Epidemiology of Acinetobacter pittii is the study of the distribution and determinants of Acinetobacter pittii infection in human populations. Acinetobacter pittii bacterium belongs to the Acinetobacter calcoaceticus-baumannii complex, a group of closely related species that can cause nosocomial infections, especially in immunocompromised patients. Some of the epidemiological aspects of Acinetobacter pittii infection include:
Acinetobacter pittii infection has a worldwide distribution but may vary in prevalence and diversity among different regions and countries. It may also show seasonal variation, with higher summer rates than winter. It is more prevalent in tropical and subtropical regions than in temperate regions.
The mortality rate of Acinetobacter pittii infection may vary depending on the type and severity of infection, the underlying conditions and immune status of the patients, and the availability and effectiveness of treatment. Some studies have reported mortality rates ranging from 17% to 60% for bacteremia (bloodstream infection) caused by Acinetobacter pittii. However, it may be challenging to attribute mortality solely to Acinetobacter pittii infection, as these patients may have other comorbidities or infections contributing to their death.
The prevalence rate of Acinetobacter pittii infection may vary depending on the geographic location, the season, the hospital setting, and the surveillance methods. Acinetobacter pittii infection has a worldwide distribution but may be more prevalent in tropical and subtropical regions than in temperate ones. It may also show seasonal variation, with higher summer rates than winter. It is more common in hospitalized patients, especially those critically ill, with invasive devices or procedures, prolonged antibiotic exposure, or previous colonization by Acinetobacter pittii. It is not common in healthy individuals or community settings. The ECDC is the name of a global health organization that published research that the prevalence rate of Acinetobacter pittii infection among intensive care unit (ICU) patients in Europe was 0.5% in 2019
Acinetobacter pittii infection is more common in hospitalized patients, especially those critically ill, have underlying diseases, have invasive devices or procedures, have prolonged antibiotic exposure, or have previous colonization by Acinetobacter pittii. Other risk factors may include age, gender, immunosuppression, trauma, surgery, burns, or exposure to humid climates or natural disasters.
Acinetobacter pittii is a species of Gram-negative bacteria belonging to the genus Acinetobacter. It is an opportunistic pathogen commonly associated with healthcare-associated infections, particularly in immunocompromised individuals and those with prolonged hospital stays.
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Moraxellaceae
Genus: Acinetobacter
Species: pittii
Acinetobacter pittii, like other members of the Acinetobacter genus, is a non-motile, non-spore-forming, and non-encapsulated bacterium. It has a characteristic coccobacillus shape, appearing as small, Gram-negative rods under the microscope. The bacteria have a cell envelope consisting of an outer membrane, a peptidoglycan layer, and an inner cytoplasmic membrane.
The outer membrane of Acinetobacter pittii contains various proteins and lipopolysaccharides, which contribute to its virulence and resistance mechanisms. It also serves as a protective barrier against the host immune system and antimicrobial agents. The peptidoglycan layer supports the cell wall and plays a role in cell division.
Acinetobacter pittii possesses pili and fimbriae on its outer surface, which aid in adherence to host tissues and facilitate the formation of biofilms. Biofilms are complex communities of bacteria that are notoriously difficult to eradicate and can contribute to the persistence of Acinetobacter infections.
The genome of Acinetobacter Pitti has been sequenced, revealing the presence of numerous resistance genes and virulence factors. This species has demonstrated a remarkable ability to acquire and disseminate antibiotic resistance determinants, making it a significant concern in healthcare settings.
Antigenic types of bacteria are different antigens that bacteria can express on their surface to evade the host immune system. Antigens are molecules that an immune system can detect.
The host antibodies trigger an immune response. Some bacteria can change their antigens through gene conversion, DNA inversion, hypermutation, or recombination.
