Haemophilus aegyptius, a Gram-negative bacterium associated with Brazilian Purpuric Fever (BPF), has been studied since its first observation by Koch in 1883. The bacterium was initially identified during the German Cholera Commission’s investigation of Egyptian eye disease, and subsequently, the first outbreak of BPF occurred in 1984 in Sao Paulo State, Brazil. The outbreaks mainly affected small towns in Brazil, including Fartura, Sao Jose do Rio Preto, Presidente Prudente, Serrana, Guatapara, and Promissao. Isolated cases were also reported in Australia and the United States.
The historical distribution of H. aegyptius is worldwide, with acute conjunctivitis caused by the bacterium observed in various regions, such as Egypt, France, England, and the southern states of the United States. Brazil has experienced a significant prevalence of BPF, with around 90% of individuals developing the disease after recovering from conjunctivitis.
Case-control studies in Brazilian towns like Promissao, Londrina, and Serrana have shown an association between conjunctivitis and BPF, and daycare attendance has been identified as a significant risk factor for BPF transmission. The disease primarily affects infants & young children aged 3 months to 8 years, with symptoms of purulent conjunctivitis preceding the acute onset of high fever, vomiting, abdominal pain, purpura, vascular collapse, and death. The overall patient fatality rate since the recognition of BPF is approximately 70%.
Seasonal variations have been observed in BPF cases, with harsher effects typically manifesting during summer and fewer cases reported in winter. Studies conducted by Bengtson in Georgia suggested a correlation between the breeding season of the eye gnat, Hippelates pusio, and the incidence of acute conjunctivitis caused by H. aegyptius.
Despite predominant cases in developed areas like Sao Paulo State, the extent of BPF’s impact on rural communities remains to be determined due to communication technology limitations and inadequate medical services in those regions.
Kingdom: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Pasteurellales
Family: Pasteurellaceae
Genus: Haemophilus
Species: Haemophilus aegyptius
Haemophilus aegyptius is a Gram-negative bacterium with an elongated rod shape resembling a small, slender cylinder.
Size is related to Haemophilus influenzae, which has approximate dimensions of 1 x 0.3 µm in length and width.
H. aegyptius resides in the lining of human epithelial cells, indicating its ability to colonize and adhere to these cells. Its adherence is characterized by the formation of large clusters of elongated chains of cells on the epithelial surfaces.
Haemophilus aegyptius lacks flagella and pili, which are used for motility and attachment. Consequently, it does not exhibit mobility.
Haemophilus adhesin A (HadA): HadA is a surface protein found in all Haemophilus aegyptius strains. It acts as an adhesin, binding to extracellular matrix proteins in human cells, allowing bacteria to connect. HadA improves the bacterium’s capacity to colonize and develop infections in the host by increasing adhesion.
The bpf gene cluster: It is a group of genes that encode proteins associated with Brazilian purpuric fever (BPF), a severe and potentially fatal disease caused by specific strains of Haemophilus aegyptius. This gene cluster is present in BPF-causing strains but absent in non-BPF-causing strains.
las gene: The las gene is another important virulent gene found in BPF-causing strains of Haemophilus aegyptius. This gene encodes for a protein that enhances epithelial cell entry and correlates with the invasion of human respiratory epithelial cells during the pathogenesis of BPF.
Several virulent strains of Haemophilus aegyptius have been linked to disease transmission. F3031 is an extensively researched BPF-causing strain that is well-known for its role in the occurrence of Brazilian Purpuric Fever. The genome of F3031 has been sequenced, revealing the existence of critical virulence factors such as the bpf gene cluster and the las gene. These genes help the bacterium’s ability to cause severe disease. F3283, F1946, and F3042 are also members of the H. influenzae biogroup aegyptius and share around 77% of their DNA sequences with other H. influenzae genomes.
The pathogenesis of Haemophilus aegyptius involves a series of steps that enable its invasion, colonization, and dissemination within the host, leading to various clinical manifestations, including Brazilian Purpuric Fever (BPF).
H. aegyptius is primarily transmitted by close contact with the secretions of an infected individual or contaminated objects. Once in the host, the bacterium can invade the mucous membranes of the throat, eyes, nose, ears, or respiratory tract, causing inflammation and damage.
