A case of Rhodococcus presenting as a space occupying region in the brain

1. PRESENTATION
By Dr Nida Ashraf
Resident R3 microbiology
SIUT

2. Case History
• 32 years old Wajid Ali, live renal transplant recipient in 2009.
• Admitted in ER on 17th of July with 2 episodes of generalized tonic-clonic seizures.
There was no tongue bite, fecal or urinary incontinence. Patient was managed for
seizures episode in ER and was planned for MRI and LP along with the routine labs.
• Past history: Patient has no history of same event before,however being an
immunocompromised patient showed history of multiple admissions due to various
reasons and was treated accordingly.
• Medications: Patient was on:
• Socio economic history: Patient is a resident of larkana, an employee of education and
literacy department.
• Inv: MRI brain was done on the same day of admission which showed multiple brain
abscesses after which LP was done and CSF was sent for routine testing.

3. MRI Brain

4. Differential diagnosis:
1.TB
2. Toxoplasmosis
3. CNS lymphomas
4.Cryptococcus neoformans
5.Bacterial Cause
6. Nocardia/Rhodococcus

5. Further Investigations: (24 hours)
Blood culture: showed no growth in first 24 hours.
Urine D/R: mixed insignificant growth after 24 hours
Sputum C/S: Poor quality (Epithelial cells 3+,Pus cell 1+,MZN smear- Negatve. Final report:
no bacterial pathogen isolated.
CSF(18 June): Gram stain: pus cells 1+,no Microorganism seen. D/R: glucose 62mg/dl,
protein 22mg/dl,LDH:21IU/ml, TLC was 50x10(3) with 80% neutrophils. Initial report: No
growth after 48 hours. SDA: No growth after 48 hours
CSF AFB: negative for smear. MTB PCR and Gene Xpert not detected
CMV: Negative. Anti HIV Ag/Ab non-reactive. HSV DNA PCR negative. Toxoplasma gondii
PCR negative.

6. Blood culture
Blood C/S flagged positive after 4 days and Gram smear report showed
branching? GPR.
MZN: positive

7. Provisional diagnosis:
● Contamination

8. Growth On Blood and Chocolate agar after 24 hours

9. Biochemical and API
Colonies were oxidase positive catalase positive.
API coryne was set and the organism was identified as Rodococcus species

10. CAMP Test
Organism was tested for the CAMP TEST was negative

11. Brain biopsy
Brain biopsy Tissue was also received on 27th of june. Smear report show 1+ pus
cells, GPR 1+ and was MZN+

12. After the identification sensitivity
pattern was set on chocolate agar
and shows the following sensitivity:
Sensitivity was set on chocolate
agar after identification and
found sensitive to the following
Anti bacterial agent

13. Discussion Of Case
• Rhodococcus (red coccus) is a gram
positive coccobacillus belonging to
family nocardiaceae, order
actinomycetes.
• Rhodococcus equi (R.equi) is the most
common isolate causing infections in
humans.
● Rhodococcus fascians, Rhodococcus
erythropolis, etc.
Rhodococcus on tap water agar

14. Epidemology and transmission of infections
• Rhodococcus equi (formerly Corynebacterium
equi) was first isolated in 1923 from the lungs of
foals in Sweden
• The first R. equi infection in a human was not
reported until 1967 where a young male with
autoimmune hepatitis on a corticosteroid and 6-
mercaptopurine who worked on a stockyard fell ill
with a cavitating pneumonia.
• It is found in soil and mainly infects grazing
animals.
• Causes severe pneumonia in foals and
immunocompromised individuals.
• Infection in humans can occur due to inhalation
or ingestion of the organism from soil, fertilizers
or animal exposure.

15. PATHOGENSIS
● Rhodococcus bacteria are capable of surviving and
replicating within macrophages .
● They have developed mechanisms to resist being
killed by these immune cells, allowing them to persist
and multiply.
● A distinguishing feature of the genus Rhodococcus is
the characteristic presence of large circular or linear
conjugative plasmids that supports intramacrophage
survival and is essential for animal host colonization
● VapA is also required for establishment of a persistent
infection and for intracellular growth in
macrophages where it aids in preventing maturation of
the phagosome to the stage of fusion of R. equi-
containing vacuoles with lysosomes.
● Like M. tuberculosis, lipids are a key component of
the outer cell envelope of R. equi. This mycolic acid-
containing glycolipid barrier might serve to protect the
peptidoglycan and plasma membrane from the
damaging effects of host-generated enzymes and
immune-mediated reactive intermediates.

