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PubMed1994

Microbial identification and antibiotic sensitivity testing, an aid for patients refractory to periodontal therapy. A report of 3 cases.

The importance of microbial surveillance is illustrated in 3 clinical cases. Each case demonstrated a continued lack of response to conventional periodontal treatment. Repeated bouts of periodontal abscess formation and bone loss occurred over a 3- to 4-year period, despite numerous surgeries supplemented with antibiotics. As a result, patients were termed refractory to treatment and extensive microbiological analysis and sensitivity testing was performed. Following institution of the appropriate antibiotic and conservative therapy consisting of several sessions of scaling and root planning, each of these cases demonstrated a dramatic remission of disease progression. No further breakdown has been seen for a minimum of 2 1/2 years. While anecdotal in nature, these cases support the usefulness of microbial identification coupled with antibiotic sensitivity as an adjunct to conventional conservative periodontal therapy.

Adult↗
PubMed2000

Detection of emerging resistance patterns within longitudinal surveillance systems: data sensitivity and microbial susceptibility. MYSTIC Advisory Board. Meropenem Yearly Susceptibility Test Information Collection.

Communicating information from antimicrobial resistance surveillance study data to microbiologists and physicians can be challenging. Large amounts of data, commonly reaching millions of MICs or zone diameter endpoints, must be analysed and condensed to easily-read tables or figures. Furthermore, data must not be prejudged relative to susceptibility categories, because of the diverse nature of interpretive criteria available internationally. An attempt must be made to present results of all surveillance studies in a mode that can be reinterpreted for immediate use in different geographical areas, or used to compare future data with relative ease and high accuracy. Such data displays require peer-reviewed journals to permit greater numbers of more complex tables to present results. The Meropenem Yearly Susceptibility Test Information Collection (MYSTIC) study is a year-on-year global surveillance programme in medical centres where meropenem is available for use. We have developed a presentation strategy that expands the long-term clinical value of MYSTIC results. In addition to statistical parameters, tables of cumulative percentages or numbers of strains inhibited at each tested antimicrobial concentration will be presented. Alternative figures (Finland-o-grams) could also be used, but these generally lack precise extractable rates and require more journal space. Regardless of study design, promotion of this presentation philosophy enhances any surveillance study's value to each reader or user and facilitates application to locally appropriate interpretations. The widespread use of these analysis and presentation principles as benchmarks by various resistance studies and networks is strongly encouraged, particularly by investigations across international boundaries.

Anti-Bacterial Agents↗
PubMed1988

Clinical evaluation of a latex agglutination test for streptococcal pharyngitis: performance and impact on treatment rates.

The accuracy and clinical utility of a latex agglutination test were compared with anaerobic throat culture on selective media for detection of Group A streptococcal pharyngitis in an urban pediatric emergency department. Among 255 symptomatic cases prevalence of positive culture was 29% and antigen test sensitivity was 55%. Among 100 asymptomatic controls prevalence of positive culture was 20% and antigen test sensitivity was 20%. Controls with positive cultures and cases with false negative antigen tests had significantly fewer colonies on culture than cases with true positive antigen tests (P less than 0.01). Symptoms and clinical findings were not associated with antigen test result or number of colonies on culture. Eighty percent of patients with positive cultures received treatment when the antigen test was used as an adjunct to culture, compared with a 57% treatment rate among the subgroup in whom follow-up treatment was attempted based on positive culture results alone (P less than 0.05). We conclude that: (1) the antigen test had lower sensitivity in routine clinical use than previously reported; (2) the high rate of false negative tests may result, in part, from a high proportion of specimens with low colony counts; and (3) the availability of the antigen test as an adjunct to culture significantly increased treatment rates.

Adolescent↗
PubMed2000

Comparative genetic and physiological studies of the MAP kinase Mpk1p from Kluyveromyces lactis and Saccharomyces cerevisiae.

