Indian Journal of Medical Microbiology Medknow Publications on behalf of Indian Association of Medical Microbiology ISSN: 0255-0857 EISSN: 1998-3646 Vol. 29, Num. 1, 2011, pp. 4-12

Indian Journal of Medical Microbiology, Vol. 29, No. 1, January-March, 2011, pp. 4-12

Review Article

Burkholderia cepacia complex: Beyond pseudomonas and acinetobacter

V Gautam, L Singhal, P Ray

Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India

Correspondence Address: V Gautam, Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India, r_vg@yahoo.co.uk

Date of Submission: 30-Nov-2010
Date of Acceptance: 06-Dec-2010

Code Number: mb11003

PMID: 21304187

DOI: 10.4103/0255-0857.76516

Abstract

Keywords: Burkholderia cepacia complex, cystic fibrosis, nonfermenter, septicaemia

Introduction

What better microbial challenge to unite agricultural and medical microbiologists than an organism that reduces an onion to a macerated pulp, protects other crops from bacterial and fungal disease, devastates the health and social life of cystic fibrosis (CF) patients and not only is resistant to the most famous of antibiotics, penicillin, but can use it as a nutrient. ^[1]

Even after a decade, four nonfermenting gram-negative bacilli (NFGNB) continue to be recognised as notorious multidrug-resistant organisms. These are Pseudomonas aeruginosa, Acinetobacter calcoaceticus-baumannii complex, Stenotrophomonas maltophilia and Burkholderia cepacia complex (BCC). ^[2] Pseudomonas cepacia was originally described by William Burkholder in 1950 as the causative agent of bacterial rot of onion bulbs and was later transferred to the new genus Burkholderia in 1992. ^[3],[4] BCC, a devastating pulmonary pathogen in CF and chronic granulomatous disease (CGD) patients, has also been reported as a cause of bacteraemia, particularly in patients with indwelling catheters, urinary tract infection, septic arthritis, peritonitis and respiratory tract infection. The ability for Burkholderia species to thrive in the diverse range of environments is testament to the fact that they can be considered as one of the most versatile groups of gram-negative bacteria. BCC survives and multiplies in aqueous hospital environments, including detergent solutions and intravenous fluids, where it may persist for long periods. ^[4],[5] Outbreaks of BCC septicaemia have been documented in intensive care units (ICUs), oncology units and renal failure patients. ^[6] The ability of BCC to cause disease is not limited to the human host, as these bacteria are also important plant pathogens. In addition, BCC bacteria may have useful commercial properties and facilitate highly beneficial processes such as the breakdown of pollutants or enhancement of crop yield. ^[7]

BCC has emerged as an important cause of morbidity and mortality in hospitalised patients largely because of high intrinsic antibiotic resistance. ^[4] It has always been a tedious task for a routine microbiological laboratory to identify the NFGNBs, and poor laboratory proficiency in identification of BCC prevails worldwide, including our own country. For this reason, reports of disease due to this organism are rare from India. ^{[8],[9],[10],[11],[12]} It needs to be differentiated from P. aeruginosa as BCC has inherently contrasting susceptibility pattern to that of P. aeruginosa. BCC is the fourth most common pathogenic NFGNB worldwide after P. aeruginosa, A. calcoaceticus-baumannii complex and S. maltophilia. ^[4] However, in Postgraduate Institute of Medical Education and Research (PGIMER), BCC has been recognised as the third most common nonfermenter over the last 6 years. ^{[8],[9],[10],[11]}

Taxonomy

In 1950, William Burkholder, an American microbiologist first described this microorganism as the causative agent of bacterial rot of onion bulbs at Cornell University. Until 1992, it was classified as P. cepacia. In 1992, P. cepacia and six other species belonging to rRNA group II of the genus Pseudomonas were transferred to the new genus Burkholderia, a name given in honour of its discoverer. ^[3],[4] In contrast to the genus Pseudomonas, the genus Burkholderia belongs to the subdivision of the phylum Proteobacteria. All Burkholderia species possess very large genomes ranging between 6 and 9 Mb in size, and it is this huge genetic capacity which underpins their versatility in disease and natural biology. All species also separate this DNA into two or more chromosomal replicons which may add greater flexibility in the acquisition, loss and expression of genes. Their classification has undergone considerable taxonomic changes over the last two decades. Based on phenotypic and genotypic analyses, BCC is currently divided into 10 genomic species [Table - 1]. ^[13] The term genomovar was introduced to denote phenotypically similar genomic species and presently, genomovars are recognised as new species. Recently, seven novel species, B. latens, B. diffusa, B. arboris, B. seminalis, B. metallica, B. contaminans and B. sabiae, have been proposed as members of the BCC, using a polyphasic approach based on comparative 16S ribosomal RNA and recA sequencing, multilocus sequence typing (MLST) and intermediate DNA-DNA binding values. ^[14],[15]