Haemophilus aegyptius possesses various factors that aid in the adherence and colonization of the host’s epithelial cells, including fimbriae, pili, and adhesins. A unique adhesin called Haemophilus adhesin A (HadA) plays a crucial role in facilitating bacterial attachment to extracellular matrix proteins of human cells.
To invade the host’s cells, H. aegyptius employs different factors, such as outer membrane proteins, lipopolysaccharides, and toxins. Among these, the las gene encodes a protein that enhances epithelial cell entry and correlates with cell invasion of human respiratory epithelial cells during BPF pathogenesis.
After invading the host’s cells, the bacterium can enter the bloodstream & disseminate throughout the body using capsules, siderophores, and iron-binding proteins. The bpf gene cluster, unique to BPF-causing strains, encodes proteins associated with BPF and potentially aids in bacterial survival and evasion of the host’s immune response.
Throughout its interaction with the host, H. aegyptius can cause damage to tissues and organs by releasing endotoxins, exotoxins, proteases, and inflammatory mediators. This damage gives rise to different clinical manifestations, such as otitis media, conjunctivitis, and severe Brazilian Purpuric Fever.
Haemophilus aegyptius has a polysaccharide capsule those aids in evading the host’s immunological response. IgG1 antibodies are immunoglobulin G antibodies that the immune system produces in response to bacterial antigens. IgG1 anti-capsular antibodies attack the bacterial capsule in the case of Haemophilus aegyptius, rendering the bacterium more susceptible to opsonization & phagocytosis. These antibodies can reduce the bacterium’s pathogenicity & increase its detection by immune cells, assisting in its destruction.
The complement system is a collection of serum proteins that aid in the immune response to bacteria and other infections. Complement proteins, particularly C3b, are deposited on the bacterial surface when the system is activated. It is known as C3-dependent opsonization and improves phagocyte identification of the pathogen. C3b functions as an opsonin, allowing phagocytes to attach to the bacterium and promoting phagocytosis & destruction.
Specific receptors on immune cells, particularly phagocytes, identify opsonized bacteria. For example, fc receptors on macrophages and neutrophils bind to the Fc region of IgG antibodies and C3b-coated bacterial surfaces, respectively. When these receptors are activated, phagocytosis occurs, resulting in the internalization and destruction of the bacterium within the phagocyte’s intracellular vesicles.
Haemophilus aegyptius is a pathogenic bacterium that can cause many illnesses, each with its own clinical symptoms. When it infects the middle ear, it can cause otitis media, characterized by ear pain, fever, fluid draining from the ears, hearing impairments, & irritability. In conjunctivitis, sometimes known as “pink eye,” H. aegyptius can cause redness, swelling, fluid discharge from one or both eyes, a burning feeling, and light sensitivity.
This bacterium is also linked to a more severe and potentially fatal illness, Brazilian purpuric fever (BPF). High fever- 38.5 °C and above, vomiting, abdominal pain, & the development of hemorrhagic skin lesions are all symptoms of BPF. It is a severe form of septicemia that, if left untreated, can result in shock, organ failure, and even death.
It is crucial to note that Haemophilus influenzae biogroup aegyptius, specifically the HaeBPF strain, has been related to acute conjunctivitis and Brazilian purpuric fever cases. This strain’s BPF is especially severe and necessitates prompt medical intervention.
Culture method: It is conducted using a selective medium known as chocolate agar. This specialized medium contains blood and factors X (hemin) and V (NAD), which are essential for the growth of Haemophilus aegyptius. The culture is performed by inoculating a specimen, such as blood, cerebrospinal fluid, conjunctival swabs, or other body fluids, onto the chocolate agar plate. The plate is then incubated in a controlled environment for 24 to 48 hours.
Noticeable colonies of Haemophilus aegyptius on the chocolate agar can be seen after incubation. These colonies have a tiny, spherical, grayish appearance and a smooth texture. H. aegyptius appears typically as a Gram-negative, elongated rod-shaped bacteria under the microscope.
Serotyping: The test employs antibodies capable of reacting with several antigens found on the surface of Haemophilus aegyptius. Serotyping allows for distinguishing H. aegyptius from H. influenzae, which may cause identical infections but has distinct antigenic types. Furthermore, serotyping is particularly useful in detecting Haemophilus aegyptius strains associated with Brazilian Purpuric Fever (BPF), which includes the HaeBPF strain.
