Bacteroides caccae is a common resident of the human intestine, which plays a vital role in food digestion and synthesizing beneficial nutrients. While the epidemiology of Bacteroides caccae infections is not extensively studied, several cases have been reported in the medical literature. Most of these infections occurred in patients with risk factors or underlying medical conditions such as hypertension, gastrointestinal bleeding, renal failure, diabetes, or immunosuppression. These factors may contribute to the susceptibility to Bacteroides caccae infections.
The transmission of Bacteroides caccae infections is typically endogenous, meaning that the bacteria originate from the patient’s intestinal flora. Currently, no evidence suggests direct transmission from person to person or from animals to humans. However, animal bites or scratches can introduce Bacteroides caccae or other anaerobic bacteria into wounds, leading to infections.
Bacteroides bacteremia, a severe infection caused by Bacteroides species, has been associated with a high mortality rate, ranging from 16% to 45%, depending on treatment efficacy. Reported cases include bacteremia caused by B. caccae in patients with renal hypertension and gastrointestinal bleeding. Effective treatment with appropriate antibiotics, such as metronidazole and cefoperazone-sulbactam or metronidazole and ciprofloxacin, has been successful in some cases, leading to patient recovery after hospitalization.
Studies from countries such as China, Poland, and Canada have reported infections caused by Bacteroides species closely related to B. caccae. Recently 16 cases worldwide have been documented. These infections included various clinical presentations, such as wound infections after animal bites, chronic oral infections, osteomyelitis, surgical site infections, and urinary tract infections. In some cases, antibiotic resistance was observed, underscoring the importance of targeted and appropriate antimicrobial therapy.
Kingdom: Bacteria
Phylum: Bacteroidota
Class: Bacteroidia
Order: Bacteroidales
Family: Bacteroidaceae
Genus:Bacteroides
Species:Bacteroides caccae
Bacteroides caccae is a saccharolytic anaerobic bacterium with rod-shaped cells that can exist in pairs. The rods have rounded ends and are somewhat bent.It features a gram-negative cell wall structure and an exterior membrane wrapped by a thin peptidoglycan coating.
The size ranges from 1.4 – 1.6 μm wide and 2.5 – 12 μm long.Bacteroides caccae‘s DNA GC content ranges between 40 and 46 mol%, representing the proportion of the cytosine and guanine nucleotides in its DNA.
Bacteroides caccae, like other bacteria, has virulent proteins and genes that serve a role in pathogenicity & host interactions. The TonB-linked outer membrane protein OmpW is one such virulent protein. This protein was discovered in Bacteroides caccae and shares characteristics with other bacterial TonB-linked outer membrane proteins.
When iron or vitamins are scarce in the environment, OmpW allows the bacteria to improve their absorption ability. The existence of a TonB box in OmpW, a highly conserved region, suggests that it could possess an integral part in food uptake & commensal bacterial survival in the intestine.
Additionally, the immunological finding of elevated anti-OmpW IgA levels in some patients with Crohn’s disease suggests a potential link between Bacteroides caccae and the pathogenesis of this inflammatory bowel disease. Crohn’s disease is characterized by chronic inflammation in the gastrointestinal tract, and the presence of OmpW-specific IgA antibodies in affected individuals indicates a possible immune response to the bacterium.
Bacteroides caccae is a bacterial species isolated from several fecal samples from various geographical areas. Several strains of Bacteroides caccae have been found and characterized, providing essential insights into the bacterium’s genetic variety and possible toxicity.ATCC 43185 is the type strain of Bacteroides caccae obtained from a fecal sample in Texas.
This strain has been completely sequenced. It now serves as the reference genome for the NIH Human Microbiome Project, furthering our understanding microbiome of the human gut and its role in health & disease.
CCUG 38735, CIP 104201, JCM 9498, NCTC 13051, VPI 3452A, and DSM 19024 are other strains of Bacteroides caccae deposited in culture collections worldwide. Each strain was isolated from fecal samples in different countries, including Sweden, France, Japan, the UK, the USA, and Germany.
Bacteroides caccae, often found in the human intestine, can cause significant infections if it escapes & enters the bloodstream or other sterile places, significantly if the intestinal barrier is damaged due to trauma, surgery, or other disorders. Severe infections like septicemia, abscesses, osteomyelitis, & meningitis can result.
