal tests was asserted for all methicillin-susceptible (n = 25), -resistant (n = 29) and borderline beta-lactamase-hyperproducer (n = 10) strains. Whereas these tests failed to detect 4 of 5 rare borderline strains containing few cells with high-level methicillin resistance (i.e., a frequency of 10(-7)-10(-8)), a "two-temperature" disk diffusion method, performed simultaneously at 35 and 42 degrees C, detected all of such strains.

Ampicillin↗
PubMed2000

Effect of supragingival plaque control on subgingival microflora and gingivo-periodontal tissues.

The aim of this study was to carry out a short term evaluation of the effect of supragingival plaque control on the subgingival microflora and gingivoperiodontal tissues in patients with moderate and severe periodontitis. A total of 92 sites from 23 patients were studied; patients ranged between 35 and 60 years of age (x 46.4 +/- 1.71). Plaque Index (PI), Gingival Index (GI), Bleeding on Probing (BP), Probing Depth (PD), and Attachment Level (AL) were measured. Subgingival microflora of the same sites was studied by dark field microscopy, and cultures in non-selective and selective media for Actinobacillus actinomycetemcomitans (Aa), Prevotella intermedia/nigrescens (Pi/n), Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn). The patients were included in a supragingival plaque control program which included oral hygiene training and assessment, and professional control of supragingival plaque and calculus. After 28 days, measurement of clinical parameters and the microbiological study were repeated. The sites were divided according to baseline PD values into: Group 1 (5 mm), Group 2 (6 mm) and Group 3 (> or = 7 mm). Results revealed a significant reduction in PI scores, GI scores, PB and PD in groups 2 and 3. No significant difference in AL was observed in any of the three groups. PI scores were found to decrease significantly in group 1, and GI scores, BP and PD tended to decrease. A significant increase in coccoid cells and a significant decrease in motile rods and spirochetes, both small and total, was observed in groups 2 and 3. Group 1 showed a significant decrease in medium and total spirochetes. At the end of the study, a significant decrease in Pi/n was found in all three groups. Significant decreases were found in Pg and Fn in Groups 3 and 2 respectively. Although it holds true that supragingival plaque control reduced a potentially pathogenic subgingival microbiota, this effect was not sufficient to be compatible with healthy gingivoperiodontal tissues.

Adult↗
PubMed1999

Pharmacokinetics and pharmacodynamics of amoxicillin-sulbactam, a novel aminopenicillin-beta-lactamase inhibitor combination, against Escherichia coli.

We evaluated the pharmacokinetics of amoxicillin-sulbactam (AMX-SUL), a novel drug combination, and its pharmacodynamics against Escherichia coli in 12 volunteers receiving a single oral dose (1, 000 mg). Peak serum bactericidal and urine inhibitory activities in most volunteers were observed against E. coli strains for which AMX-SUL MICs were low (2- to 4-mg/liter) (2 strains) and high (>/=16-mg/liter) (47 strains), respectively.

Adult↗
PubMed1997

Broth disk elution method for anaerobic bacteria: a collaborative study to assess its reliability for clinical purposes.

A collaborative study involving seven laboratories was undertaken to evaluate the reproducibility and the reliability of the broth disk elution test against anaerobic bacteria by comparing with the reference agar dilution method. A two breakpoint broth test was also evaluated. Assays were performed using the same testing conditions (i.e. medium, temperature, atmosphere and incubation time). One hundred Gram-negative and Gram-positive clinical isolates were initially studied. Overall agreement of 98.5% and 97.5%, were found for disk elution and the two breakpoint tests, respectively. In order to assess the reliability of the disk elution test, two different lots (LOT1 and LOT2) of disks of piperacillin and clindamycin were selected, to obtain two final concentrations after dilution (10 and 60 mg/mL; 1 and 4 mg/mL, respectively). Two hundred and eighty assays were performed against one strain of both Bacteroides fragilis(piperacillin MIC, 8.0 mg/mL; clindamycin MIC, <0.5 mg/mL) and Bacteroides thetaiotaomicron(piperacillin MIC, 16.0 mg/mL; clindamycin MIC, <0.5 mg/mL). With LOT 1, considering both species and both antibiotics, the agreement among six laboratories ranged from 85% to 100% (P > 0.05) with the higher concentration. Overall agreement among all laboratories was 91%. No optimal agreement (>90%) for clindamycin-Bacteroides thetaiotaomicron using the LOT1 (77%) was found. Since this finding was not observed with LOT2 (100% agreement), discrepancies were attributed to variation between lots. Overall agreement with LOT2 was 100% for all centres. The present study indicates that the broth disk elution method proved to be a reliable and suitable alternative for routine susceptibility testing for anaerobic bacteria, as a resistance screening method for clinical purposes.

