The pneumococcus at the millennium: not down, not out.
In the 12 decades that will have elapsed between the first isolation of the pneumococcus and the coming millennium, much of fundamental biologic importance has been learned from the study of this bacterium and the diseases it causes. Streptococcus pneumoniae is associated with the development of Gram's stain, the Quellung reaction, and many of the fundamentals of immunology. It has also played a significant role in the history of antimicrobial therapy. After a transitory period of euphoria engendered by the improved prognosis of pneumococcal pneumonia resulting from therapeutic advances, recognition that the newer treatments could not bring about the recovery of those sustaining early irreversible physiologic injury led to renewed interest in immunoprophylaxis. Added impetus to this approach has been fostered by the recent rapid increase in the number of pneumococcal isolates resistant to antimicrobial agents and in the magnitude of their resistance. Pneumococcal vaccines are increasingly relevant. (+info)
Accessory DNA in the genomes of representatives of the Escherichia coli reference collection.
Different strains of the Escherichia coli reference collection (ECOR) differ widely in chromosomal size. To analyze the nature of the differential gene pool carried by different strains, we have followed an approach in which random amplified polymorphic DNA (RAPD) was used to generate several PCR fragments. Those present in some but not all the strains were screened by hybridization to assess their distribution throughout the ECOR collection. Thirteen fragments with various degrees of occurrence were sequenced. Three of them corresponded to RAPD markers of widespread distribution. Of these, two were housekeeping genes shown by hybridization to be present in all the E. coli strains and in Salmonella enterica LT2; the third fragment contained a paralogous copy of dnaK with widespread, but not global, distribution. The other 10 RAPD markers were found in only a few strains. However, hybridization results demonstrated that four of them were actually present in a large selection of the ECOR collection (between 42 and 97% of the strains); three of these fragments contained open reading frames associated with phages or plasmids known in E. coli K-12. The remaining six fragments were present in only between one and four strains; of these, four fragments showed no similarity to any sequence in the databases, and the other two had low but significant similarity to a protein involved in the Klebsiella capsule synthesis and to RNA helicases of archaeal genomes, respectively. Their percent GC, dinucleotide content, and codon adaptation index suggested an exogenous origin by horizontal transfer. These results can be interpreted as reflecting the presence of a large pool of strain-specific genes, whose origin could be outside the species boundaries. (+info)
A national audit of the laboratory diagnosis of tuberculosis and other mycobacterial diseases within the United Kingdom.
In order to audit United Kingdom laboratory diagnostic and reference services including novel molecular methods for tuberculosis, a questionnaire was sent to laboratories submitting specimens to the PHLS Mycobacterium Reference Unit (MRU) and regional centres and to the Scottish Mycobacteria Reference Laboratory (SMRL) in 1996-7. Nationally, 67.2% of laboratories responded. Most UK laboratories were fully or conditionally CPA accredited and take part in the NEQAS proficiency scheme. On average only 3.3% of primary samples submitted for mycobacterial diagnosis in 1995 produced a mycobacterial culture from approximately half as many patients (that is, a mean of 1488 specimens producing 49 isolates from 23 patients). Potentially over 380,000 specimens are processed for mycobacteria in the UK each year. The majority of laboratories use 4% NaOH +/- NALC for specimen decontamination. Culture on solid media was used by most laboratories and 62.9% also use liquid media. Most laboratories incubated cultures for eight weeks. Few laboratories use molecular diagnostic methods. Laboratories were most likely to use molecular methods for diagnosing tuberculous meningitis and for specimens from immunocompromised patients, although usage was strongly influenced by cost. Within England and Wales 43.9% (47/107) and 56% (61/109) of laboratories wanted a rapid service for rifampicin resistance detection in M tuberculosis from immunocompetent and immunocompromised patients, respectively. In regard to a tuberculous meningitis service, 80.5% (43/112) and 84.3% (102/121) of laboratories wanted this service for immunocompetent and immunocompromised patients, respectively. The quality of reference services was rated as "very good"/"good" by 85.6% of respondents nationally. Rapid molecular amplification diagnostic services were established at the PHLS MRU for rifampicin drug resistance detection nationally and for tuberculous meningitis at the MRU. (+info)
Student and faculty performance in clinical simulations with access to a searchable information resource.