The bacteria have a TonB-linked outer cell membrane protein which may aid in absorbing vital minerals such as iron or vitamins inside the intestinal environment, promoting growth and survival. OmpW has been linked to an immunological response in some Crohn’s disease patients, who exhibit higher levels of anti-OmpW IgA antibodies in their serum.
Bacteroides caccae also has the potential to create bacteriocins, which are antimicrobial peptides that can kill or inhibit other bacteria. These bacteriocins have been proven effective against various Bacteroides species and Clostridium difficile, a bacterium that causes antibiotic-associated diarrhea and colitis.
Bacteroides caccae can also cause human peripheral blood mononuclear cells to produce the cytokine interleukin-10. IL-10 has anti-inflammatory properties and can control the immune response to reduce excessive inflammation and tissue damage. Furthermore, Bacteroides caccae increases the levels of co-stimulatory substances CD80 and CD86 on PBMCs, increasing T cell activation and implying potential immunomodulatory effects on the host immune system.
Toll-like receptor 4 (TLR4) is activated during host defense against Bacteroides caccae and other commensals belonging to Bacteroidia class. TLR4 is a critical receptor that recognizes specific molecules associated with bacterial pathogens, such as lipopolysaccharides (LPS) found in Bacteroides caccae‘s outer membrane. When TLR4 on intestinal epithelial cells or immune cells contacts these compounds, it triggers a signaling cascade that activates canonical NF-κB signaling.
The NF-κB signaling pathway acts as a “rheostat” that regulates the degree of immune stimulation elicited by commensal bacteria. In the case of Bacteroidia communities, the activation of TLR4 is the primary driver of immune effects on intestinal immunity. This robust TLR4 activation contributes to the induction of various immune defenses, including the production of cytokines like TNF, CXCL1, CXCL2, and GM-CSF, which play essential roles in inflammation & immune response.
In contrast, commensals from the Clostridia class within the Firmicutes phylum signal via both TLR2 and TLR4 exert their effects on intestinal immunity. This activation of multiple receptors likely contributes to the complexity and diversity of immune responses induced by Clostridia communities.
The immune response to commensals is a finely balanced process. Excessive or dysregulated immune stimulation can lead to inflammation and tissue damage. Therefore, the host employs regulatory mechanisms, such as the production of anti-inflammatory cytokines like Interleukin 6, to prevent excessive immune responses.
Bacteroides caccae is commonly involved in polymicrobial infections that affect various body sites. One of the hallmark manifestations of Bacteroides infections is the formation of abscesses.
Abscesses are collections of pus that develop because of localized infections. These infections can occur in different body areas, including the abdomen, pelvis, brain, lungs, liver, skin, soft tissue, and blood. Abscesses can lead to symptoms such as pain, swelling, redness, and fever.
In the abdomen and pelvis, Bacteroides caccae infections can cause peritonitis, which is the inflammation of the lining of the abdominal cavity. Peritonitis can arise from perforation or rupture of the gastrointestinal tract, such as in cases of appendicitis or diverticulitis. This condition causes severe abdominal pain, vomiting, nausea, and shock, necessitating prompt medical attention.
Genitourinary infections, especially in women, can also be caused by Bacteroides caccae. These infections include pelvic inflammatory disease (PID), tubo-ovarian abscess, endometritis, and chorioamnionitis. Such infections can present with symptoms like pelvic pain, abnormal vaginal discharge, fever, and in some cases, infertility.
Additionally, Bacteroides caccae can cause oral and upper respiratory infections, contributing to tooth abscess, periodontitis, peritonsillar abscess, sinusitis, and parotiditis. These infections can lead to toothache, gum bleeding, sore throat, nasal congestion, and facial swelling.
Culture method: Culture is reliable and definitive for identifying Bacteroides caccae and determining its antimicrobial susceptibility. It requires anaerobic conditions and specific media like blood agar or Bacteroides-bile-esculin (BBE) agar. BBE agar helps differentiate Bacteroides caccae from other species by hydrolyzing esculin and producing dark colonies with brown-black halos. Culture should be performed on uncontaminated specimens, such as blood, peritoneal or pleural fluid, or abscess aspirates. Routine anaerobic culture of community-acquired intra-abdominal infections is considered optional.
