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PubMed1994

Rhodococcus equi infection in HIV-positive patients: report of 5 cases and literature overview.

The importance of Rhodococcus equi infection, an uncommon human pathogen that almost exclusively affects immunocompromised hosts, has greatly increased following the advent of acquired immune deficiency syndrome (AIDS) epidemics. Until the present time, 38 cases of R. equi infection have been described in human immunodeficiency virus (HIV)-infected patients; we now report a further five personal cases. R. equi was acquired via respiratory exposure to animals in less than half of the patients, and caused invasive pulmonary infection (91%), bacteraemia and sometimes bloodstream dissemination. R. equi was easily cultured from sputum or blood, but its diagnosis was often difficult due to microbiological and clinical similarities with other pathogens. The persistence of the micro-organism inside macrophages and its high tissular load represent the major limitation to an effective treatment. Several antibiotics are active in vitro, but their efficacy in vivo depends on macrophage uptake and/or bactericidal activity. Treatment should start with at least two intravenous bactericidal antibiotics for 3-4 weeks, and then continue with oral therapy for a period of up to several months with at least two intracellularly active drugs. Surgical resection of the lesions may be beneficial in selected cases.

AIDS-Related Opportunistic Infections↗
PubMedDate not supplied

Cytologic appearance of Rhodococcus equi in bronchoalveolar lavage specimens. A case report.

Immunocompromised patients are at risk of developing infections caused by Rhodococcus equi, a gram-positive bacillus that can cause pneumonia in patients with acquired immunodeficiency syndrome. To the author's knowledge this is the first report describing the cytologic features of the infection in a patient who had a confirmatory tissue biopsy and positive culture. Infection with R equi may go unrecognized by pathologists unaware of its presentation and appearance in cytologic material.

Actinomycetales Infections↗
PubMedDate not supplied

Rhodococcus equi: fatal pneumonia in a patient without AIDS.

Rhodococcus equi infections are being recognized with greater frequency in immunocompromised patients and the population infected with the human immunodeficiency virus (HIV). R. equi usually causes a progressive pneumonia that may or may not cavitate and is relatively refractory to antibiotic therapy. We report a case of fatal R. equi pneumonia in a normal host.

Actinomycetales Infections↗
PubMed1994

[Pulmonary malacoplakia and Rhodococcus equi pneumonia in a patient infected with the human immunodeficiency virus. A case report with review of the literature].

We report a case of pulmonary malakoplakia in a patient suffering from AIDS secondary to a Rhodococcus equi pneumonia. The association between these two pathologies only occurring in the immunodepressed does not seen fortuitous. Deficiency in cellular immunity and macrophage cellular activity as well as failure of intracellular bactericidal and phagolysosomal function are very probably the links. The treatment of this opportunistic germ rests on prolonged poly-antibiotic therapy or indeed surgical excision.

AIDS-Related Opportunistic Infections↗
PubMed1993

Rhodococcus equi infection: a cause of cavitary pulmonary disease in immuno-compromised patients.

Rhodococcus equi is a facultatively-aerobic, gram-positive and intracellular bacteria that causes pulmonary and disseminated infections in immuno-compromised patients. It is a common agent that causes pneumonia in farm animals and only rarely is transmitted to man. I report a case of pneumonia caused by this agent in a patient with AIDS who had been misdiagnosed as tuberculosis and treated as such for five months before the correct diagnosis was made. The diagnosis should be suspected on clinical and radiologic grounds as treatment is considerably different from other opportunistic pathogens in AIDS.

AIDS-Related Opportunistic Infections↗
PubMed1994

[Pneumonia by Rhodococcus equi in patients with HIV infection].

We present the case of a patient with AIDS who developed abscessified pneumonia by Rhodococcus equi. We publish this case given the rare frequency of presentation of this opportunistic infection in this type of patient and given its good clinical evolution, on the contrary of other cases described so far in the literature. The good evolution of the patient may be due to an early diagnosis, less than one month, and the combined medical therapy with rifampicine and tetracyclines.

AIDS-Related Opportunistic Infections↗
PubMed1994

Analysis of three 2,3-dihydroxybiphenyl 1,2-dioxygenases found in Rhodococcus globerulus P6. Identification of a new family of extradiol dioxygenases.

