ABSTRACT
OBJECTIVE: This study was aimed to demonstrate the clinical benefits of rearranged during transfection (RET) genetic screening in patients with apparently sporadic medullary thyroid cancer (MTC) not only to identify the hereditary nature of the disease in the index case but also to discover family members harbouring the same germline mutations (i.e. gene carriers) who are unaware of their condition. CONTEXT: RET genetic screening allowed the identification of germline RET mutations in apparently sporadic MTC resulting in their re-classification as hereditary forms. PATIENTS AND MEASUREMENTS: RET genetic screening was performed in 729 apparently sporadic MTC patients by direct sequencing RET exons 5, 8, 10, 11 and 13-16. Clinical and biochemical evaluation of gene carriers was also performed. RESULTS: We discovered an unsuspected germline RET mutation in 47 of 729 (6·5%) apparently sporadic MTC who were re-classified as hereditary. We found 60 of 146 (41·1%) gene carriers, 35 of whom had biochemical or clinical evidence of MTC. Thirty gene carriers underwent total thyroidectomy and 27 of 30 (90%) were persistently cured after a mean follow-up of 6·0 years. As a further result of RET genetic screening, we observed a significantly higher prevalence of familial medullary thyroid cancer (FMTC) in our series with respect to the largest series of the International RET Consortium (P = 0·0002). CONCLUSIONS: RET genetic screening of patients with apparently sporadic MTC represents a major tool for the preclinical diagnosis and early treatment of unsuspected affected family members and allows the identification of a relevant percentage of hidden FMTC.
Subject(s)
Genetic Testing/methods , Adolescent , Adult , Aged , Aged, 80 and over , Carcinoma/diagnosis , Carcinoma/genetics , Carcinoma, Medullary/congenital , Carcinoma, Neuroendocrine , Female , Humans , Male , Middle Aged , Multiple Endocrine Neoplasia Type 2a/genetics , Neoplastic Syndromes, Hereditary/diagnosis , Neoplastic Syndromes, Hereditary/genetics , Polymerase Chain Reaction , Thyroid Neoplasms/diagnosis , Thyroid Neoplasms/genetics , Young AdultABSTRACT
It has been clearly established that the inoculum size greatly affects the results of antibiotic susceptibility tests performed in both liquid and solid media in standard laboratory growth conditions (i.e. planktonic). Recently methods were developed to perform antibiotic susceptibility tests on bacteria growing in sessile conditions. The present study investigates the effect of the inoculum size on results obtained by these methods. Results show that the inoculum size does not affect tests performed in sessile conditions. A simple and reliable method is proposed to be applied to routine microbiological laboratory procedures.
Subject(s)
Anti-Bacterial Agents/pharmacology , Microbial Sensitivity Tests/methods , Pseudomonas aeruginosa/drug effects , Pseudomonas aeruginosa/growth & development , Staphylococcus aureus/drug effects , Staphylococcus aureus/growth & development , Staphylococcus epidermidis/drug effects , Staphylococcus epidermidis/growth & development , Reproducibility of ResultsABSTRACT
The antibacterial activity of 6 antibiotics towards 10 gram-positive and 6 gram-negative glycocalyx-producing strains, has been evaluated by employing a method which partially simulates the in vivo colonization of prosthetic devices. The results showed that routine antibiotic sensitivity tests are not predictive about the response of the glycocalyx-embedded bacteria, and that prophylaxis may be useful with ofloxacin and clindamycin, before placing a prosthetic device. Once bacterial colonization had already occurred, however, none of the tested antibiotics was able to eradicate the sessile bacterial form. The minimum bactericidal concentration (MBC) values, indeed, were much higher than those determined on the planktonic form, and were much higher than serum and tissue levels that can be reached in vivo.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteria/metabolism , Bacterial Infections/metabolism , Catheters, Indwelling , Microbial Sensitivity Tests , Prostheses and Implants , Bacteria/drug effects , Bacterial Infections/drug therapy , Cell Membrane/metabolism , Microbial Sensitivity Tests/methodsABSTRACT
The effect of the type of sugar used as substrate on the susceptibility of Streptococcus mutans to antibiotics was evaluated. Thirty strains, grown in excess of sucrose (s-MIC) and in excess of glucose (g-MIC), were tested for susceptibility to four cephalosporins. About 21% of the strains were sensitive in the presence of sucrose and resistant in the presence of glucose, whereas only 3% of the strains showed the opposite situation. The mean values of the s-MICs of the four cephalosporins were significantly lower than those of the g-MICs. These findings may also be explained by the synthesis, in excess of sucrose, of insoluble glucan by Streptococcus mutans which increases the interbacterial distance and promotes antibiotic diffusion. Given the susceptibility of Streptococcus mutans grown in excess of sucrose to cefotaxime and cefepime, these antibiotics may be used in the primary prevention of infective endocarditis, when subjects predisposed to endocarditis need invasive dental therapy.
