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Maltitol is fermented in the colon due to only partial hydrolysis in the small intestine. In the present study, we examined effects of dietary maltitol on dimethylhydrazine-induced intestinal tumor in rats. In experiment 1, rats were fed a fiber-free diet or diets supplemented with 1 or 5 g/100 g maltitol for 27 wk. Each group of rats was injected with dimethylhydrazine or vehicle alone for the first 14 wk of the experimental period. Maltitol supplementation at 1 g/100 g of the diet significantly reduced tumor incidence in the cecum and the 5% supplement reduced tumor incidence in both the cecum and proximal colon in dimethylhydrazine-treated rats. In experiment 2, we investigated the effect of the 1 g/100 g maltitol diet on the short chain fatty acid concentrations in cecal contents of placebo and dimethylhydrazine-treated rats. Intake of the 1 g/100 g maltitol diet doubled (P < 0.05) the concentration of butyrate but did not affect acetate or propionate in the cecal contents. These results suggest that dietary maltitol has a protective effect against dimethylhydrazine-induced tumors in rat cecum and proximal colon and that butyrate produced by bacterial fermentation of maltitol in the cecum may be involved in the protection. [ABSTRACT FROM AUTHOR]

Recent molecular studies have shown Mycobacterium porcinum, recovered from cases of lymphadenitis in swine, to have complete 16S rDNA sequence identity and >70% DNA-DNA homology with human isolates within the M. fortuitum third biovariant complex. We identified 67 clinical and two environmental isolates of the M. fortuitum third biovariant sorbitol-negative group, of which 48 (70%) had the same PCR restriction enzyme analysis (PRA) profile as the hsp65 gene of M. porcinum (ATCC 33776(T)) and were studied in more detail. Most U.S. patient isolates were from Texas (44%), Florida (19%), or other southern coastal states (15%). Clinical infections included wound infections (62%), central catheter infections and/or bacteremia (16%), and possible pneumonitis (18%). Sequencing of the 16S rRNA gene (1,463 bp) showed 100% identity with M. porcinum ATCC 33776(T). Sequencing of 441 bp of the hsp65 gene showed four sequevars that differed by 2 to 3 bp from the porcine strains. Clinical isolates were positive for arylsulfatase activity at 3 days, nitrate, iron uptake, D-mannitol, i-myo-inositol, and catalase at 68 degrees C. They were negative for L-rhamnose and D-glucitol (sorbitol). Clinical isolates were susceptible to ciprofloxacin, sulfamethoxazole, and linezolid and susceptible or intermediate to cefoxitin, clarithromycin, imipenem, and amikacin. M. porcinum ATCC 33776(T) gave similar results except for being nitrate negative. These studies showed almost complete phenotypic and molecular identity between clinical isolates of the M. fortuitum third biovariant D-sorbitol-negative group and porcine strains of M. porcinum and confirmed that they belong to the same species. Identification of M. porcinum presently requires hsp65 gene PRA or 16S rRNA or hsp65 gene sequencing.

The simultaneous appearance of new cavitary lesions in the lungs and two or more isolations of Mycobacterium avium-Mycobacterium intracellulare complex (MAC) by daily or monthly sputum examination in the initial few days or the initial 6 months shows the presence of lung disease caused by MAC. Three isolations of MAC by three to six daily or monthly sputum examination confirms the occurrence of lung disease caused by MAC. These criteria and their basis were published by the present author in 1974 and 1978. The criteria are almost the same as those published by the American Thoracic Society in 1997.

Branched-chain alpha-keto acid dehydrogenase complex is the rate limiting enzyme in catabolism of branched-chain amino acids. In this study, we examined effects of dietary protein and exercise on the complex activity in digestive tracts (stomach, small intestine and colon) of rats. Rats were fed a high (30%) or low (8%) protein diet for 3 weeks and a half of rats in each diet group was exercised by 85 min running just prior to sacrifice on the final day of the experiment. Total and actual (active form) activities of the complex were markedly high in stomach compared to other two tissues and the actual activity in stomach was significantly elevated by exercise only in rats fed the high protein diet. Both total and actual activities in colon were only a few percentage of those in stomach, and those in small intestine was further less. These results suggest that rat stomach is the tissue active in catabolism of branched-chain amino acids, which is promoted by combination of high protein diet and exercise.