Journal Article↗
PubMed1996

Species belonging to the "Streptococcus milleri" group: antimicrobial susceptibility and comparative prevalence in significant clinical specimens.

The association between the three species belonging to the "Streptococcus milleri" group and different sites of isolation was examined for 73 successive strains recovered from clinically significant, purulent infections. Susceptibility testing was performed on 64 of these strains. The present study supports the association of particular species with different clinical sources. Susceptibility data suggest that emerging penicillin resistance among Streptococcus anginosus and Streptococcus intermedius isolates may represent a potential clinical problem in the therapeutic management of infections caused by these species.

Anti-Bacterial Agents↗
PubMed1995

Detection of high- and moderately high-level resistance to gentamicin and streptomycin in Enterococcus faecium by a disc diffusion method.

We evaluated an agar disc diffusion test for the detection of high-level (> or = 2000 mg/L) and moderately high-level resistance to gentamicin (MIC, > or = 128- < or = 1024 mg/L) and streptomycin (MIC, > or = 256- < or = 1024 micrograms/ml) with 70 clinical isolates of Enterococcus faecium. Results obtained using disks containing 120 micrograms gentamicin and 300 micrograms streptomycin were compared with MICs determined by an agar dilution method. Based on the scattergrams, the closest zone diameter correlations with MIC breakpoints were as follows: susceptible, > or = 16 mm; and resistant, < or = 10 mm, for both streptomycin and gentamicin. No major or very major errors were found with either aminoglycoside using these values. We conclude that agar disk diffusion test can be used to accurately detect high-level or moderately high-level gentamicin and streptomycin resistance in E. faecium.

Anti-Bacterial Agents↗
PubMed1995

[Diarrhea due to microsporidia in a patient with AIDS].

A 26-year-old male AIDS patient with diarrhea of two-months evolution is reported here. The most relevant intestinal pathogens, including Cryptosporidium parvum, were ruled out by routine microbiological tests. Stool samples stained with an "oblong" Ziehl-Neelsen method (fucsin, 7 min instead of 3 min) allowed visualization of organisms resembling microsporidia. Both modified trichrome and calcofluor stains showed organisms compatible with Enterocytozoon bieneusi. Significant titer of antibodies (> or = 1/800) against 4 different microsporidial species were obtained from the serum of the patient by an ELISA test. Clinical improvement was observed after treatment with albendazole, 400 mg twice daily for 4 weeks, even though microsporidial spores were still detected in stool specimens. To our knowledge, this is the first microsporidial infection reported in Argentina.

AIDS-Related Opportunistic Infections↗
PubMed1985

[Specificity against group A, C, and G streptococci of the reverse CAMP test for identifying Clostridium perfringens].

We studied "reverse CAMP" test specificity for the identification of Clostridium perfringens, and the probable existence of cross-reactions with groups A, C and G streptococci. Ninety eight Clostridium strains were tested with ten S. agalactiae, ten S. pyogenes, two group C streptococci and one group G. All the strains of S. agalactiae yielded a positive "reverse CAMP" reaction when it was performed with C. perfringens strains. Cross-reactions were not detected when C. perfringens were tested with groups A, C or G streptococci. The "reverse CAMP" test proved to be specific for all the C. perfringens strains used.