Biochemical tests: These can be achieved via confirmatory tests for the V and X factor requirements. A single suspicious colony in a chocolate agar plate is transferred onto Mueller Hinton agar plates for this test. Then, on streaked plates, commercially accessible X, V, & XV factor discs or strips are inserted. For 18-24 hours, the plates are incubated at 37°C under a 5-10% CO2 environment. H. influenzae can only develop around the combined XV disc when observed growing around the discs, showing its X and V factor specs. H. influenzae will develop between the two discs if just the V and X factor discs (no XV) are used & put at least 2 cm apart.
Vaccination is the most effective way to prevent Haemophilus aegyptius infections, particularly the type b (Hib) strain that causes invasive illness.
To prevent Hib, a safe and effective vaccine is available, and it is advised for all children before the age of six months, with a booster dose of around one year. The Hib vaccine can protect against invasive Hib disease and minimize bacterial carriage in the nasopharynx.
Handwashing with water and soap or applying alcohol-based hand rubs regularly. Avoiding close contact with people who are sick or show signs of infection.
Haemophilus aegyptius – microbewiki (kenyon.edu)
Haemophilus aegyptius bacteraemia in brazilian purpuric fever – ScienceDirect
Haemophilus aegyptius, a Gram-negative bacterium associated with Brazilian Purpuric Fever (BPF), has been studied since its first observation by Koch in 1883. The bacterium was initially identified during the German Cholera Commission’s investigation of Egyptian eye disease, and subsequently, the first outbreak of BPF occurred in 1984 in Sao Paulo State, Brazil. The outbreaks mainly affected small towns in Brazil, including Fartura, Sao Jose do Rio Preto, Presidente Prudente, Serrana, Guatapara, and Promissao. Isolated cases were also reported in Australia and the United States.
The historical distribution of H. aegyptius is worldwide, with acute conjunctivitis caused by the bacterium observed in various regions, such as Egypt, France, England, and the southern states of the United States. Brazil has experienced a significant prevalence of BPF, with around 90% of individuals developing the disease after recovering from conjunctivitis.
Case-control studies in Brazilian towns like Promissao, Londrina, and Serrana have shown an association between conjunctivitis and BPF, and daycare attendance has been identified as a significant risk factor for BPF transmission. The disease primarily affects infants & young children aged 3 months to 8 years, with symptoms of purulent conjunctivitis preceding the acute onset of high fever, vomiting, abdominal pain, purpura, vascular collapse, and death. The overall patient fatality rate since the recognition of BPF is approximately 70%.
Seasonal variations have been observed in BPF cases, with harsher effects typically manifesting during summer and fewer cases reported in winter. Studies conducted by Bengtson in Georgia suggested a correlation between the breeding season of the eye gnat, Hippelates pusio, and the incidence of acute conjunctivitis caused by H. aegyptius.
Despite predominant cases in developed areas like Sao Paulo State, the extent of BPF’s impact on rural communities remains to be determined due to communication technology limitations and inadequate medical services in those regions.
Kingdom: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Pasteurellales
Family: Pasteurellaceae
Genus: Haemophilus
Species: Haemophilus aegyptius
Haemophilus aegyptius is a Gram-negative bacterium with an elongated rod shape resembling a small, slender cylinder.
Size is related to Haemophilus influenzae, which has approximate dimensions of 1 x 0.3 µm in length and width.
H. aegyptius resides in the lining of human epithelial cells, indicating its ability to colonize and adhere to these cells. Its adherence is characterized by the formation of large clusters of elongated chains of cells on the epithelial surfaces.
Haemophilus aegyptius lacks flagella and pili, which are used for motility and attachment. Consequently, it does not exhibit mobility.
Haemophilus adhesin A (HadA): HadA is a surface protein found in all Haemophilus aegyptius strains. It acts as an adhesin, binding to extracellular matrix proteins in human cells, allowing bacteria to connect. HadA improves the bacterium’s capacity to colonize and develop infections in the host by increasing adhesion.