Acinetobacter pittii may have different types of antigens, such as O or somatic antigens, K or capsular antigens, and H or flagellar antigens. O antigens are part of the lipopolysaccharide (LPS) layer covering gram-negative bacteria’s outer membrane. LPS is also known as endotoxin and can trigger a robust immune response in the host. O antigens are composed of repeating units of sugars that vary in number, composition, and arrangement among different bacteria. K antigens are polysaccharides that form a capsule around some bacteria and protect them from phagocytosis and complement-mediated lysis. K antigens are also composed of repeating units of sugars that vary among different bacteria. H antigens are proteins that form the flagella, long whip-like structures that help bacteria move and attach to surfaces. Flagella also have different types and arrangements among different bacteria.
The antigenic types of Acinetobacter pittii have yet to be well studied, but some studies have suggested that they may vary depending on the source and location of the isolates. For example, one study found that Acinetobacter pittii isolates from China had different O antigen profiles than those from Europe. Another study found that Acinetobacter pittii isolates from clinical specimens had different K antigen profiles. The antigenic variation of Acinetobacter pittii may have implications for its diagnosis, typing, and vaccine development.
Acinetobacter pittii strains are bacteria isolated from different sources and locations and have different genetic and phenotypic characteristics. Some of the strains of Acinetobacter pittii that have been reported in the literature include:
Strain sw-1: A strain isolated from 7619-m seawater of the Mariana Trench and efficiently utilized long-chain n-alkanes (C18–C36) as carbon sources.
Strain RUH 2206: A strain isolated from a patient with bacteremia in the Netherlands and resistant to multiple antibiotics.
Strain 320: A strain isolated from a patient with pneumonia in China with a different O antigen profile than European strains.
Strain NIPH 519: A strain isolated from a patient with wound infection in Norway with a different K antigen profile than other clinical isolates.
These are some examples of strains of Acinetobacter pittii that have been studied for their genetic and phenotypic diversity, pathogenicity, and antibiotic resistance. More strains may be discovered and characterized in the future, as Acinetobacter pittii is an emerging nosocomial pathogen.
Pathogenesis of Acinetobacter pittii is the process by which Acinetobacter pittii causes infection and disease in humans. Acinetobacter pittii is a gram-negative bacterium that belongs to the Acinetobacter calcoaceticus-baumannii complex, a group of closely related species that can cause nosocomial infections, especially in immunocompromised patients. Some of the pathogenic mechanisms of Acinetobacter pittii include:
Adherence and invasion: Acinetobacter pittii can adhere to and invade various human cells and tissues, such as epithelial cells, endothelial cells, fibroblasts, and macrophages. It can also form biofilms on biotic and abiotic surfaces, such as wounds, catheters, or medical devices. Adherence and invasion are mediated by various factors, such as pili, fimbriae, outer membrane proteins, lipopolysaccharide (LPS), and extracellular polysaccharide (EPS).
Resistance and persistence: Acinetobacter pittii can resist and persist in hostile environments, such as desiccation, oxidative stress, nutrient limitation, pH changes, and antimicrobial agents. It can also evade or modulate the host immune system by altering its surface antigens, producing capsule or biofilm, inhibiting phagocytosis or complement activation, or inducing apoptosis or cytokine production in host cells.
Toxins and enzymes: Acinetobacter pittii can produce toxins and enzymes that can damage the host cells and tissues, such as hemolysins, phospholipases, proteases, lipases, siderophores, and endotoxins. These factors can cause cell lysis, membrane disruption, tissue necrosis, iron acquisition, inflammation, and septic shock.
Acinetobacter pittii host defenses are the mechanisms the human body uses to protect itself from infection by this bacterium.
Some of the host defenses of Acinetobacter pittii include:
Intact skin and mucosal surfaces: The skin and mucous membranes act as physical barriers that prevent the entry of Acinetobacter pittii and other microorganisms into the body. They also secrete antimicrobial substances such as lysozyme, defensins, and lactoferrin that can kill or inhibit the growth of bacteria.
Neutrophil activity: Neutrophils are white blood cells, part of the innate immune system. They can recognize and phagocytose (engulf and digest) Acinetobacter pittii and other bacteria. They also release reactive oxygen species (ROS) and antimicrobial peptides that can damage the bacterial cell wall and membrane.
