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PubMed2001

Evaluation of E test, disk diffusion and broth microdilution to establish tentative quality control limits and review susceptibility breakpoints for two aerobic actinomycetes.

A single laboratory study was carried out to compare E Test with broth microdilution and disk diffusion to establish tentative quality control ranges for Nocardia asteroides ATCC 19247 and Rhodococcus equi ATCC 6939 against a panel of eight antimicrobial agents. Reproducibility testing was performed on 12 consecutive days to establish tentative quality control ranges. A total of 36 clinical strains of the Nocardia asteroides complex and 5 Rhodococcus strains were used in the study. Both candidate control strains and clinical strains grew well on cation-adjusted Mueller-Hinton agar. Adequate growth occurred at 48 to 72 h for the Nocardia isolates and 24 to 48 h for Rhodococcus. A standardized primary inoculum of 5 x 10(4) CFU/mL was used for performance of E Test and disk diffusion for the Nocardia isolates. Tentative population-based error rates were calculated using current breakpoints for Enterobacteriaceae for E Test compared with disk diffusion for the 36 clinical strains of Nocardia species. Significant very major error rates were observed for imipenem (22%) and minor error rates varied from 2.7% to 50%. These methods require more extensive validation before definitive breakpoint criteria can be established.

Aerobiosis↗
PubMed1985

Cefadroxil in the horse: pharmacokinetics and in vitro antibacterial activity.

Sodium cefadroxil was administered as a single intravenous dose (25 mg/kg) to six healthy adult mares. Plasma samples were collected over a 24-h period and cefadroxil concentrations were measured by microbiological assay. The pharmacokinetic behavior of the drug was appropriately described in terms of a one-compartment open model. Values for the major pharmacokinetic terms were: extrapolated initial plasma concentration = 59.2 +/- 15.0 micrograms/ml; half-life = 46 +/- 20 min; apparent volume of distribution = 462 +/- 191 ml/kg; and body clearance = 7.0 +/- 0.6 ml/min.kg. In a subsequent study, a suspension of cefadroxil monohydrate was administered intragastrically (25 mg/kg) to the same six horses. Plasma concentrations of the drug peaked at 1-2 h but, in general, absorption was both poor and inconsistent. The data were unsuitable for determination of cefadroxil bioavailability from this oral dosage form. Ninety-nine isolates of eleven bacterial species obtained from clinically ill horses were tested for susceptibility to cefadroxil. All strains of Streptococcus equi, Streptococcus zooepidemicus, coagulase-positive staphylococci, Corynebacterium pseudotuberculosis and five out of six strains of Actinobacillus suis were highly susceptible to the drug (MIC less than 4 micrograms/ml). Escherichia coli, Klebsiella pneumoniae and Salmonella sp. showed intermediate susceptibility (MIC 4-16 micrograms/ml), while all isolates of Corynebacterium (Rhodococcus) equi, Enterobacter cloacae and Pseudomonas aeruginosa proved to be highly resistant to cefadroxil (MIC greater than 128 micrograms/ml).

Animals↗
PubMed1990

Pulmonary malacoplakia in a child.

Pulmonary malacoplakia is a rare condition with only five previously reported cases in the literature, all occurring in adults. We describe a case of malacoplakia of the lung in a 6-year-old female with acute lymphoblastic leukemia in remission and a Rhodococcus equi pneumonia and septicemia. The case demonstrates that pulmonary malacoplakia can occur in immunocompromised pediatric patients and that malacoplakia should, therefore, be added to the list of causes of nodular lung infiltrates in immunocompromised children.

Child↗
PubMed2003

Structural and functional features of Rhodococcus ruber lipoarabinomannan.