PCR assay: Polymerase Chain Reaction is a molecular approach that detects and amplifies specific Bacteroides caccae DNA sequences. Although PCR is more rapid and sensitive than culture, it does not provide information on antibiotic susceptibility or bacterial viability. It can, however, be used to identify Bacteroides caccae host-specific genetic markers, which can aid in determining the fecal contamination source in water or food samples. Performing two or more sets of blood cultures and identifying anaerobic bacteria utilizing Matrix-Assisted Laser Desorption Ionization-Time of Flight mass spectroscopy can considerably improve the positive detection rate of blood cultures.
Serology: It is an immunological technique that measures the level of antibodies against Bacteroides caccae in the serum of patients. It can indicate exposure or infection by Bacteroides caccae, although it may not reflect the status or severity of infection. Serology can also detect specific antigens of Bacteroides caccae, such as OmpW, a TonB-linked outer membrane protein that may play a role in pathogenicity or immunogenicity. For instance, elevated levels of anti-OmpW IgA antibodies have been observed in some patients with Crohn’s disease compared to ulcerative colitis patients or healthy individuals.
A robust immune system protects against Bacteroides caccae and other pathogen infections. A healthy lifestyle that includes balanced nutrition, frequent exercise, appropriate sleep, & stress management can help promote immune function.
Antibiotic overuse and misuse can lead to the development of antibiotic resistance. Antibiotic stewardship is critical for ensuring antibiotics are used appropriately and only when necessary to treat Bacteroides caccae infections.
Proper preparation, cooking food & storage procedures can lower the incidence of foodborne diseases, including Bacteroides caccae infections. Washing fruits and vegetables, heating food at the proper temperatures, and minimizing cross-contamination between raw & cooked meals are all critical precautions.
Bacteroides caccae is a common resident of the human intestine, which plays a vital role in food digestion and synthesizing beneficial nutrients. While the epidemiology of Bacteroides caccae infections is not extensively studied, several cases have been reported in the medical literature. Most of these infections occurred in patients with risk factors or underlying medical conditions such as hypertension, gastrointestinal bleeding, renal failure, diabetes, or immunosuppression. These factors may contribute to the susceptibility to Bacteroides caccae infections.
The transmission of Bacteroides caccae infections is typically endogenous, meaning that the bacteria originate from the patient’s intestinal flora. Currently, no evidence suggests direct transmission from person to person or from animals to humans. However, animal bites or scratches can introduce Bacteroides caccae or other anaerobic bacteria into wounds, leading to infections.
Bacteroides bacteremia, a severe infection caused by Bacteroides species, has been associated with a high mortality rate, ranging from 16% to 45%, depending on treatment efficacy. Reported cases include bacteremia caused by B. caccae in patients with renal hypertension and gastrointestinal bleeding. Effective treatment with appropriate antibiotics, such as metronidazole and cefoperazone-sulbactam or metronidazole and ciprofloxacin, has been successful in some cases, leading to patient recovery after hospitalization.
Studies from countries such as China, Poland, and Canada have reported infections caused by Bacteroides species closely related to B. caccae. Recently 16 cases worldwide have been documented. These infections included various clinical presentations, such as wound infections after animal bites, chronic oral infections, osteomyelitis, surgical site infections, and urinary tract infections. In some cases, antibiotic resistance was observed, underscoring the importance of targeted and appropriate antimicrobial therapy.
Kingdom: Bacteria
Phylum: Bacteroidota
Class: Bacteroidia
Order: Bacteroidales
Family: Bacteroidaceae
Genus:Bacteroides
Species:Bacteroides caccae
Bacteroides caccae is a saccharolytic anaerobic bacterium with rod-shaped cells that can exist in pairs. The rods have rounded ends and are somewhat bent.It features a gram-negative cell wall structure and an exterior membrane wrapped by a thin peptidoglycan coating.
The size ranges from 1.4 – 1.6 μm wide and 2.5 – 12 μm long.Bacteroides caccae‘s DNA GC content ranges between 40 and 46 mol%, representing the proportion of the cytosine and guanine nucleotides in its DNA.
Bacteroides caccae, like other bacteria, has virulent proteins and genes that serve a role in pathogenicity & host interactions. The TonB-linked outer membrane protein OmpW is one such virulent protein. This protein was discovered in Bacteroides caccae and shares characteristics with other bacterial TonB-linked outer membrane proteins.
When iron or vitamins are scarce in the environment, OmpW allows the bacteria to improve their absorption ability. The existence of a TonB box in OmpW, a highly conserved region, suggests that it could possess an integral part in food uptake & commensal bacterial survival in the intestine.