Complement system: A complement system is a group of proteins that circulate in the blood and can be activated by Acinetobacter pittii and other bacteria. The complement system can enhance the phagocytosis of bacteria by neutrophils and macrophages, opsonize (coat) bacteria for clearance by the spleen and liver, and form membrane attack complexes (MACs) that can lyse (burst) bacterial cells.
Antibody production: Antibodies are proteins produced by B cells, a white blood cell part of the adaptive immune system. Antibodies can bind to specific antigens (molecules) on the surface of Acinetobacter pittii and other bacteria. It can neutralize the bacteria, prevent their attachment to host cells, or activate the complement system and phagocytosis.
T cell activation: T cells are another white blood cell part of the adaptive immune system. T cells can recognize antigens presented by antigen-presenting APCs, including macrophages and dendritic cells that have phagocytosed Acinetobacter pittii and other bacteria.
Clinical manifestations of Acinetobacter pittii infections:
Pneumonia: Acinetobacter pittii can cause pneumonia, particularly in individuals who are critically ill or have compromised immune systems. Symptoms may include cough, fever, chest pain, shortness of breath, and productive sputum.
Urinary tract infections (UTIs): UTIs caused by Acinetobacter pittii can present with symptoms such as frequent urination, burning sensation during urination, cloudy or bloody urine, and pelvic pain.
Wound infections: Acinetobacter pittii is known to cause wound infections, especially in individuals with surgical wounds or open injuries. Symptoms may include redness, swelling, pain, pus discharge, and delayed wound healing.
Bloodstream infections: Acinetobacter pittii can enter the bloodstream, leading to a severe condition known as bacteremia. Symptoms of bloodstream infections may include fever, chills, rapid heart rate, low blood pressure, and general signs of sepsis.
Meningitis: Although less common, Acinetobacter pittii can also cause meningitis, an infection of the membranes surrounding the brain and spinal cord. Meningitis may present with symptoms such as severe headache, neck stiffness, fever, sensitivity to light, altered mental status, and seizures.
The diagnosis of Acinetobacter pittii infection typically involves several steps, including:
Clinical evaluation: The healthcare provider will assess the patient’s symptoms, medical history, and risk factors for infection. Common Acinetobacter pittii infections include bloodstream infections, pneumonia, urinary tract infections, wound infections, and infections associated with medical devices like catheters or ventilators.
Sample collection: To confirm the presence of Acinetobacter pittii, samples from the suspected infection site are collected. The sample type depends on the suspected infection but may include blood, sputum, urine, wound swabs, or other relevant specimens.
Laboratory testing: The collected samples are sent to a microbiology laboratory for analysis. The laboratory will perform various tests to isolate and identify the bacteria. These tests may include:
Gram staining: This initial test helps classify the bacteria as gram-negative and provides a preliminary assessment of its morphology.
Culture: The sample is plated on specific culture media that promote the growth of Acinetobacter species. The bacteria are then isolated and allowed to grow for further analysis.
Biochemical tests: Various biochemical tests, such as oxidase test, catalase test, and others, are performed to identify the bacteria as Acinetobacter pittii. These tests help differentiate it from other species within the Acinetobacter genus.
Antibiotic susceptibility testing: The isolated bacteria are tested against different antibiotics to determine their susceptibility patterns. This information helps guide appropriate treatment choices.
Molecular identification: In some cases, further molecular testing PCR, for example, is a procedure that may be used or sequencing techniques to confirm the species as Acinetobacter pittii and rule out other closely related species.
Acinetobacter pittii infection can be prevented by practicing proper hygiene and avoiding exposure to contaminated environments or equipment. Some of the preventive measures include:
Limiting your exposure to hospitals or other healthcare settings where Acinetobacter pittii may be present, especially if you have a weakened immune system or a chronic medical condition.
Frequently wash your hands with soap and water or use an alcohol-based hand sanitizer, especially before and after touching any wounds, catheters, or medical devices.
Do not touch your mouth, nose, or eyes with unclean hands, as this can introduce bacteria into your body.
Requesting caregivers wash their hands before and after touching you or any of your belongings.