The genus Rhodococcus is part of the phylogenetic group nocardioform actinomycetes, which also includes the genus MYCOBACTERIUM: Members of this phylogenetic group have a characteristic cell envelope structure, which is dominated by various complex lipids. Among these, lipoglycans are of particular interest since mycobacterial lipoarabinomannans are important immunomodulatory molecules that are likely to be involved in the subsequent fate of mycobacterial bacilli once inside phagocytic cells. Rhodococcus ruber is a species closely related to an established opportunistic human pathogen, Rhodococcus equi. This paper reports the isolation and characterization of R. ruber lipoarabinomannan, designated as RruLAM. SDS-PAGE and gas chromatography analyses revealed that RruLAM was of an intermediate size between Mycobacterium tuberculosis lipoarabinomannan and lipomannan. Using a combination of chemical degradation and (1)H, (13)C-NMR experiments, the carbohydrate structure of RruLAM was unambiguously shown to be composed of a linear (alpha1-->6)-Manp backbone substituted at some O-2 positions by a single t-alpha-Araf sugar unit. Integration of the anomeric proton signals provided an indication of the degree of branching as approximately 45 %. The RruLAM structure is much simpler than that established for M. tuberculosis lipoarabinomannan but is also different from that determined for the closely related species and opportunistic human pathogen, R. equi. RruLAM was unable to induce the production of TNF-alpha by either human or murine macrophage cell lines, suggesting that more sophisticated structures, such as phosphoinositol capping motifs, are required for such activity.

Animals↗
PubMed1990

In vitro susceptibility of selected veterinary bacterial pathogens to ciprofloxacin, enrofloxacin and norfloxacin.

The minimum inhibitory concentrations (MIC) of ciprofloxacin, enrofloxacin, and norfloxacin were tested for approximately ten clinical isolates of each of Actinobacillus pleuropneumoniae, Actinobacillus suis, Actinomyces pyogenes, Corynebacterium pseudotuberculosis, Erysipelothrix rhusiopathiae, Haemophilus parasuis, Haemophilus somnus, Pasteurella haemolytica, Pasteurella multocida, Rhodococcus equi, Streptococcus equi, Streptococcus suis and Streptococcus zooepidemicus. Ciprofloxacin and enrofloxacin had similar activity and were more active than norfloxacin. All isolates had an MIC of 1.0 microgram/mL or less for ciprofloxacin and enrofloxacin, and these drugs had particularly marked activity against the gram-negative bacteria tested.

Actinobacillus↗
PubMed2006

Sequence analysis of three plasmids harboured in Rhodococcus erythropolis strain PR4.

Rhodococcus erythropolis strain PR4 has been isolated as an alkane-degrading bacterium. The strain harbours one linear plasmid, pREL1 (271 577 bp) and two circular plasmids, pREC1 (104 014 bp) and pREC2 (3637 bp), all with some sequence similarities to other Rhodococcus plasmids. For pREL1, pREC1 and pREC2, 298, 102 and 3 open reading frames, respectively, were predicted. Linear plasmid pREL1 has several regions homologous to plasmid pBD2 found in R. erythropolis BD2. Sequence analysis of pREL1 and pBD2 identified common metal-resistance genes on both, but pREL1 also encodes alkane-degradation genes not found on pBD2, with enzyme constituents some of which are quite different from those of other organisms. The alkane hydroxylase consisted of a cytochrome P450 monooxygenase, a 2Fe-2S ferredoxin, and a ferredoxin reductase. The ferredoxin reductase amino acid sequence resembles the AlkT (rubredoxin reductase) sequence. A zinc-containing alcohol dehydrogenase further oxydizes alkanols, alkane oxidation products catalysed by alkane hydroxylase. Of the circular plasmids, the pREC1 sequence is partially similar to the sequence of pREAT701, the virulence plasmid found in Rhodococcus equi. pREC1 has no pREAT701 virulence genes and encodes genes for beta-oxidation of fatty acids. Thus, joint actions of enzymes encoded by pREL1 and pREC1 may enable efficient mineralization of alkanes.

Base Sequence↗
PubMed1990

Infected wounds and repeated septicemia in a case of factitious illness.

