Bacteriocine production in group B streptococci

The bacteriocinogeny of 45 bovine and human group B streptococci strains was studied. All 45 strains were examined as producers and indicators. Of the 45 strains tested, 30 were bacteriocinogenic and 30 were sensitive to bacteriocines. Generally, group B streptococci were weak bacteriocine producers. Bacteriocinogeny and sensitivity to bacteriocines may coexist in the same organism, but sensitivity to a homologous bacteriocine was never observed. The inhibitory activity of bovine strains against other bovine and human strains was stronger than that exerted by strains of human origin. The spectra of activity of the strains tested were narrow. In one strong bacteriocinogenic strain, a loss of bacteriocinogeny was observed, but hemolysin production by this particular strain remained unaffected

In‐vitro bacteriocin‐mediated antagonism by oral streptococci against human carrier strains of staphylococci

All strains of oral streptococci tested and specially those of Streptococcus mutans, Strep. sanguis and Strep. minor produced more than one distinct bacteriocin‐like substance with variable inhibitory activity on 20 indicator staphylococci. Inhibitory activity was comparatively higher on nasal strains of Staph. aureus and Staph. epidermidis than on strains of both species isolated from the mouth. Nineteen of 20 staphylococcal indicators were inhibited by 1–12 of the 12 effector streptococci. Sensitivity of nasal staphylococci to bacteriocins (frequency of positive inhibitory tests and total inhibition zone diameters) was significantly higher (P < 0·001, χ2 test and P < 0·05, t test respectively) than that of oral ones. The sensitivity of nasal over oral Staph. aureus (P < 0·001 and P < 0·01) and of oral Staph. epidermidis over oral Staph. aureus (P < 0·01 and P < 0·05) was also significantly higher. The evaluation of variability of inhibitory patterns of bacteriocins produced by streptococci (p‐typing), of sensitivity patterns of staphylococci to bacteriocins (s‐typing) and of the significantly higher sensitivity of nasal over oral staphylococci to bacteriocins from the epidemiological and ecological veiwpoints are discussed. Copyright © 1991, Wiley Blackwell. All rights reserve

Effects of thrombolysis on vectorcardiographic indices of ventricular repolarization: correlation with ST-segment resolution

To investigate the effects of thrombolysis on vectorcardiographic (VCG) descriptors of ventricular repolarization in association with ST-segment resolution, 70 consecutively recruited patients with acute myocardial infarction underwent digital 12-lead electrocardiograms (ECGs) before and at 3 hours after thrombolysis. The alterations in the VCG descriptors spatial T amplitude and spatial QRS-T angle from the pre- to the post-thrombolysis ECG, as well as the ST-segment resolution, were calculated. Angiography revealed patency of the infarct-related coronary artery after thrombolysis in 52 (74%) patients (group A) and occlusion in 18 (26%) (group B). The spatial T amplitude was highly significantly reduced after thrombolysis in group A (P < .0001), but only marginally reduced in group B (P = .016). The spatial QRS-T angle was also significantly, although only marginally, reduced after thrombolysis in group A (P = .019), whereas it was not changed after thrombolysis in group B (P = .868). An ST-segment resolution of 60% and a 25% reduction in the spatial T amplitude after thrombolysis were able to identify patency of the infarct-related coronary artery with sensitivities of 90% and 77% and specificities of 94% and 74%, respectively. Both VCG descriptors were significantly affected by thrombolysis in patients with acute myocardial infarction, but constituted only moderate markers of thrombolysis efficacy, as evidenced by the presence of patency in the infarct-related coronary artery, compared with the ST-segment resolution. (c) 2005 Elsevier Inc. All rights reserved

Exercise-induced prolongation of the infarct-related Q-waves as a marker of myocardial viability in the infarcted area

Objective: It is known that exercise-induced ischemia in patients with coronary artery disease (CAD) may produce QRS prolongation in the surface electrocardiogram (ECG). To investigate the presence of exercise-induced Q-wave prolongation in patients with single-vessel CAD and Q-wave myocardial infarction (MI), in association with the presence of reversible perfusion defects during thallium scintigraphy in the infarcted area. Methods: 107 consecutive patients (89 males, mean age 56 8 years) were evaluated. All patients underwent coronary arteriography, maximal treadmill exercise testing and thallium-201 scintigraphy. Q-wave duration was measured both before exercise testing and during maximal heart rate from 12-lead ECGs recorded with a paper speed of 50 mm/s. Results: Only 57 out of the 107 studied patients showed reversible perfusion defects in the infarcted area during thallium scintigraphy. Q-wave duration was significantly increased from the resting to the stress ECG (DeltaQ-wave duration) in patients with reversible perfusion defects in the infarcted areas (10+/-13 ms), but not in patients with fixed defects in the infarcted zone (-2.0+/-5 ms, p<0.01). The sensitivities and the specificities of Q-wave prolongation, ST segment elevation, and the combination of ST segment elevation with ST segment depression in the reciprocal leads for the detection of myocardial viability in the infarcted area were 82%, 48%, 29% and 88%, 50%, and 90%, respectively. Conclusions: Exercise-induced Q-wave prolongation is demonstrated in those patients with single-vessel CAD and a recent MI who show reversible perfusion defects in thallium scintigraphy. Exercise-induced Q-wave prolongation was found to be a sensitive and specific ECG marker for the detection of myocardial viability in the infarcted area. (C) 2004 Elsevier Ireland Ltd. All rights reserved