Insisting caregivers practice aseptic techniques when inserting or removing any catheters, tubes, or needles from your body.
Taking antibiotics only when necessary and precisely as your doctor prescribes and completing the entire course of treatment to avoid antibiotic resistance.
Cleaning and covering wounds or skin lesions with sterile dressings and changing them regularly.
Acinetobacter pittii biofilm formation on inanimate surfaces after long-term desiccation – ScienceDirect
Phenotypic Variation and Carbapenem Resistance Potential in OXA-499-Producing Acinetobacter pittii – PubMed (nih.gov)
Epidemiology of Acinetobacter pittii is the study of the distribution and determinants of Acinetobacter pittii infection in human populations. Acinetobacter pittii bacterium belongs to the Acinetobacter calcoaceticus-baumannii complex, a group of closely related species that can cause nosocomial infections, especially in immunocompromised patients. Some of the epidemiological aspects of Acinetobacter pittii infection include:
Acinetobacter pittii infection has a worldwide distribution but may vary in prevalence and diversity among different regions and countries. It may also show seasonal variation, with higher summer rates than winter. It is more prevalent in tropical and subtropical regions than in temperate regions.
The mortality rate of Acinetobacter pittii infection may vary depending on the type and severity of infection, the underlying conditions and immune status of the patients, and the availability and effectiveness of treatment. Some studies have reported mortality rates ranging from 17% to 60% for bacteremia (bloodstream infection) caused by Acinetobacter pittii. However, it may be challenging to attribute mortality solely to Acinetobacter pittii infection, as these patients may have other comorbidities or infections contributing to their death.
The prevalence rate of Acinetobacter pittii infection may vary depending on the geographic location, the season, the hospital setting, and the surveillance methods. Acinetobacter pittii infection has a worldwide distribution but may be more prevalent in tropical and subtropical regions than in temperate ones. It may also show seasonal variation, with higher summer rates than winter. It is more common in hospitalized patients, especially those critically ill, with invasive devices or procedures, prolonged antibiotic exposure, or previous colonization by Acinetobacter pittii. It is not common in healthy individuals or community settings. The ECDC is the name of a global health organization that published research that the prevalence rate of Acinetobacter pittii infection among intensive care unit (ICU) patients in Europe was 0.5% in 2019
Acinetobacter pittii infection is more common in hospitalized patients, especially those critically ill, have underlying diseases, have invasive devices or procedures, have prolonged antibiotic exposure, or have previous colonization by Acinetobacter pittii. Other risk factors may include age, gender, immunosuppression, trauma, surgery, burns, or exposure to humid climates or natural disasters.
Acinetobacter pittii is a species of Gram-negative bacteria belonging to the genus Acinetobacter. It is an opportunistic pathogen commonly associated with healthcare-associated infections, particularly in immunocompromised individuals and those with prolonged hospital stays.
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Moraxellaceae
Genus: Acinetobacter
Species: pittii
Acinetobacter pittii, like other members of the Acinetobacter genus, is a non-motile, non-spore-forming, and non-encapsulated bacterium. It has a characteristic coccobacillus shape, appearing as small, Gram-negative rods under the microscope. The bacteria have a cell envelope consisting of an outer membrane, a peptidoglycan layer, and an inner cytoplasmic membrane.
The outer membrane of Acinetobacter pittii contains various proteins and lipopolysaccharides, which contribute to its virulence and resistance mechanisms. It also serves as a protective barrier against the host immune system and antimicrobial agents. The peptidoglycan layer supports the cell wall and plays a role in cell division.
Acinetobacter pittii possesses pili and fimbriae on its outer surface, which aid in adherence to host tissues and facilitate the formation of biofilms. Biofilms are complex communities of bacteria that are notoriously difficult to eradicate and can contribute to the persistence of Acinetobacter infections.
The genome of Acinetobacter Pitti has been sequenced, revealing the presence of numerous resistance genes and virulence factors. This species has demonstrated a remarkable ability to acquire and disseminate antibiotic resistance determinants, making it a significant concern in healthcare settings.