Epidemiology

BCC organisms are distributed ubiquitously and found most commonly on plant roots, the rhizosphere, soil and moist environments. The ability of BCC to cause disease is not limited to the human host, as these bacteria are also important plant pathogens. ^[16] In addition, BCC may have useful commercial properties and have been used in agriculture as biocontrol agents and in the bioremediation of toxic agents. ^[7],[16] Plants of the Gramineae group appear to be particularly important rhizospheric hosts for BCC bacteria. Unlike P. aeruginosa which may be carried by around 10% of humans (e.g., as a gut coloniser), BCC bacteria have not yet been recovered from human sources other than the sites of infection. Therefore, in the absence of patient-to-patient transmission in CF infection, the natural environment must be the reservoir of BCC infection. ^[13] A highly comprehensive evidence has recently been shown by MLST, whereby greater than 20% of the clinical isolates were indistinguishable from environmental isolates recovered from diverse environments such as river water, onion, radish, maize rhizosphere, pharmaceutical solutions, hospital equipment, shampoo and industrial settings. ^[17]

The availability of rapid and accurate tests for genomovar identification allowed for a comprehensive analysis of the prevalence of different BCC species. By the age of 18 years, about 3.5% of CF patients harbour BCC. B. cenocepacia and B. multivorans are more predominant amongst CF patients than non-CF patients in four CF populations (United States, Canada, Italy and Australia). ^{[18],[19],[20]} Other than B. cenocepacia and B. multivorans, the remaining formally named species account for less than 10% of all CF infections caused by the complex. ^[13] Since 2000, B. multivorans infection has been more prevalent than B. cenocepacia infection amongst the UK CF population, indicating that regional differences may be present in the epidemiological distribution of BCC. ^[21] For the isolates recovered from non-CF opportunistic infections, B. cenocepacia IIIA is again the most dominant in terms of total numbers. ^[13] However, some authors have detected B. cepacia more frequently amongst non-CF patients. ^[20]

Further analysis of the different recA lineages revealed significant geographical differences. Although type IIIB strains represented 75% of all US B. cenocepacia isolates, type IIIA strains are more prevalent in Canada and Europe, accounting for about 70% of all genomovar III isolates. ^[13],[22] The unique distribution of selected BCC genomovars indicates the presence of epidemic strains exhibiting particular virulence and transmissibility. So far, the following two genetic elements have been identified that are associated with epidemic spread: cblA, a gene encoding a protein for cable pilus production, and esmR (or the B. cepacia epidemic strain marker), detected only in B. cenocepacia strains. cblA and esmR sequences may be encoded on a chromosomal region which is unstable in some B. cenocepacia epidemic strains. ^[23],[24] As B. cenocepacia ET12 (′Edinburgh⁄Toronto⁄ET12 epidemic B. cepacia′ lineage) is mainly isolated from clinical settings and not from the natural environment, we assume not only that these species occupy the same niche, but also that genetic exchange is occurring within human beings and not in the natural environment. ^[25]

In contrast to B. cenocepacia, where direct patient-to-patient contact and socialisation have been reported as the most probable mechanisms by which infections spread, the mode of transmission for B. multivorans infection has not been determined. ^[26] It is interesting that despite having more than 100 isolates of B. ambifaria, not one has been recovered from a source of infection outside of CF, suggesting that this species may have very limited virulence as an invasive human opportunistic pathogen. ^[13]

It has been observed that B. cenocepacia can replace other Burkholderia spp. In a study by Mahenthiralingam et al., B. cenocepacia strains replaced B. multivorans in 6 patients, and were associated with a poor clinical outcome and high mortality. ^[27] Out of the five isolates from a 50-year-old female patient admitted in PGIMER, three isolates (out of four isolates processed) were B. cepacia (restriction fragment length polymorphism [RFLP] type E) and the last isolate identified was B. cenocepacia (RFLP type G). ^[10]