MAP kinases are essential components of signal transduction pathways in yeasts and higher eukaryotes. Here, we report on the isolation of the gene encoding the MAP kinase KlMpk1p by complementation of the respective Saccharomyces cerevisiae deletion mutant with a genomic library from Kluyveromyces lactis. Sequencing revealed the presence of an open reading frame capable of encoding a protein of 520 amino acid residues with a deduced molecular mass of 59.726 Da. The deduced protein sequence displayed a high degree of similarity to known MAP kinases from yeast to man, with an overall identity of 70 % to ScMpk1p. One-hybrid analysis demonstrated the presence of a cryptic transcriptional activation domain in the C-terminal part of the protein. Deletion of this sequence in ScMpk1p resulted in a reduced MAP kinase activity (measured by an indirect assay), an increased sensitivity towards caffeine and an increased resistance against Calcofluor white. Complete deletion mutants of Klmpk1 display an osmo-remedial phenotype on rich medium, but are capable of growth in the absence of osmotic stabilization on synthetic medium. As Scmpk1 deletion mutants, they are sensitive to cell surface destabilizing agents such as Calcofluor white and SDS, and growth is inhibited in the presence of 5 mM caffeine. Overexpression of KlMPK1 did not produce a growth defect in S. cerevisiae or in K. lactis.

Amino Acid Sequence↗
PubMed2004

Comparison of dio-bacit, bacitracin-trimethoprim/ sulphamethoxazole and latex agglutination in the diagnosis of Group A beta-hemolytic streptococci.

Not only is Group A beta-hemolytic Streptococcus (GAS) the most frequent cause of bacterial pharyngitis, it is also the culprit in various skin and systemic infections, acute rheumatic fever, post streptococcal glomerulonephritis, and other disorders and complications. A new, ready-to-use media, Dio-Bacit, in a two section plate containing 5% sheep blood agar on one side and sheep blood agar with bacitracin (2 microg/ml) on the other was compared for its efficiency in identifying GAS with bacitracin and bacitracin + sulphamethaxazole / trimethoprim disk tests applied after isolation of beta-hemolytic colonies. We also used the latex-agglutination test as the gold standard method for differentiating GAS from streptococci belonging to other groups. Compared with the latex-agglutination test, we found the sensitivity and specificity of the Dio-Bacit method to be 92.0% and 96.9%, respectively. Dio-Bacit plates provide an easy and very useful way to identify GAS within one day, saving time, labor, and money for routine diagnostic microbiology laboratories.

Adult↗
PubMedDate not supplied

Protection of Xanthomonas against arsenic toxicity involves the peroxide-sensing transcription regulator OxyR.

Arsenic has been shown to mediate its toxicity through induced generation of reactive oxygen species. Here, we examined the role of oxidative stress-inducible genes (katA, ahpC and ohr) and their regulators (oxyR and ohrR) in the response to arsenic treatment in a plant pathogenic bacterium, Xanthomonas campestris pv. phaseoli (Xp). Overproduction of peroxide-scavenging enzymes (KatA, AhpCF and Ohr) did not enhance arsenic tolerance in wild-type Xp. Furthermore, inactivation of katA, ahpC, ohr, and ohrR genes had no effect on the level of arsenic resistance. By contrast, an oxyR mutant (Xp oxyR) showed increased sensitivity to both pentavalent arsenate and, to a greater extent, trivalent arsenite. The resistance of cells to arsenite treatment was significantly affected by the level of iron. Cells were 10-fold more sensitive to arsenite killing in the presence of excess iron, while removal of iron by an iron chelator (2,2'-dipyridyl) protected Xanthomonas from arsenite toxicity. The arsenite-sensitive phenotype of Xp oxyR could be complemented by the expression of functional OxyR from a plasmid vector, but not by the expression of other known OxyR-regulated peroxide-scavenging enzymes such as KatA and AhpCF, Ohr and OhrR. The data suggested that as yet unidentified, OxyR-regulated gene(s) are involved in conferring arsenic resistance in Xp. To our knowledge, this is the first report showing that the peroxide-sensing regulator OxyR is involved in arsenic resistance.

Arsenic↗
PubMed1987

Clinical efficacy and safety of sulbactam/ampicillin in patients suffering from chronic liver disease.

