Smooth Colony Type Research Articles

Type I interferon induced by TLR2-TLR4-MyD88-TRIF-IRF3 controls Mycobacterium abscessus subsp. abscessus persistence in murine macrophages via nitric oxide

Mycobacterium abscessus (MAB) is an emerging, rapidly growing non-tuberculous Mycobacterium causing therapy-resistant pulmonary disease especially in patients with cystic fibrosis (CF). Smooth and rough colony type MAB can be isolated from infected patients whereby rough colony type MAB are more often associated with severe disease. Disease severity is also associated with an alternated type I interferon (IFN-I) response of the MAB-infected patients. However the relevance of this response for the outcome of MAB infection is still unknown. In this study, we analyzed the IFNβ expression of murine macrophages infected with a MAB rough colony strain (MAB-R) isolated from a patient with progressive CF and compared it to macrophages infected with the MAB smooth colony type reference strain (MAB-S). We found that MAB-R infected macrophages expressed significantly more IFNβ mRNA and protein than MAB-S infected macrophages. Higher IFNβ induction by MAB-R was associated with higher TNF expression and intracellular killing while low IFNβ induction was associated with lower TNF expression and persistence of MAB-S. IFNβ induction was independent of the intracellular cGAS-STING recognition pathway. MAB appeared to be recognized extracellularly and induced IFNβ expression via TLR2-TLR4-MyD88-TRIF-IRF3 dependent pathways. By using macrophages lacking the IFN-I receptor we demonstrate that MAB induced IFN-I response essentially contributed to restricting MAB-R and MAB-S infections by activating macrophage Nos2 expression and nitric oxide production. Thus IFN-I seem to influence the intrinsic ability of macrophages to control MAB infections. As MAB persists over long time periods in susceptible patients, our findings suggest that virulence of MAB strains is promoted by an insufficient IFN-I response of the host.

Phenotypic variation in Acidovorax radicisN35 influences plant growth promotion

Acidovorax radicis N35, isolated from surface-sterilized wheat roots (Triticum aestivum), showed irreversible phenotypic variation in nutrient broth, resulting in a differing colony morphology. In addition to the wild-type form (rough colony type), a phenotypic variant form (smooth colony type) appeared at a frequency of 3.2×10(-3) per cell per generation on NB agar plates. In contrast to the N35 wild type, the variant N35v showed almost no cell aggregation and had lost its flagella and swarming ability. After inoculation, only the wild-type N35 significantly promoted the growth of soil-grown barley plants. After co-inoculation of axenically grown barley seedlings with differentially fluorescently labeled N35 and N35v cells, decreased competitive endophytic root colonization in the phenotypic variant N35v was observed using confocal laser scanning microscopy. In addition, 454 pyrosequencing of both phenotypes revealed almost identical genomic sequences. The only stable difference noted in the sequence of the phenotype variant N35v was a 16-nucleotide deletion identified in a gene encoding the mismatch repair protein MutL. The deletion resulted in a frameshift that revealed a new stop codon resulting in a truncated MutL protein missing a functional MutL C-terminal domain. The mutation was consistent in all investigated phenotype variant cultures and might be responsible for the observed phenotypic variation in A.radicis N35.

Effects of Penicillin G on Morphology and Certain Physiological Parameters of Lactobacillus acidophilus ATCC 4356

Evidence shows that probiotic bacteria can undergo substantial structural and morphological changes in response to environmental stresses, including antibiotics. Therefore, this study investigated the effects of penicillin G (0.015, 0.03, and 0.06 mg/l) on the morphology and adhesion of Lactobacillus acidophilus ATCC 4356, including the colony morphotype, biofilm production, hydrophobicity, H₂O₂ formation, S-layer structure, and slpA gene expression. Whereas only smooth colonies grew in the presence of penicillin, rough and smooth colony types were observed in the control group. L. acidophilus ATCC 4356 was found to be hydrophobic under normal conditions, yet its hydrophobicity decreased in the presence of the antibiotic. No biofilm was produced by the bacterium, despite testing a variety of different culture conditions; however, treatment with penicillin G (0.015-0.06 mg/l) significantly decreased its production of H₂O₂ formation and altered the S-layer protein structure and slpA gene expression. The S-protein expression decreased with 0.015 mg/l penicillin G, yet increased with 0.03 and 0.06 mg/l penicillin G. In addition, the slpA gene expression decreased in the presence of 0.015 mg/l of the antibiotic. In conclusion, penicillin G was able to alter the S-layer protein production, slpA gene expression, and certain physicochemical properties of Lactobacillus acidophilus ATCC 4356.

