Evaluation of fecal samples from mares as a source of Rhodococcus equi for their foals by use of quantitative bacteriologic culture and colony immunoblot analyses

Grimm, Michael B.; Cohen, Noah D.; Slovis, Nathan M.; Mundy, G. D.; Harrington, Jessica; Libal, Melissa C.; Takaı̈, Shinji; Martens, Ronald J.

doi:10.2460/ajvr.68.1.63

Cited by 42 publications

(57 citation statements)

References 31 publications

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“…in diverse environments. Conservation of cluster 3 in R. equi is consistent with the proposal that feces are an important reservoir for this animal pathogen (8). In at least the case of T. curvata, this gene cluster occurs beyond Rhodococcus spp.…”

Section: Discussionsupporting

confidence: 69%

Gene Cluster Encoding Cholate Catabolism in Rhodococcus spp

et al. 2012

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bBile acids are highly abundant steroids with important functions in vertebrate digestion. Their catabolism by bacteria is an important component of the carbon cycle, contributes to gut ecology, and has potential commercial applications. We found that Rhodococcus jostii RHA1 grows well on cholate, as well as on its conjugates, taurocholate and glycocholate. The transcriptome of RHA1 growing on cholate revealed 39 genes upregulated on cholate, occurring in a single gene cluster. Reverse transcriptase quantitative PCR confirmed that selected genes in the cluster were upregulated 10-fold on cholate versus on cholesterol. One of these genes, kshA3, encoding a putative 3-ketosteroid-9␣-hydroxylase, was deleted and found essential for growth on cholate. Two coenzyme A (CoA) synthetases encoded in the cluster, CasG and CasI, were heterologously expressed. CasG was shown to transform cholate to cholyl-CoA, thus initiating side chain degradation. CasI was shown to form CoA derivatives of steroids with isopropanoyl side chains, likely occurring as degradation intermediates. Orthologous gene clusters were identified in all available Rhodococcus genomes, as well as that of Thermomonospora curvata. Moreover, Rhodococcus equi 103S, Rhodococcus ruber Chol-4 and Rhodococcus erythropolis SQ1 each grew on cholate. In contrast, several mycolic acid bacteria lacking the gene cluster were unable to grow on cholate. Our results demonstrate that the above-mentioned gene cluster encodes cholate catabolism and is distinct from a more widely occurring gene cluster encoding cholesterol catabolism. Bile salts are surface-active steroids with an important role in the uptake and metabolism of lipophilic substrates in vertebrates. These steroids, which include cholate and chenodeoxycholate, are synthesized in the liver from cholesterol, and their eventual fate is excretion in feces or urine. Bile salts may be modified, either by microbiological activity in the duodenum or by host cell bioactivity, leading to their conjugation to glycine, taurine, or sulfate. As such, biodegradation of the various bile salts is a significant process in carbon cycling in soil and aquatic environments. The processes involved in microbial transformation of steroids are also relevant for biotechnological applications in the synthesis and/or selective modification of steroid-based drugs (29).Despite the cytotoxicity of cholate toward various prokaryotic and eukaryotic cells, several bacterial species, especially members of the Proteobacteria (27, 28) and Actinomycetales (9, 32), are able to efficiently metabolize this substrate to sustain growth. Recent studies on microbial bile salts degradation have focused on the Proteobacteria. Genes encoding several steps in cholate degradation were identified, mainly in Comamonas testosteroni TA441 and Pseudomonas sp. strain Chol1. In the former strain, genes responsible for oxidation of the steroid nucleus were found (10-13), while in the latter, genes responsible for degradation of the cholate side chain were identified, in...

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Section: Discussionsupporting

confidence: 69%

Gene Cluster Encoding Cholate Catabolism in Rhodococcus spp

et al. 2012

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“…Use of the modified NANAT agar medium effectively minimized concomitant growth of bacterial and fungal contaminants without inhibiting growth of R equi. 28 Culture plates were incubated at 37°C for 36 hours. One to 5 colonies of R equi were harvested and streaked onto blood agar media plates and incubated at 37°C for 48 hours.…”

Section: Methodsmentioning

confidence: 99%

“…Microbiological culture of fecal specimens was performed in duplicate by use of a modified NANAT R equi-selective agar medium, as described elsewhere 28 ; both positive and negative control samples were used. Use of the modified NANAT agar medium effectively minimized concomitant growth of bacterial and fungal contaminants without inhibiting growth of R equi.…”

Section: Methodsmentioning

confidence: 99%

Chemoprophylactic effects of azithromycin against Rhodococcus equi–induced pneumonia among foals at equine breeding farms with endemic infections

Chaffin

Cohen²,

Martens³

2008

javma

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Azithromycin chemoprophylaxis effectively reduced the cumulative incidence of pneumonia attributable to R equi among foals at breeding farms with endemic R equi infections. There was no evidence of resistance to azithromycin. Nonetheless, caution must be used because it is possible that resistance could develop with widespread use of azithromycin as a preventative treatment. Further investigation is needed before azithromycin chemoprophylaxis can be recommended for control of R equi infections.