Additionally, the immunological finding of elevated anti-OmpW IgA levels in some patients with Crohn’s disease suggests a potential link between Bacteroides caccae and the pathogenesis of this inflammatory bowel disease. Crohn’s disease is characterized by chronic inflammation in the gastrointestinal tract, and the presence of OmpW-specific IgA antibodies in affected individuals indicates a possible immune response to the bacterium.
Bacteroides caccae is a bacterial species isolated from several fecal samples from various geographical areas. Several strains of Bacteroides caccae have been found and characterized, providing essential insights into the bacterium’s genetic variety and possible toxicity.ATCC 43185 is the type strain of Bacteroides caccae obtained from a fecal sample in Texas.
This strain has been completely sequenced. It now serves as the reference genome for the NIH Human Microbiome Project, furthering our understanding microbiome of the human gut and its role in health & disease.
CCUG 38735, CIP 104201, JCM 9498, NCTC 13051, VPI 3452A, and DSM 19024 are other strains of Bacteroides caccae deposited in culture collections worldwide. Each strain was isolated from fecal samples in different countries, including Sweden, France, Japan, the UK, the USA, and Germany.
Bacteroides caccae, often found in the human intestine, can cause significant infections if it escapes & enters the bloodstream or other sterile places, significantly if the intestinal barrier is damaged due to trauma, surgery, or other disorders. Severe infections like septicemia, abscesses, osteomyelitis, & meningitis can result.
The bacteria have a TonB-linked outer cell membrane protein which may aid in absorbing vital minerals such as iron or vitamins inside the intestinal environment, promoting growth and survival. OmpW has been linked to an immunological response in some Crohn’s disease patients, who exhibit higher levels of anti-OmpW IgA antibodies in their serum.
Bacteroides caccae also has the potential to create bacteriocins, which are antimicrobial peptides that can kill or inhibit other bacteria. These bacteriocins have been proven effective against various Bacteroides species and Clostridium difficile, a bacterium that causes antibiotic-associated diarrhea and colitis.
Bacteroides caccae can also cause human peripheral blood mononuclear cells to produce the cytokine interleukin-10. IL-10 has anti-inflammatory properties and can control the immune response to reduce excessive inflammation and tissue damage. Furthermore, Bacteroides caccae increases the levels of co-stimulatory substances CD80 and CD86 on PBMCs, increasing T cell activation and implying potential immunomodulatory effects on the host immune system.
Toll-like receptor 4 (TLR4) is activated during host defense against Bacteroides caccae and other commensals belonging to Bacteroidia class. TLR4 is a critical receptor that recognizes specific molecules associated with bacterial pathogens, such as lipopolysaccharides (LPS) found in Bacteroides caccae‘s outer membrane. When TLR4 on intestinal epithelial cells or immune cells contacts these compounds, it triggers a signaling cascade that activates canonical NF-κB signaling.
The NF-κB signaling pathway acts as a “rheostat” that regulates the degree of immune stimulation elicited by commensal bacteria. In the case of Bacteroidia communities, the activation of TLR4 is the primary driver of immune effects on intestinal immunity. This robust TLR4 activation contributes to the induction of various immune defenses, including the production of cytokines like TNF, CXCL1, CXCL2, and GM-CSF, which play essential roles in inflammation & immune response.
In contrast, commensals from the Clostridia class within the Firmicutes phylum signal via both TLR2 and TLR4 exert their effects on intestinal immunity. This activation of multiple receptors likely contributes to the complexity and diversity of immune responses induced by Clostridia communities.
The immune response to commensals is a finely balanced process. Excessive or dysregulated immune stimulation can lead to inflammation and tissue damage. Therefore, the host employs regulatory mechanisms, such as the production of anti-inflammatory cytokines like Interleukin 6, to prevent excessive immune responses.
Bacteroides caccae is commonly involved in polymicrobial infections that affect various body sites. One of the hallmark manifestations of Bacteroides infections is the formation of abscesses.
Abscesses are collections of pus that develop because of localized infections. These infections can occur in different body areas, including the abdomen, pelvis, brain, lungs, liver, skin, soft tissue, and blood. Abscesses can lead to symptoms such as pain, swelling, redness, and fever.
In the abdomen and pelvis, Bacteroides caccae infections can cause peritonitis, which is the inflammation of the lining of the abdominal cavity. Peritonitis can arise from perforation or rupture of the gastrointestinal tract, such as in cases of appendicitis or diverticulitis. This condition causes severe abdominal pain, vomiting, nausea, and shock, necessitating prompt medical attention.