A population structure analysis of B. cenocepacia revealed that 86.7% of all restriction types clustered into three major clonal complexes, comprising epidemic clones ET12 (RT-6 complex), PHDC (the Philadelphia-District Columbia) (RT-46 complex) and Midwest (RT-88 complex). ^[28] These clones have a wide geographic distribution and exhibit varying degrees of genetic recombination. Infection with clone ET12 has been associated with increased mortality and the so-called "cepacia syndrome." ^[29] In the United States, other epidemic strains such as the PHDC and Mid-West strains were also identified and classified as the B. cenocepacia recA III-B subgroup. ^[30] A strain belonging to PHDC clonal lineage has been isolated from organic soils in four agricultural fields that had been planted with onions for several years. This indicates that environmental strains may play a pivotal role in the epidemiology of BCC infections and could explain the ongoing human acquisition despite infection control measures. ^[31] In contrast to some reports advocating the identification of the cblA gene as a means of influencing patient segregation and infection control strategies, the absence of such markers from some epidemic strains indicates that the cblA or esmR markers may not be reliable indicators of transmissibility. ^[28],[32]

It is interesting that man-made industrial settings also appear to be prone to contamination with BCC bacteria. Contamination with BCC bacteria may also occur in the oil and fuel industry, which is not surprising given that these bacteria are able to grow on a diverse range of hydrocarbon substrates. ^[33] Using MLST, several BCC sequence types have been found that overlap clinical, industrial and natural sources [Figure - 1], which clearly demonstrates the remarkably versatility of this group of bacteria to survive and grow in highly diverse environments. ^[13]

International Burkholderia cepacia Working Group

The International Burkholderia cepacia Working Group (IBCWG) was established in Spring, 1996 with support from the Cystic Fibrosis Foundation (US). It gathers emerging clinical and research data on BCC. It serves to keep the CF medical community informed of developments regarding these bacteria, and encourages and coordinates continuing clinical and basic research on these bacteria. The IBCWG includes microbiologists involved in basic science research and CF physicians from the United States, Canada, Australia and Europe (http://www.cff.org).

Clinical Spectrum

Patients with CF and those with CGD are predisposed to infection by BCC bacteria. BCC is being increasingly recognised as an important pathogen of human beings in both immunocompromised and hospitalised patients who are infected by contact with contaminated equipment during hospitalisation. BCC bacteraemia should be considered in febrile patients with nosocomial infections, especially those who have an indwelling catheter, are on ventilators, have CF or have immune dysfunction. ^{[4],[21],[34]}

Cystic Fibrosis

Chronic microbial colonisation of the major airways, leading to exacerbations of pulmonary infection, is the major cause of morbidity and mortality in patients with CF (the most common lethal genetic disorder in Caucasian populations). Staphylococcus aureus and P. aeruginosa are the primary etiologic agents of pulmonary infection in patients with CF. In childhood or early adolescence, patients with CF become chronically infected with P. aeruginosa.^[34] As life expectancy has increased in patients with CF, BCC has emerged as an important pathogen, and it is being recovered from approximately 10% of adults with CF. Pulmonary colonisation/infection by these bacteria may persist for months or even years, but a minority of adolescent and young adult patients with CF may exhibit "cepacia syndrome" characterised by high fever, severe progressive respiratory failure, leukocytosis and elevated erythrocyte sedimentation rate. The patient may develop bacteraemia and die within 6 months. Other patients with CF may be infected with BCC without a corresponding decline in clinical status. ^[13],[34] Overall, in common with many other opportunistic pathogens, it appears that severe disease and death may result after infection with all BCC species dependent on the clinical state and predisposition of CF individuals at the time of infection. Clinical outcomes may vary greatly amongst CF patients infected with the same strain. ^[26],[29]

Non-CF Patients

BCC infections in immunocompetent patients occur only sporadically, but several cases of pseudoepidemics and nosocomial infections, often caused by contaminated disinfectants and anaesthetic solutions, have been reported. BCC bacteraemia, most often catheter-related and polymicrobial, has been reported in cancer patients and in patients undergoing haemodialysis, and nosocomial pneumonia was observed in intensive care patients who were mechanically ventilated and pretreated with broad-spectrum antibiotics such as fluoroquinolones and ceftazidime. ^{[4],[6],[34],[35]} BCC skin and soft tissue infection may occur in patients with burns or surgical wounds and in soldiers with prolonged foot immersion in water. Genitourinary tract infections caused by BCC have been reported after urethral instrumentation, after transrectal prostate biopsy or through exposure to contaminated solutions. ^[34]

