Keywords
Burkholderia cepacia complex (BCC) - hematological malignancies - immunocompromised individuals - bacteremia
-
Burkholderia vietnamiensis
Introduction
Burkholderia cepacia is a pathogenic gram-negative, aerobic bacillus usually isolated from the aquatic
milieu. It is identified as B. cepacia complex (BCC), which consists of 24 species, of which the most commonly isolated
are B. cepacia, B. multivorans, B. cenocepacia, B. vietnamiensis, B. ambifaria, B. anthina, B. pyrrocinia,
B. ubonensis, B. dolosa, and B. stabiliz.[1]
[2] Bacteria belonging to the BCC group have recently emerged as the cause of opportunistic
infections in immunocompromised individuals. The number of immunosuppressed individuals
has increased in the wake of elderly debilitated patients, chronic kidney disease
patients, cancer patients on chemotherapy, organ transplant patients, cystic fibrosis
patients, and patients on immunosuppressant therapy, coronavirus disease 2019 infections,
etc.[3]
[4]
[5]
Immunosuppression in the case of cancer patients undergoing chemotherapy may either
be due to the nature of the disease or it may be caused by the treatment.[6] Several studies have reported the isolation of the opportunistic pathogen as an
outbreak-causing agent while admitted to the wards due to contamination of drugs and
intravenous fluids.[7] In this case series, we describe three cases of community-acquired Burkholderia vietnamiensis bacteremia in young patients of B-cell acute lymphocytic leukemia, who were admitted
to a 1,600-bedded teaching hospital in Northern India.
Case 1
A 29-year-old female presented to the internal medicine outpatient department on March
6, 2022 with chief complaints of fever with chills and rigors, cough, and chest pain
for the past 15 days. Her routine blood investigations showed a hemoglobin of 3 g/L,
a total leukocyte count of 2,400 cells per cubic mm and a differential leukocyte count
of neutrophil 68%, lymphocytes 29%, monocytes 2%, and eosinophils 1% suggestive of
pancytopenia. Due to unusually low total leukocyte count, infective cause of fever
was ruled out that was confirmed by a blood culture bottle sent to the department
of microbiology on the day of presentation with fever that flagged negative after
5 days of incubation. She was referred to the hematology outpatient department where
she was advised to undergo a bone marrow examination to know the cause of pancytopenia
on March 22, 2022. Her bone marrow examination on hematoxylin and eosin staining was
suggestive of almost complete replacement by small and medium-sized blast cells ([Fig. 1]) without any family history of the same. The blast cells were myeloperoxidase negative.
B-Cell lineage was identified by flow cytometry and she was diagnosed with B-cell
type acute lymphocytic leukemia. The patient continued to have persistent fever and
pleuritic chest pain, for which she was admitted to the inpatient department of hematology
department. She underwent high-resolution chest tomography (HRCT) ([Fig. 2]) on which nodular opacities were observed suggestive of fungal pneumonia for which
liposomal amphotericin B was started on third day of admission, although no respiratory
sample was sent to obtain any microbiological evidence of fungal pneumonia. She became
afebrile for 2 days but started to develop fever again.
Fig. 1 Bone marrow examination of case 1 on hematoxylin and eosin staining was suggestive
of almost complete replacement by small- and medium-sized blast cells (B-acute lymphoblastic
leukemia). The circle and arrow represents the presence of immature red blood cells
and white blood cells in the peripheral smear of the patients.
Fig. 2 High-resolution chest tomography of case 1 showing nodular opacities suspected of
fungal pneumonia.
Blood sample inoculated in two pairs of aerobic and anaerobic BD BACTEC (automated
blood culture system, Becton Dickinson and Company, Becton Drive, Franklin Lakes,
NJ, United States) blood culture bottles and for procalcitonin assay were sent to
the bacteriology section of the department of microbiology on the fifth day of admission.