Genitourinary infections, especially in women, can also be caused by Bacteroides caccae. These infections include pelvic inflammatory disease (PID), tubo-ovarian abscess, endometritis, and chorioamnionitis. Such infections can present with symptoms like pelvic pain, abnormal vaginal discharge, fever, and in some cases, infertility.
Additionally, Bacteroides caccae can cause oral and upper respiratory infections, contributing to tooth abscess, periodontitis, peritonsillar abscess, sinusitis, and parotiditis. These infections can lead to toothache, gum bleeding, sore throat, nasal congestion, and facial swelling.
Culture method: Culture is reliable and definitive for identifying Bacteroides caccae and determining its antimicrobial susceptibility. It requires anaerobic conditions and specific media like blood agar or Bacteroides-bile-esculin (BBE) agar. BBE agar helps differentiate Bacteroides caccae from other species by hydrolyzing esculin and producing dark colonies with brown-black halos. Culture should be performed on uncontaminated specimens, such as blood, peritoneal or pleural fluid, or abscess aspirates. Routine anaerobic culture of community-acquired intra-abdominal infections is considered optional.
PCR assay: Polymerase Chain Reaction is a molecular approach that detects and amplifies specific Bacteroides caccae DNA sequences. Although PCR is more rapid and sensitive than culture, it does not provide information on antibiotic susceptibility or bacterial viability. It can, however, be used to identify Bacteroides caccae host-specific genetic markers, which can aid in determining the fecal contamination source in water or food samples. Performing two or more sets of blood cultures and identifying anaerobic bacteria utilizing Matrix-Assisted Laser Desorption Ionization-Time of Flight mass spectroscopy can considerably improve the positive detection rate of blood cultures.
Serology: It is an immunological technique that measures the level of antibodies against Bacteroides caccae in the serum of patients. It can indicate exposure or infection by Bacteroides caccae, although it may not reflect the status or severity of infection. Serology can also detect specific antigens of Bacteroides caccae, such as OmpW, a TonB-linked outer membrane protein that may play a role in pathogenicity or immunogenicity. For instance, elevated levels of anti-OmpW IgA antibodies have been observed in some patients with Crohn’s disease compared to ulcerative colitis patients or healthy individuals.
A robust immune system protects against Bacteroides caccae and other pathogen infections. A healthy lifestyle that includes balanced nutrition, frequent exercise, appropriate sleep, & stress management can help promote immune function.
Antibiotic overuse and misuse can lead to the development of antibiotic resistance. Antibiotic stewardship is critical for ensuring antibiotics are used appropriately and only when necessary to treat Bacteroides caccae infections.
Proper preparation, cooking food & storage procedures can lower the incidence of foodborne diseases, including Bacteroides caccae infections. Washing fruits and vegetables, heating food at the proper temperatures, and minimizing cross-contamination between raw & cooked meals are all critical precautions.
Bacteroides caccae is a common resident of the human intestine, which plays a vital role in food digestion and synthesizing beneficial nutrients. While the epidemiology of Bacteroides caccae infections is not extensively studied, several cases have been reported in the medical literature. Most of these infections occurred in patients with risk factors or underlying medical conditions such as hypertension, gastrointestinal bleeding, renal failure, diabetes, or immunosuppression. These factors may contribute to the susceptibility to Bacteroides caccae infections.
The transmission of Bacteroides caccae infections is typically endogenous, meaning that the bacteria originate from the patient’s intestinal flora. Currently, no evidence suggests direct transmission from person to person or from animals to humans. However, animal bites or scratches can introduce Bacteroides caccae or other anaerobic bacteria into wounds, leading to infections.
Bacteroides bacteremia, a severe infection caused by Bacteroides species, has been associated with a high mortality rate, ranging from 16% to 45%, depending on treatment efficacy. Reported cases include bacteremia caused by B. caccae in patients with renal hypertension and gastrointestinal bleeding. Effective treatment with appropriate antibiotics, such as metronidazole and cefoperazone-sulbactam or metronidazole and ciprofloxacin, has been successful in some cases, leading to patient recovery after hospitalization.
Studies from countries such as China, Poland, and Canada have reported infections caused by Bacteroides species closely related to B. caccae. Recently 16 cases worldwide have been documented. These infections included various clinical presentations, such as wound infections after animal bites, chronic oral infections, osteomyelitis, surgical site infections, and urinary tract infections. In some cases, antibiotic resistance was observed, underscoring the importance of targeted and appropriate antimicrobial therapy.