Mycobacterium chelonae-like organisms are nonpigmented rapidly growing mycobacteria whose clinical significance is unknown. We evaluated 87 sporadic isolates encountered in a clinical laboratory. Most isolates (62%) were respiratory; only 2 of 54 (4%) (both from patients with AIDS) were clinically significant. Among 33 nonrespiratory isolates, 20 of 33 (or 61%) were clinically significant. Clinical diseases included posttraumatic wound infections and catheter-related sepsis. Routine biochemical features included growth inhibition by 5% NaCl (100%), a smooth colony morphology (94%), positive 3-day arylsulfatase reaction (84%), no color or a light tan color on iron uptake (100%), and variable nitrate reduction (45%). Additional characteristics that helped to separate this group from M. chelonae and Mycobacterium abscessus were susceptibility to cephalothin (90%) and ciprofloxacin (100%), utilization of mannitol (94%) and citrate (83%) as carbon sources, and unique patterns of mycolic acid esters by high-performance liquid chromatography. This group was quite drug susceptible, with 100% of isolates inhibited by amikacin, imipenem, cefoxitin, cefmetazole, and the newer quinolones ciprofloxacin and ofloxacin. Three examples of this group, including a proposed type strain, have been deposited in the American Type Culture Collection.

beta-lactamases from 259 strains of rapidly growing mycobacteria that included the third biovariant complex of Mycobacterium fortuitum, M. peregrinum, M. abscessus, M. chelonae, the M. chelonae-like organisms (MCLO), and M. smegmatis were analyzed by isoelectric focusing (IEF). All isolates produced acidic beta-lactamases with major band isoelectric points (pIs) between 4.4 and 6.0. Each of the 6 taxonomic groups exhibited 1 or 2 characteristic beta-lactamase IEF patterns. Heterogeneity among IEF patterns was evident in 5 of the 6 groups, however, and was greatest among the third biovariant complex of M. fortuitum. beta-lactamase patterns correlated with previously identified taxonomic subgroups of M. smegmatis and the third biovariant complex of M. fortuitum. beta-lactamase IEF analysis of MCLO strains isolated from two outbreaks demonstrated its possible usefulness for epidemiologic evaluation.

A total of 55 patients with pulmonary disease caused by Mycobacterium avium and by Mycobacterium intracellulare were compared for their prognosis. Causative mycobacteria were identified by the DNA probes (Gen-Probe) method. Of the 55 patients, 28 had pulmonary disease caused by M avium and the remaining 27, by M intracellulare. Of the former group, four patients had progressive disease, and three of them died during the observation period. In contrast, only one of the latter group had progressive disease. On the other hand, only one of the former group was cured. In contrast, six of the latter group were cured, showing the closure of cavity and the disappearance of mycobacteria from the sputum. The prognosis of pulmonary disease caused by M avium appears to be worse than that caused by M intracellulare.

Mycobacterium avium and Mycobacterium intracellulare are differentiated from each other by thin-layer chromatography of lipid fraction extracted after incubation with [35S]methionine. The former contained a petroleum ether-soluble sulfolipid and the latter did not.

Bacteriostatic and bactericidal activities of rifampicin, isoniazid, streptomycin, enviomycin and ethambutol against Mycobacterium tuberculosis, Mycobacterium avium--M. intracellulare complex and Mycobacterium kansasii were studied in different growth phases. Bacteriostatic activities of the drugs were similar in different growth phases, except isoniazid. M. tuberculosis was much less susceptible to isoniazid in the lag phase than in the log and the stationary phases. In contrast, bactericidal activity was influenced by the growth phase. M. tuberculosis was killed by isoniazid, streptomycin and rifampicin. The bactericidal activity of isoniazid was strongest. The bactericidal activity of isoniazid and streptomycin was most marked in the log phase. M. avium complex and M. kansasii resisted the bactericidal activity, but some strains of M. avium complex were killed by streptomycin and enviomycin, and the activities of these two drugs were most marked in the lag phase.