During 19 years an assistant nurse, now 35 years old, has been repeatedly treated for several malingered and self-induced disorders escalating to self-mutilation. An ulcer of her right leg never epithelialised in spite of various local treatments and surgical intervention. During repeated attacks of self-induced septicemia altogether 11 different bacterial species were isolated; on 8 occasions Rhodococcus equi. The septicemias were successfully treated with antibiotics. The underlying psychiatric problem, a borderline personality disorder, has not been possible to treat in a conventional manner. Probably due to collaboration between the plastic surgeon and the psychiatrist she has had fewer attendances and shorter hospital stays lately. Her prognosis is still dubious as regards further self-mutilation and other expressions of self-destructive behaviour.

Actinomycetales Infections↗
PubMed2003

Pathogenic Nocardia, Rhodococcus, and related organisms are highly susceptible to imidazole antifungals.

Rhodococcus equi and species of Nocardia and Gordonia may be human opportunistic pathogens. We find that these, as well as several isolates from closely related genera, are highly susceptible to the imidazoles bifonazole, clotrimazole, econazole, and miconazole, whose MICs are </=1 micro g/ml. In liquid cultures 1 micro g of the drug/ml was bacteriostatic and 10 micro g/ml was bactericidal. On solid media at 10 micro g of azole/ml no resistant mutants could be isolated. An MIC of 1 to 15 micro g/ml was observed with ketoconazole, whereas none of these organisms was inhibited by the triazoles fluconazole and voriconazole (100 micro g/ml). Imidazoles may offer the prospect of treatment of nocardioform mycetomas and may provide the basis for the development of additional antimicrobial agents to combat these pathogens.

Antifungal Agents↗
PubMed1994

Permeabilization of mycolic-acid-containing actinomycetes for in situ hybridization with fluorescently labelled oligonucleotide probes.

The application of whole-cell hybridization using labelled oligonucleotide probes in microbial systematics and ecology is limited by difficulties in permeabilizing many Gram-positive organisms. In this investigation paraformaldehyde treatment, acid methanolysis and acid hydrolysis were evaluated as a means of permeabilizing mycolic-acid-containing actinomycetes prior to hybridization with a fluorescently labelled oligonucleotide probe designed to bind to a conserved sequence of bacterial 16S rRNA. Methods were evaluated on stationary-phase cultures of Gordona bronchialis, Mycobacterium fortuitum, Nocardia asteroides, N. brasiliensis, Rhodococcus equi, R. erythropolis, R. fascians, R. rhodochrous and Tsukamurella paurometabola, none of which could be probed following 4% (w/v) paraformaldehyde fixation. For comparison and to test the general applicability of mild acid pretreatments, Bacillus subtilis, Lactobacillus plantarum, Escherichia coli and Pseudomonas putida were also studied. The data showed that most of the mycolic-acid-containing organisms were successfully permeabilized by mild acid hydrolysis in 1 M HCl at 37 degrees C. Cells were treated for different lengths of time. In general, the mycolic-acid-containing organisms required between 30 and 50 min hydrolysis, whereas B. subtilis, E. coli and P. putida were rendered permeable in only 10 min. Interestingly, L. plantarum could not be permeabilized using acid hydrolysis even after 60 min exposure to 1 M HCl.

Actinomyces↗
PubMed1990

Parallel antitumor, granuloma-forming and tumor-necrosis-factor-priming activities of mycoloyl glycolipids from Nocardia rubra that differ in carbohydrate moiety: structure-activity relationships.