Kingdom: Bacteria
Phylum: Bacteroidota
Class: Bacteroidia
Order: Bacteroidales
Family: Bacteroidaceae
Genus:Bacteroides
Species:Bacteroides caccae
Bacteroides caccae is a saccharolytic anaerobic bacterium with rod-shaped cells that can exist in pairs. The rods have rounded ends and are somewhat bent.It features a gram-negative cell wall structure and an exterior membrane wrapped by a thin peptidoglycan coating.
The size ranges from 1.4 – 1.6 μm wide and 2.5 – 12 μm long.Bacteroides caccae‘s DNA GC content ranges between 40 and 46 mol%, representing the proportion of the cytosine and guanine nucleotides in its DNA.
Bacteroides caccae, like other bacteria, has virulent proteins and genes that serve a role in pathogenicity & host interactions. The TonB-linked outer membrane protein OmpW is one such virulent protein. This protein was discovered in Bacteroides caccae and shares characteristics with other bacterial TonB-linked outer membrane proteins.
When iron or vitamins are scarce in the environment, OmpW allows the bacteria to improve their absorption ability. The existence of a TonB box in OmpW, a highly conserved region, suggests that it could possess an integral part in food uptake & commensal bacterial survival in the intestine.
Additionally, the immunological finding of elevated anti-OmpW IgA levels in some patients with Crohn’s disease suggests a potential link between Bacteroides caccae and the pathogenesis of this inflammatory bowel disease. Crohn’s disease is characterized by chronic inflammation in the gastrointestinal tract, and the presence of OmpW-specific IgA antibodies in affected individuals indicates a possible immune response to the bacterium.
Bacteroides caccae is a bacterial species isolated from several fecal samples from various geographical areas. Several strains of Bacteroides caccae have been found and characterized, providing essential insights into the bacterium’s genetic variety and possible toxicity.ATCC 43185 is the type strain of Bacteroides caccae obtained from a fecal sample in Texas.
This strain has been completely sequenced. It now serves as the reference genome for the NIH Human Microbiome Project, furthering our understanding microbiome of the human gut and its role in health & disease.
CCUG 38735, CIP 104201, JCM 9498, NCTC 13051, VPI 3452A, and DSM 19024 are other strains of Bacteroides caccae deposited in culture collections worldwide. Each strain was isolated from fecal samples in different countries, including Sweden, France, Japan, the UK, the USA, and Germany.
Bacteroides caccae, often found in the human intestine, can cause significant infections if it escapes & enters the bloodstream or other sterile places, significantly if the intestinal barrier is damaged due to trauma, surgery, or other disorders. Severe infections like septicemia, abscesses, osteomyelitis, & meningitis can result.
The bacteria have a TonB-linked outer cell membrane protein which may aid in absorbing vital minerals such as iron or vitamins inside the intestinal environment, promoting growth and survival. OmpW has been linked to an immunological response in some Crohn’s disease patients, who exhibit higher levels of anti-OmpW IgA antibodies in their serum.
Bacteroides caccae also has the potential to create bacteriocins, which are antimicrobial peptides that can kill or inhibit other bacteria. These bacteriocins have been proven effective against various Bacteroides species and Clostridium difficile, a bacterium that causes antibiotic-associated diarrhea and colitis.
Bacteroides caccae can also cause human peripheral blood mononuclear cells to produce the cytokine interleukin-10. IL-10 has anti-inflammatory properties and can control the immune response to reduce excessive inflammation and tissue damage. Furthermore, Bacteroides caccae increases the levels of co-stimulatory substances CD80 and CD86 on PBMCs, increasing T cell activation and implying potential immunomodulatory effects on the host immune system.
Toll-like receptor 4 (TLR4) is activated during host defense against Bacteroides caccae and other commensals belonging to Bacteroidia class. TLR4 is a critical receptor that recognizes specific molecules associated with bacterial pathogens, such as lipopolysaccharides (LPS) found in Bacteroides caccae‘s outer membrane. When TLR4 on intestinal epithelial cells or immune cells contacts these compounds, it triggers a signaling cascade that activates canonical NF-κB signaling.