The bpf gene cluster: It is a group of genes that encode proteins associated with Brazilian purpuric fever (BPF), a severe and potentially fatal disease caused by specific strains of Haemophilus aegyptius. This gene cluster is present in BPF-causing strains but absent in non-BPF-causing strains.
las gene: The las gene is another important virulent gene found in BPF-causing strains of Haemophilus aegyptius. This gene encodes for a protein that enhances epithelial cell entry and correlates with the invasion of human respiratory epithelial cells during the pathogenesis of BPF.
Several virulent strains of Haemophilus aegyptius have been linked to disease transmission. F3031 is an extensively researched BPF-causing strain that is well-known for its role in the occurrence of Brazilian Purpuric Fever. The genome of F3031 has been sequenced, revealing the existence of critical virulence factors such as the bpf gene cluster and the las gene. These genes help the bacterium’s ability to cause severe disease. F3283, F1946, and F3042 are also members of the H. influenzae biogroup aegyptius and share around 77% of their DNA sequences with other H. influenzae genomes.
The pathogenesis of Haemophilus aegyptius involves a series of steps that enable its invasion, colonization, and dissemination within the host, leading to various clinical manifestations, including Brazilian Purpuric Fever (BPF).
H. aegyptius is primarily transmitted by close contact with the secretions of an infected individual or contaminated objects. Once in the host, the bacterium can invade the mucous membranes of the throat, eyes, nose, ears, or respiratory tract, causing inflammation and damage.
Haemophilus aegyptius possesses various factors that aid in the adherence and colonization of the host’s epithelial cells, including fimbriae, pili, and adhesins. A unique adhesin called Haemophilus adhesin A (HadA) plays a crucial role in facilitating bacterial attachment to extracellular matrix proteins of human cells.
To invade the host’s cells, H. aegyptius employs different factors, such as outer membrane proteins, lipopolysaccharides, and toxins. Among these, the las gene encodes a protein that enhances epithelial cell entry and correlates with cell invasion of human respiratory epithelial cells during BPF pathogenesis.
After invading the host’s cells, the bacterium can enter the bloodstream & disseminate throughout the body using capsules, siderophores, and iron-binding proteins. The bpf gene cluster, unique to BPF-causing strains, encodes proteins associated with BPF and potentially aids in bacterial survival and evasion of the host’s immune response.
Throughout its interaction with the host, H. aegyptius can cause damage to tissues and organs by releasing endotoxins, exotoxins, proteases, and inflammatory mediators. This damage gives rise to different clinical manifestations, such as otitis media, conjunctivitis, and severe Brazilian Purpuric Fever.
Haemophilus aegyptius has a polysaccharide capsule those aids in evading the host’s immunological response. IgG1 antibodies are immunoglobulin G antibodies that the immune system produces in response to bacterial antigens. IgG1 anti-capsular antibodies attack the bacterial capsule in the case of Haemophilus aegyptius, rendering the bacterium more susceptible to opsonization & phagocytosis. These antibodies can reduce the bacterium’s pathogenicity & increase its detection by immune cells, assisting in its destruction.
The complement system is a collection of serum proteins that aid in the immune response to bacteria and other infections. Complement proteins, particularly C3b, are deposited on the bacterial surface when the system is activated. It is known as C3-dependent opsonization and improves phagocyte identification of the pathogen. C3b functions as an opsonin, allowing phagocytes to attach to the bacterium and promoting phagocytosis & destruction.
Specific receptors on immune cells, particularly phagocytes, identify opsonized bacteria. For example, fc receptors on macrophages and neutrophils bind to the Fc region of IgG antibodies and C3b-coated bacterial surfaces, respectively. When these receptors are activated, phagocytosis occurs, resulting in the internalization and destruction of the bacterium within the phagocyte’s intracellular vesicles.
Haemophilus aegyptius is a pathogenic bacterium that can cause many illnesses, each with its own clinical symptoms. When it infects the middle ear, it can cause otitis media, characterized by ear pain, fever, fluid draining from the ears, hearing impairments, & irritability. In conjunctivitis, sometimes known as “pink eye,” H. aegyptius can cause redness, swelling, fluid discharge from one or both eyes, a burning feeling, and light sensitivity.
