Rial D. Rolfe

Some cases of late-onset (regressive) autism may involve abnormal flora because oral vancomycin, which is poorly absorbed, may lead to significant improvement in these children. Fecal flora of children with regressive autism was compared with that of control children, and clostridial counts were higher. The number of clostridial species found in the stools of children with autism was greater than in the stools of control children. Children with autism had 9 species of Clostridium not found in controls, whereas controls yielded only 3 species not found in children with autism. In all, there were 25 different clostridial species found. In gastric and duodenal specimens, the most striking finding was total absence of non-spore-forming anaerobes and microaerophilic bacteria from control children and significant numbers of such bacteria from children with autism. These studies demonstrate significant alterations in the upper and lower intestinal flora of children with late-onset autism and may provide insights into the nature of this disorder.

Several species of anaerobic bacteria display variable Gram stain reactions which often make identification difficult. A simple, rapid method utilizing a 3% solution of potassium hydroxide to distinguish between gram-positive and gram-negative bacterial was tested on 213 strains of anaerobic bacteria representing 19 genera. The Gram stain reaction and KOH test results were compared with the antibiotic disk susceptibilities (vancomycin and colistin) the preliminary grouping of anaerobic bacteria. All three procedures were in agreement for the majority of strains examined. Some strains of clostridia, eubacteria, and bifidobacteria stained gram negative or gram variable; the KOH and antibiotic disk susceptibility tests correctly classified these strains as gram-positive. The KOH test incorrectly grouped some strains of Bacteroides sp., Fusobacterium sp., Leptotrichia buccalis, and Veillonella parvula, but all Gram stain results for these strains were consistent for gram-negative bacteria. The KOH test is a useful supplement to the Gram stain and antibiotic disk susceptibility testing for the initial classification of anaerobic bacteria.

METABOLIC acidosis caused by D-lactic acid, the optical isomer of L-lactic acid, was recently described by Oh et al. in a patient with a short-bowel syndrome.1 We encountered a similar condition in two patients with prior gut surgery. One patient had undergone an extensive small-bowel resection after mesenteric infarction, and the other had had a jejunoileal bypass for obesity. These patients presented with repeated episodes of stupor or coma, metabolic acidosis with an increased anion gap, normal plasma levels of L-lactate, and elevated plasma levels of D-lactate. Treatment with oral vancomycin resulted in normalization of the neurologic and metabolic status. . . .

The effect of atmospheric oxygen on the viability of 13 strains of anaerobic bacteria, two strains of facultative bacteria, and one aerobic organism was examined. There were great variations in oxygen tolerance among the bacteria. All facultative bacteria survived more than 72 h of exposure to atmospheric oxygen. The survival time for anaerobes ranged from less than 45 min for Peptostreptococcus anaerobius to more than 72 h for two Clostridium perfringens strains. An effort was made to relate the degree of oxygen tolerance to the activities of superoxide dismutase, catalase, and peroxidases in cell-free extracts of the bacteria. All facultative bacteria and a number of anaerobic bacteria possessed superoxide dismutase. There was a correlation between superoxide dismutase activity and oxygen tolerance, but there were notable exceptions. Polyacrylamide gel electropherograms stained for superoxide dismutase indicated that many of the anaerobic bacteria contained at least two electrophoretically distinct enzymes with superoxide dismutase activity. All facultative bacteria contained peroxidase, whereas none of the anaerobic bacteria possessed measurable amounts of this enzyme. Catalase activity was variable among the bacteria and showed no relationship to oxygen tolerance. The ability of the bacteria to reduce oxygen was also examined and related to enzyme content and oxygen tolerance. In general, organisms that survived for relatively long periods of time in the presence of oxygen but demonstrated little superoxide dismutase activity reduced little oxygen. The effects of medium composition and conditions of growth were examined for their influence on the level of the three enzymes. Bacteria grown on the surface of an enriched blood agar medium generally had more enzyme activity than bacteria grown in a liquid medium. The data indicate that superoxide dismutase activity and oxygen reduction rates are important determinants related to the tolerance of anaerobic bacteria to oxygen.