Subject(s)
Anti-Bacterial Agents/pharmacology , Cephalosporins/pharmacology , Glucose/pharmacology , Streptococcus mutans/drug effects , Sucrose/pharmacology , Child , Child, Preschool , Humans , beta-Lactam ResistanceABSTRACT
The percentage of anaerobic micro-organisms in the subgingival microflora represents a simple microbiological index which not only refers to the state but also the risks of periodontal health. The present study aimed to compare two different methods of calculating this index. The study was performed in 45 subjects with moderate gingivitis provoked by the previous application of dental fixtures anchored to both arches. A sample of subgingival microflora was collected from each patient at the level of the vestibular gingival sulcus of the first upper right molar. This was then vortexed, diluted and inoculated in three series of plates. It was chosen to use Walker's culture medium. The total bacterial count was evaluated by incubating the first series of plates in anaerobiosis; the anaerobic bacterial was calculated by subtracting from the total the of facultative aerobic-anaerobic micro-organisms, which in turn was obtained using two methods: the first (method AE) consisted of incubating another series of plates in aerobiosis; the second (method M) involved incubating the last series of plates in anaerobiosis, and adding metronidazole to the culture medium in a solution of 2.5 mg/l. The plates were then kept at 37 degrees C for seven days. The mean percentage of anaerobic microorganisms, given by the percentage ratio between anaerobic and total, relating to the 45 cases studied, was as follows: using method AE: 57.8 +/- 26.3%, and using method M: 40.2 +/- 27.2%. Both figures come close to that proposed and calculated using a much more sophisticated method by Slots, namely 41.5 +/- 19.2% in the event of gingivitis.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Bacteria, Anaerobic/isolation & purification , Gingiva/microbiology , Adolescent , Adult , Bacteria, Anaerobic/drug effects , Colony Count, Microbial/instrumentation , Colony Count, Microbial/methods , Evaluation Studies as Topic , Gingivitis/microbiology , Humans , Metronidazole/pharmacologySubject(s)
Bacillus cereus/enzymology , Dicloxacillin/pharmacology , Penicillinase/biosynthesis , Ampicillin , Bacillus cereus/drug effects , Binding Sites , Binding, Competitive , Carboxylic Acids/pharmacology , Enzyme Induction/drug effects , Kinetics , Mathematics , Optical Rotation , Oxazoles/pharmacology , Protein Binding , Structure-Activity Relationship , Temperature , Time Factors , beta-Lactamase InhibitorsSubject(s)
Bacteria/drug effects , Bacterial Infections/drug therapy , Cephalosporins/pharmacology , Animals , Bacillaceae/drug effects , Bacteroides/drug effects , Cefoperazone , Cephalosporins/therapeutic use , Enterobacteriaceae/drug effects , Male , Mice , Microbial Sensitivity Tests , Propionibacterium/drug effects , Staphylococcus aureus/drug effects , beta-Lactamases/metabolismABSTRACT
On the premise that a microorganism is sensitive or resistant to a chemoantibiotic according to it's concentrations in biological fluids and tissues, the A. examines those methods available in chemoantibiotic titration such as chemical, enzymatic, radio-immunologic, turbidimetric, potentiometric and agar-diffusion methods. By further evaluating the limits and capacities of these different methods, the A. describes in larger detail the agar-diffusion method which is considered more sensitive, practical and efficient. A brief report is made on the possibility of measuring antibiotic association.