The polychlorobiphenyl-degrading bacterium Rhodococcus globerulus P6 contains three bphC genes encoding 2,3-dihydroxybiphenyl 1,2-dioxygenases. One of them, bphC1, is clustered with the bphB gene which encodes 2,3-dihydroxy-4-phenylhexa-4,6-diene dehydrogenase and constitutes part of the bph operon specifying the degradation of biphenyl. The nucleotide sequence of bphB and the three bphC genes has been determined. The protein products of the bphBC1 gene cluster were found to exhibit significant homology with the corresponding proteins of analogous degradative pathways in Gram-negative bacteria; the highest homology was in those of the toluene degradation pathway of Pseudomonas putida strain F1. No homology was found between bphC2 and bphC3 and any other sequence in the database. At least two of the three meta cleavage enzymes are inducible by biphenyl. 2,3-Dihydroxybiphenyl 1,2-dioxygenase II, encoded by the bphC2 gene, was purified to apparent homogeneity from a recombinant Escherichia coli strain. The enzyme differed from other extradiol dioxygenases in having a subunit molecular mass of 21 kDa and a hexameric structure. The enzyme contains one tightly bound iron per subunit. These characteristics demonstrate that the 2,3-dihydroxybiphenyl 1,2-dioxygenases encoded by bphC2 and bphC3 belong to a new class of extradiol dioxygenases.

Amino Acid Sequence↗
PubMed1993

[Detection of Rhodococcus equi antibodies in human serum].

The authors investigated in sera of patients with pneumonia the presence of antibodies against the equi factor Rhodococcus equi. For examination they used agar immunodiffusion and a test for neutralizing the equi factor. Some 110 sera of different donors were examined. In agar immunodiffusion they used the equi factor as antigen either in the separated form or equi factor produced by the growing strain of R. equi. The neutralization test was implemented on agar media with red blood cells sensitized with staphylococcal beta-haemolysin. In all serological tests 27 sera reacted positively only by precipitation 30 sera, while 53 sera did not contain antibodies against the equi factor. The authors discuss the impact of the assembled results and the possible participation of R. equi in human disease.

Actinomycetales Infections↗
PubMed1995

A physical map of the 85 kb virulence plasmid of Rhodococcus equi 103.

A physical map of the 85 kb virulence plasmid pOTS from Rhodococcus equi 103 was constructed. The restriction map contains 2 AsnI, 5 BglII, 9 EcoRI, 4 HindIII, and 3 XbaI sites. The positions of the EcoRI and HindIII of pOTS are identical to that of the 85 kb virulence plasmid of R. equi ATCC 33701 reported recently by others. EcoRI restriction fragment sizes were similar in the 85 kb plasmids isolated from 4 horse derived R. equi but, except apparently for the 28.3 and possibly 2.0 and 1.5 kb fragments, were different in an 80.1 kb plasmid isolated from a pig source R. equi.

Animals↗
PubMed1996

Role of CD4+, CD8+ and double negative T-cells in the protection of SCID/beige mice against respiratory challenge with Rhodococcus equi.

To evaluate the contributions of T-lymphocyte subsets in pulmonary immunity against Rhodococcus equi, C.B-17 SCID/beige mice were adoptively transferred with splenic lymphocytes from congenic BALB/c mice previously infected with R. equi. Spleen cells were enriched for either CD4+ or CD8+ populations before inoculation, Flow cytometry showed that each enriched population contained less than 0.5% cross contamination. Groups of adoptively transferred SCID/beige mice were sacrificed 6 and 13 d after intranasal infection with R. equi. Bacterial clearance was measured in the lungs, liver and spleen. Lesion development was assessed by gross and histopathological score and the fate of transferred cells assessed by flow cytometry and by immunohistochemistry. SCID/beige mice receiving either CD4+ or CD8+ T-cells were able to clear the infection better than control mice. On d 6 post-infection, bacterial numbers were significantly lower in the lungs of CD4+ transferred mice as compared to CD8+ mice. By d 13, both groups had cleared R. equi from all organs. CD4+ cells were however identified in the lung and spleen of CD8+ recipients at d 13 making conclusions about the role of CD8+ cells in R. equi clearance impossible. By contrast, no significant increases in CD8+ lymphocytes were observed in the organs of CD4+ recipients. All mice developed suppurative bronchopneumonia but lesions were most severe in the CD4+ group. Immunohistochemistry and flow cytometry confirmed that CD4+ and CD8+ cells had migrated to the lungs of adoptively transferred mice. Serum antibody against R, equi was not detected by ELISA in the recipients. SCID/beige mice receiving CD4-CD8- cells were unable to clear R. equi. The study supports the suggestion that CD4+ cells have a central role in R. equi clearance in mice.