This bacterium is also linked to a more severe and potentially fatal illness, Brazilian purpuric fever (BPF). High fever- 38.5 °C and above, vomiting, abdominal pain, & the development of hemorrhagic skin lesions are all symptoms of BPF. It is a severe form of septicemia that, if left untreated, can result in shock, organ failure, and even death.
It is crucial to note that Haemophilus influenzae biogroup aegyptius, specifically the HaeBPF strain, has been related to acute conjunctivitis and Brazilian purpuric fever cases. This strain’s BPF is especially severe and necessitates prompt medical intervention.
Culture method: It is conducted using a selective medium known as chocolate agar. This specialized medium contains blood and factors X (hemin) and V (NAD), which are essential for the growth of Haemophilus aegyptius. The culture is performed by inoculating a specimen, such as blood, cerebrospinal fluid, conjunctival swabs, or other body fluids, onto the chocolate agar plate. The plate is then incubated in a controlled environment for 24 to 48 hours.
Noticeable colonies of Haemophilus aegyptius on the chocolate agar can be seen after incubation. These colonies have a tiny, spherical, grayish appearance and a smooth texture. H. aegyptius appears typically as a Gram-negative, elongated rod-shaped bacteria under the microscope.
Serotyping: The test employs antibodies capable of reacting with several antigens found on the surface of Haemophilus aegyptius. Serotyping allows for distinguishing H. aegyptius from H. influenzae, which may cause identical infections but has distinct antigenic types. Furthermore, serotyping is particularly useful in detecting Haemophilus aegyptius strains associated with Brazilian Purpuric Fever (BPF), which includes the HaeBPF strain.
Biochemical tests: These can be achieved via confirmatory tests for the V and X factor requirements. A single suspicious colony in a chocolate agar plate is transferred onto Mueller Hinton agar plates for this test. Then, on streaked plates, commercially accessible X, V, & XV factor discs or strips are inserted. For 18-24 hours, the plates are incubated at 37°C under a 5-10% CO2 environment. H. influenzae can only develop around the combined XV disc when observed growing around the discs, showing its X and V factor specs. H. influenzae will develop between the two discs if just the V and X factor discs (no XV) are used & put at least 2 cm apart.
Vaccination is the most effective way to prevent Haemophilus aegyptius infections, particularly the type b (Hib) strain that causes invasive illness.
To prevent Hib, a safe and effective vaccine is available, and it is advised for all children before the age of six months, with a booster dose of around one year. The Hib vaccine can protect against invasive Hib disease and minimize bacterial carriage in the nasopharynx.
Handwashing with water and soap or applying alcohol-based hand rubs regularly. Avoiding close contact with people who are sick or show signs of infection.
Haemophilus aegyptius – microbewiki (kenyon.edu)
Haemophilus aegyptius bacteraemia in brazilian purpuric fever – ScienceDirect
Haemophilus aegyptius, a Gram-negative bacterium associated with Brazilian Purpuric Fever (BPF), has been studied since its first observation by Koch in 1883. The bacterium was initially identified during the German Cholera Commission’s investigation of Egyptian eye disease, and subsequently, the first outbreak of BPF occurred in 1984 in Sao Paulo State, Brazil. The outbreaks mainly affected small towns in Brazil, including Fartura, Sao Jose do Rio Preto, Presidente Prudente, Serrana, Guatapara, and Promissao. Isolated cases were also reported in Australia and the United States.
The historical distribution of H. aegyptius is worldwide, with acute conjunctivitis caused by the bacterium observed in various regions, such as Egypt, France, England, and the southern states of the United States. Brazil has experienced a significant prevalence of BPF, with around 90% of individuals developing the disease after recovering from conjunctivitis.
Case-control studies in Brazilian towns like Promissao, Londrina, and Serrana have shown an association between conjunctivitis and BPF, and daycare attendance has been identified as a significant risk factor for BPF transmission. The disease primarily affects infants & young children aged 3 months to 8 years, with symptoms of purulent conjunctivitis preceding the acute onset of high fever, vomiting, abdominal pain, purpura, vascular collapse, and death. The overall patient fatality rate since the recognition of BPF is approximately 70%.
Seasonal variations have been observed in BPF cases, with harsher effects typically manifesting during summer and fewer cases reported in winter. Studies conducted by Bengtson in Georgia suggested a correlation between the breeding season of the eye gnat, Hippelates pusio, and the incidence of acute conjunctivitis caused by H. aegyptius.