Multiple intravenous injections (30 micrograms, ten times) in ICR mice of trehalose dimycolate and glucose monomycolate from Nocardia rubra, containing C36-48 mycolic acids, showed a prominent antitumor effect on a subcutaneously implanted sarcoma-180, an allogeneic sarcoma of mice with a significant granuloma formation in lungs, spleen and liver. On the other hand, mycoloyl glycolipids other than glucose monomycolate and trehalose dimycolate, such as mannose or fructose mycolate, showed no significant activity for tumor regression or granuloma formation in mice. Trehalose dimycolate and glucose monomycolate from N. rubra, and glucose monomycolate with C56-60 mycolic acids from Rhodococcus terrae also showed a distinctive priming activity for tumor necrosis factor (TNF), when lipopolysaccharide from Escherichia coli was administered as an eliciting agent. The TNF activity in the sera of mice was abrogated almost completely by anti-(murine TNF alpha) antibody with protein-A-agarose. Again in contrast, mannose and fructose mycolate from N. rubra and glucose monomycolate with C30-34 mycolic acids from Rhodococcus equi did not show such activities in mice. Meth-A, a syngeneic fibrosarcoma of BALB/c mice, was less sensitive to administration of glycolipids than sarcoma-180. These results indicated that the existence of a glucose or trehalose molecule was necessary for the expression of immunomodifying activities among various mycoloyl glycolipids differing in carbohydrate structure. However, since the administration of lipopolysaccharide was essentially required as an eliciting agent for the induction of TNF, while no eliciting agent was required for the antitumor activities, TNF does not seem to contribute directly to the antitumor activities of mycoloyl glycolipids in our systems. There was, however, a parallel structure-activity relationship among granuloma-forming, antitumor and TNF-priming activities, indicating that the structures of both the carbohydrate moiety and the mycoloyl residues influenced an initial step, such as macrophage activation, commonly and profoundly.

Animals↗
PubMed1999

Etiology, clinical features and outcome of splenic microabscesses in HIV-infected patients with prolonged fever.

A prospective study was conducted to determine the etiology, clinical features, and outcome in a series of 32 consecutively enrolled HIV-infected patients with prolonged fever in whom high resolution (7.5 Mhz) sonography revealed multiple splenic microabscesses. Conventional (3.5 Mhz) sonography showed no splenic abnormalities in any patients. The diagnoses were: tuberculosis (14), visceral leishmaniasis (7), disseminated Mycobacterium avium complex infection (5), Salmonella spp. bacteremia (2), lymphoma (2), disseminated Rhodococcus equi infection (1), disseminated Candida krusei infection (1) and Pneumocystis carinii pneumonia (1). Twenty-eight patients were followed up for six months and four were lost to follow-up. In 16 patients with a clinical cure and microbiological eradication, the findings on follow-up high resolution sonography were normal, and in two patients the microabscesses persisted; ten patients died. In conclusion, the findings suggest splenic microabscesses may be a frequent condition in HIV-infected patients with prolonged fever, being an unspecific manifestation of the opportunistic diseases causing fever of unknown origin in this population. They cannot be detected by conventional abdominal sonography, whereas high resolution sonography is a useful technique for their detection and follow-up.

AIDS-Related Opportunistic Infections↗
PubMed2003

Frozen cancellous bone allografts: positive cultures of implanted grafts in posterior fusions of the spine.

We have carried out a study on the behaviour pattern of implanted allografts initially stored in perfect conditions (aseptically processed, culture-negative and stored at -80 degrees C) but which presented positive cultures at the implantation stage. There is no information available on how to deal with this type of situation, so our aim was to set guidelines on the course of action which would be required in such a case. This was a retrospective study of 112 patients who underwent a spinal arthrodesis and in whom a total of 189 allograft pieces were used. All previous bone and blood cultures and tests for hepatitis B and C, syphilis and HIV (via PCR techniques) were negative. The allografts were stored by freezing them at -80 degrees C. A sample of the allograft was taken for culture in the operating theatre just before its implantation in all cases. The results of the cultures were obtained 3-5 days after the operation. There were 22 allografts with positive culture results (12%) after implantation. These allografts were implanted in 16 patients (14%). Cultures were positive for staphylococci coagulase negative (ECN) in 10 grafts (46%), Pseudomonas stutzeri in two grafts (9%), Corynebacterium jeikeium in two grafts (9%), staphylococci coagulase positive in two grafts (9%) and for each of the following organisms in one case each (4%): Corynebacterium spp., Actinomyces odontolyticus, Streptococcus mitis, Peptostreptococcus spp., Rhodococcus equi and Bacillus spp. No clinical infection was seen in any of these patients. Positive cultures could be caused by non-detected contamination at harvesting, storing or during manipulation before implantation. The lack of clinical signs of infection during the follow-up of our patients may indicate that no specific treatment different from our antibiotic protocol is required in the case of positive culture results of a graft piece after implantation.