Actinomycetales Infections↗
PubMedDate not supplied

[The degradation of plasticizers by Rhodococcus erythropolis 40F].

A Rhodococcus erythropolis 40 phi strain isolated from the soil utilizes 0.1-2% v/v dibutylphthalate (DBP) and di-(2-ethylhexyl)-phthalate (DEHP) as a single carbon source. The strain metabolizes DBP and DEHP via the following steps: diester --> phthalate --> benzoate --> p-hydroxybenzoate --> 3,4-dihydroxybvenzoate --> 3-ketoadipinate.

Biodegradation, Environmental↗
PubMed1997

Rhodococcus equi pneumonia.

Corynebacterium equi is a pleomorphic gram-positive rod that was first isolated in 1923 by Magnusson, and is the cause of suppurative broncho-pneumonia in foals. The organism, now know as Rhodococcus equi, is ubiquitous in nature and is increasingly recognized as pathogenic, particularly in the immunocompromised population. Cavitary pneumonia clinically resembling Mycobacterium tuberculosis is the most common manifestation of R equi disease, but extrapulmonary infections are seen as well. Long term treatment with intracellularly active antimicrobial agents is required.

Actinomycetales Infections↗
PubMed1997

Use of Rhodococcus equi virulence-associated protein for immunization of foals against R equi pneumonia.

OBJECTIVE: To evaluate use of the virulence-associated protein of Rhodococcus equi in immunizing foals against R equi pneumonia. ANIMALS: Eight (experimental group) and 6 (controls) mares with their foals. PROCEDURE: Virulence-associated protein extracted from R equi was used to prepare an acetone-precipitated. Triton X-extracted (APTX) antigen. After determination of the efficacy of passive immunization, in untreated foals or in foals given plasma from a horse vaccinated with APTX antigen or from a nonvaccinated horse, a field trial was done to evaluate the efficacy of vaccination of 8 mares, twice with APTX before parturition, and of their foals at ages 3 and 5 weeks; 6 mares and their foals served as unvaccinated controls. All 2-day-old foals were given plasma from local donor horses inoculated with a locally produced bacterin. Serum opsonizing activity produced by vaccination with APTX was determined. Passively immunized foals were challenge exposed with an aerosol of virulent R equi. Foals of the field trial were exposed to enzootic R equi infection. RESULTS: Inoculation with APTX resulted in high IgG antibody liters with opsonizing activity. Passive immunization of foals with plasma from an immunized horse enhanced bacterial clearance from the lungs, compared with that in foals not given plasma or given plasma without APTX antibodies. Vaccination of mares and foals exposed to natural infection resulted in development of R equi pneumonia in 4 of 8 vaccinated foals, but in only 1 of 6 unvaccinated foals. CONCLUSIONS: Vaccination with APTX antigen led to high-titer, opsonizing antibody. Plasma from a vaccinated horse appeared to enhance clearance of R equi from the lungs of foals. Paradoxically, vaccination of mares and their foals with APTX antigen did not protect foals and may have enhanced R equi pneumonia in the foals.

Actinomycetales Infections↗
PubMedDate not supplied

Location, catalytic activity, and subunit composition of NAD-reducing hydrogenases of some Alcaligenes strains and Rhodococcus opacus MR22.

Six new strains of Alcaligenes enriched for and isolated as nickel-resistant bacteria resemble Alcaligenes eutrophus H16 and contain both an NAD-reducing, tetrameric soluble hydrogenase and a membrane-bound hydrogenase. None of the soluble hydrogenases share with the Rhodococcus opacus MR11 enzyme tetramer the property of being cleaved easily into two dimeric moieties [a hydrogenase (betadelta) and an NADH:acceptor oxidoreductase (alphagamma)], in the absence of nickel or at low ionic strength. The soluble hydrogenase of the newly isolated strain MR22 of R. opacus equalled that of strain MR11. The absence of a membrane-bound hydrogenase in Alcaligenes denitrificans strain 4a-2 and in Alcaligenes ruhlandii was confirmed.