Outbreaks

Outbreaks have been reported originating from diverse sources such as contaminated nebulisers, chlorhexidine solution, alcohol-free mouthwash, multidose albuterol vials used amongst multiple patients, indigo-carmine dye used in enteral feeding, tap water, bottled water, cosmetics, napkins, nasal sprays and ultrasound gel. ^{[4],[20],[34]} An epidemic of BCC bacteraemia and pseudobacteraemia occurred in the medical ICU at the Clinical Centre of the National Institutes of Health. Sixteen patients in ICU became colonised or infected with this organism in a 21-month period, whereas BCC had been isolated only 16 times in the preceding 90 months from the entire hospital. Intensive investigation of the involved ICU and its surrounding environment eventually demonstrated that a blood gas analyser in an adjacent satellite laboratory was the reservoir for the outbreak. Replacement of the machine resulted in termination of the outbreak. ^[36] Its ability to grow in distilled water and ability to fix CO ₂ from air makes BCC probably the most nutritionally adaptable of all pseudomonads. ^[37]

Indian Scenario

Indian CF patients

CF was thought to be extremely rare in India. However, published reports, reviews and comments indicate that CF is probably far more common in people of Indian origin than previously thought but is underdiagnosed or missed in the majority of cases. A total of 1200 children were subjected to sweat chloride test and 120 (3.5%) children were diagnosed of having CF in a study conducted at All India Institute of Medical Sciences (AIIMS). Henceforth, cystic fibrosis services at AIIMS were established with the help of International Cystic Fibrosis (Mucoviscidosis) Association. ^[38] The first patient of CF was diagnosed at PGI in 1968 (six cases). ^[39] At present, there are approximately 60 CF patients on regular follow-up in Advanced Paediatric Centre. Since this organism is difficult to eradicate after colonisation, initial screening plays a pivotal role, and the patient may be accordingly segregated. There is no report of isolation of BCC from Indian CF patients. However, recently, it has been isolated from six patients of CF at PGIMER from the respiratory specimens and blood (unpublished data).

Indian non-CF cases

In India, there are no precise reports of the prevalence of BCC infection due to the lack of specific laboratory tests and, in most cases, these bacteria have been ambiguously reported as NFGNB or simply Pseudomonas spp. For this reason, reports of diseases due to these organisms are rare and it has been reported from few tertiary care centres in north India. ^{[8],[9],[10],[11]} A sudden upsurge of BCC has been observed in non-CF-septicaemic patients of PGIMER, Chandigarh, and in Escorts Heart Institute and Research Centre (EHIRC), Delhi. Within four years (2006-2009), approximately 150 isolates of BCC were obtained in PGIMER. This is in comparison to a study by Reik et al. who reported 90 isolates over the span of eight years from various clinical specimens of non-CF patients. ^[8],[20] BCC from PGIMER has been isolated from blood cultures, pus, respiratory specimens, body fluids and CSF. All BCC isolates of EHIRC, Delhi, were from blood culture. At PGIMER, BCC has been isolated from the patients admitted in the different wards of PGIMER, with increased isolation from children admitted in the Advanced Pediatric Centre. ^[8],[10] BCC has been recognised as the third most common nonfermenter over the last six years in PGIMER after P. aeruginosa and A. calcoaceticus-baumannii complex. ^{[8],[9],[10],[11]} It has been observed that B. cenocepacia (RFLP type G, [Figure - 2]) continues to be the most prevalent species of BCC amongst Indian non-CF patients (PGIMER and Escorts, 2006). This is a cause of concern as patients with B. cenocepacia infections face the highest mortality and have higher rate of transmission. ^{[8],[9],[10],[11]}

