“…Can any bacterial species be considered pathogenic if given the right environment? Combining our findings with previous work on C. crescentus suggests that Caulobacter can carry out many of the processes typical of other pathogens, including biofilm formation, antibiotic resistance, killing of non-self bacteria, and Galleria host killing [7,10,50,51]. Unlike the patient-isolated C. mirare, the CB15 C. crescentus strain studied here is an environmental isolate from a freshwater lake [2].…”
Section: Plos Onesupporting
confidence: 71%
“…All previous studies looking at the in vivo pathogenic potential of Caulobacter used murine cell lines or immunocompetent mouse models [20,37]. In contrast, all clinical reports of human Caulobacter infections occurred in hospital settings with patients who are likely immunocompromised [7][8][9][10]. Since different bacteria may be virulent in different contexts, using a variety of host models may prove beneficial for understanding the contexts in which a bacterium can be toxic.…”
Section: Discussionmentioning
confidence: 99%
“…Historically, this genus has been considered non-pathogenic due to lack of presence in infection cases, no obvious pathogenicity islands, and increased bacterial mortality at human body temperatures [5]. However, the last two decades have seen several reports of symptomatic infections associated with Caulobacter species [6][7][8][9][10]. All reported cases of Caulobacter infections appear to be hospital-acquired by immunocompromised patients, suggesting that these infections are opportunistic.…”
The Caulobacter genus, including the widely-studied model organism Caulobacter crescentus, has been thought to be non-pathogenic and thus proposed as a bioengineering vector for various environmental remediation and medical purposes. However, Caulobacter species have been implicated as the causative agents of several hospital-acquired infections, raising the question of whether these clinical isolates represent an emerging pathogenic species or whether Caulobacters on whole possess previously-unappreciated virulence capability. Given the proposed environmental and medical applications for C. crescentus, understanding the potential pathogenicity of this bacterium is crucial. Consequently, we sequenced a clinical Caulobacter isolate to determine if it has acquired novel virulence determinants. We found that the clinical isolate represents a new species, Caulobacter mirare that, unlike C. crescentus, grows well in standard clinical culture conditions. C. mirare phylogenetically resembles both C. crescentus and the related C. segnis, which was also thought to be non-pathogenic. The similarity to other Caulobacters and lack of obvious pathogenesis markers suggested that C. mirare is not unique amongst Caulobacters and that consequently other Caulobacters may also have the potential to be virulent. We tested this hypothesis by characterizing the ability of Caulobacters to infect the model animal host Galleria mellonella. In this context, two different lab strains of C. crescentus proved to be as pathogenic as C. mirare, while lab strains of E. coli were non-pathogenic. Further characterization showed that Caulobacter pathogenesis in the Galleria model is mediated by lipopolysaccharide (LPS), and that differences in LPS chemical composition across species could explain their differential toxicity. Taken together, our findings suggest that many Caulobacter species can be virulent in specific contexts and highlight the importance of broadening our methods for identifying and characterizing potential pathogens.
“…Can any bacterial species be considered pathogenic if given the right environment? Combining our findings with previous work on C. crescentus suggests that Caulobacter can carry out many of the processes typical of other pathogens, including biofilm formation, antibiotic resistance, killing of non-self bacteria, and Galleria host killing [7,10,50,51]. Unlike the patient-isolated C. mirare, the CB15 C. crescentus strain studied here is an environmental isolate from a freshwater lake [2].…”
Section: Plos Onesupporting
confidence: 71%
“…All previous studies looking at the in vivo pathogenic potential of Caulobacter used murine cell lines or immunocompetent mouse models [20,37]. In contrast, all clinical reports of human Caulobacter infections occurred in hospital settings with patients who are likely immunocompromised [7][8][9][10]. Since different bacteria may be virulent in different contexts, using a variety of host models may prove beneficial for understanding the contexts in which a bacterium can be toxic.…”
Section: Discussionmentioning
confidence: 99%
“…Historically, this genus has been considered non-pathogenic due to lack of presence in infection cases, no obvious pathogenicity islands, and increased bacterial mortality at human body temperatures [5]. However, the last two decades have seen several reports of symptomatic infections associated with Caulobacter species [6][7][8][9][10]. All reported cases of Caulobacter infections appear to be hospital-acquired by immunocompromised patients, suggesting that these infections are opportunistic.…”
The Caulobacter genus, including the widely-studied model organism Caulobacter crescentus, has been thought to be non-pathogenic and thus proposed as a bioengineering vector for various environmental remediation and medical purposes. However, Caulobacter species have been implicated as the causative agents of several hospital-acquired infections, raising the question of whether these clinical isolates represent an emerging pathogenic species or whether Caulobacters on whole possess previously-unappreciated virulence capability. Given the proposed environmental and medical applications for C. crescentus, understanding the potential pathogenicity of this bacterium is crucial. Consequently, we sequenced a clinical Caulobacter isolate to determine if it has acquired novel virulence determinants. We found that the clinical isolate represents a new species, Caulobacter mirare that, unlike C. crescentus, grows well in standard clinical culture conditions. C. mirare phylogenetically resembles both C. crescentus and the related C. segnis, which was also thought to be non-pathogenic. The similarity to other Caulobacters and lack of obvious pathogenesis markers suggested that C. mirare is not unique amongst Caulobacters and that consequently other Caulobacters may also have the potential to be virulent. We tested this hypothesis by characterizing the ability of Caulobacters to infect the model animal host Galleria mellonella. In this context, two different lab strains of C. crescentus proved to be as pathogenic as C. mirare, while lab strains of E. coli were non-pathogenic. Further characterization showed that Caulobacter pathogenesis in the Galleria model is mediated by lipopolysaccharide (LPS), and that differences in LPS chemical composition across species could explain their differential toxicity. Taken together, our findings suggest that many Caulobacter species can be virulent in specific contexts and highlight the importance of broadening our methods for identifying and characterizing potential pathogens.
“…Caulobacter species are commonly considered non-pathogenic and present in both the oral and gastrointestinal tract ( Table S4 ). However, a few cases reported that Caulobacter isolates may be associated with recurrent peritonitis of peritoneal dialysis patients [ 14 , 15 ]. Fig.…”
Section: Resultsmentioning
confidence: 99%
“…This type of infection can potentially progress to fatal bacteremia, even in individuals without pre-existing health issues, and it may pose a significant risk to premature infants [ 30 ]. While Caulobacter species are generally considered non-pathogenic and can be found in both the oral and gastrointestinal tract, a few reported cases have associated Caulobacter isolates with recurrent peritonitis in peritoneal dialysis patients [ 14 , 15 ]. Delftia acidovorans is rarely implicated as a human pathogen.…”
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