Despite predominant cases in developed areas like Sao Paulo State, the extent of BPF’s impact on rural communities remains to be determined due to communication technology limitations and inadequate medical services in those regions.
Kingdom: Bacteria
Phylum: Pseudomonadota
Class: Gammaproteobacteria
Order: Pasteurellales
Family: Pasteurellaceae
Genus: Haemophilus
Species: Haemophilus aegyptius
Haemophilus aegyptius is a Gram-negative bacterium with an elongated rod shape resembling a small, slender cylinder.
Size is related to Haemophilus influenzae, which has approximate dimensions of 1 x 0.3 µm in length and width.
H. aegyptius resides in the lining of human epithelial cells, indicating its ability to colonize and adhere to these cells. Its adherence is characterized by the formation of large clusters of elongated chains of cells on the epithelial surfaces.
Haemophilus aegyptius lacks flagella and pili, which are used for motility and attachment. Consequently, it does not exhibit mobility.
Haemophilus adhesin A (HadA): HadA is a surface protein found in all Haemophilus aegyptius strains. It acts as an adhesin, binding to extracellular matrix proteins in human cells, allowing bacteria to connect. HadA improves the bacterium’s capacity to colonize and develop infections in the host by increasing adhesion.
The bpf gene cluster: It is a group of genes that encode proteins associated with Brazilian purpuric fever (BPF), a severe and potentially fatal disease caused by specific strains of Haemophilus aegyptius. This gene cluster is present in BPF-causing strains but absent in non-BPF-causing strains.
las gene: The las gene is another important virulent gene found in BPF-causing strains of Haemophilus aegyptius. This gene encodes for a protein that enhances epithelial cell entry and correlates with the invasion of human respiratory epithelial cells during the pathogenesis of BPF.
Several virulent strains of Haemophilus aegyptius have been linked to disease transmission. F3031 is an extensively researched BPF-causing strain that is well-known for its role in the occurrence of Brazilian Purpuric Fever. The genome of F3031 has been sequenced, revealing the existence of critical virulence factors such as the bpf gene cluster and the las gene. These genes help the bacterium’s ability to cause severe disease. F3283, F1946, and F3042 are also members of the H. influenzae biogroup aegyptius and share around 77% of their DNA sequences with other H. influenzae genomes.
The pathogenesis of Haemophilus aegyptius involves a series of steps that enable its invasion, colonization, and dissemination within the host, leading to various clinical manifestations, including Brazilian Purpuric Fever (BPF).
H. aegyptius is primarily transmitted by close contact with the secretions of an infected individual or contaminated objects. Once in the host, the bacterium can invade the mucous membranes of the throat, eyes, nose, ears, or respiratory tract, causing inflammation and damage.
Haemophilus aegyptius possesses various factors that aid in the adherence and colonization of the host’s epithelial cells, including fimbriae, pili, and adhesins. A unique adhesin called Haemophilus adhesin A (HadA) plays a crucial role in facilitating bacterial attachment to extracellular matrix proteins of human cells.
To invade the host’s cells, H. aegyptius employs different factors, such as outer membrane proteins, lipopolysaccharides, and toxins. Among these, the las gene encodes a protein that enhances epithelial cell entry and correlates with cell invasion of human respiratory epithelial cells during BPF pathogenesis.
After invading the host’s cells, the bacterium can enter the bloodstream & disseminate throughout the body using capsules, siderophores, and iron-binding proteins. The bpf gene cluster, unique to BPF-causing strains, encodes proteins associated with BPF and potentially aids in bacterial survival and evasion of the host’s immune response.
Throughout its interaction with the host, H. aegyptius can cause damage to tissues and organs by releasing endotoxins, exotoxins, proteases, and inflammatory mediators. This damage gives rise to different clinical manifestations, such as otitis media, conjunctivitis, and severe Brazilian Purpuric Fever.