Laboratory Diagnosis

It has always been a tedious task for a routine microbiological laboratory to identify this NFGNB, and poor laboratory proficiency prevails worldwide. In routine clinical laboratories, the identification of putative BCC isolates is generally performed using a combination of selective media, conventional biochemical analysis and/or commercial systems. Three media commonly used are as follows: the P. cepacia agar (PCA), the oxidation-fermentation polymyxin bacitracin lactose agar (OFPBL),and more recently the B. cepacia selective agar (BCSA) (containing 1% lactose and 1% sucrose in an enriched base of casein and yeast extract with 600 U of polymyxin B per ml, 10 μg of gentamicin per ml and 2.5 μg of vancomycin per ml). ^[4],[37] A comparison of all three media revealed a superior performance of the BCSA, achieving 43, 93, and 100% growth of BCC organisms at 24, 48, and 72 hours, respectively. BCSA is more selective, acts by suppressing growth of non-BCC bacteria, whereas BCC members form visible, smooth, pinpoint colonies within 24 hours. Non-BCC organisms that are capable of growing on BCSA are B. gladioli, Ralstonia spp. and Pandoraea spp.^[40],[41] To aid routine diagnostic laboratories, the authors have described the methods to identify BCC by conventional biochemical reactions with the available infrastructure and resources, which may be substantiated by molecular methods for species identification. ^[11] Out of 58,717 blood cultures performed at PGIMER from April, 2007 to March, 2009, 21% (12 331/58 717) tested positive for bacterial culture and 1,256 (1 256/12 331, 10.2%) of these positive cultures grew NFGNB. Of these 1,256 NFGNB, 825 (825/1,256, 65.7%) were Acinetobacter spp., 324 (324/1,256, 25.8%) were Pseudomonas spp. and 60 (60/1,256, 4.8%) were BCC. Thirty five (35/1,256, 2.8%) isolates were identified as S. maltophilia. Twelve (12/1,256, 0.9%) isolates could not be identified with the limited available conventional biochemical tests (unpublished data). Hence, by the conventional methods for the identification of the NFGNB, 99% of the NFGNB in a routine microbiology laboratory can be identified, and accordingly the appropriate antimicrobial therapy can be given to the patient.

Automated Identification Systems

Members of the BCC can be identified by available commercial tests, such as API 20NE, Phoenix, MicroScan or Vitek. Identification through commercial kits and automated systems is not fool-proof as many non-Burkholderia betaproteobacteria (Ralstonia picketti and Pandoraea species) are misidentified as BCC and some BCC strains as P. aeruginosa. A large polyphasic analysis of 1,051 isolates from 115 CF treatment centres in 91 US cities conducted in 2000 revealed an overall misidentification rate of 11% for isolates identified as BCC by referring laboratories. This rate was even higher (36%) for isolates not specifically identified or identified as a species other than BCC. ^[4],[42] In authors′ experience, S. maltophilia has been labeled as BCC (95% probability indicated by the system, Vitek) and another system (Microscan Walkaway) labeled BCC as Burkholderia pseudomallei (99% probability). ^[11] The laboratories which are tentatively identifying Burkholderia species using an automated system should confirm isolate identity by growth on BCSA, conventional biochemical testing and, if necessary, molecular techniques. ^{[4],[11],[37]}

Molecular identification

Identification is usually performed by DNA-based polymerase chain reaction (PCR) methods, exploiting sequence differences in the single locus of the 16S rRNA gene or recA gene (recA is a protein essential for repair and recombination of DNA) to assign isolates to the appropriate species. This is achieved by PCR using primers specific for the BCC, RFLP analysis of the product and further PCR with a series of species-specific primers. However, misidentification of BCC species has occurred using these approaches as a RFLP-based strategy. Furthermore, the medically important BCC member B. cenocepacia is divided into four different recA phylotypes (IIIA-D), complicating the identification of this species. The BCC fur gene-based PCR (encoding the ferric uptake regulator protein) has also been found to be useful for differentiating between members of the BCC. ^[15],[24]

Based on PCR-based techniques, unidentified isolates have been reported in previous epidemiological studies. ^{[8],[10],[24],[43],[44],[45]} In a Brazilian study, 41 CF isolates of BCC were identified by culture, and confirmation of identity and genomovar determination was obtained in 32 isolates by recA-based PCR. ^[46] Fifty two BCC clinical isolates from two centres in northern region of India were subjected to recA-based PCR. Nine (9/40) isolates from PGIMER and five (5/12) isolates from EHIRC, Delhi remained unidentified by recA-based PCR. ^[8]

Other techniques used to discriminate beyond the species-level include multilocus restriction typing, pulsed-field gel electrophoresis, random amplified polymorphic DNA and BOX-PCR. A relatively new technique that is fast becoming the "gold standard" of bacterial typing methods is MLST. MLST utilises the amplification by PCR and DNA sequencing of seven putative housekeeping genes. The method provides highly discriminatory information from gene sequencing which can be shared and compared easily between laboratories. ^[47] Recently, expanded MLST typing has been described that addresses the shortcomings in the original MLST methodology. It could type 25 BCC strains that failed to be recognized with the original BCC MLST. ^[48]