Characterization of a flocculation-like phenotype in Cryptococcus neoformans and its effects on pathogenesis

We investigated the phenomenon of cell-cell aggregation (flocculation) in a serotype D strain of Cryptococcus neoformans (ATCC 24067, isolate RC-2). Cell aggregation into clumps of 5-40 cells (clump+ cells) occurred during the early log phase and disappeared in the beginning of the stationary phase (clump- cells). The cell aggregation phenomenon was medium dependent. Clump+ cells could be dispersed by either vortexing or proteinase K digestion. Most importantly, the transient change in cellular phenotype changed several important host-pathogen interactions. Adherence of clump+ cells to murine macrophage-like cells J774.16 was significantly (P < 0.001) enhanced compared with adherence of clump- cells. Furthermore, complement-mediated phagocytosis efficacy of dispersed clump+ cells was significantly higher (P < 0.001) compared with clump- cells. Similar findings were documented with an in vivo phagocytosis assay. Infection of mice with a low inoculum (10(4)) of clump+ cells resulted in lower fungal burden when compared with mice infected with clump- cells. Accordingly, mice infected with clump+ cells survived significantly longer than mice infected with clump- cells. These results indicate that the cellular phenotype undergoes significant changes that result in a transient flocculation-like phenotype. We hypothesize that this cell-cell aggregation is the result of changes in protein content in the polysaccharide capsule. We conclude from our data that the change in cellular phenotype has a dramatic effect on cell adherence, and on complement-mediated phagocytosis, both of which can affect the pathogenesis of the disease in the host. Our results underscore the complexity of studies that investigate host pathogen interactions and may explain differences and inconsistencies observed in in vitro and in vivo assays.

Seroreactive species-specific lipooligosaccharides of Mycobacterium mucogenicum sp. nov. (formerly Mycobacterium chelonae-like organisms): identification and chemical characterization.

Strains of the new species Mycobacterium mucogenicum exhibit physiological and biochemical features very similar to those of the other species of the Mycobacterium fortuitum complex. To define taxonomic criteria for easy identification of M. mucogenicum, the glycolipid patterns of the reference strains and of 32 environmental and clinical isolates were examined by TLC. It was concluded that all M. mucogenicum strains of smooth colony morphology contained species-specific alkali-labile glycoconjugates. Three different patterns were observed among the strains of the smooth colony type. Fractionation followed by conventional chemical analyses of the purified glycolipids showed the specific glycolipids to be lipooligosaccharides (LOS). The three LOS showed a similar fatty acid composition consisting of straight chain (dodeca-, tetradeca-, hexadecanoyl and hexadecenoyl) and methylbranched (2,4-dimethyleicosanoyl and 2,4-dimethyleicosenoyl) fatty acyl substituents. The most commonly encountered LOS (present in 76% of the smooth strains) contained a tetraacylated pentasaccharide composed of four moles of glucose and one mole of a 2,4-di-O-methylhexose. A LOS composed of arabinose, glucose and mannose was present in 20% of the smooth strains, whereas the newly proposed type strain of M. mucogenicum (ATCC 49650) was the only strain that contained a LOS composed of glucose and galactose. Serological studies clearly differentiated most of the strains of M. mucogenicum from those of the other members of the M. fortuitum complex, and demonstrated the existence of serovars within the former species. Altogether, these data confirm the validity of the new species but show ATCC 49651 to be the most representative strain.

Isolation and characterization of moderately halophilic bacteria from fully cured salted cod (bachalao)

A total of 128 Strains of moderately halophilic bacteria were isolated from wet, dry and desalted bachalao (salted codfish) as well as from fresh cod and curing salt. The viable count of these bacteria in fully cured wet and dry bachalao ranged from 103 to 107 per g. All strains were characterized with 40 phenotypic tests and clustered using the SSM coefficient and UPGMA linking analysis. The strains clustered into five phena at 75% similarity, with 77 strains in phenon A and 37 in phenon E. Two main colony types, smooth and rough, were observed and correspond to phena A, B and C on one hand and phenon E on the other. These two types seem to represent the dominating bacterial flora in fully cured, wet and dry bachalao, respectively. Representative strains of the smooth colony type were characterized further and found to grow well in 0.1–4.5 mol I−1 NaCl and at 15–37°C. They have not, at present, been assigned to any known bacterial species.

Bordetella avium: An Opportunistic Pathogen in Leghorn Chickens

Experiments were conducted in order to produce bordetellosis in specific-pathogen-free (SPF) leghorn chickens. In the first and second of three experiments, young turkeys and chickens, respectively, were allotted into groups and challenged at 2 weeks of age with one of seven different isolates of Bordetella avium and two isolates of B. avium-like bacteria. Isolates of B. avium with the smooth colony type were pathogenic in turkeys but not in chickens. The B. avium-like bacteria and B. avium isolates with rough colonial morphology were nonpathogenic. In the third experiment, SPF leghorn chicks were vaccinated at 1 day of age with infectious bronchitis virus, Newcastle disease virus, or both and then challenged with B. avium at 7 days of age. Chickens vaccinated and then challenged with B. avium showed clinical signs and lesions similar to bordetellosis in turkeys. No clinical signs were observed in unchallenged chickens. Thus, we conclude that B. avium is an opportunistic pathogen in SPF leghorn chickens.

