Burkholderia cepacia complex infections: More complex than the bacterium name suggest

Consecutive outbreaks of Burkholderia cepacia complex caused by intrinsically contaminated chlorhexidine mouthwashes

BACKGROUND

We report 2 consecutive outbreaks of the Burkholderia cepacia complex (Bcc) in an intensive care unit (ICU) and describe its characteristics and consequences.

METHODS

Over a 72-day period, a multidisciplinary ICU team detected 2 distinct periods of high and unusual incidence of Bcc isolates that were recovered from cultures of endotracheal aspirate. Cultures of tap water, ultrasound gel and mouthwash (opened and unopened bottles) were performed. Bcc was identified with the BD-Phoenix and MALDI-TOF MS systems, with molecular typing using the enterobacterial repetitive intergenic consensus-polymerase chain reaction technique.

RESULTS

In both outbreak 1 (6 patients) and outbreak 2 (5 patients), the point sources of Bcc were chlorhexidine mouthwashes of 2 different brands, both of them intrinsically contaminated. All patients had a clinical diagnosis of ventilator-associated pneumonia (VAP), and 6 died. MALDI-TOF MS identified 2 species of Bcc (B. cenocepacia and B. cepacia). Enterobacterial repetitive intergenic consensus-polymerase chain reaction typing confirmed 100% genetic similarity between patient and mouthwash isolates from each period. The first outbreak was controlled in 20 days and the second in 6 days.

CONCLUSIONS

The surveillance program for multidrug-resistant organisms, especially in high-risk patients, with the active participation of a multidisciplinary team, was crucial for success in controlling these outbreaks.

Burkholderia cepacia Sepsis in a Previously Healthy Full-Term Infant

Burkholderia cepacia causes sepsis in neonates who are immunocompromised or exposed via nosocomial transmission. We report a case of B. cepacia sepsis in a previously healthy 5-week-old male originally treated for bacterial pneumonia per chest X-ray findings and 3 days of fevers. Regardless of appropriate antibiotics and an initial negative blood culture, he developed severe hypoglycemia, circulatory collapse with disseminated intravascular coagulopathy, and expired. A second blood culture taken following transfer to the intensive care unit resulted positive for B. cepacia postmortem. Review of the newborn screen and family history was otherwise normal. Subsequent postmortem autopsy showed multifocal bilateral pneumonia with necrotizing granulomatous and suppurative portions of lung tissue. Additionally, there was a prominent cavitary lesion 2.5 cm in the right lower lobe with branching and septate fungal hyphae. Stellate microabscesses with granulomas were present in the liver and spleen. These findings plus B. cepacia bacteremia are highly suggestive of an immunocompromised status. Review of the literature shows that its presence has been associated with chronic granulomatous disease. Therefore, in a persistently febrile infant not responding to antibiotics for common microbes causing community-acquired pneumonia, immunodeficiency workup should ensue in addition to respective testing for chronic granulomatous disease especially if B. cepacia culture-positive as it is strongly associated with neutrophil dysfunction.

Pocket Irrigation and Technique During Reconstructive Surgery: An American Society of Plastic Surgery Survey of Current Practice

BACKGROUND

Expander-to-implant is the most common breast reconstruction procedure in the United States. Irrigation with triple antibiotic solution (TAS), as described by Adams et al in 2006, has become standard of care to lower bacterial bioburden. However, several alternative solutions have been implemented with the literature lacking a consensus regarding use (Plast Reconstr Surg. 2006;117:30-36).

OBJECTIVE

We distributed a peer-reviewed survey among a cohort of American Society of Plastic Surgery (ASPS) members to assess pocket irrigation technique during implant-based reconstructive surgery. We then conducted a pilot in vitro study to determine antibacterial efficacy of the most preferred irrigation at preferred dwell times against select bacterial species linked to breast pocket contamination during reconstructive implant-based surgery.

METHODS

The survey was distributed a total of 3 times to a random cohort of 2488 ASPS members in January 2018. During in vitro studies, pure cultures of common breast flora were exposed to TAS versus saline control at 1, 2, and 5 minutes in a simulated in vivo cavity. Viable plate counts were used to assess cell viability.

RESULTS

The response rate was above the ASPS survey average at 16% (n = 407). The population reflected a cross-section of practice types and experience levels. Triple antibiotic solution without Betadine was the favored irrigation at 41%, with 73% of its users preferring dwell times of 2 minutes or less. Over 30 distinct breast pocket irrigation solutions were identified. Bacteria added to the in vivo cavity survived a 2-minute dwell time with TAS as follows: 51% Staphylococcus epidermidis, 69% Escherichia coli, 88% Enterococcus faecalis, 88% Pseudomonas aeruginosa, and 98% Acinetobacter baumannii.