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“…The strains included soil and clinical isolates, as well as ATCC strains (see Table 2). Soil isolates include MillB, HDP5B, and HDP1C (13,25). A total of 29 clinical isolates collected from various sources, including trans-tracheal wash, lung, lymph node, and the feces of infected foals, were used in this study (S1, S2, S3, L1, L1p-, 98-099, 99-110, 99-158, 99-171, 99-180, 99-228, 99-232, 99-120, 99-134, 00-051, 00-050, 01-116, 02-125, 04-172, 04-181, 04-195, 04-200, 04-239, 05-300, 05-305, 05-306, 05-338, 05-373, and 06-383).…”

Section: Methodsmentioning

confidence: 99%

Genomic and Functional Analyses of Rhodococcus equi Phages ReqiPepy6, ReqiPoco6, ReqiPine5, and ReqiDocB7

Summer

Liu

Gill

et al. 2011

Appl Environ Microbiol

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The isolation and results of genomic and functional analyses of Rhodococcus equi phages ReqiPepy6, ReqiDocB7, ReqiPine5, and ReqiPoco6 (hereafter referred to as Pepy6, DocB7, Pine5, and Poco6, respectively) are reported. Two phages, Pepy6 and Poco6, more than 75% identical, exhibited genome organization and protein sequence likeness to Lactococcus lactis phage 1706 and clostridial prophage elements. An unusually high fraction, 27%, of Pepy6 and Poco6 proteins were predicted to possess at least one transmembrane domain, a value much higher than the average of 8.5% transmembrane domain-containing proteins determined from a data set of 36,324 phage protein entries. Genome organization and protein sequence comparisons place phage Pine5 as the first nonmycobacteriophage member of the large Rosebush cluster. DocB7, which had the broadest host range among the four isolates, was not closely related to any phage or prophage in the database, and only 23 of 105 predicted encoded proteins could be assigned a functional annotation. Because of the relationship of Rhodococcus to Mycobacterium, it was anticipated that these phages should exhibit some of the features characteristic of mycobacteriophages. Traits that were identified as shared by the Rhodococcus phages and mycobacteriophages include the prevalent long-tailed morphology and the presence of genes encoding LysBlike mycolate-hydrolyzing lysis proteins. Application of DocB7 lysates to soils amended with a host strain of R. equi reduced recoverable bacterial CFU, suggesting that phage may be useful in limiting R. equi load in the environment while foals are susceptible to infection.Although the "tailed phage," or members of the virus order Caudovirales, constitute the majority of DNA diversity on the planet, the genomes of only a few hundred are known. Moreover, the genomic data that are available for bacteriophages are extremely unevenly distributed in terms of host species, with two-thirds derived from phages of only eight host genera or closely related bacterial species, including those belonging to the Staphylococcus, Mycobacterium, Pseudomonas, Lactococcus, and Burkholderia genera and the Enterobacteriaceae family (28). Nevertheless, some important themes have emerged from analyzing multiple phages that infect closely related host genera. One theme emerging is that despite rampant lateral gene transfer, there are recognizable "phage types" spanning geography and host taxa. Casjens (11a) was able to group 73 tailed-enterophage genomes into 13 phage types, the members of which were more closely related to each other by a number of criteria than they were to any member of another type. It should be noted that the classic enterophages do not include representatives of all phage types. When groups of phages from other host clades are sequenced, new phages and new phage types are identified. For example, among the sequenced phages of Burkholderia, there are members of the established , Mu, and P2 temperate phage types, as well as entirely new virulent phage types, such a...

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Evaluation of fecal samples from mares as a source of Rhodococcus equi for their foals by use of quantitative bacteriologic culture and colony immunoblot analyses

Cited by 42 publications

References 31 publications

Gene Cluster Encoding Cholate Catabolism in Rhodococcus spp

Gene Cluster Encoding Cholate Catabolism in Rhodococcus spp

Chemoprophylactic effects of azithromycin against Rhodococcus equi–induced pneumonia among foals at equine breeding farms with endemic infections

Genomic and Functional Analyses of Rhodococcus equi Phages ReqiPepy6, ReqiPoco6, ReqiPine5, and ReqiDocB7

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