Blood cultures were taken from 47 patients 1-2 min after dental extraction. These samples were tested by the radiometric Bactec 460 and Oxoid Signal systems for the detection of streptococcal and anaerobic bacteraemias. Streptococci were isolated from 19 (40%) patients and anaerobes from 15 (32%). In this study the Oxoid Signal system was significantly better for isolating oral anaerobes than the Bactec system; five isolates were obtained with the Bactec system and 14 with the Signal system. There was no significant difference in the isolation of streptococci between these two systems (Bactec 14, Oxoid Signal 10). The contamination rate was 4.1% for Bactec and 7.5% for the Oxoid Signal system.

Adult↗

PubMed1992

Clinical comparison of Sentinel, a novel blood culture system, with radiometric Bactec 460 and Isolator 10 in the detection of streptococcal and anaerobic bacteraemias.

AIMS: To compare the performance of the Sentinel blood culture system with two other systems for the recovery of streptococci and anaerobes. METHODS: Blood cultures were taken from 55 patients one to two minutes after dental extraction. The samples were tested by the radiometric Bactec 460; the Isolator 10, which works by lysis centrifugation; and Sentinel, a fully automated system, which detects bacterial growth by changes in the voltage between two electrodes in the media. Positive samples were subcultured and streptococci and anaerobes were further identified. Terminal subcultures were performed on all negative samples. RESULTS: Sentinel was comparable with Bactec, with Sentinel recovering 20 streptococci and 14 anaerobes; Bactec isolated 26 streptococci and 15 anaerobes. The recovery of Streptococcus sanguis was significantly better from Bactec than Sentinel. The Isolator 10 recovered significantly fewer streptococci and anaerobes than either Bactec or Sentinel. Sentinel was noticeably quicker in detecting anaerobes than Bactec 460. However, there was no comparable difference with streptococci. Contaminants were recovered from 10% of Isolator 10, 2.7% of Bactec, and 7.2% of Sentinel bottles. CONCLUSIONS: Sentinel and Bactec 460 were broadly comparable in the detection of viridans streptococci and oral anaerobes, and both systems were significantly better than the Isolator 10. However, the prototype Sentinel, was significantly poorer than Bactec for the recovery of S sanguis.

Adult↗

PubMed1992

High level gentamicin resistance in enterococcal and streptococcal isolates from blood culture.

The combination of an aminoglycoside with a cell wall active agent is often necessary for the satisfactory management of serious enterococcal and streptococcal infections. High level gentamicin resistance (MIC > 1000 micrograms/ml) eradicates the synergy between these two classes of antibiotics and treatment of these infections becomes difficult. Over a four year period we assessed the susceptibility of blood culture isolates of enterococci, Streptococcus agalactiae (group B), and clinically significant viridans-type streptococci. The susceptibility of the organisms to gentamicin could be determined utilizing high content aminoglycoside discs. We report an increasing prevalence of high level gentamicin resistance in enterococci in South London, with 44% of isolates being resistant in the first quarter of 1991. None of the streptococcal isolates demonstrated high level gentamicin resistance. We recommend screening for high level gentamicin resistance in all enterococcal and streptococcal cases where aminoglycoside-penicillin synergy is desired.

Drug Resistance, Microbial↗

PubMed1970

Conduction velocity in myelinated nerve fibres of Xenopus laevis.

1. The relationship between conduction velocity and nerve diameter in single myelinated nerve fibres from Xenopus laevis was measured and was found to be linear.2. The relationship between conduction velocity and temperature in nerve fibres of various diameters was measured over the range 15-30 degrees C and was found to be linear for each fibre.3. The slope of the conduction velocity-temperature relationship was directly proportional to the diameter of the nerve fibre.4. The form of the conduction velocity-temperature relationship was determined by numerical solution of the Frankenhaeuser-Huxley equations for the case of a propagated action potential. The computation predicted that conduction velocity is a linear function of temperature over the range studied.

Action Potentials↗

PubMed1970

Persistent proatlantal artery.

A case of persistent proatlantal artery is described and the developmental anatomy reviewed. This vessel, arising from the internal carotid artery in the neck, is liable to be confused with the hypoglossal artery, but unlike the latter it forms the vertebral artery outside the skull and enters through the foramen magnum.

Atlanto-Occipital Joint↗