A pair of aerobic and anaerobic blood culture bottles flagged positive within 48 hours
of incubation, followed by the second pair of blood culture bottles in the next 24 hours,
thus confirming the pathogenic nature of the microorganism. A subculture from both
pairs on MacConkey agar ([Fig. 3]) and blood agar ([Fig. 4]) showed nonfermenting colonies that were identified as Burkholderia vietnamiensis by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS)
assay (BioMérieux, France, Model no. VITEK MS, SN 51192) with a confidence value of
99.9% with the detection profile of MALDI-TOF-MS for B. cepacia complex that is more than 95.5% and [Fig. 5] represents the MALDI-TOF spectrum of B. vietnamiensis for this isolate. Her procalcitonin was 2.31 ng/mL, well above the cutoff value of
0.5 ng/mL performed by chemiluminescence method. Antibiotic sensitivity testing was
performed for the same by the Kirby Bauer disc diffusion method in accordance with
the Clinical and Laboratory Standards Institute (CLSI) guideline,[1] with sensitivity for levofloxacin interpreted using the zone-diameter breakpoints
of Pseudomonas species and was found sensitive to imipenem and meropenem. She was started on intravenous
meropenem-cilastatin combination 1 g every 8 hours for 7 days following the antibiotic
sensitivity testing and her fever started responding after 7 days of starting the
antibiotics along with amphotericin B. A repeat blood culture was sent on the 7th
day of antibiotic therapy and was reported sterile and repeated procalcitonin levels
were reduced to 0.15 ng/mL. She was started on dasatinib and dexamethasone as per
hospital protocol and tolerated this therapy well with no fever spikes or severe cytopenia.
As her total leukocyte count was below 10,000/µL, she was started on dasatinib 50 mg
once daily (OD) and was not increased further due to known interaction with antifungal
voriconazole that was stepped down after the course of liposomal amphotericin B for
radiologically confirmed fungal pneumonia. Her family was counseled for her need for
a bone marrow transplant. She was lost to follow-up in the hematology outpatient department
after 15 days of discharge.
Fig. 3 A subculture from a blood culture bottle on MacConkey agar showing non-lactose fermenting
colonies.
Fig. 4 A subculture from a blood culture bottle on blood agar showing hemolytic colonies
on blood agar.
Fig. 5 Matrix-assisted laser desorption/ionization-time of flight spectrum of Burkholderia vietnamiensis isolate identified from case 1.
Case 2
A 22-year-old man presented to the internal medicine outpatient department on January
8, 2022 with chief complaints of generalized weakness and pain in the upper limb for
the past 15 days. He was advised for routine blood investigation that revealed cytopenia
with hemoglobin of 4 g/L, a total leukocyte count of 4,800 cells per cubic mm, and
a differential leukocyte count of neutrophil 70%, lymphocytes 27%, monocytes 2%, and
eosinophils 1% and was referred to the hematology outpatient department where his
bone marrow examination performed on January 24, 2022 revealed B-cell acute lymphoblastic
leukemia on hematoxylin and eosin staining. No family history of any hematological
malignancies was reported. The patient came for a follow-up to the outpatient department
within 15 days with high-grade fever and vomiting. On evaluation, he was found to
have a non-neutropenic fever. His chest X-ray was normal. According to standard protocol
for diagnosis of sepsis, blood samples were sent for procalcitonin assay performed
by chemiluminescence method and a pair of BACTEC blood cultures was raised and sent
to the bacteriology section of the department of microbiology. His procalcitonin was
36 ng/mL and his BACTEC blood culture flagged positive after 48 hours of incubation.
On subculture, MacConkey agar revealed growth of nonlactose fermenting, gram-negative
bacilli blood agar showed hemolytic colonies that was identified as B. vietnamiensis by MALDI-TOF-MS assay (BioMérieux, France) with a confidence value of 98.9% with
the detection profile of MALDI-TOF-MS for B. cepacia complex that is more than 95.5%. On antibiotic sensitivity testing by Kirby–Bauer
disc diffusion method in accordance with the CLSI guidelines,[1] with sensitivity for levofloxacin interpreted using the zone-diameter breakpoints
of Pseudomonas species and the isolate was found sensitive to meropenem and levofloxacin. The patient was
started on intravenous meropenem-cilastatin combination 600 mg every 6 hours for 10
days according to the antibiotic susceptibility and the patient started to respond
to treatment. His fever and vomiting subsided after 48 hours of antibiotic administration.
His procalcitonin dropped to 2 ng/mL after the progress of treatment, while a pair
of repeat BD BACTEC blood cultures sent to the microbiology department after 7 days
of antibiotic treatment was reported sterile after 5 days of incubation. The intravenous
antibiotics were continued for 10 days and the patient was further started on tab.
prednisolone 100 mg OD and folic acid 5 mg OD as per protocol of the hospital. He
was discharged in stable condition and was advised to continue chemotherapy as per
schedule. He presented to the outpatient department after 15 days of discharge, devoid
of any symptoms of infection, and was allocated his schedule for next chemotherapy
session.