Sulbactam is a new beta-lactamase inhibitor with pharmacokinetic characteristics in humans similar to those of ampicillin. A total of 41 patients hospitalized in the Clinic of Infectious Diseases, University of Naples, for chronic liver diseases, were treated with sulbactam/ampicillin (ratio 1:2) for urinary, respiratory, biliary tract or soft tissue infections. Sulbactam/ampicillin was administered im or iv at a dosage of 3-9 g/day depending on the site and severity of the infection. All the patients treated with sulbactam/ampicillin had clinical signs and symptoms of infection, and all the organisms isolated were sensitive to sulbactam/ampicillin (MIC less than 16 mg/l). For both Gram-positive and Gram-negative bacteria the sulbactam/ampicillin MICs were much lower than the ampicillin MICs. In agreement with the favourable in-vitro results, we observed good therapeutic efficacy. 85% of the patients recovered or improved within a few days of therapy, with no clinical relapses, and in 81% of the infections the responsible bacteria were completely eradicated. We observed a low number of side effects (3/41 oral candidosis; 3/41 pain at the im injection site) and no change in the blood chemistry tests.

Adult↗
PubMed1991

DNA damage by 8-methoxypsoralen plus near ultraviolet light (PUVA) and its repair in Escherichia coli: genetic analysis.

Mutants of Escherichia coli, hyper-resistant and sensitive to 8-methoxypsoralen plus near ultraviolet light (PUVA) have been isolated and studied. Results show that a mutation, located at 57.2 min on the linkage map of E. coli, is responsible for the hyper-resistant phenotype. It is also responsible for the synthesis of a 55-kdal protein in high concentrations. In a wild-type cell the synthesis of this enzyme is inducible by mitomycin C. There are indications that the mutation may have occurred in a regulatory gene, puvR, and as a result the operon, including a putative puvA gene (the structural gene for the synthesis of the 55-kdal protein), is expressed constitutively. A model for the control of the PUV operon is proposed.

Bacterial Proteins↗
PubMed1989

Ticarcillin/clavulanate in severe infections in patients with varying renal function.

The therapeutic efficacy of ticarcillin/clavulanate was assessed in 71 patients with severe infections: 38 acute pyelonephritis, 16 septicaemia and 19 miscellaneous infections. The patients were classified according to their renal function in: Group A, normal (16 cases); B, mild renal impairment (RI) with creatinine clearance (Clcr) between 80 and 40 ml/min (18 cases); C, moderate RI with Clcr between 40 and 15 ml/min (12 cases); D, severe RI with (Clcr) between 15 and 5 ml/min (13 cases) and E, terminal with (Clcr) less than 5 ml/min (12 cases). A total of 105 microorganisms (48.6% resistant to ticarcillin): 31 Pseudomonas aeruginosa, 18 Escherichia coli, 21 other Enterobacteriaceae, 2 Haemophilus influenzae, 10 Bacteroides spp., 14 enterococci, 8 staphylococci and 1 streptococcus, were isolated. All except six Ps. aeruginosa were sensitive to ticarcillin/clavulanate, using 75:10 microgram discs. Bacteriological eradication was obtained in 97% of the cases on the third day and at the end of treatment, and in 82% of the cases after one month. In all the assessable cases, the clinical symptoms disappeared on the third day except in one patient who developed a resistant strain (Klebsiella oxytoca). The wide range of bacteria assessed and the clinical-bacteriological success rates demonstrated that the ticarcillin/clavulanate combination had an efficacy/safety profile that could be considered excellent. Tolerance was good and side effects were not observed. This study confirms the practical efficacy of the recommended dosages derived from our previous kinetic studies in RI.

Adult↗
PubMed1999

DNA polymerase II (polB) is involved in a new DNA repair pathway for DNA interstrand cross-links in Escherichia coli.