Recent studies have shown that Nocardia asteroides isolates have five major antibiotic resistance patterns; one of these patterns identifies isolates of Nocardia farcinica. In the current study, we investigated a second pattern characterized by susceptibility to ampicillin and erythromycin. This pattern was seen in 17% of 223 clinical isolates identified by standard techniques as N. asteroides and associated with diseases typical for nocardiae. Biochemically, isolates with this drug pattern were relatively homogeneous and identical to the type strain and previous descriptions of Nocardia nova. The strains studied were unique among nocardiae in having both alpha- and beta-esterase activity (85 and 95%, respectively). However, the arylsulfatase activity at 14 days (75%) and antimicrobial susceptibility patterns, including susceptibility to erythromycin (100%), were the only routinely available methods that would separate N. nova strains from other members of N. asteroides. N. asteroides should be considered a complex because current clinical identification schemes include isolates of N. farcinica and N. nova and may well include additional species. This is the first detailed description of N. nova as a pathogen in humans.

Six cases of chronic tenosynovitis of the hand due to the Mycobacterium terrae complex were identified. All isolates from the six cases were identified as Mycobacterium nonchromogenicum by high-performance liquid chromatography and by testing for susceptibility to ofloxacin and to 5% NaCl. Ethambutol, sulfonamides (or trimethoprim-sulfamethoxazole), erythromycin, and streptomycin are the drugs most active against isolates of the M. terrae complex, and therapy with some combination of these agents plus surgical debridement offers the best current treatment of this disease. This study supports the contention arising from previous case reports of pulmonary disease that M. nonchromogenicum is the pathogenic member of the M. terrae complex.

Isolation of Mycobacterium avium complex from sputum specimens in association with the appearance of a new cavitary (or infiltrative) lesion was studied in 299 patients from whom the organism was isolated one or more times. Of the patients studied, 114 showed only single isolation. Of these 114, only two patients (2 percent) had association with appearance of a cavitary lesion. Of 29 patients who showed two isolations, 26 (90 percent) had the association. Of 40 patients who showed three isolations, 39 (98 percent) had the association. All 116 patients who showed four or more isolations had the association with appearance of a cavitary lesion. Accordingly, of a total of 185 patients who showed two or more isolations, 181 (98 percent) had the association. Of these 181, 176 (97 percent) showed two or more isolations in the sputum examinations made in the initial three days. Therefore, the sputum examination in the first three days after onset of disease is most important for the diagnosis of disease caused by Mycobacterium avium complex. Since the probability that casual isolation of the organism occurs twice is extremely low, we can make the diagnosis of pulmonary infection caused by this organism by evidence of two or more isolations of the organism in the first few days after the onset of disease, which is associated with appearance of a new cavitary (or infiltrative) lesion. Moreover, theoretical consideration made in this study has led us to conclude that patients who have had a single isolation of the organism together with a new cavitary lesion should be regarded as having an infection.

Previous studies of Mycobacterium fortuitum identified isolates that did not fit its two recognized biovariants. Eighty-five clinical isolates of this group, the "third biovariant complex", were evaluated. They represented 16% of 410 isolates of M. fortuitum submitted to a Texas laboratory and 22% of 45 isolates in Queensland, Australia. Most infections (76%) involved skin, soft tissue, or bone and occurred after metal puncture wounds or open fractures. Isolates differed from biovar fortuitum in resistance to pipemidic acid and use of mannitol and inositol as carbon sources. Two subgroups were present, and examples were deposited in the American Type Culture Collection. Isolates were resistant to doxycycline and one-third were resistant to cefoxitin. All were susceptible to amikacin, ciprofloxacin, sulfamethoxazole, and imipenem. Surgical debridement combined with drug therapy based on in vitro susceptibilities resulted in cures of cutaneous disease or osteomyelitis. DNA homology studies are needed to determine the taxonomic status of these organisms.

