Initial detection of bacteremia by subculture of unvented tryptic soy broth blood culture bottles

Routine subculture of macroscopically negative blood cultures is a traditional blood culture procedure. The need to perform routine early (6-17 hr) and late (48 hr) subculture of unvented blood culture bottles when a simultaneous subculture of the vented bottle is performed has been questioned. Blood cultures in paired vented and unvented tryptic soy broth (TSB) bottles from 4574 patients were examined retrospectively. Subculture of unvented TSB bottles provided initial detection of 412 (5.0%) isolates from 277 (6.1%) patients and was comparable to that of vented TSB bottles for Pseudomonas and all other microorganisms, except for the Enterobacteriaceae (p less than 0.001; vented TSB), Candida (p less than 0.001; vented TSB), and Haemophilus influenzae (p less than 0.01; unvented TSB). Of the H. influenzae isolates, 46% were detected initially by subculture of the unvented TSB bottles; early subculture recovered 67% of these isolates. The value of subculture of unvented TSB bottles is minimized when subculture of the vented TSB bottle is routinely performed; however, routine subculture of the unvented bottle is recommended whenever TSB is used for detection of bacteremia in patients in whom H. influenzae infection is possible.     

Behavioral characteristics of centrally administered adenosine analogs

Mice were implanted with chronic indwelling cannulae in the lateral cerebral ventricle. A series of adenosine analogs and related compounds were injected into the lateral ventricle (ICVT) and their effects on spontaneous locomotor activity recorded. All analogs produced dose-related decreases in locomotor activity. 5'-N6-ethyl-carboxamidoadenosine (NECA) was the most potent compound tested, with a number of N6-substituted analogs also being effective depressants of activity. Caffeine, administered either intracerebroventricularly or intraperitoneally, antagonized the depressant effects of the adenosine analogs. 3-Isobutyl-1-methylxanthine, administered ICVT, depressed locomotor activity. However, after caffeine, IBMX elicited behavioral stimulation. Agents which inhibit the transport of adenosine (dipyridamole, dilazep, papaverine) depressed locomotor activity, as did erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA, an inhibitor of adenosine deaminase. The effects of dilazep, papaverine and EHNA, but not of dipyridamole, were antagonized by caffeine. These results further substantiate the notion that endogenous adenosine is involved in the regulation of central nervous system excitability.     

Mathematical Modelling of Drug Transport in Emulsion Systems

Two mathematical models for the prediction of drug transport in triphasic (oil, water and micellar) emulsion systems as a function of micellar concentration have been developed and these models were evaluated by comparing experimental and simulated data. Fick's first law was used to derive a transport model for hydrophilic drugs, assuming that the oil/water (o/w) partitioning process was fast compared with membrane transport and therefore drug transport was limited by the membrane. Consequetive rate equations were used to model transport of hydrophobic drugs in emulsion systems assuming that the o/w interface acts as a barrier to drug transport. Benzoic acid and phenol were selected as hydrophilic model drugs. Phenylazoaniline and benzocaine were selected as hydrophobic model drugs. Transport studies at pH 3.0 and 7.0 were conducted using side-by-side diffusion cells. According to the hydrophilic model, an increase in micellar concentration is expected to decrease drug transport rates. The effective permeability coefficients (P_eff) of drugs were calculated using an equation relating P_eff and the total apparent volume of drug distribution (determined experimentally using drug/membrane permeability and partition coefficient values). The hydrophobic model was fitted to the experimental data for the cumulative amount of model drug in the receiver cells using a weighted least-squares estimation program (PCNONLIN). The oil/continuous phase partitioning rates (k₁) and the membrane transport rates (k₂) were estimated. The goodness of fit was assessed from the correlation coefficients of plots of predicted versus experimental data. The predicted data were consistent with the experimental data for both the hydrophilic and hydrophobic models.     

Prosthetic valve endocarditis.