In this study we explore how students' use of an easily accessible and searchable database affects their performance in clinical simulations. We do this by comparing performance of students with and without database access and compare these to a sample of faculty members. The literature supports the fact that interactive information resources can augment a clinician's problem solving ability in small clinical vignettes. We have taken the INQUIRER bacteriological database, containing detailed information on 63 medically important bacteria in 33 structured fields, and incorporated it into a computer-based clinical simulation. Subjects worked through the case-based clinical simulations with some having access to the INQUIRER information resource. Performance metrics were based on correct determination of the etiologic agent in the simulation and crosstabulated with student access of the information resource; more specifically it was determined whether the student displayed the database record describing the etiologic agent. Chi-square tests show statistical significance for this relationship (chi 2 = 3.922; p = 0.048). Results support the idea that students with database access in a clinical simulation environment can perform at a higher level than their counterparts who lack access to such information, reflecting favorably on the use of information resources in training environments. (+info)
"The branches into which bacteriology is now ramifying" revisited.
The American Society for Microbiology was originally founded in 1899 as the Society of American Bacteriologists. The transition from "bacteriology" to "microbiology" and from an emphasis on the identity of the membership (bacteriologists) to an emphasis on the discipline (microbiology) was a contentious one that occurred in several steps. This article reviews the history and events that accompanied this development. (+info)
Robert Earle Buchanan: an unappreciated scientist.
Robert Earle Buchanan (1883-1973), 19th President of the Society of American Bacteriologists (later American Society for Microbiology), was one of the more important 20th century microbiologists. He was a dominant force in creating the field of bacterial systematics and made significant contributions to microbial physiology. He also numbered a number of influential textbooks. A reasonable conclusion is that Buchanan was a major cultivator of modern microbiology. To justify that assertion, I have four major objectives in this essay: i) a brief biographical review of Buchanan's early life; ii) a brief review of his scientific contributions, many of which go beyond his recognized contributions to bacterial systematics; iii) Buchanan was an important academic administrator who created the microbiology program and fostered a strong graduate education program at Iowa State, iv)finally, I close the essay with a focus on Buchanan's "moral character." (+info)
Improved, low-cost selective culture medium for Actinobacillus actinomycetemcomitans.
Actinobacillus actinomycetemcomitans is considered to be one of the major oral putative pathogens, especially in cases of juvenile periodontitis. This microorganism requires nutritionally complex media for growth, and therefore the media for its primary isolation usually include blood agar or serum in their base. In this study we present a new medium, Dentaid-1, which improves the detection of A. actinomycetemcomitans in periodontal samples. In its composition, blood and serum have been omitted, hence reducing its cost and making it a more restrictive medium against the growth of other microorganisms with high nutritional requirements. The growth yields of pure cultures of the bacteria on Dentaid-1 were comparable to those on nonselective blood agar. Moreover, clinical efficacy was evaluated in subgingival samples from 77 subjects with adult periodontitis. Dentaid-1 detected A. actinomycetemcomitans in 24 subjects, while a previously described tryptic soy-serum-bacitracin-vancomycin agar detected the microorganism in only 19 subjects (79.1%). Dentaid-1 is a low-cost, noninhibitory formula for the improved diagnosis and monitoring of patients subgingivally infected by this important oral putative pathogen. (+info)
Direct identification of Mycobacterium avium complex and Mycobacterium gordonae from MB/BacT bottles using AccuProbe.
We evaluated the ability of the AccuProbe (Gen-Probe, San Diego, Calif.) to detect Mycobacterium gordonae and Mycobacterium avium complex directly in liquid medium flagged positive by the MB/BacT (Organon Teknika Corp., Durham, N.C.). Seventy-one bottles from clinical specimens containing M. gordonae and 34 containing M. avium, confirmed by culture, were tested by direct AccuProbe assay for both organisms after additional incubation for > or = 48 h and centrifugation at 4,500 x g for 15 min. Relative light unit (RLU) values were analyzed using the manufacturer's recommended cutoff of 30,000 RLU and a lower cutoff of 10,000 RLU. Using the 30,000 RLU cutoff, 55 of 71 (77.5%) specimens containing M. gordonae yielded positive results, whereas 28 of 34 (82.3%) M. avium complex specimens were correctly identified by direct probe. No specimens shown by culture to contain either M. gordonae or M. avium complex tested positive with the probe for the opposite organism (100% specificity). When the cutoff was lowered to 10,000 RLU, 67 of 71 M. gordonae (94.4%) and 32 of 34 M. avium complex (94.1%) specimens were correctly identified. This difference was significant for M. gordonae (P = 0.004) but not for M. avium complex (P = 0.26) compared to detection using the recommended RLU cutoff. Specificity was 100% for specimens containing M. gordonae that were tested with the M. avium complex probe using the 10,000 RLU cutoff, whereas specificity for specimens containing M. avium complex tested with the M. gordonae probe was 97%. Using a lower RLU cutoff for determining a positive result using the M. gordonae or M. avium complex probes when testing instrument-positive MB/BacT bottles directly will improve sensitivity without substantially compromising specificity. (+info)