The susceptibility to rifampicin and streptomycin of the Mycobacterium avium-Mycobacterium intracellulare complex was augmented by the addition of Tween 80 into 7H10 agar medium with OADC, whereas the susceptibility to ethambutol and sulfadimethoxine was either not changed or reduced by the addition of Tween 80. In 7H10 agar medium without OADC, however, susceptibilities to both rifampicin and sulfadimethoxine were reduced by the addition of Tween 80 to the medium. A number of hypotheses are made to explain these phenomena.

A recent study of Nocardia asteroides revealed that 95% of clinical strains had one of five antibiotic resistance patterns. We found the pattern of resistance to cefotaxime and cefamandole in 19% of 200 clinical N. asteroides isolates. Isolates with this drug resistance pattern were from numerous geographic sources and were associated with significant clinical disease (56% of patients had disseminated infections). Phenotypic studies revealed that these isolates were relatively homogeneous and matched previous descriptions and reference strains of the controversial species N. farcinica. Growth at 45 degrees C, acid production from rhamnose, ability to utilize acetamide as a nitrogen and carbon source, and resistance to tobramycin and cefamandole were features of N. farcinica that could be tested in the clinical laboratory and allowed their distinction from N. asteroides. The serious nature of disease due to N. farcinica and its resistance to the newer cephalosporins suggest a clinical need for laboratory identification of this species. (Current tests used in clinical laboratories do not distinguish N. farcinica from N. asteroides.) This is the first recognition that N. farcinica has a specific drug resistance pattern and confirms the previously described concept that drug resistance patterns of N. asteroides may be associated with specific taxonomic groups.

Although mycobacteria grow in Dubos liquid medium showing an arithmetic linear growth, the initial few days of growth were found to correspond to an 'induction' period. In this period, rapid increase of the amount of growth occurred, whereas increase of the number of colony-forming units remained at a low level. This finding shows that the rapid increase of the amount of growth is accompanied by rapid death of multiplied bacteria. In a successive period, which was considered to correspond to the logarithmic growth phase, a 1:1 correspondence existed between the amount of growth and the number of colony-forming units. The induction period is not considered to be a lag phase, in which the bacteria grow slowly, but a period of unbalanced relationship between the growth and the viability. Even when we inoculated different sizes of bacteria, the amounts of growth became similar in both inoculations after several days of incubation. However, the number of colony-forming units remained always smaller in the use of small inocula than in the use of large inocula. In the use of small inocula, much more rapid increase of the amount of growth occurred. However, this rapid increase gave rise to rapid death of bacteria.

The growth of the type strain of Mycobacterium aurum was compared between flask and tube, both of which contained the same concentration of bacteria in synthetic media and had the same air-contact dimension but had different dimensions of the glass wall of vessels contacting the medium. Much better growth occurred in the flask, which had a smaller dimension of the glass wall contacting the medium, than in the tube, which had a larger dimension. The finding shows that the growth of bacteria is influenced by the dimension of the glass wall of vessels. It was considered that a high chance of the attack shock for bacteria given by the Brownian movement lowers the multiplication of bacteria.

Tests reported to be useful for the differentiation of species or groups of mycobacteria are reviewed. Some systems of identification of these organisms are composed of relatively small or large numbers of tests. These systems remain at present "national" identification systems; no "international" system agreed on by scientists worldwide exists. Such an international system is desirable.