The NF-κB signaling pathway acts as a “rheostat” that regulates the degree of immune stimulation elicited by commensal bacteria. In the case of Bacteroidia communities, the activation of TLR4 is the primary driver of immune effects on intestinal immunity. This robust TLR4 activation contributes to the induction of various immune defenses, including the production of cytokines like TNF, CXCL1, CXCL2, and GM-CSF, which play essential roles in inflammation & immune response.
In contrast, commensals from the Clostridia class within the Firmicutes phylum signal via both TLR2 and TLR4 exert their effects on intestinal immunity. This activation of multiple receptors likely contributes to the complexity and diversity of immune responses induced by Clostridia communities.
The immune response to commensals is a finely balanced process. Excessive or dysregulated immune stimulation can lead to inflammation and tissue damage. Therefore, the host employs regulatory mechanisms, such as the production of anti-inflammatory cytokines like Interleukin 6, to prevent excessive immune responses.
Bacteroides caccae is commonly involved in polymicrobial infections that affect various body sites. One of the hallmark manifestations of Bacteroides infections is the formation of abscesses.
Abscesses are collections of pus that develop because of localized infections. These infections can occur in different body areas, including the abdomen, pelvis, brain, lungs, liver, skin, soft tissue, and blood. Abscesses can lead to symptoms such as pain, swelling, redness, and fever.
In the abdomen and pelvis, Bacteroides caccae infections can cause peritonitis, which is the inflammation of the lining of the abdominal cavity. Peritonitis can arise from perforation or rupture of the gastrointestinal tract, such as in cases of appendicitis or diverticulitis. This condition causes severe abdominal pain, vomiting, nausea, and shock, necessitating prompt medical attention.
Genitourinary infections, especially in women, can also be caused by Bacteroides caccae. These infections include pelvic inflammatory disease (PID), tubo-ovarian abscess, endometritis, and chorioamnionitis. Such infections can present with symptoms like pelvic pain, abnormal vaginal discharge, fever, and in some cases, infertility.
Additionally, Bacteroides caccae can cause oral and upper respiratory infections, contributing to tooth abscess, periodontitis, peritonsillar abscess, sinusitis, and parotiditis. These infections can lead to toothache, gum bleeding, sore throat, nasal congestion, and facial swelling.
Culture method: Culture is reliable and definitive for identifying Bacteroides caccae and determining its antimicrobial susceptibility. It requires anaerobic conditions and specific media like blood agar or Bacteroides-bile-esculin (BBE) agar. BBE agar helps differentiate Bacteroides caccae from other species by hydrolyzing esculin and producing dark colonies with brown-black halos. Culture should be performed on uncontaminated specimens, such as blood, peritoneal or pleural fluid, or abscess aspirates. Routine anaerobic culture of community-acquired intra-abdominal infections is considered optional.
PCR assay: Polymerase Chain Reaction is a molecular approach that detects and amplifies specific Bacteroides caccae DNA sequences. Although PCR is more rapid and sensitive than culture, it does not provide information on antibiotic susceptibility or bacterial viability. It can, however, be used to identify Bacteroides caccae host-specific genetic markers, which can aid in determining the fecal contamination source in water or food samples. Performing two or more sets of blood cultures and identifying anaerobic bacteria utilizing Matrix-Assisted Laser Desorption Ionization-Time of Flight mass spectroscopy can considerably improve the positive detection rate of blood cultures.
Serology: It is an immunological technique that measures the level of antibodies against Bacteroides caccae in the serum of patients. It can indicate exposure or infection by Bacteroides caccae, although it may not reflect the status or severity of infection. Serology can also detect specific antigens of Bacteroides caccae, such as OmpW, a TonB-linked outer membrane protein that may play a role in pathogenicity or immunogenicity. For instance, elevated levels of anti-OmpW IgA antibodies have been observed in some patients with Crohn’s disease compared to ulcerative colitis patients or healthy individuals.
A robust immune system protects against Bacteroides caccae and other pathogen infections. A healthy lifestyle that includes balanced nutrition, frequent exercise, appropriate sleep, & stress management can help promote immune function.
Antibiotic overuse and misuse can lead to the development of antibiotic resistance. Antibiotic stewardship is critical for ensuring antibiotics are used appropriately and only when necessary to treat Bacteroides caccae infections.
Proper preparation, cooking food & storage procedures can lower the incidence of foodborne diseases, including Bacteroides caccae infections. Washing fruits and vegetables, heating food at the proper temperatures, and minimizing cross-contamination between raw & cooked meals are all critical precautions.
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