Antigenic types of bacteria are different antigens that bacteria can express on their surface to evade the host immune system. Antigens are molecules that an immune system can detect.
The host antibodies trigger an immune response. Some bacteria can change their antigens through gene conversion, DNA inversion, hypermutation, or recombination.
Acinetobacter pittii may have different types of antigens, such as O or somatic antigens, K or capsular antigens, and H or flagellar antigens. O antigens are part of the lipopolysaccharide (LPS) layer covering gram-negative bacteria’s outer membrane. LPS is also known as endotoxin and can trigger a robust immune response in the host. O antigens are composed of repeating units of sugars that vary in number, composition, and arrangement among different bacteria. K antigens are polysaccharides that form a capsule around some bacteria and protect them from phagocytosis and complement-mediated lysis. K antigens are also composed of repeating units of sugars that vary among different bacteria. H antigens are proteins that form the flagella, long whip-like structures that help bacteria move and attach to surfaces. Flagella also have different types and arrangements among different bacteria.
The antigenic types of Acinetobacter pittii have yet to be well studied, but some studies have suggested that they may vary depending on the source and location of the isolates. For example, one study found that Acinetobacter pittii isolates from China had different O antigen profiles than those from Europe. Another study found that Acinetobacter pittii isolates from clinical specimens had different K antigen profiles. The antigenic variation of Acinetobacter pittii may have implications for its diagnosis, typing, and vaccine development.
Acinetobacter pittii strains are bacteria isolated from different sources and locations and have different genetic and phenotypic characteristics. Some of the strains of Acinetobacter pittii that have been reported in the literature include:
Strain sw-1: A strain isolated from 7619-m seawater of the Mariana Trench and efficiently utilized long-chain n-alkanes (C18–C36) as carbon sources.
Strain RUH 2206: A strain isolated from a patient with bacteremia in the Netherlands and resistant to multiple antibiotics.
Strain 320: A strain isolated from a patient with pneumonia in China with a different O antigen profile than European strains.
Strain NIPH 519: A strain isolated from a patient with wound infection in Norway with a different K antigen profile than other clinical isolates.
These are some examples of strains of Acinetobacter pittii that have been studied for their genetic and phenotypic diversity, pathogenicity, and antibiotic resistance. More strains may be discovered and characterized in the future, as Acinetobacter pittii is an emerging nosocomial pathogen.
Pathogenesis of Acinetobacter pittii is the process by which Acinetobacter pittii causes infection and disease in humans. Acinetobacter pittii is a gram-negative bacterium that belongs to the Acinetobacter calcoaceticus-baumannii complex, a group of closely related species that can cause nosocomial infections, especially in immunocompromised patients. Some of the pathogenic mechanisms of Acinetobacter pittii include:
Adherence and invasion: Acinetobacter pittii can adhere to and invade various human cells and tissues, such as epithelial cells, endothelial cells, fibroblasts, and macrophages. It can also form biofilms on biotic and abiotic surfaces, such as wounds, catheters, or medical devices. Adherence and invasion are mediated by various factors, such as pili, fimbriae, outer membrane proteins, lipopolysaccharide (LPS), and extracellular polysaccharide (EPS).
Resistance and persistence: Acinetobacter pittii can resist and persist in hostile environments, such as desiccation, oxidative stress, nutrient limitation, pH changes, and antimicrobial agents. It can also evade or modulate the host immune system by altering its surface antigens, producing capsule or biofilm, inhibiting phagocytosis or complement activation, or inducing apoptosis or cytokine production in host cells.
Toxins and enzymes: Acinetobacter pittii can produce toxins and enzymes that can damage the host cells and tissues, such as hemolysins, phospholipases, proteases, lipases, siderophores, and endotoxins. These factors can cause cell lysis, membrane disruption, tissue necrosis, iron acquisition, inflammation, and septic shock.
Acinetobacter pittii host defenses are the mechanisms the human body uses to protect itself from infection by this bacterium.
