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Accentuate the Gram positive: an unusual infection in an oncology patient
  1. Natalie Kemp1,
  2. Tim Malpas1,
  3. Jessica Bate2
  1. 1 Paediatrics, Jersey General Hospital, Saint Helier, Jersey
  2. 2 Paediatric Oncology, Southampton Children's Hospital, Southampton, UK
  1. Correspondence to Dr Tim Malpas, Paediatrics, Jersey General Hospital, Saint Helier JE1 3QS, Jersey; timmalpas{at}hotmail.com

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A 3-year-old boy was diagnosed with Wilms tumour. A central line was inserted and treatment was commenced as per the Children’s Cancer and Leukaemia Group preoperative guidelines for Wilms tumour, following which a nephrectomy was performed. During week 7 of postoperative chemotherapy with vincristine and actinomycin, he developed a fever of 38.5°C at home and was immediately brought to hospital.

Question 1

Which of the following scenarios would cause you to delay administration of broad spectrum antibiotics?

  1. A nurse remeasures his temperature and it is 37.5°C

  2. On clinical assessment he is well and has only minor coryzal symptoms

  3. Neutrophil count 24 hours previously was 1.5×109/L

  4. Blood samples could not be obtained because the central line is difficult to access

  5. None of the above.

He was commenced on intravenous piperacillin with tazobactam. Initial full blood count showed neutrophils to be 1.4×109/L.

Fever persisted with mild malaise but no localising symptoms or signs. A chest X-ray (CXR) was performed (figure 1).

Figure 1

Chest radiograph after 1 week of fever.

Question 2

Is the chest X-ray most suggestive of:

  1. Viral infection?

  2. Bacterial infection?

  3. Disseminated mycobacterial infection?

  4. Pulmonary fungal infection?

  5. Metastatic Wilms tumour?

CT chest showed multiple pulmonary nodules (figure 2). After 7 days of incubation, blood cultures taken on admission grew Gram-positive rods. Four subsequent blood cultures also grew Gram-positive rods. Identification of the organism was challenging. Isolates were sent to a reference laboratory. The central line was removed.

Figure 2

CT chest with pulmonary nodules (arrowed).

Question 3

Which of the following organisms are Gram-positive rods?

  1. Fusobacterium necrophorum

  2. Corynebacterium diphtheriae

  3. Yersinia pestis

  4. Borrelia burgdorferi

  5. Mycobacterium chelonae

Mycobacterium chelonae was identified by the reference laboratory in the original blood culture isolate using 16S RNA genotyping.

Treatment was changed to imipenem, amikacin and clarithromycin, followed by a course of linezolid for 6 weeks. He was then treated with clarithromycin for 6 months. The CXR changes resolved.

Answers can be found on page 2.

ANSWERS TO THE QUESTIONS ON PAGE 1

Answer to question 1: E

Suspected febrile neutropenia should be treated as a medical emergency and empirical antibiotics should be administered within 1 hour of presentation. If unwell, the child should be treated with intravenous antibiotics regardless of neutrophil count or temperature. As per the National Institute for Health and Care Excellence guidance,1 antibiotic treatment should commence with β lactam monotherapy (eg, piperacillin-tazobactam). Those receiving high-dose intravenous methotrexate should be treated with meropenem as piperacillin/tazobactam is contraindicated.

Clinical decision rules (CDR) such as the AUS febrile neutropaenia risk score2 developed from data collected in Australia the UK and Switzerland, should be used to assess a child's risk of septic complications.

Answer to question 2: C

Viral infection leads to bilateral perihilar peribronchial thickening and infiltrates.

Bacterial pneumonia results in focal segmental or lobar opacities.

Miliary pulmonary tuberculosis appears as widespread uniform 1–3 mm diameter nodules. Non-tuberculous mycobacterial infection may be similar in appearance but often with larger 3–10 mm nodules.

Pulmonary fungal infections such as that caused by the fungus Pneumocystis jirovecii lead to homogeneous changes on CXR.

Metastatic Wilms tumour tends to produce rounded well-defined opacities in the lungs.

Answer to question 3: B and E

Fusobacterium necrophorum is a Gram-negative rod that can cause Lemierre’s syndrome, infectious thrombophlebitis of the internal jugular vein.

Corynebacterium diphtheriae is a Gram-positive rod, the cause of diphtheria.

Yersinia pestis is a Gram-negative coccobacillus causing plague.

Borrelia burgdorferi is a Gram-negative spirochete that causes Lyme disease.

M. chelonae is a Gram-positive rod, one of so-called rapidly growing mycobacteria. Culture can take up to 6 weeks. These organisms are increasingly recognised as causing venous catheter-related infections in immunosuppressed patients. Combination therapy is recommended with clarithromycin as a mainstay. The duration of treatment is uncertain but is for at least 6 months. The prognosis is favourable.

Conclusion

Rapidly growing mycobacteria are Gram-positive organisms increasingly recognised as causing infection in immunosuppressed patients.3 4 Identification requires a specialist reference laboratory, and is required to refine treatment, which is lengthy.

Ethics statements

Patient consent for publication

Acknowledgments

The authors thank Dr Sanjay Patel, Consultant in Paediatric Infectious Disease, Southampton Children's Hospital, for his helpful comments.

References

Footnotes

  • Twitter @jessica_bate

  • Contributors All authors contributed to the writing of this paper.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; internally peer reviewed.