16. GROWTH CHARACTERSTICS
● Colonial Morphology: Rhodococcus equi colonies on solid agar
media can appear smooth, mucoid, and creamy or Salmon pink in
color. The colonies usually appear in 48 hrs.Colonies usually
shows lack of aerial hypae.
● Growth Temperature: Rhodococcus equi is mesophilic and
typically grows well at temperatures ranging from 25-37°C (77-
98.6°F). This range is consistent with the body temperatures of
horses and humans.
● Aerobic Growth: Like other members of the Rhodococcus genus,
Rhodococcus equi is an obligate aerobic bacterium, requiring
oxygen for growth.
● Gram Stain Result: Rhodococcus spp will appear purple/blue
short rods arranged in bundles . the presence of mycolic
acids,make it partial acid fast(MZN POSITIVE).
● Biochemical reactions: R. equi are characterized by the
presence of catalase, urease, lipase, and phosphatase and by the
absence of oxidase, DNAse, elastase, lecithinase, and protease.
Fig 1 (A) Gram staining of Rhodococcus
corynebacterioides isolated from blood cultures (B) colonial
appearance of R. corynebacterioides on a sheep blood agar
plate.

17. Spectrum Of Diseases:
● Approximately 10%–15% of
infections occur in seemingly
immunocompetent hosts with the
remainder divided between
patients with HIV infection and
patients who are otherwise
immunocompromised
● pulmonary infection is present in
∼80% of cases.
● Bacteremia occurs in >80% of
immunocompromised patients
and 30% of immunocompetent
patients .
Clinical manifestation
Pulmonary
manifestations
1.Necrotizing
Pneumonia
2.Lung abscess
3.Pulmonary
nodules
ExtraPulmonary
Manifestations
1.Bacteremia
2.Brain abscess
3.Renal abscess
4.Wound infections
5.Catheter related
infections etc:

18. ● Immunocompetent host.. An extensive review of R. equi infections in
immunocompetent hosts was recently published [Of the 19 reported cases,
localized infections accounted for nearly 50%, including all infections in
children. Pulmonary infection was present in >40% of infected patients.
● R. equi infection after transplantation. Approximately 10% of R.
equi infections occur in transplant recipients, primarily as a late complication
in patients receiving immunosuppressive therapy.
● Patients with HIV infectio.. HIV-infected patients account for approximately
two-thirds of cases of R. equi infection in humans .Infection occurred primarily
with CD4 counts of <100 cells/μL, and the mortality rate was high

19. Conclusion:
● R. equi is a rare but recognized pathogen in humans and has emerged as an
important cause of morbidity and mortality among immunocompromised
patients.
● Increasing awareness of R. equi infection improves the likelihood of its accurate
and timely diagnosis.
● Further clinical and laboratory research is needed to better define the routes of
acquisition and the mechanisms of pathogenesis of R. equi infection and the
appropriate treatments for it.

20. References:
● Rhodococcus equi: An Emerging Pathogen David M. Weinstock, Arthur E. BrownClinical Infectious Diseases, Volume 34,
Issue 10, 15 May 2002, Pages 1379–1385, https://doi.org/10.1086/340259
● Bennett JE, Dolin R, Blaser MJ. Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases E-Book:
Elsevier Health Sciences; 2019..
● Rahamat-Langendoen JC, van Meurs M, Zijlstra JG, Lo-Ten-Foe JRJDm, disease i. Disseminated Rhodococcus equi infection
in a kidney transplant patient without initial pulmonary involvement. 2009;65(4):427-30.
● Lee K, Rho M, Yu M, Kwak J, Hong S, Kim J, et al. A case of recurrent meningitis caused by Rhodococcus species successfully
treated with antibiotic treatment and intrathecal injection of vancomycin through an Ommaya reservoir. 2015;47(3):183-9.
Varotti G, Barabani C, Dodi F, Bertocchi M, Mondello R, Cupo P, et al. Unusual Extrapulmonary Rhodococcus Equi Infection in
a Kidney Transplant Patient. 2015;14(6):676-8.
● Menon V, Gottlieb T, Gallagher M, Cheong EJTID. Persistent R hodococcus equi infection in a renal transplant patient: case
report and review of the literature. 2012;14(6):E126-E33.
● Macken E, de Jonge H, Van Caesbroeck D, Verhaegen J, Van Kerkhoven D, Van Wijngaerden E, et al. Rhodococcus equi
sepsis in a renal transplant recipient: a case study. 2015;1(3).
● Kohl O, Tillmanns HH. Cerebral infection with Rhodococcus equi in a heart transplant recipient. J Heart Lung Transplant.
2002;21(10):1147-9. Yamshchikov AV, Schuetz A, Lyon GMJTLid. Rhodococcus equi infection. 2010;10(5):350-9.
● Roda RH, Young M, Timpone J, Rosen JJDm, disease i. Rhodococcus equi pulmonary–central nervous system syndrome:
brain abscess in a patient on high-dose steroids—a case report and review of the literature. 2009;63(1):96-9.

21. Two unique features of R. equi help distinguish it from other organisms. First,
synergistic hemolysis occurs when R. equi cultured on sheep blood agar are
cross-streaked with other bacteria, including Staphylococcus aureus, Listeria
monocytogenes, and Corynebacterium pseudo-tuberculosis. Second, antagonism
between imipenem and other b-lactam antibiotics has been documented in vitro.
This antagonism is widespread among R. equi isolates and is novel among gram-
positive bacteria.
Serologic assays have not been clinically validated and are not commercially
available.