Some of the host defenses of Acinetobacter pittii include:
Intact skin and mucosal surfaces: The skin and mucous membranes act as physical barriers that prevent the entry of Acinetobacter pittii and other microorganisms into the body. They also secrete antimicrobial substances such as lysozyme, defensins, and lactoferrin that can kill or inhibit the growth of bacteria.
Neutrophil activity: Neutrophils are white blood cells, part of the innate immune system. They can recognize and phagocytose (engulf and digest) Acinetobacter pittii and other bacteria. They also release reactive oxygen species (ROS) and antimicrobial peptides that can damage the bacterial cell wall and membrane.
Complement system: A complement system is a group of proteins that circulate in the blood and can be activated by Acinetobacter pittii and other bacteria. The complement system can enhance the phagocytosis of bacteria by neutrophils and macrophages, opsonize (coat) bacteria for clearance by the spleen and liver, and form membrane attack complexes (MACs) that can lyse (burst) bacterial cells.
Antibody production: Antibodies are proteins produced by B cells, a white blood cell part of the adaptive immune system. Antibodies can bind to specific antigens (molecules) on the surface of Acinetobacter pittii and other bacteria. It can neutralize the bacteria, prevent their attachment to host cells, or activate the complement system and phagocytosis.
T cell activation: T cells are another white blood cell part of the adaptive immune system. T cells can recognize antigens presented by antigen-presenting APCs, including macrophages and dendritic cells that have phagocytosed Acinetobacter pittii and other bacteria.
Clinical manifestations of Acinetobacter pittii infections:
Pneumonia: Acinetobacter pittii can cause pneumonia, particularly in individuals who are critically ill or have compromised immune systems. Symptoms may include cough, fever, chest pain, shortness of breath, and productive sputum.
Urinary tract infections (UTIs): UTIs caused by Acinetobacter pittii can present with symptoms such as frequent urination, burning sensation during urination, cloudy or bloody urine, and pelvic pain.
Wound infections: Acinetobacter pittii is known to cause wound infections, especially in individuals with surgical wounds or open injuries. Symptoms may include redness, swelling, pain, pus discharge, and delayed wound healing.
Bloodstream infections: Acinetobacter pittii can enter the bloodstream, leading to a severe condition known as bacteremia. Symptoms of bloodstream infections may include fever, chills, rapid heart rate, low blood pressure, and general signs of sepsis.
Meningitis: Although less common, Acinetobacter pittii can also cause meningitis, an infection of the membranes surrounding the brain and spinal cord. Meningitis may present with symptoms such as severe headache, neck stiffness, fever, sensitivity to light, altered mental status, and seizures.
The diagnosis of Acinetobacter pittii infection typically involves several steps, including:
Clinical evaluation: The healthcare provider will assess the patient’s symptoms, medical history, and risk factors for infection. Common Acinetobacter pittii infections include bloodstream infections, pneumonia, urinary tract infections, wound infections, and infections associated with medical devices like catheters or ventilators.
Sample collection: To confirm the presence of Acinetobacter pittii, samples from the suspected infection site are collected. The sample type depends on the suspected infection but may include blood, sputum, urine, wound swabs, or other relevant specimens.
Laboratory testing: The collected samples are sent to a microbiology laboratory for analysis. The laboratory will perform various tests to isolate and identify the bacteria. These tests may include:
Gram staining: This initial test helps classify the bacteria as gram-negative and provides a preliminary assessment of its morphology.
Culture: The sample is plated on specific culture media that promote the growth of Acinetobacter species. The bacteria are then isolated and allowed to grow for further analysis.
Biochemical tests: Various biochemical tests, such as oxidase test, catalase test, and others, are performed to identify the bacteria as Acinetobacter pittii. These tests help differentiate it from other species within the Acinetobacter genus.
Antibiotic susceptibility testing: The isolated bacteria are tested against different antibiotics to determine their susceptibility patterns. This information helps guide appropriate treatment choices.
Molecular identification: In some cases, further molecular testing PCR, for example, is a procedure that may be used or sequencing techniques to confirm the species as Acinetobacter pittii and rule out other closely related species.