CONCLUSION

Our survey data demonstrate significant variability in practice and lack of consensus among ASPS members regarding antimicrobial irrigation during reconstructive breast surgery. Our in vitro data underscores the importance of relating clinical practices with laboratory studies of microorganisms potentially linked to breast pocket contamination and suggests that TAS requires either dwell times greater than 5 minutes and/or the inclusion of efficacious antimicrobial agents (eg, Betadine). This finding has the potential to impact antimicrobial pocket irrigation and technique during breast reconstruction.

Synthesis and Antimicrobial Activity of Burkholderia-Related 4-Hydroxy-3-methyl-2-alkenylquinolines (HMAQs) and Their N-Oxide Counterparts

The Burkholderia genus offers a promising potential in medicine because of the diversity of biologically active natural products encoded in its genome. Some pathogenic Burkholderia spp. biosynthesize a specific class of antimicrobial 2-alkyl-4(1H)-quinolones, i.e., 4-hydroxy-3-methyl-2-alkenylquinolines (HMAQs) and their N-oxide derivatives (HMAQNOs). Herein, we report the synthesis of a series of six HMAQs and HMAQNOs featuring a trans-Δ² double bond at the C2-alkyl chain. The quinolone scaffold was obtained via the Conrad-Limpach approach, while the (E)-2-alkenyl chain was inserted through Suzuki-Miyaura cross-coupling under microwave radiation without noticeable isomerization according to the optimized conditions. Subsequent oxidation of enolate-protected HMAQs cleanly led to the formation of HMAQNOs following cleavage of the ethyl carbonate group. Synthetic HMAQs and HMAQNOs were evaluated in vitro for their antimicrobial activity against different Gram-negative and Gram-positive bacteria as well as against molds and yeasts. The biological results support and extend the potential of HMAQs and HMAQNOs as antimicrobials, especially against Gram-positive bacteria. We also confirm the involvement of HMAQs in the autoregulation of the Hmq system in Burkholderia ambifaria.

Regulation of Virulence by Two-Component Systems in Pathogenic Burkholderia

The regulation and timely expression of bacterial genes during infection is critical for a pathogen to cause an infection. Bacteria have multiple mechanisms to regulate gene expression in response to their environment, one of which is two-component systems (TCS). TCS have two components. One component is a sensory histidine kinase (HK) that autophosphorylates when activated by a signal. The activated sensory histidine kinase then transfers the phosphoryl group to the second component, the response regulator, which activates transcription of target genes. The genus Burkholderia contains members that cause human disease and are often extensively resistant to many antibiotics. The Burkholderia cepacia complex (BCC) can cause severe lung infections in patients with cystic fibrosis (CF) or chronic granulomatous disease (CGD). BCC members have also recently been associated with several outbreaks of bacteremia from contaminated pharmaceutical products. Separate from the BCC is Burkholderia pseudomallei, which is the causative agent of melioidosis, a serious disease that occurs in the tropics, and a potential bioterrorism weapon. Bioinformatic analysis of sequenced Burkholderia isolates predicts that most strains have at least 40 TCS. The vast majority of these TCS are uncharacterized both in terms of the signals that activate them and the genes that are regulated by them. This review will highlight TCS that have been described to play a role in virulence in either the BCC or B. pseudomallei Since many of these TCS are involved in virulence, TCS are potential novel therapeutic targets, and elucidating their function is critical for understanding Burkholderia pathogenesis.

Differences in Cystic Fibrosis-Associated Burkholderia spp. Bacteria Metabolomes after Exposure to the Antibiotic Trimethoprim

The Burkholderia cepacia complex is a group of closely related bacterial species with large genomes that infect immunocompromised individuals and those living with cystic fibrosis. Some of these species are found more frequently and cause more severe disease than others, yet metabolomic differences between these have not been described. Furthermore, our understanding of how these species respond to antibiotics is limited. We investigated the metabolomics differences between three most prevalent Burkholderia spp. associated with cystic fibrosis: B. cenocepacia, B. multivorans, and B. dolosa in the presence and absence of the antibiotic trimethoprim. Using a combination of supervised and unsupervised metabolomics data visualization and analysis tools, we describe the overall differences between strains of the same species and between species. Specifically, we report, for the first time, the role of the pyomelanin pathway in the metabolism of trimethoprim. We also report differences in the detection of known secondary metabolites such as fragin, ornibactin, and N-acylhomoserine lactones and their analogs in closely related strains. Furthermore, we highlight the potential for the discovery of new secondary metabolites in clinical strains of Burkholderia spp. The metabolomics differences described in this study highlight the personalized nature of closely related Burkholderia strains.

