|Year : 2015 | Volume
| Issue : 5 | Page : 168-170
Bacillus cereus bacteraemia in a patient of acute myeloid leukaemia
Ratnamani Sharma, Ratna Rao
Department of Microbiology, Apollo Hospitals Jubilee Hills, Hyderabad, Andhra Pradesh, India
|Date of Submission||17-Mar-2014|
|Date of Acceptance||10-Jun-2014|
|Date of Web Publication||6-Feb-2015|
Department of Microbiology, Apollo Hospitals Jubilee Hills, Hyderabad, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
|How to cite this article:|
Sharma R, Rao R. Bacillus cereus bacteraemia in a patient of acute myeloid leukaemia. Indian J Med Microbiol 2015;33, Suppl S1:168-70
|How to cite this URL:|
Sharma R, Rao R. Bacillus cereus bacteraemia in a patient of acute myeloid leukaemia. Indian J Med Microbiol [serial online] 2015 [cited 2019 Sep 23];33, Suppl S1:168-70. Available from: http://www.ijmm.org/text.asp?2015/33/5/168/150982
Immunocompromised patients are at high risk for acquiring infections. With the advances in microbiology, better diagnosis and treatment options are available. The empiric therapy in the febrile neutropenic patient is challenging and depends on the susceptibility patterns of organisms specific to that hospital. The correct identification of the organism becomes imperative to guide the therapy in these patients. In addition to opportunistic pathogens, even organisms which are part of our normal flora also cause infections in these patients. We report here a case of bacteraemia with Bacillus cereus.
A 24-year-old female, who was undergoing chemotherapy for acute myeloid leukaemia (AML), was admitted in our ICU with febrile episodes from one week. She was started on Amoxicillin + Clauvulinic acid as empiric therapy by the oncologist for this fever. Two sets of blood cultures were sent to our lab. Three blood cultures flagged positive after 72 h, and Gram stain showed Gram-positive rods resembling aerobic spore bearers (ASB) which is usually how the contaminants appear. Growth seen on blood agar was moist, grey with beta haemolysis. [Figure 1]. The organism was catalase and oxidase positive. Gram stain showed Gram-positive thick rods. Identification was done with the help of biochemical reactions and confirmed as Bacillus cereus with Vitek 2 Identification system (BioMeriéux, France). On the basis of this report, an infectious disease specialist started her on Erythromycin empirically.
Repeat blood cultures of two more sets grew same organism. The isolate was found to be susceptible to imepenem, vancomycin, clindamycin, erythromycin and levofloxacin. It was resistant to penicillin and beta lactam/betalactamase inhibitor drugs. As the patient was not responding to erythromycin, antibiotics were escalated to vancomycin and imepenem.
In spite of this, the patient continued to have fever; therefore, clindamycin was added to the above combination. Central line was also removed suspecting it as a source of infection and was sent for culture. Central line tip grew B. cereus (semi-quantitative, with more than 15 colony-forming units per catheter segment). The patient responded to treatment and was discharged after 2 weeks of therapy. Subsequent blood cultures were negative. The patient was apparently asymptomatic for 8 weeks and again presented to the hospital with febrile episode and diarrhoea. Bone marrow aspiration was done and sent for cultures and cytology. It showed relapse of AML. Blood cultures were negative. Bone marrow cultures flagged positive on BacT Alert and again grew B. cereus indicating that probably the organism had not been completely eradicated from the blood and persisted in the bone marrow. Stool culture did not grow B. cereus but showed heavy growth of Candida. Patient was put on imepenem and clindamycin again but the patient could not be saved and expired after 1 week due to the underlying condition.
Bacillus species are known to be responsible for several systemic infections, especially in immunocompromised patients. The most commonly reported systemic infection is bacteraemia. Bacillus bacteraemia can be serious and even fatal in immunocompromised patients  Infection with this bacteria can have a fulminant clinical course and reports of meningitis have been published .
The inability to identify the underlying cause and providing susceptibility pattern on time may have fatal outcomes. Microbiologists need to be aware of the possibility of B. cereus as a cause of bacteraemia in such patients, and the treatment should be guided by the susceptibility patterns. Central line care is also to be stressed upon as a part of infection control practice is to prevent central line-associated blood stream infection (CRBSI). B. cereus has been associated with biofilms formation. 
Usually, patients on AML and anti-fungals are put on empiric antibiotic therapy against Gram-negative bacteria which does not cover B. cereus. Thus, when B. cereus is suspected, the clinician should immediately be informed so as to start appropriate antibiotics. In addition, longer duration of therapy needs to be considered for complete eradication.
B. cereus has a propensity to produce beta lactamases  ; therefore, early suspicion and proper antibiotic therapy is needed to have better outcomes in these patients.
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