Adolescent↗
PubMed1990

The development and evaluation of an enzyme-linked immunosorbent assay for the detection of Mycobacterium bovis.

A double antibody sandwich layer enzyme-linked immunosorbent assay (ELISA) was used to detect Mycobacterium bovis. The ELISA detected M. bovis is pure culture at concentrations of 1 x 10(5) colony-forming units (CFU) ml-1 and greater, compared to a minimum detection level of 1 x 10(6) CFU ml-1 for isolation techniques. Neither technique detected M. bovis at 1 x 10(4) CFU ml-1. The ELISA did not cross-react with common mycobacterial contaminants such as Mycobacterium avium intracellulare-scrofulaceum complex serotypes 18 and 42, M. terrae, M. fortuitum, M. flavescens and with Escherichia coli or Rhodococcus equi. Further work is needed to evaluate this assay in detecting M. bovis in tissues and the environment.

Animals↗
PubMed1992

Analysis of the immunodominant antigens of Corynebacterium pseudotuberculosis.

Antibodies to seven antigens in a whole cell lysate of Corynebacterium pseudotuberculosis ranging in molecular mass from 22 to 120 kilodaltons (kDa) were present in sera of 40 sheep and goats infected with C. pseudotuberculosis. Three antigens of about 120, 68, and 31.5 kDa in size were consistently detected with sera from all animals and twenty-two sera had antibodies to 64, 43, 40, and 22 kDa antigens. None of these antigens were detected by sera from 160 sheep in a C. pseudotuberculosis-free research flock. An NaCl extract of C. pseudotuberculosis cells contained one major protein of about 31.5 kDa and four minor proteins of 68, 64, 43, and 22 kDa in molecular mass as shown by Coomassie Blue staining. Immunoblot analysis demonstrated that the three immunodominant antigens identified in the whole cell extract were contained in the NaCl extract. The 31.5-kDa protein was purified from the NaCl extract by fast-protein liquid chromatography gel filtration to near homogeneity. The purified 31.5-kDa protein showed phospholipase D activity as indicated by synergistic hemolysis with Rhodococcus equi factors and sphingomyelinase activity. The 31.5-kDa protein reacted with antibodies in serum from a sheep naturally infected with C. pseudotuberculosis. This serum also had phospholipase D neutralizing activity. On the basis of its molecular mass, biological activity, N-terminal amino acid sequence analysis, and immunoreactivity, the 31.5-kDa protein was identified as the phospholipase D exotoxin of C. pseudotuberculosis.

Amino Acid Sequence↗
PubMed1996

Genetic differences between nitrate-negative and nitrate-positive C. pseudotuberculosis strains using restriction fragment length polymorphisms.

Corynebacterium pseudotuberculosis has been classified into two biotypes according to ability to breakdown nitrate (Biberstein et al., 1971). Restriction enzyme analysis (REA) has shown to reflect this differentiation, but numerous bands generated by this technique make interpretation difficult (Songer et al., 1988). Restriction fragment length polymorphism's (RFLP's) has become an accepted genetic tool and was used in this study to determine if differences in nitrate reduction and other phenotypic characteristics could be identified genetically. Thirteen C. pseudotuberculosis isolates from four species of domestic animals from different parts of the world were investigated for phenotypic and genetic differences. Three closely related bacteria, Corynebacterium ulcerans, Actinomyces pyogenes (previously C. pyogenes),and Rhodococcus equi (previously C. equi) were included in the study to determine if the RFLP bands were unique to C. pseudotuberculosis. All C. pseudotuberculosis isolates were positive for urease production. Some differences in maltose and sucrose fermentation ability and nitrate reduction were recorded. Genetic differences were identified between the nitrate-positive group and the nitrate-negative group using non-radioactive ribosomal RNA (rRNA) probes Southern blotted to restriction digests of ApaI, PstI, and SstI. A small number of bands were seen, with distinct differences between the nitrate-positive and the nitrate-negative strains. No genetic variations were seen between strains which reflected differences in carbohydrate fermentation. Strains isolated from different animal species and from different parts of the world could not be differentiated genetically using these three restriction enzymes.