Subject(s)
Anti-Infective Agents/analysis , Agar , Diffusion , Hydrogen-Ion Concentration , Methods , Nephelometry and Turbidimetry , Potentiometry , Radioimmunoassay , Tissue DistributionABSTRACT
The microbiological properties of cephapirin, a new semisynthetis cephalosporin, have been studied. This antibiotic, if compared with ampicillin, shows a greater activity against gram positive bacteria, a lack of sensitivity to staphlococcal beta-lactamase, and a lower sensitivity to those produced by gram-negative bacteria. Useful therapeutic of cephapirin levels can be detected in human serum 6 h after administration of 500 and 1,000 mg parenterally.
Subject(s)
Bacteria/drug effects , Cephalosporins/pharmacology , Cephapirin/pharmacology , Ampicillin/blood , Ampicillin/pharmacology , Animals , Bacteria/enzymology , Blood Proteins/metabolism , Cephapirin/blood , Drug Evaluation, Preclinical , Escherichia coli/drug effects , Humans , Hydrolases/pharmacology , Klebsiella pneumoniae/drug effects , Mice , Microbial Sensitivity Tests , Protein Binding , Staphylococcus/drug effectsABSTRACT
We found that nalidixic acid is a good inhibitor of conjugal transfer of R-plasmids and that related compounds show the same properties. We investigated recently synthetized quinolinic molecules. The inhibition was not due to bacterial activity of the compounds against donors, recipients or R transconjugants; in fact, the drug concentrations were twice or four times lower than the M.I.C. values. The new molecules showed a marked inhibitory effect in various R-mating experiments.
Subject(s)
4-Quinolones , Anti-Bacterial Agents/pharmacology , Anti-Infective Agents , Conjugation, Genetic/drug effects , Nalidixic Acid/pharmacology , Quinolines/pharmacology , Quinolones , Ciprofloxacin , Escherichia coli/drug effects , Nalidixic Acid/analogs & derivatives , NorfloxacinABSTRACT
We found it of interest to try to determine a microbiological parameter for the effects that sub-inhibitory doses of a chemotherapeutic agent may have on bacteria. To this end, the antibacterial activity of nalidixic acid was analyzed and our attention was directed to evidence of the production of beta-lactamase by 60 strains. The tests carried out showed that sub-inhibitory concentrations of nalidixic acid, from 2 to 64 times lower than the MIC (minimum inhibitory concentrations), were able to inhibit production of penicillinases in the 14 strains of Staphylococcus spp. tested, while only in 7 of the 21 strains of Gram-negative bacteria. Strains from our collection of beta-lactamase producing bacteria were analyzed, and our results confirmed that nalidixic acid inhibits plasmidic and chromosomic beta-lactamases.
Subject(s)
Gram-Negative Bacteria/enzymology , Gram-Positive Bacteria/enzymology , Nalidixic Acid/pharmacology , beta-Lactamases/biosynthesis , Gram-Negative Bacteria/drug effects , Gram-Positive Bacteria/drug effectsABSTRACT
The validity of nonsimultaneous association of penicillinase-sensitive beta-lactam antibiotics with halogenated isoxazolylpenicillins was tested in various Enterobacteriaceae strains. With several bacterial strains, expecially if producers of beta-lactamase type IV, exposure of either the bacterial suspensions of the brothsupernatant to the isoxazolylpenicillins appears both in vivo and in vitro to reduce the extent of subsequent hydrolysis of penicillinase-sensitive beta-lactam antibiotics.