Case 3
A 5-year-old boy presented to the pediatric outpatient department on May 15, 2022
with chief complaints of fever and generalized weakness for the past 10 days. His
hemoglobin was 3.6 g/L, a total leukocyte count of 1,800 cells per cubic mm, and a
differential leukocyte count of neutrophil 62%, lymphocytes 36%, monocytes 1%, and
eosinophils 1% suggestive of pancytopenia. His fever subsided on administration of
oral antipyretics and a baseline blood culture sample in BACTEC blood culture bottle
sent to the department flagged negative after 5 days of incubation and he was referred
to the hematology outpatient department where hematoxylin and eosin staining of his
bone marrow examination performed on May 29, 2022 revealed B-cell acute lymphoblastic
leukemia without any family history of the same. On further evaluation, his HRCT chest
was within normal limits. According to standard protocol for diagnosing sepsis, blood
sample was drawn for procalcitonin assay and a pair of BACTEC blood cultures was sent
to the bacteriology section of the department of microbiology. His procalcitonin performed
by chemiluminescence method was 6.50 ng/mL and BACTEC blood culture flagged positive
after 72 hours of incubation. On subculture, MacConkey agar revealed growth of nonlactose
fermenting; gram-negative bacilli blood agar showed hemolytic colonies that was identified
as B. vietnamiensis by MALDI-TOF-MS assay (BioMérieux, France) with a confidence value of 95.84% with
the detection profile of MALDI-TOF-MS for B. cepacia complex that is more than 95.5%. On antibiotic sensitivity testing by Kirby–Bauer
disc diffusion method in accordance with the CLSI guidelines,[1] with sensitivity for levofloxacin interpreted using the zone-diameter breakpoints
of Pseudomonas species and the isolate was tested for and was found sensitive to ciprofloxacin, meropenem,
and minocycline. The patient was started on intravenous meropenem-cilastatin combination
600 mg every 6 hour for 10 days and after 3 days of treatment the patient was afebrile,
although he still complained of generalized weakness. Patient was continued on intravenous
antibiotics and was further started on folic acid syrup OD. He was discharged in stable
condition and came for follow-up after 21 days and was advised to continue chemotherapy
as per schedule.
Discussion
BCC consists of a species named B. vietnamiensis that was the causative microorganism, identified from the blood culture of two patients
suffering from bacteremia and impending sepsis. Burkholderia species naturally occur
in the environment, especially in the aquatic milieu.[2] It is an aerobic, gram-negative bacillus that was found responsible for causing
an array of infections in immunocompromised patients.[3]
The number of immunosuppressed individuals has increased in the wake of increasing
human immunodeficiency virus-positive cases, elderly debilitated patients, chronic
kidney disease patients, cancer patients on chemotherapy, organ transplant patients,
cystic fibrosis patients, and patients on immunosuppressant therapy, etc.[4]
[5]
[6] Bacteria belonging to the BCC group have recently emerged as the cause of opportunistic
infections in immunocompromised individuals. Immunosuppression in the case of cancer
patients undergoing chemotherapy may either be due to the nature of the disease or
it may be caused by the treatment.[7] Several studies have reported the isolation of the opportunistic pathogen as an
outbreak-causing agent while admitted to the wards due to contamination of drugs and
intravenous fluids.[8] It was predominantly reported as a respiratory pathogen in cystic fibrosis patients
by Ashour and El-Sharif but can also cause infections in immunosuppressed patients
like those suffering from chronic granulomatous disease, hematological malignancies,
and solid tumors.[9]
BCC is the probable causative agent causing bacteremia, pneumonia, genital tract infections,
and surgical wound infections.[10] A review of recently reported cases of B. vietnamiensis infections in literature is mentioned in [Table 1]. Cases of BCC bacteremia were reported in immunocompromised patients in several
cases but most were identified as an outbreak of nosocomial infections among patients
admitted to a particular hospital. A study conducted by Singhal et al reported an
outbreak of bacteremia among cancer patients admitted to a tertiary care center due
to an infected antiemetic solution.[8]
Table 1
The review of literature for infections caused by Burkholderia vietnamiensis (n = 7)
|
Sl. no.
|
Author name
|
Age and gender of patients
|
Year of publication
|
Place
|
Symptoms
|
Radiological investigations
|
Diagnosis
|
Treatment
|
Outcome
|
|
1.