Animals↗
PubMed1985

[Infection of a cerebrospinal fluid shunt system by Bacillus circulans and Bacillus larvae].

A two episodes case of CSF ventriculo-atrial shunt infection due to B. circulans and B. larvae is presented. B. circulans was first isolated from 4 blood cultures and CSF (shunt valve tap). The patient showed a brain damage syndrome reversible with antibiotic treatment. Lethal toxin production was demonstrated for the B. circulans strain in a mouse model. This strain was found to be a variant of Gordon's description as it produced urease and was tolerant to 7% NaCl. The patient recovered after cefotaxime, cotrimoxazole and rifampicin treatment. A second infection due to B. larvae was detected two months later. The shunt system was removed due to obstruction and a scanning electron microscopy study was performed. Confluent masses of white blood cells and rods were observed on the inner surface of the catheter. As for as we know, this is the first case of human infection due to B. larvae.

Adolescent↗
PubMedDate not supplied

[Clostridium difficile diarrhea: frequency of detection in a medical center in Buenos Aires, Argentina].

Clostridium difficile has been recognized as the most important enteric pathogen of nosocomial antibiotic-associated diarrhea (CDAD) in adults from industrialized countries. The importance of C. difficile as a cause of diarrhea in ambulatory patients appears underestimated or under-recognized. Since the 1980's, outbreaks of CDAD have been increasingly reported, but there are few data available in Argentina. We developed a retrospective study to provide some information about CDAD in our country. From July 1998 to November 1999, a total of 245 fecal specimens from hospitalized and some ambulatory patients were tested in order to confirm the diagnosis of CDAD. C. difficile cytotoxin (toxin B) was identified by detecting its cytopathic effect on monolayers of McCoy culture cells. For culture and isolation of C. difficile, stool samples were prepared by ethanol shock prior to plating onto a selective medium which contained blood, cefoxitin and fructose. Of the 245 samples, 14 (5.8%) were identified as positive by the cell cytotoxicity assay. Using the criteria of isolation of cytotoxigenic C. difficile positivity increased to 6.5% (16 samples). Thirteen of the positive results were from hospitalized patients (81.3%) and 3 (18.7%) from outpatients. The mean age of inpatients was 72.9 years (ranging from 47 to 88). All patients had received 2 or more antimicrobial agents (most of them beta-lactams) 2 months before the appearance of diarrhea. There was one patient who had received only chemotherapy. The prevalence of CDAD in this study was less than in others previously reported. This difference may be due to the fact that not all general practitioners include testing for C. difficile when the patient with diarrhea had previously received antibiotics. More educational programs should be directed to all physicians, concerning the role of C. difficile as an important enteric pathogen in patients who have undergone treatment with antimicrobial or chemotherapeutic agents.

Adult↗
PubMedDate not supplied

[Clinical and microbiological study of adult periodontal disease].

The aim of this study was to carry out a microbiological evaluation of sites with and without clinical evidence of moderate and severe periodontitis and their correlation with clinical parameters. A total of 52 disease sites and 10 healthy sites were selected according to clinical criteria. The following clinical indexes were measured for all the sites: plaque index, gingival index, blood on probing, depth on probing and insertion level. Samples of subgingival plaque were collected for culture and for differential counts of microbial morphotypes. In disease sites the most frequently isolated were: Prevotella intermedia/nigrescens (65%), Porphyromonas gingivalis (23%), Actinobacillus actinomycetemcomitans (23%), Fusobacterium nucleatum (10%) and Peptostreptococcus sp. (31%). The aerobic gram-positive microflora was predominant in healthy sites. Significant differences were observed in microbial morphotypes between healthy and disease sites: cocci 18.71% and 78.90%, motile rods 46.12% and 16.70%, total spirochetes 26.48% and 2.80%, respectively. The presence of motile rods, spirochetes and P. intermedia/nigrescens were the parameters with most sensitivity to suspect periodontal disease. There were significant differences in the subgingival microflora between healthy and disease sites in patients with moderate and severe periodontitis.