Mycobacterium avium complex strains previously not exposed to any antituberculosis agents could be divided into two groups according to their susceptibility to rifampicin and ansamycin; one group susceptible to 80 micrograms/ml rifampicin and to 1.25 micrograms/ml ansamycin, and another resistant to these concentrations. In each group, the ratio of the minimal inhibitory concentration of ansamycin against that of rifampicin was greatly different depending on the strain. This naturally occurring resistance to rifampicin and ansamycin was frequently correlated to naturally occurring resistance to ethambutol, kanamycin, enviomycin, kitasamycin, and minocycline, but not correlated to that to isoniazid and sulfadimethoxine. Ansamycin was more active than rifampicin against M. bovis, M. kansasii, M. marinum, M. xenopi, and M. haemophilum.

We studied the usefulness of antibody estimation by the enzyme-linked immunosorbent assay (ELISA) technique in the differential diagnosis of pulmonary mycobacterial diseases. Sera from patients with active pulmonary diseases caused by Mycobacterium tuberculosis (n = 42) or Mycobacterium avium-intracellulare complex (MAI) (n = 26) and from healthy controls (n = 75) were assayed for IgG and IgA antibody titers to antigen of M. tuberculosis and MAI. The IgG and IgA antibody titers to M. tuberculosis antigen were significantly higher in patients with mycobacterial diseases than in healthy controls, however, there was no significant difference between patients with pulmonary tuberculosis and those with pulmonary diseases due to M. avium-intracellulare complex (MAID). The IgG and IgA antibody titers to MAI antigen in MAID patients were significantly higher than in healthy controls and in patients with pulmonary tuberculosis. ELISA for IgG antibody against M. tuberculosis antigen had a sensitivity of 54.8% and a specificity of 73.1% in the differential diagnosis of pulmonary tuberculosis. The estimation of the IgA antibody against MAI antigen using ELISA is more useful for the differential diagnosis of MAID because of its sensitivity (69.2%) and specificity (90.5%).

The principles of classification and identification of microorganisms are stated briefly. Reliable classification and identification are achieved by numerical methods. A simple method of testing the distinctness of taxa (clusters or species) involves three steps: determination of the hypothetical median or mean organism (HMO) for each taxon, estimation of matching coefficients (M values) for individual strains of each taxon to the HMO of the same taxon and to HMOS of other taxa, and definition of the range of a taxon as M +/- 2SD, where M is the mean M value to the HMO. The minimal number of characteristics needed for reliable classification is greater than 40, and none of the characteristics should be related or biased. A species should be defined by more than four strains. After distinct taxa are defined and named as species, new isolates are tested to determine which taxon they belong to. This test is done by a numerical method: comparison of a new isolate with the HMO of various species and testing whether the resulting M values fall within the ranges of any of these species. If an M value of a new isolate falls within the range of taxon X and M values to the HMOS of other species are outside the limits of those species, the isolate is identified as belonging to taxon X. A simple, conventional (nonnumerical) identification system consisting of a small number of tests may be used in clinical laboratories, but one should always keep in mind that identification by such a system often leads to misidentification. Causes of misidentification are false reactions (misjudgment of results), inadequate choice of test characteristics, and use of too small a number of tests.

Numerical identification using the range of a species defined as (M +/- 2s)% was shown to be suitable for the identification of slowly growing mycobacteria. In the formula, M is the mean matching coefficient for individual strains of each species to the hypothetical median organism pattern of their own species and s is the standard deviation.

A new antituberculosis agent, ofloxacin (DL8280), inhibited the growth of Mycobacterium tuberculosis at concentrations of 0.63 to 1.25 micrograms/ml. There were no cross-resistance relationships between this agent and other antituberculosis agents. The agent delayed the growth rate of M. tuberculosis (strain H37Rv) at concentrations of 0.2 to 0.5 microgram/ml. It showed considerable bactericidal activity at concentrations a little higher than the growth-inhibitory concentration. The combined effect with other antituberculosis agents seemed to be additive. The pattern of resistance that developed with this agent was the obligatory two-step pattern, and there were 2 resistant phenotypes.