Therapy

A significant problem in managing BCC-infected patients is the organism′s resistance to various antimicrobials and lack of newer effective antibiotics. BCC is intrinsically resistant to antimicrobial agents such as aminoglycosides, first-and second-generation cephalosporins, antipseudomonal penicillins and polymyxins. These various groups are commonly used in Pseudomonas infections, and the value of proper identification of BCC comes to the forefront. ^[4],[37] BCC often develops resistance to β-lactams due to presence of inducible chromosomal β-lactamases and altered penicillin-binding proteins. Antibiotic efflux pumps in BCC mediate resistance to chloramphenicol, trimethoprim and fluoroquinolones. On initial isolation, the organism may be susceptible to trimethoprim-sulfamethoxazole and antipseudomonal β-lactams. However, under antimicrobial pressure, resistance quickly develops and the clinicians frequently face the challenge of managing a patient infected with an organism resistant to all available antimicrobials. Some antibiotics such as ceftazidime, carbapenem and ciprofloxacin display some in vitro activities against BCC. As per the CLSI 2010 guidelines, the drugs recommended against BCC are ceftazidime, minocycline, meropenem and cotrimoxazole. ^[4],[37] With the exception of the epidemic B. cenocepacia ET12 lineage, previous studies of the BCC have shown greatest susceptibility to meropenem, irrespective of species status. ^[49] The antimicrobial susceptibility profile of PGIMER isolates revealed near-complete resistance to fluoroquinolones and more than 50% resistance to carbapenems, the first-line therapeutics of choice against serious pseudomonal infections. ^{[8],[10],[11]} These isolates behaved similar to non-CF nosocomial Italian isolates by showing susceptibility to ceftazidime. ^[50]

Successful treatment using combinations of meropenem with ciprofloxacin and tobramycin has been reported, as has been for ceftazidime and tobramycin. Additional nebulisation of antimicrobial agents such as meropenem or tobramycin has been reported to be effective as well. ^[4] Amongst more recently developed antimicrobial agents, doripenem appears to have therapeutical potential against BCC. ^[51] All 50 clinical isolates of BCC obtained from various specimens over the last four years in PGIMER were found susceptible to doripenem by E-test as per CLSI 2010 guidelines (unpublished data). ^[52]

Prevention and Control

Patients may acquire BCC either from the environment or through patient-to-patient transmission. ^[13],[17] BCC has generated considerable anxiety amongst patients with CF and has led to the development of stringent infection control procedures for managing CF patients with BCC infection. ^[53] These include discontinuing sponsorship and support of CF summer camps and segregation of colonised patients. In 2002, no new patients were infected with BCC for the next 1 year with the introduction of such measures in Palermo, Italy. ^[54] However, segregation will not prevent sporadic acquisition of BCC organisms from natural environments. ^[18] Accepted prophylactic measures include (a) an appropriate antibiotic policy, particularly a critical use of ciprofloxacin, cefepime and imipenem; (b) strict hand hygiene and institution of barrier techniques for colonised or infected patients and (c) surveillance amongst CF patients and identification of potential nosocomial reservoirs such as the public water system, commercially available drinking water, sink drains and medical equipment. Education of patients and health care workers is a cornerstone of such preventive measures. Implementation of these draconian infection control measures has a tremendous impact on the lives of CF patients, and not all patients or caregivers accept such measures. The widespread use of BCC in agriculture and bioremediation of contaminated environmental sites causes a conflict about its commercial use in light of its potentially life-threatening impact on CF patients. ^[7],[16] After a risk assessment of BCC bacteria as model opportunistic pathogens with biopesticidal uses in 1999, the United States Environmental Protection Agency placed a moratorium on the new registrations of products containing these bacteria (Federal Register; http://www.epa.gov/fedrgstr/EPA-PEST/2004/September/Day-29/p21695.htm ). ^[13]

Conclusions

BCC, a devastating pulmonary pathogen in CF patients, has also been reported as a cause of bacteraemia in few centres from our country. Due to its ability to thrive in the diverse range of environments, BCC contributes to increased morbidity and mortality in hospitalised patients. Various outbreaks and pseudo-outbreaks of BCC septicaemia have also been documented in these patients. ^{[4],[20],[34]} Due to high intrinsic resistance and being one of the most antimicrobial-resistant organisms encountered in the clinical laboratory, these infections can prove very difficult to treat and, in some cases, result in death. ^[4] Therefore, it needs to be correctly identified and differentiated from P. aeruginosa as BCC has inherently contrasting susceptibility pattern to that of P. aeruginosa. In addition, BCC has diverse properties and has been used in agriculture as biocontrol agent and in the bioremediation of toxic agents. ^[7],[16] BCC is phenotypically unremarkable, and the complex exhibits an extensive diversity of genotypes. ^[13]

Hence, Burkholderia cepacia complex can be termed as a diverse complex, truly complex.

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