Actinobacillus Infections↗
PubMedDate not supplied

["In vitro" activity of ten antimicrobial agents against anaerobic bacteria. A collaborative study, 1999-2002].

The antimicrobial activity of ampicillin, ampicillin-sulbactam, cefoxitin, ceftriaxone, imipenem, piperacillin, piperacillin-tazobactam, clindamycin, metronidazole, and azitromycin was assesed against 166 strains of anaerobic bacteria recovered from eight hospitals in Buenos Aires. The strains studied were Bacteroides fragilis group (65), Fusobacterium spp. (26), Prevotella spp. (21), Porphyromonas spp. (10), Clostridium difficile (10), other clostridia (12), and gram-positive cocci (22). The MICs were determined by the agar dilution method according to NCCLS document M11-A5. Metronidazole and piperacillin-tazobactam were the most active antimicrobial agents tested and exhibited MIC90 values of < or = 2 microg/ml and < or = 4 microg/ml against gram-negative organisms, and < or = 2 microg/ml, and < or = 8 microg/ml against gram-positive organisms, respectively. Among beta-lactams the activity against gram-negative rods was in the following order: imipenem > piperacillin > cefoxitin > ceftriaxone > ampicillin. Among the gram-positive bacteria the decreased activity was: piperacillin > imipenem > cefoxitin > ceftriaxone > ampicillin. The majority of the species studied showed different degrees of resistance to clindamycin and azitromycin. Nevertheless, 90% of Fusobacterium nucleatum and Porphyromonas spp. isolates were inhibited by 0.125 mg/ml of clindamycin and azitromycin, respectively.

Anti-Bacterial Agents↗
PubMedDate not supplied

[Non-pigmented Serratia: utility of hydrolysis of Tween 80 in its identification].

The ability of Serratia sp. to hydrolyze Tween 80 and the usefulness of this test for differentiating it from other Gram negative bacilli was studied, comparing it with the capacity of production of DNAsa by the same strains using the O-Toluidine blue method. The total number of strains assayed was 88. The sensitivity obtained was 83.9% and specificity 91.3%, with a positive predictive value of 83.9% and a negative predictive value of 91.2%. Using this method to differentiate only non-pigmented Serratia from Klebsiella sp. and Enterobacter sp. the sensitivity and specificity obtained was 100%. Concerning the cost, this method proved to be 3.86 times cheaper than the DNAsa one.

DNA, Bacterial↗
PubMedDate not supplied

[Utility of pyrrolidonyl-arylamidase detection for typing Enterobacteriaceae and non-fermenting Gram-negative bacteria].

Detection of pyrrolidonyl-aryl-amidase activity (PYR) is an important tool to identify gram-positive cocci, such as staphylococci, enterococci, streptococci, and other related genera. However, only few studies evaluating its usefulness with gram-negative rods have been published. Thus, a prospective study including 542 and 215 unique clinical isolates of Enterobacteriaceae and non-fermentative gram-negative rods, respectively, was undertaken. Strains were identified by conventional methods. PYR test was performed using a commercial kit, according to the manufacturer recommendations. Positive results were uniformly obtained for the PYR test with the following species: Citrobacter spp, Klebsiella spp, Enterobacter aerogenes, Enterobacter agglomerans group, Serratia marcescens and S. odorifera. On the other hand, negative results were uniformly displayed by E. coli (including inactive E. coli), Protease group, Salmonellia spp, Shigella spp, Acinetobacter spp, Burkholderia (Pseudomonas) cepacia and Flavobacterium spp. Variable results were shown in Pseudomonas aeruginosa, Stenotrophomonas (xanthomonas) malthophilia, Kluyvera cryocrescens, and Enterobacter cloacae. PYR test proved to be a reliable and simple tool to rapidly distinguish certain species belonging to Enterobacteriaceae (ie. Citrobacter freundii from Salmonella spp, and inactive E. coli from K. ozaenae). Further studies, including a wide diversity of species, are required to assess usefulness of the PYR test for the identification of non-fermentative gram-negative rods.

Aminopeptidases↗