Subject(s)
Anti-Bacterial Agents/pharmacology , Enterobacteriaceae/drug effects , Isoxazoles/pharmacology , Oxazoles/pharmacology , Penicillinase/pharmacology , Penicillins/pharmacology , Animals , Enterobacteriaceae/enzymology , Halogens/pharmacology , Mice , Microbial Sensitivity Tests , Penicillinase/biosynthesis , beta-Lactams/pharmacologyABSTRACT
Nalidixic acid and two recently synthetized 4-quinolones eliminated F'lac and R-plasmids from E. coli at concentrations of one half or one quarter of the minimum inhibitory concentration (MIC). Two of the three plasmids tested were cured by all derivatives, although with different frequencies. Pefloxacin was the most effective compound compared with the other quinolones and nalidixic acid the least active.
Subject(s)
Escherichia coli/drug effects , Nalidixic Acid/pharmacology , Ofloxacin/pharmacology , Pefloxacin/pharmacology , Plasmids/drug effects , Microbial Sensitivity TestsABSTRACT
Four fluoroquinolones (norfloxacin, ciprofloxacin, ofloxacin, and pefloxacin) were compared with nalidixic acid for their inhibitory effect on conjugal plasmid transfer. The inhibition was observed in mating experiments using various combinations of drugs at subinhibitory concentrations and 3 different plasmids in the E. coli k12 genetic background. Fluoroquinolones inhibited plasmid transfer to a greater extent than nalidixic acid. Ofloxacin and pefloxacin were consistently the most active agents, causing 90 to 100% inhibition of plasmid transfer in all mating systems studied.
Subject(s)
Anti-Infective Agents/pharmacology , Conjugation, Genetic/drug effects , Nalidixic Acid/pharmacology , R Factors/drug effects , Chemical Phenomena , Chemistry , Ciprofloxacin/pharmacology , Escherichia coli/drug effects , Norfloxacin/pharmacology , Ofloxacin/pharmacology , Pefloxacin/pharmacologyABSTRACT
The reliability of bioluminescence assays which employ the luciferin-luciferase ATP-dependent reaction to evaluate bacterial counts was studied, both in vitro and on urine specimens. Bioluminescence and cultural results for the most common urinary tract pathogens were analyzed. Furthermore, the influence of the culture medium, of the assaying method, and of the phase of growth on bioluminescence readings was studied. Results show that Proteus, Providencia, and Morganella strains are not correctly detected, neither in vitro nor in urine samples, by the standard assaying method. The analysis of assaying parameters demonstrated that some modifications to the extraction procedure of bacterial ATP could improve the reliability of this technique.
Subject(s)
Bacteria/isolation & purification , Biological Assay/methods , Adenosine Triphosphate , Bacteria/growth & development , Colony Count, Microbial , False Negative Reactions , Humans , Luminescent Measurements , Urine/microbiologyABSTRACT
The antimicrobial activities of nalidixic acid-cephalexin (ratio 1:1) and cinoxacin-cefadroxil (ratio 1:2) combinations have been evaluated against 396 clinical isolates; many of them were nalidixic acid- or cinoxacin-resistant organisms (MIC greater than or equal to 100 micrograms/ml). We have also tested the nalidixic acid-amoxicillin combination (ratio 1:1) against 225 amoxicillin-resistant bacterial strains (MIC greater than or equal to 800 micrograms/ml). Synergy was found for 62-70% of the Enterobacteriaceae and nonfermenter bacilli tested and for 85-92% of the gram-positive bacterial strains. The 225 clinical isolates resistant to amoxicillin (MIC greater than or equal to 800 micrograms/ml) were synergistically inhibited by the nalidixic acid-amoxicillin combination.