Gas-liquid chromatography in routine processing of blood cultures for detecting anaerobic bacteraemia

Importance of Nutrition Intervention in Autistic Patients

Along with the issues of inflated social and financial burden associated with autism spectrum disorder (ASD), specific treatment for this disorder has also not been developed. Having a thorough look at previous trials done to treat autism, we find that nutrition intervention had been used frequently as a complementary form of therapy. Indeed, an early diagnosis of nutrition deficiency and metabolic disorders done concomitantly with accurate therapeutic interventions can be a cornerstone for improving cognitive and behavioral aptitudes of people with autism. Several studies have showed that increasing the intake of specific nutrients can reduce the symptoms and comorbidities associated with autism. Consequently, nutrition intervention and appropriate supplementation can be crucial in managing and treating autism. This paper will discuss recent literature on the significance of metabolic aspects in autistic disorder and highlight the influence of nutrition intervention on the symptoms of autism.

Clinical evaluation of diagnostic hemoperfusion for in vivo enrichment of bacteria and fungi in comparison with a conventional blood culture technique

The hemoperfusion module, a newly developed technique for recovering pathogenic microorganisms from patients suffering from septicemia, was compared with conventional blood cultures. The module was interconnected with the extracorporeal circulation of 92 predominantly hemodialyzed patients. Nearly 12 liters of flowing blood (up to 200 ml min-1; mean running time, 60 min) came in contact with the coated charcoal. Of 99 modules examined, 44 (44.7%) yielded positive cultures and contained 54 potentially pathogenic bacteria or fungi (22 species). Only 32 of 190 (16.8%) conventional blood cultures were positive and contained 37 microorganisms (10 species). Even when patients were receiving antibiotic treatment, the frequency of isolation was significantly higher in hemoperfusion (21 of 44 modules positive, 47.7%) than in conventional blood cultures (10 of 88 cultures positive, 11.4%). In contrast, 23 of 55 modules (41.8%) and 22 of 102 conventional blood cultures (21.6%) were positive when patients were not treated with antibiotics prior to blood sampling. Altogether, hemoperfusion modules appeared to be superior to and more sensitive than the conventional blood cultures used and seemed to be a valuable tool for detecting septicemia.

Culture negative infective endocarditis

Twenty cases of culture negative infective endocarditis admitted to the Cardiology Department of Green Lane Hospital from 1959 to 1980 out of a total of 265 cases (7.5%), were analysed retrospectively. Cases were included only when adequate proof of endocarditis was available at surgery or postmortem. Indiscriminate use of antibiotics before taking blood cultures was the most common association with failure to obtain positive cultures, seen in 16 of the 20 patients described. Failure to obtain positive cultures in four cases was attributed to inadequate bacteriologic techniques before 1967. Where no antibiotics were given prior to collecting blood cultures and bacteriologic techniques were adequate, proven culture negative endocarditis was virtually unknown. When antibiotics have been given, repeated blood cultures are recommended following withdrawal of antibiotic for at least four days.

Acridine orange stain in the early detection of bacteria in blood cultures

A total of 1,592 blood cultures without macroscopic signs of bacterial growth in the first 12-24 h of incubation were processed for both acridine orange stain and blind subculture. One hundred and twenty-one (7.6%) blood cultures were positive by either method; of these, 105 (8.68%) were positive by both methods, 11 (9.1%) positive by acridine orange and negative by subculture, and 5 (4.1%) negative by acridine orange and positive by subculture. The difference between the 116 blood cultures positive by acridine orange and the 110 blood cultures positive by subculture was not statistically significant (p greater than 0.1). Gram stain performed on all acridine orange positive cultures failed to reveal bacteria in 14 cases. Acridine orange staining is a sensitive, rapid and reliable method for detecting bacteria in blood cultures early during incubation. The method is inexpensive and easy to perform and can be substituted for blind subcultures.

Diagnosis of bacteraemia by automated head-space capillary gas chromatography

Blood cultures from 196 patients with suspected bacteraemia or septicaemia were analysed by automated head-space gas chromatography, using a 25 m fused silica capillary column, when turbidity indicated growth. Gas chromatography correctly identified 105 cultures as positive and 71 correctly as negative. No false-positive results were obtained. Of the 20 false-negative chromatographic results, Staphylococcus spp accounted for 14. Automated head-space gas chromatography is quicker, easier and more efficient than other gas chromatographic techniques for the evaluation of blood cultures.

Can direct gas-liquid chromatography of clinical samples detect specific organisms?

A total of 1929 samples was analyzed by direct gas-liquid chromatography and the volatile fatty acid (VFA) patterns of the positive samples were compared with the results of culture. There was no correlation between any bacterial genus or species and the detailed VFA patterns although the presence of butyric or valeric acids, or both, was generally associated with the presence of anaerobes and that of acetic acid was generally associated with aerobic bacteria; however, the technique could not predict the nature of the subsequent bacterial isolate. There was also poor correlation between the VFA pattern in a given sample and the VFA pattern(s) of anaerobic bacteria subsequently isolated from that sample.

Gas-liquid chromatography of positive blood cultures for rapid presumptive diagnosis of anaerobic bacteremia

Gas-liquid chromatographic analysis of volatile fatty acid patterns was performed when growth was initially detected in 87 positive blood cultures. Isovaleric acid, butyric acid, or both were found in 39 of 43 (90%) blood cultures that contained anaerobes but were absent in all 44 cultures that contained facultatively anaerobic or aerobic bacteria. The detection of isovaleric acid indicated the presence of Bacteroides fragilis, as this acid was found in 88% of unimicrobial and 75% of polymicrobial bacteremias due to B. fragilis. Butyric acid was detected most often in blood cultures which grew Fusobacterium spp. (three of three), Clostridium spp. (six of seven), or both (three of four).