Filamentous Forms of Bordetella avium: Culture Conditions and Pathogenicity

Difficulties in preparing suitable antigen for the microagglutination (MA) test led to the discovery of a filamentous form of Bordetella avium. Broth media high in nutrients, vigorous shaking, and incubation at 37 C appeared to promote the development of filamentous forms of the organism. Peptone broth did not induce the development of filamentous forms. Eleven different isolates having both smooth and rough colony types were tested and observed to form filaments of various lengths. Filamentous forms of B. avium hemagglutinated guinea pig erythrocytes were motile, had pili and flagella, and were stable up to the fourth or fifth passage in broth media, at which time a predominance of typical coccobacillus organisms were observed. Filamentous forms of B. avium originating from smooth-colony types were pathogenic in turkey poults, whereas the filamentous forms of B. avium originating from rough-colony types were not pathogenic.

Observations on Colonial Phenotypic Variation in Bordetella avium

Two forms of Bordetella avium colonial morphology on artificial media were observed. The smooth colonial morphology is convex, with an entire edge, and has a glistening mucoid appearance when cultured on 5% bovine blood agar or tryptic soy agar. On the same media, the rough morphology has a crenated edge, a flat surface, and sometimes a wrinkled or ground-glass appearance to the surface. Colonial morphology remained stable when cultures were passaged at 37 C every 48 hours. When different salts or crystal violet were added to the media, the colonial morphology of seven different isolates did not change. Following storage at 4 C on agar, B. avium isolates switched between the smooth and rough colonial morphology, indicating that this is a reversible process. Generally, bacteria with the smooth colonial morphology were motile on sulfide indole motility (SIM) media, whereas bacteria with the rough colonial morphology were non-motile. Only the isolates with the smooth colony type colonized the upper respiratory tract of turkeys, caused clinical signs of the disease, and elicited an agglutinating antibody titer by 21 days postexposure.

Characterization of Escherichia coli obtained from newborn calves with diarrhea.

A total of 373 isolates of Escherichia coli were obtained from one or more calves with diarrhea in 155 herds during the 1974 calving season in Montana. Sixty-seven (18 percent) of the isolates representing 59 of the 155 herds were found to be enterotoxigenic as indicated by their ability to cause distention of the calf ligated intestinal segment. The 67 isolates of enterotoxigenic E. coli (ETEC) were placed in one of six different antigenic groups based upon agglutination of formolized whole cells in KO antiserum. Eighty-seven percent (58 of 67) of the ETEC had antigen 1, 2, or 3, whereas only 2.3 per cent (7 of 310) of the non-ETEC (NETEC) had antigen 1, 2, or 3. This antigen numbering system was used for convenience and is not related to any established typing system. Antigens 1, 2, and 3 do not belong to any of the O groups 1 to 157 or K groups 1 to 93 of the International Schema. Colony color or morphology of ETEC and NETEC grown on Tergitol-7 agar with triphenyltetrazolium chloride added could not be used as an indicator of enterotoxigenicity, although there was a tendency for E. coli with the smooth and mucoid colony type to be enterotoxigenic whereas rough colonies were seldom enterotoxigenic. Among ETEC isolates with antigen 1, 2, or 3, there was good correlation between colony type and antigen number. All 13 ETEC isolates with antigen 1 had the smooth colony type, 17 of 19 ETEC isolates with antigen 2 had the smooth, mucoid colony type, and all 25 isolates of ETEC with antigen 3 had the intermediate colony type. Conversely, of the 310 isolates of NETEC, none had antigen 1 and the smooth colony type; none had antigen 2 and the smooth and mucoid colony type; and only one isolate of NETEC had antigen 3 and the intermediate colony type. Sixteen of the 67 isolates of ETEC (24 percent) were motile. Fifteen of the 16 motile isolates of ETEC had the intermediate colony type, and none of the ETEC with smooth or smooth and mucoid colonies were motile.

Respiratory Pathogenicity of Bacillus Anthracis Spores: II. Genetic Variation in Respiratory Pathogenicity and Invasiveness of Colonial Variants of B: Anthracis

virulence and colony morphology with the smooth colony types exhibiting the greater virulence. However, Bacillus anthracis is generally regarded as an exception in that the smooth variants of this species have been found to be less virulent than the normal rough forms. Nungester3 has reviewed the earlier literature and has classified colonial variants of B. anthracis into some 7 categories. Nungester concludes that no or little correlation between colony type and virulence occurs in B. anthracis since he observed both virulent and avirulent cultures of the same

STUDIES ON THE MODE OF SPREAD OF B. ENTERITIDIS MOUSE TYPHOID INFECTION

Thirteen batches of mice from nine different sources were tested for the presence of mouse typhoid bacilli. Individuals from nine of the groups were found to be infected with the B. enteritidis type, four with the paratyphoid B, one with both, and one with neither type. With two exceptions, smooth type colonies alone were found. These results are in conformity with similar observations as reported by others and confirm the general belief that smooth colony types of paratyphoid-enteritidis bacilli prevail throughout the various stages of rodent typhoid infection.