Haemophilus aegyptius has a polysaccharide capsule those aids in evading the host’s immunological response. IgG1 antibodies are immunoglobulin G antibodies that the immune system produces in response to bacterial antigens. IgG1 anti-capsular antibodies attack the bacterial capsule in the case of Haemophilus aegyptius, rendering the bacterium more susceptible to opsonization & phagocytosis. These antibodies can reduce the bacterium’s pathogenicity & increase its detection by immune cells, assisting in its destruction.
The complement system is a collection of serum proteins that aid in the immune response to bacteria and other infections. Complement proteins, particularly C3b, are deposited on the bacterial surface when the system is activated. It is known as C3-dependent opsonization and improves phagocyte identification of the pathogen. C3b functions as an opsonin, allowing phagocytes to attach to the bacterium and promoting phagocytosis & destruction.
Specific receptors on immune cells, particularly phagocytes, identify opsonized bacteria. For example, fc receptors on macrophages and neutrophils bind to the Fc region of IgG antibodies and C3b-coated bacterial surfaces, respectively. When these receptors are activated, phagocytosis occurs, resulting in the internalization and destruction of the bacterium within the phagocyte’s intracellular vesicles.
Haemophilus aegyptius is a pathogenic bacterium that can cause many illnesses, each with its own clinical symptoms. When it infects the middle ear, it can cause otitis media, characterized by ear pain, fever, fluid draining from the ears, hearing impairments, & irritability. In conjunctivitis, sometimes known as “pink eye,” H. aegyptius can cause redness, swelling, fluid discharge from one or both eyes, a burning feeling, and light sensitivity.
This bacterium is also linked to a more severe and potentially fatal illness, Brazilian purpuric fever (BPF). High fever- 38.5 °C and above, vomiting, abdominal pain, & the development of hemorrhagic skin lesions are all symptoms of BPF. It is a severe form of septicemia that, if left untreated, can result in shock, organ failure, and even death.
It is crucial to note that Haemophilus influenzae biogroup aegyptius, specifically the HaeBPF strain, has been related to acute conjunctivitis and Brazilian purpuric fever cases. This strain’s BPF is especially severe and necessitates prompt medical intervention.
Culture method: It is conducted using a selective medium known as chocolate agar. This specialized medium contains blood and factors X (hemin) and V (NAD), which are essential for the growth of Haemophilus aegyptius. The culture is performed by inoculating a specimen, such as blood, cerebrospinal fluid, conjunctival swabs, or other body fluids, onto the chocolate agar plate. The plate is then incubated in a controlled environment for 24 to 48 hours.
Noticeable colonies of Haemophilus aegyptius on the chocolate agar can be seen after incubation. These colonies have a tiny, spherical, grayish appearance and a smooth texture. H. aegyptius appears typically as a Gram-negative, elongated rod-shaped bacteria under the microscope.
Serotyping: The test employs antibodies capable of reacting with several antigens found on the surface of Haemophilus aegyptius. Serotyping allows for distinguishing H. aegyptius from H. influenzae, which may cause identical infections but has distinct antigenic types. Furthermore, serotyping is particularly useful in detecting Haemophilus aegyptius strains associated with Brazilian Purpuric Fever (BPF), which includes the HaeBPF strain.
Biochemical tests: These can be achieved via confirmatory tests for the V and X factor requirements. A single suspicious colony in a chocolate agar plate is transferred onto Mueller Hinton agar plates for this test. Then, on streaked plates, commercially accessible X, V, & XV factor discs or strips are inserted. For 18-24 hours, the plates are incubated at 37°C under a 5-10% CO2 environment. H. influenzae can only develop around the combined XV disc when observed growing around the discs, showing its X and V factor specs. H. influenzae will develop between the two discs if just the V and X factor discs (no XV) are used & put at least 2 cm apart.
Vaccination is the most effective way to prevent Haemophilus aegyptius infections, particularly the type b (Hib) strain that causes invasive illness.
To prevent Hib, a safe and effective vaccine is available, and it is advised for all children before the age of six months, with a booster dose of around one year. The Hib vaccine can protect against invasive Hib disease and minimize bacterial carriage in the nasopharynx.
Handwashing with water and soap or applying alcohol-based hand rubs regularly. Avoiding close contact with people who are sick or show signs of infection.
Haemophilus aegyptius – microbewiki (kenyon.edu)
Haemophilus aegyptius bacteraemia in brazilian purpuric fever – ScienceDirect
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