From January 1963 until January 1974, 45 patients had prosthetic valve endocarditis. Symptoms of prosthetic valve endocarditis developed within 2 months after operation (early onset) in 16 patients (36%) and more than 2 months after operation (late onset) in 29 patients (64%). Overall mortality among the 45 patients was 56% (88% among those with early onset and 40% among those with late onset). Medical therapy alone was curative in 60% of the surviving patients. Combined medical and surgical therapy was curative in 40% of the survivors. The most frequent isolates in the early-onset group were Staphylococcus aureus (44%) and Gram-negative bacilli (38%); associated mortality was 86% and 83%, respectively. The most frequent isolates in the late-onset group were viridans streptococci (41%) and Gram-negative bacilli (31%); the mortality was 25% and 22% respectively. Suggestions are offered for operative antimicrobial prophylaxis and for medical and surgical treatment of prosthetic valve endocarditis. Prompt surgical replacement of an infected prosthesis is necessary when medical therapy fails.     

Factors predisposing to the development of progressive massive fibrosis in coal miners.

Altogether 238 759 miners employed by the National Coal Board were examined in the third of the Board's radiological surveys from 1969 to 1973 inclusive. Excluding those diagnosed as having progressive massive fibrosis (PMF) on that occasion, 210 847 were in collieries still operating at the time of the fourth survey four to five years later 132 728 attended for radiography at the same colliery on the second occasion, and were used to study the attack rate of PMF. In all groups in the age range 35-54 and having category 2 simple pneumoconiosis (SPN) or less, 80% or more had a second radiograph. It was found that the probability of developing PMF increased sharply with rising category of SPN; however, half the cases occurred in men having SPN categories 0 or 1, who were in the majority. Current coalface work had no significant effect on the attack rate. Age increased the attack rate of PMF within each major SPN category (0, 1, 2, and 3), especially the higher categories. All or part of this effect may have been due to the fact that SPN in younger men with categories 1 and 2 tends to lie in the lower range within these categories. Similarly, a lower distribution of SPN within each category associated with a low overall local prevalence may account wholly or in part for the great difference between the attack rates of PMF supervening on each category of SPN in Scotland and South Wales. The rank (quality) of coal mined had no effect on the attack rate.     

In-vitro activities of cefamandole and cephalothin against 1,881 clinical isolates. A multi-center study

By use of an agardilution technic, 1,881 clinical isolates were tested against cefamandole and cephalothin. The isolates represented 18 genera, recovered in five geographically separate centers within the United States. The majority of strains were susceptible (MICs less than or equal to 8 micrograms/ml) to both drugs. Cefamandole showed greater activity against most of the bacterial pathogens. Enterococci, Serratia spp., and Acinetobacter spp. were resistant to both drugs. Cephalothin was more active against Staphylococcus aureus, and both cephalosporins were relatively inactive against methicillin-resistant strains of S. aureus. Enterobacter spp. and indole-positive Proteus spp. were susceptible to cefamandole but resistant to cephalothin.     

Sensitivity, precision, and accuracy of the Y1 adrenal cell enterotoxin assay.

The Y1 adrenal cell assay for heat-labile enterotoxin (LT) was found to be relatively insensitive for filtrates of toxigenic Escherichia coli H10407. When observations were made blindly and subjected to rigorous controls, reliable detection of LT occured only at filtrate dilutions from 1:4 to 1:10. Detection of LT was unreliable when E. coli H10407 was mixed with another enteric organism. Overall, 7.1% of observers' reports from a single assay were imprecise, and 2.6% would have resulted in errors in detection of LT; however, triplicate assays prevented false positive reports of LT detection. Routine testing for LT production in the clinical diagnostic laboratory awaits a simpler, more sensitive, and more direct method of testing stool specimens.     

Evaluation of a biphasic medium for blood cultures.

A study comparing the recovery of microorganisms from a transiently vented biphasic brain heart infusion medium bottle and a vacuum bottle containing tryptic soy broth demonstrated that growth was initially detected on the slant of the biphasic bottle or on a routine subculture of either broth in nearly 50% of instances. All organisms were isolated equally well in both bottles, with the exception of Staphylococcus aureus, which was isolated significantly more frequently from the biphasic bottle, and anaerobic bacteria, which were isolated significantly more frequently from the tryptic soy broth bottle.