DNA-DNA interstrand cross-links are the cytotoxic lesions for many chemotherapeutic agents. A plasmid with a single nitrogen mustard (HN2) interstrand cross-link (inter-HN2-pTZSV28) was constructed and transformed into Escherichia coli, and its replication efficiency (RE = [number of transformants from inter-HN2-pTZSV28]/[number of transformants from control]) was determined to be approximately 0.6. Previous work showed that RE was high because the cross-link was repaired by a pathway involving nucleotide excision repair (NER) but not recombination. (In fact, recombination was precluded because the cells do not receive lesion-free homologous DNA.) Herein, DNA polymerase II is shown to be in this new pathway, since the replication efficiency (RE) is higher in a polB+ ( approximately 0. 6) than in a DeltapolB (approximately 0.1) strain. Complementation with a polB+-containing plasmid restores RE to wild-type levels, which corroborates this conclusion. In separate experiments, E. coli was treated with HN2, and the relative sensitivity to killing was found to be as follows: wild type < polB < recA < polB recA approximately uvrA. Because cells deficient in either recombination (recA) or DNA polymerase II (polB) are hypersensitive to nitrogen mustard killing, E. coli appears to have two pathways for cross-link repair: an NER/recombination pathway (which is possible when the cross-links are formed in cells where recombination can occur because there are multiple copies of the genome) and an NER/DNA polymerase II pathway. Furthermore, these results show that some cross-links are uniquely repaired by each pathway. This represents one of the first clearly defined pathway in which DNA polymerase II plays a role in E. coli. It remains to be determined why this new pathway prefers DNA polymerase II and why there are two pathways to repair cross-links.

DNA Polymerase II↗
PubMed1996

A Saccharomyces cerevisiae mutant defines a new locus essential for resistance to the antitumour drug bleomycin.

The antitumor drug bleomycin can produce a variety of lesions in the cellular DNA by a free radical dependent mechanism. To understand how these DNA lesions are repaired, bleomycin-hypersensitive mutants were isolated from the yeast Saccharomyces cerevisiae. We report here the analysis of one mutant, DRY25, that showed extreme sensitivity to bleomycin. This mutant also exhibited hypersensitivity to hydrogen peroxide and t-butyl hydroperoxide, but showed no sensitivity to other DNA-damaging agents, including gamma-rays, ultraviolet light, and methyl methanesulfonate. Subsequent analysis revealed that strain DRY25 was severely deficient in the repair of bleomycin-induced DNA lesions. Under normal growth conditions, DRY25 displayed a 3-fold increase in the frequency of chromosomal translocation that was further stimulated by 5- to 15-fold when the cells were treated with either bleomycin or hydrogen peroxide, but not by methyl methanesulfonate, as compared with the wild type. Genetic analysis indicated that the mutant defect was independent of the nucleotide excision, postreplication, or recombinational DNA-repair pathways. These data suggest that one conceivable defect of DRY25 is that it lacks a protein that protects the cell against oxidative damage to DNA. A clone that fully complemented DRY25 defect was isolated and the possible roles of the complementing gene are discussed.

Antibiotics, Antineoplastic↗
PubMed2003

Functional analysis of a PcsB-deficient mutant of group B streptococcus.

Group B streptococcus (GBS) is the major cause of bacterial sepsis and meningitis in neonates and poses a significant threat to parturient women. Recently, we identified in GBS the polypeptide PcsB, which is a protein required for cell separation of GBS, and which is also involved in the antibiotic sensitivity of these bacteria. In the present study, the introduction of the pcsB-carrying plasmid pATpcsB into the PcsB-deficient GBS mutant Sep1 restored the phenotype and the antibiotic susceptibility of this strain to that of the GBS wild-type. Although Northern blots revealed a four- to five-fold increased transcription of pcsB in pATpcsB-carrying GBS strains, overexpression of pcsB did not result in higher amounts of PcsB in the cell wall and in the culture supernatant of GBS, indicating regulatory mechanisms that control the translation or secretion of PcsB in these bacteria. In the culture supernatant of mutant Sep1 significant amounts of enolase were identified. As this protein was also present in extracts of cell wall-bound proteins from the GBS wild-type, it can be speculated that GBS can translocate enolase across the cytoplasmic membrane. Northern blot analysis exhibited similar expression of the enolase gene in the GBS strains 6313 and Sep1, indicating that mutant Sep1 is impaired in the anchoring of this protein to its cell wall.

Amino Acid Sequence↗