|
Magalhães et al[11]
|
23 months/male
|
2002
|
Brazil, South America
|
Known case of cystic fibrosis with acute bronchitis
|
NA
|
Acute bronchitis caused by Burkholderia vietnamiensis
|
Ciprofloxacin, cotrimoxazole, and amikacin
|
Alive
|
|
2.
|
Carvalho et al[12]
|
13 years/male
|
2005
|
Brazil, South America
|
Know case of cystic fibrosis for evaluation of his sputum sample for 9 years
|
NA
|
Chronic respiratory infection of a cystic fibrosis patient with B. vietnamiensis
|
NA
|
Alive
|
|
3.
|
Marquette et al[13]
|
29 years/male
|
2015
|
Cambridge, United Kingdom
|
Known case of cystic fibrosis on a prophylactic treatment regimen using temocillin
|
NA
|
Prophylactic treatment regimen against B. vietnamiensis in Cystic fibrosis patients
|
Nebulized temocillin
|
Alive
|
|
4.
|
Zhang et al[14]
|
71 years/male
|
2018
|
Hangzhou, Zhejiang, P. R. China
|
Complaint of episodic fever for 1 week, accompanied by general malaise, nausea, and
vomiting
|
Abdominal CT scans revealed a 5 cm abscess located in liver segment IV
|
Hepatic rupture due to purulent infection caused by B. vietnamiensis in a diabetic patient
|
Cefoperazone and ornidazole
|
Alive
|
|
5.
|
Spoletini et al[15]
|
22 years/female
|
2019
|
Leeds, United Kingdom
|
Lung transplant prospect with bacterial colonization and pulmonary exacerbation
|
NA
|
Pulmonary exacerbation with B. vietnamiensis in organ transplant recipient
|
Minocycline and ceftazidime-avibactam
|
Alive
|
|
6.
|
Rohit et al[16]
|
33 years /female
|
2020
|
Tamil Nadu, India
|
Large breast abscess
|
pus was collected by ultrasound guided aspiration
|
Purulent skin infection caused by B. vietnamiensis
|
Levofloxacin
|
Alive
|
|
7.
|
This case
|
Age of the patients for case 1 is 29 years, 22 years, and 5 years old
|
2022
|
Lucknow, Uttar Pradesh, India
|
Fever, malaise, cough with expectoration in B-cell acute lymphocytic leukemia patients
|
Bilateral patchy consolidation in the first case of the series
|
B. cepacia complex bacteremia. We found 3 cases of B. vietnamiensis in patients suffering from B-ALL patients
|
Levofloxacin, ceftazidime, meropenem, cotrimoxazole, and minocycline
|
First patient was lost to follow-up and the other two were alive
|
Abbreviations: B-ALL, B-acute lymphoblastic leukemia; CT, computed tomography; NA,
not available.
The identification of community-acquired BCC has rarely been reported, but their existence
in the soil and water where the microorganism is acted upon by a plethora of plant
metabolites renders it intrinsically resistant to antipseudomonal penicillins, first-
and second-generation cephalosporins, and aminoglycosides.[2] The isolates identified by us in our cases were susceptible to carbapenem and fluoroquinolones,
but in all three cases the patients were symptomatic before admission and the BACTEC
blood culture from all three patients readily recovered the isolate on subculture
on blood and MacConkey agar.
Environmental, drug, and medicated fluid surveillance can yield the source of an outbreak
for these rare opportunistic isolates in the hospital setting, as has been performed
by Mihaila and Blaga,[7] Singhal et al,[8] and Tavares et al.[17] Due to the lack of community environmental surveillance measures, we could not identify
the source of infection and the mechanism of acquiring the infection, but the study
makes it clear that immunosuppressed individuals are susceptible to acquiring such
rare infections from the community. We endorse the use of MALDI-TOF assay for its
ability to differentiate among all 24 species of BCC up to 100% for its identification.
The isolation of rare microorganisms like B. vietnamiensis needs to be discussed more frequently to know and frame the appropriate treatment
for them.
Conclusion
The identification of rare opportunistic pathogens like B. vietnamiensis and adequate treatment in the pandemic-ridden era is the need of the hour due to
a rise in immunocompromised conditions owing to the rigorous use of antimicrobials
and steroids. Its intrinsic resistance to first and second-generation cephalosporins
and polymyxin can cause a state of alarm during treatment via empirical antibiotics.
Thus, the MALDI-TOF-MS assay helps direct the appropriate therapy to the patients.
