Burkholderia

Historically, considered  Pseudomonas  species - previously known as  Pseudomonas  multivorans  and  Pseudomonas  kingie.

• Aerobic gram-negative bacteria
• Acquire motility via multitrichous polar flagella.
• Do not ferment glucose 
• Many clinical isolates give a weak oxidase reaction. 
• Slow-growing morphotypes, may go undetected in routine cultures
• Free-livingorganisms present in most aquatic and humid environment, including hospital drinking water. 
• nine  genomovars  grouped  under  “B.  cepacia  complex”  (BCC)
• Burkholderia cenocepacia and Burkholderia multivorans are the prominent bacterial strains isolated from patients with cysticfibrosis.

Infection- 

1.  Lung - 
   

• B. cepacia  gained notoriety as the cause of a rapidly fatal syndrome of respiratory distress and septicemia (the “cepacia syndrome”) in CF patients.
  
• B.  cepacia  regarded  as  important  multi-drug resistant  gram-negative  bacteria  in  the  immunosuppressed  cancer  and transplant  populations.
  
• Nebulizer-associated  BCC  pneumonia  outbreaks  have  occurred  in patients  with  lymphoid  and  myeloid  neoplasms  receiving  aerosolized antimicrobial  prophylaxis
• The risk for  nosocomial  BCC  pneumonia  includes  patients  in  a  critical  care  unit for  longer  than  1  week,  those  requiring  assisted  ventilation,  and  those on  broad-spectrum  antimicrobial  therapy. 
• Hospital  fomites  and  ventilator  humidification  system  may be  potential  sources

      2. Skin,  Skin  Structure,  and  Joint  Infection - 

• Risk  factors - patients receiving  care  in  burn  units  and  those  in  critical  care  units  exposed  to contaminated  disinfectants  or  unsterilized  skin  moisturizing  products.
• Hematogenous  B.  cepacia  dissemination  may  present  as ecthyma  gangrenosum–like  skin  lesions,  particularly  in  patients  with underlying  cancer  or  other  immunosuppression.
• B.  cepacia  septic  arthritis  via  hematogenous  seeding  is  serious,  although  a  rare  complication.

      3. Genitourinary  Tract  Infection - 

• Iatrogenic  infection  from  manipulation  of  the  genitourinary  tract  such as  with  transrectal  prostate  biopsy  and  a  cystoscopy-related  intramural bladder  wall  B.  cepacia  abscess  have  been  rarely  observed.
• In  critical  care  units,  nosocomial  B.  cepacia  genitourinary  tract  infection arises  from  prior  colonization  of  a  urinary  catheter.

Diagnosis-

• Antibiotic-containing  media  can  be  used  to  promote  selective  growth (e.g.,  Pseudomonas  cepacia  agar,  oxidation-fermentation  polymyxin bacitracin  lactose  agar,  and  B.  cepacia  selective  agar).  These  culture media  containing  gentamicin,  polymyxin  B,  and  vancomycin  can  be used  to  isolate  over  90%  of  BCC  within  48  to  72  hours.
• Upto 36% of Burkholderia speciesmay be misidentified by automated systems as other nonfermentativebbacteria,such as Achromobacter or Ralstonia.

Resistance patterns - 

• Drug-resistance  pathways  include  efflux  pumps  (including  adenosine triphosphate–binding  cassette  transporters),  antimicrobial  degradation  and/or  modifying  enzymes,  and  altered  membrane  function.

Rx- 

• Monotherapy not recommended as high chances of failure and infection relapse
• Carbapenems, TMP/SMX, chloramphenicol, and tetracycline
• Susceptible to minocycline(38%), meropenem(26%), and ceftazidime(23%).
• Ceftazidime, tobramycin, and ciprofloxacin retain antimicrobial activity against planktonic and biofilm-embedded organisms.
• Tigecycline  is  less  effective  compared  with  minocycline,  and  overexpression  of  efflux  pumps  may  result  in  development  of  de  novo  drug resistance.
• Combination therapy for serious pulmonary infection (e.g., in CF) is suggested when multidrug-resistant strains are implicated. 
• The combination  of  meropenem  and TMP-SMX  may be antagonistic, however. 

Ref-

Mandell - Principles and practice of Infectious Diseases , 8th edition 

Harrison’s Principles of Internal Medicine, 19th edition