Major Aspects of Burkholderia gladioli and Burkholderia cepacia Infections in Children

BACKGROUND

Burkholderia cepacia complex is an aerobic, non-spore-forming, catalase-positive, nonfermentative, Gram-negative bacterium common in environment. It is a serious pathogen especially for patients with cystic fibrosis (CF). But pathogenicity of Burkholderia is not limited to patients with CF. Herein, we aimed to reveal clinical patterns and outcomes of Burkholderia infections in pediatric patients in our hospital and also antimicrobial susceptibility of the isolated strain.

METHODS

This retrospective study was conducted in Ankara Hematology Oncology Children's Training and Research Hospital. Patients with isolates of Burkholderia spp. between January 6, 2013, and January 12, 2018, were included in the study.

RESULTS

Burkholderia spp. was isolated from 55 patients. 94.6% of these patients had underlying diseases and had prior hospitalization within a year. Burkholderia gladioli grew in 15 patients' samples (27.3%); 38 patients grew B. cepacia (69.1%). None of the patients that B. gladioli was isolated was diagnosed as CF;. all had nosocomial infections. B. gladioli seemed to be more susceptible to aminoglycosides, piperacillin-tazobactam, carbapenems and ciprofloxacin than B. cepacia (P = 0.00), whereas B. cepacia seemed to be more susceptible to ceftazidime than B. gladioli (P = 0.032). In addition, B. cepacia was more susceptible to trimethoprim-sulfamethoxazole and levofloxacin than B. gladioli, but this difference was not statistically significant (P = 0.76).

CONCLUSIONS

The incidence of nosocomial infections caused by Burkholderia spp. is rare especially in pediatric literature. In our study, nosocomial Burkholderia infections occurred mostly in intensive care unit patients. The surveillance of Burkholderia infections is still very important, and the clinicians should be aware of changing epidemiology and increasing resistance of the microorganism. Besides, there are no internationally agreed minimal inhibitory concentration breakpoints and disk-diffusion test thresholds for susceptibility testing for Burkholderia. Thus, the methods which were used for antibiotic susceptibility testing in our center might cause uncertainty about the results and internationally agreed minimal inhibitory concentration breakpoints and disk-diffusion test thresholds for susceptibility testing for Burkholderia is still a gap to fill for the current literature.

Burkholderia cepacia complex outbreak originating from contaminated wash gloves

Burkholderia cepacia complex isolates were detected from four patients who were admitted to the heart centre of southern Switzerland, between April and June 2019. An outbreak investigation was conducted. The three available patient samples were whole genome sequenced, showing that they all are Burkholderia cepacia species, and that two are identical. Isolates grown from sealed packages of disinfectant-free wash gloves used for personal hygiene were also genomically identical. The wash gloves appear to be the origin of the outbreak, contamination of which most likely occurred at the manufacturing site.

Outbreak of Burkholderia cepacia complex infections associated with contaminated octenidine mouthwash solution, Germany, August to September 2018

Three German patients developed nosocomial pneumonia after cardiac surgery and had Burkholderia cepacia complex detected in respiratory specimens. Two patients died of septic multi-organ failure. Whole-genome sequencing detected genetically identical B. cepacia complex strains in patient samples, from a batch of octenidine mouthwash solution, which had been used for nursing care, as well as in samples obtained from the manufacturer during production. Contamination of medical products during manufacturing may lead to international outbreaks.

Potent modulation of the CepR quorum sensing receptor and virulence in a Burkholderia cepacia complex member using non-native lactone ligands

The Burkholderia cepacia complex (Bcc) is a family of closely related bacterial pathogens that are the causative agent of deadly human infections. Virulence in Bcc species has been shown to be controlled by the CepI/CepR quorum sensing (QS) system, which is mediated by an N-acyl L-homoserine lactone (AHL) signal (C₈-AHL) and its cognate LuxR-type receptor (CepR). Chemical strategies to block QS in Bcc members would represent an approach to intercept this bacterial communication process and further delineate its role in infection. In the current study, we sought to identify non-native AHLs capable of agonizing or antagonizing CepR, and thereby QS, in a Bcc member. We screened a library of AHL analogs in cell-based reporters for CepR, and identified numerous highly potent CepR agonists and antagonists. These compounds remain active in a Bcc member, B. multivorans, with one agonist 250-fold more potent than the native ligand C₈-AHL, and can affect QS-controlled motility. Further, the CepR antagonists prolong C. elegans survival in an infection model. These AHL analogs are the first reported non-native molecules that both directly modulate CepR and impact QS-controlled phenotypes in a Bcc member, and represent valuable chemical tools to assess the role of QS in Bcc infections.

Misidentification of Burkholderia pseudomallei and Other Burkholderia Species From Pediatric Infections in Mexico

Burkholderia pseudomallei and Burkholderia cepacia complex are poorly studied in Mexico. The genotypic analysis of 38 strains isolated from children with pneumonia were identified and showed that both Burkholderia groups were present in patients. From our results, it is plausible to suggest that new species are among the analyzed strains.