Previous investigations demonstrated three taxonomic groups among 22 clinical isolates of Mycobacterium smegmatis. These studies were expanded to 71 clinical isolates, of which 35 (49%) (group 1) were identical to five ATCC reference strains including the type strain ATCC 19420'. Twenty-eight isolates (39%) were group 2, and eight isolates (11 %) were group 3. Isolates of groups 2 and 3 were most often associated with post-traumatic or post-surgical wound infections including osteomyelitis, were susceptible to sulfamethoxazole, amikacin, imipenem and the tetracyclines, variably resistant to clarithromycin, and susceptible (group I ) , intermediately resistant (group 2) or resistant (group 3) to tobramycin. The three groups were similar by routine biochemical and growth characteristics, but had different mycolic acid dimethoxy-4-coumarinylmethyl ester elution patterns by HPLC and different PCR-restriction enzyme patterns of a 439 bp fragment of the hsp-65 gene. Group 3 isolates differed from group 1 by 18 bp by 165 rRNA sequencing and exhibited < 25% homology by DNA-DNA hybridization, being most closely related to Mycobacterium mageritense.

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The objectives of this study were to investigate the effects of (1) the addition of nitrate and (2) an increase in dietary oil on methane (CH4) and hydrogen (H2) emissions from 2 breeds (cross-bred Charolais and purebred Luing) of finishing beef cattle receiving 2 contrasting basal diets consisting (grams per kilogram DM) of 500:500 (Mixed) and 80:920 (Concentrate) forage to concentrate ratios. Within each basal diet there were 3 treatments: (i) control treatments (mixed-CTL and concentrate-CTL) contained rapeseed meal as the protein source, which was replaced with either (ii) calcium nitrate (mixed-NIT and concentrate-NIT) supplying 21.5 g nitrate/kg DM, or (iii) rapeseed cake (mixed-RSC and concentrate-RSC) to increase dietary oil from 27 (CTL) to 53 g/kg DM (RSC). Following adaption to diets, CH4 and H2 emissions were measured on 1 occasion from each of the 76 steers over a 13-wk period. Dry matter intakes tended (P = 0.051) to be greater for the concentrate diet than the mixed diet; however, when expressed as grams DMI per kilogram BW, there was no difference between diets (P = 0.41). Dry matter intakes for NIT or RSC did not differ from CTL. Steers fed a concentrate diet produced less CH4 and H2 than those fed a mixed diet (P < 0.001). Molar proportions of acetate (P < 0.001) and butyrate (P < 0.01) were lower and propionate (P < 0.001) and valerate (P < 0.05) higher in the rumen fluid from steers fed the concentrate diet. For the mixed diet, CH4 yield (grams per kilogram DMI) was decreased by 17% when nitrate was added (P < 0.01), while H2 yield increased by 160% (P < 0.001). The addition of RSC to the mixed diet decreased CH4 yield by 7.5% (P = 0.18). However, for the concentrate diet neither addition of nitrate (P = 0.65) nor increasing dietary oil content (P = 0.46) decreased CH4 yield compared to concentrate-CTL. Molar proportions of acetate were higher (P < 0.001) and those of propionate lower (P < 0.01) in rumen fluid from NIT treatments compared to respective CTL treatments. Overall, reductions in CH4 emissions from adding nitrate or increasing the oil content of the mixed diet were similar to those expected from previous reports. However, the lack of an effect of these mitigation strategies when used with high concentrate diets has not been previously reported. This study shows that the effect of CH4 mitigation strategies is basal diet-dependent.

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Several di-, tri-, and oligopeptides were incubated individually in vitro with rumen fluid from two sheep receiving a mixed grass hay/concentrate diet and with washed cells of Prevotella (formerly Bacteroides) ruminicola M384 and P. ruminicola B(1)4. The rates of breakdown of most peptides were similar in the rumen fluid from the two sheep. Acidic and proline-containing peptides tended to be more slowly degraded than neutral or basic peptides. The dipeptide at the N-terminus of higher peptides was observed as an early product of hydrolysis, confirming that a dipeptidyl aminopeptidase type of activity was present. The relative rates of breakdown of dipeptides by P. ruminicola were different from that of rumen fluid, but the hydrolysis of higher peptides followed a similar pattern, and dipeptides from the N-terminus were detected as early products.

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Disseminated disease due to rapidly growing mycobacteria is manifested by positive blood cultures and multiple skin and subcutaneous abscesses. A patient had T-cell lymphoma and disseminated disease; he also had neutropenia intermittently. Single-agent therapy with amikacin sulfate or cefoxitin sodium was not adequate during periods of neutropenia, and combination therapy was necessary to control the infection. Clinical response correlated with detectable serum inhibitory levels of the antimicrobial agents. Surprisingly, the organism was not killed by either amikacin or cefoxitin, a finding that correlated with the absence of serum bactericidal levels. This case suggests that granulocytes may play a role in the host's response to this organism, and determination of serum inhibitory and possible bactericidal levels may be useful in monitoring therapy.