Animals↗
PubMedDate not supplied

Development of a serologic panel for the recognition of nocardial infections in a murine model.

A murine model was used to develop a sensitive and specific serologic test for clinical and subclinical infections caused by Nocardia. The following tests were used: (a) enzyme-linked immunosorbent assays (ELISAs) with culture filtrate and cytoplasmic extract antigens from Nocardia asteroides; (b) ELISA with N. asteroides trehalose dimycolate (cord factor); (c) indirect immunofluorescent antibody assay with whole cells of N. asteroides; and (d) Western-blot analysis for the 54 to 55-kD, 36-kD, and 62-kD proteins of N. asteroides. The sera from BALB/c mice, experimentally infected with nonlethal doses of three species of Nocardia, nine species of Mycobacterium, Rhodococcus equi, two species of Actinomadura, and two species of Streptomyces were tested using this panel. The serologic tests did, indeed, identify mice infected with nocardiae and could differentiate them from mice infected with the other actinomycetes, including mycobacteria.

Actinomycetales↗
PubMedDate not supplied

Antimicrobial activity of cefotaxime tested against infrequently isolated pathogenic species (unusual pathogens).

The cefotaxime sodium spectrum of activity is very broad and includes many common species and a variety of less frequently isolated pathogens. We have reviewed the clinical microbiology literature (44 references) and the data base of the University of Iowa Hospitals and Clinics (Iowa City, IA) to collect data on the activity of cefotaxime against the less common species. Cefotaxime was consistently active against Actinobacillus actinomycetemcomitans, Capnocytophaga spp., Eikenella corrodens, Erysipelothrix rhusiopathiae, Pasteurella multocida, Plesiomonas shigelloides, and Fusobacterium nucleatum. The species Alcaligenes xylosoxidans, Flavobacterium spp., Stenotrophomonas (Xanthomonas) maltophilia, Bacillus cereus, Listeria monocytogenes, and Rhodococcus equi were uniformly cefotaxime resistant. For many other species there was considerable variation in reported minimum inhibitory concentrations. These data may be helpful in guiding therapy of unusual infections, particularly in the case of fastidious species, where the appropriate susceptibility testing methodology may not be immediately or routinely available.

Bacteria, Anaerobic↗
PubMed2006

Pet ownership in immunocompromised children--a review of the literature and survey of existing guidelines.

Pet ownership has been associated with both emotional and physical health benefits. However, owning pets may also pose health risks to immunocompromised patients through zoonotic transmission of disease. Our initial impression was that there is a lack of any evidence base in information given by health care professionals regarding these risks. We therefore aimed to produce evidence-based guidelines addressing this issue. A Pubmed search was undertaken and a variety of literature on zoonoses reviewed. Existing guidelines were evaluated and a survey of all Paediatric Oncology Centres in the UK performed. There is a paucity of level 1 and 2 data addressing this issue and clearly more studies, particularly Randomised Controlled Trials (RCTs), are required. Nevertheless, general themes emerged and certain specific guidance was produced based on that produced by the Centres for Disease Control and Prevention in the US. Animal-associated pathogens of concern include Toxoplasma gondii, Cryptosporidium spp., Salmonella spp., Campylobacter spp., Giardia lamblia, Rhodococcus equi, Bartonella spp., Bordetella bronchiseptica, Chlamydia psittaci and dermatophytes. Despite this, the literature would suggest that with the exception of Bartonella henselae and dermatophytes only a relatively small number of infections in people are likely to be associated with pet contact. The majority of pet species do not appear to pose a major risk to immunocompromised children. Some animals, particularly reptiles, should be avoided because of the high risk of salmonellosis. Guidelines include general advice on good hygiene practices, veterinary care, pet foods, purchasing of new pets and age restrictions. Health care professionals should actively enquire about household pets and provide accurate information and practical advice on how to minimise the risk of infection. However, the overall benefits of the human-animal bond must be considered and with proper handling and husbandry immunocompromised patients should be able to continue to enjoy the significant benefits of pet ownership.

Age Factors↗