Alcaligenes↗
PubMed1997

[Review of 105 cases of isolation of Rhodococcus equi in humans].

BACKGROUND: Rhodococcus equi (formerly Corynebacterium) has been long considered an exclusively zoopathogenic microbe causing mainly granulomatous pneumonias and lung abscesses in young foals. The aim of this paper was to analyse substantial features of R, equi infections hitherto reported in man. METHODS AND RESULTS: MEDLINE database was searched for relevant reports. When the original source was not obtained the data from reviews were employed. Together, 105 cases of R, equi infection in man were reported. Median age was 35 years with a range from 9 months to 83 years. The male: female ratio was 3.3. Lungs were involved in 72 cases (69%), extrapulmonary abscesses as the only symptom of infection were described in 9 cases, septic state in 7 cases. Clinical outcome was known in 98 cases, being fatal in 41 (42%). Therapy was mentioned in 70 reports, the most often used drugs being erythromycin (30 cases, 12 deaths), rifampicin (19 cases, 7 deaths) and vancomycin (18 cases, 6 deaths). R. equi was isolated from the sputum of 69% patients with the pulmonary involvement. Blood cultures were positive in 35% of cases. Out of total, 49% persons were HIV positive. Median age for HIV positive patients was 32 years with a range from 18 to 71 years, for HIV negative patients 52 years with a range from 9 months to 83 years. There were 97% males in the HIV positive group in contrast to 59% in the HIV negative group (p < 0.01). Lungs were involved in 90% of HIV positive and 48% of HIV negative cases (p < 0.01). Extrapulmonary abscesses as the only sign of infection were seen in 2% of HIV positive persons and in 15% of HIV negative ones (p < 0.05). Outcome was fatal for 60% of the HIV positive hosts and for 28% of the HIV negative individuals (p < 0.01). R. equi was isolated from the sputum of 80% pneumonic HIV positive patients and of 50% of pneumonic patients without HIV infection (p < 0.05). R. equi was detected in the blood of 67% of HIV positive patients and of 33% of HIV negative ones (p < 0.01). CONCLUSIONS: The analysis of published reports shows that whereas R. equi causes mainly pneumonia in persons with HIV infection, in HIV negative individuals extrapulmonary manifestations slightly prevail, most often abscesses, sepsis, eye involvement and wound infections.

AIDS-Related Opportunistic Infections↗
PubMed1997

[Rhodococcus equi--a newly recognized opportunistic pathogen in man].

The review informs about substantial features of Rhodococcus equi with emphasis on the analysis of 115 as yet published and still expanding reports on the isolation of this zoopathogenic nocardioform actinomycete from man. Microbiological laboratories of human medicine have to learn not only how to identify R. equi but also recognize it as an opportunistic pathogen in particular in persons with the deficient immunity. R. equi is a gram-positive, encapsulated diphtheroid coccobacillus, partially acid fast. It grows well on common media, its colonies being after 48 hours characteristically mucoid, coalescing, irregular and mostly lightly pinkish. Biochemically it is little active, nevertheless it causes typical synergic haemolysis of erythrocytes influenced by staphylococcal beta-toxin. R. equi is found in soil and manure, especially in horse manure. It causes above all granulomatous pneumonia in young foals. In humans, it causes mostly pneumonia and lung abscess, more frequently in persons with immunity deficiency incl. AIDS, less often extrapulmonary abscesses, sepsis and wound infections. The disease are commonly chronic and recurrent. The ability of R. equi to persist in macrophages and destroy them is important in the pathogenesis of infection. In resistance to infection the cell-mediated immunity seems to be of major importance. The port of entry are the lungs, less often the alimentary tract or injured skin. About a third of the persons gives a history of contact with animals, manure or soil. The standard treatment is prolonged administration of a combination of rifampin and erythromycin. The isolation of R. equi is easy and if a laboratory suspects the presence of this microorganism, its identification is not difficult.

Actinomycetales Infections↗
PubMed1997

Purulent meningitis due to Rhodococcus equi. A case of posttraumatic infection.

Opportunistic infections due to Rhodococcus equi have been increasingly reported in the immunocompromised population, especially in patients with AIDS. In this report, we present an unusual case of purulent meningitis that developed in an immunocompetent six-year-old child through direct inoculation of R. equi.

Animals↗