Acinetobacter pittii infection can be prevented by practicing proper hygiene and avoiding exposure to contaminated environments or equipment. Some of the preventive measures include:
Limiting your exposure to hospitals or other healthcare settings where Acinetobacter pittii may be present, especially if you have a weakened immune system or a chronic medical condition.
Frequently wash your hands with soap and water or use an alcohol-based hand sanitizer, especially before and after touching any wounds, catheters, or medical devices.
Do not touch your mouth, nose, or eyes with unclean hands, as this can introduce bacteria into your body.
Requesting caregivers wash their hands before and after touching you or any of your belongings.
Insisting caregivers practice aseptic techniques when inserting or removing any catheters, tubes, or needles from your body.
Taking antibiotics only when necessary and precisely as your doctor prescribes and completing the entire course of treatment to avoid antibiotic resistance.
Cleaning and covering wounds or skin lesions with sterile dressings and changing them regularly.
Acinetobacter pittii biofilm formation on inanimate surfaces after long-term desiccation – ScienceDirect
Phenotypic Variation and Carbapenem Resistance Potential in OXA-499-Producing Acinetobacter pittii – PubMed (nih.gov)
Epidemiology of Acinetobacter pittii is the study of the distribution and determinants of Acinetobacter pittii infection in human populations. Acinetobacter pittii bacterium belongs to the Acinetobacter calcoaceticus-baumannii complex, a group of closely related species that can cause nosocomial infections, especially in immunocompromised patients. Some of the epidemiological aspects of Acinetobacter pittii infection include:
Acinetobacter pittii infection has a worldwide distribution but may vary in prevalence and diversity among different regions and countries. It may also show seasonal variation, with higher summer rates than winter. It is more prevalent in tropical and subtropical regions than in temperate regions.
The mortality rate of Acinetobacter pittii infection may vary depending on the type and severity of infection, the underlying conditions and immune status of the patients, and the availability and effectiveness of treatment. Some studies have reported mortality rates ranging from 17% to 60% for bacteremia (bloodstream infection) caused by Acinetobacter pittii. However, it may be challenging to attribute mortality solely to Acinetobacter pittii infection, as these patients may have other comorbidities or infections contributing to their death.
The prevalence rate of Acinetobacter pittii infection may vary depending on the geographic location, the season, the hospital setting, and the surveillance methods. Acinetobacter pittii infection has a worldwide distribution but may be more prevalent in tropical and subtropical regions than in temperate ones. It may also show seasonal variation, with higher summer rates than winter. It is more common in hospitalized patients, especially those critically ill, with invasive devices or procedures, prolonged antibiotic exposure, or previous colonization by Acinetobacter pittii. It is not common in healthy individuals or community settings. The ECDC is the name of a global health organization that published research that the prevalence rate of Acinetobacter pittii infection among intensive care unit (ICU) patients in Europe was 0.5% in 2019
Acinetobacter pittii infection is more common in hospitalized patients, especially those critically ill, have underlying diseases, have invasive devices or procedures, have prolonged antibiotic exposure, or have previous colonization by Acinetobacter pittii. Other risk factors may include age, gender, immunosuppression, trauma, surgery, burns, or exposure to humid climates or natural disasters.
Acinetobacter pittii is a species of Gram-negative bacteria belonging to the genus Acinetobacter. It is an opportunistic pathogen commonly associated with healthcare-associated infections, particularly in immunocompromised individuals and those with prolonged hospital stays.
Kingdom: Bacteria
Phylum: Proteobacteria
Class: Gammaproteobacteria
Order: Pseudomonadales
Family: Moraxellaceae
Genus: Acinetobacter
Species: pittii
Acinetobacter pittii, like other members of the Acinetobacter genus, is a non-motile, non-spore-forming, and non-encapsulated bacterium. It has a characteristic coccobacillus shape, appearing as small, Gram-negative rods under the microscope. The bacteria have a cell envelope consisting of an outer membrane, a peptidoglycan layer, and an inner cytoplasmic membrane.
The outer membrane of Acinetobacter pittii contains various proteins and lipopolysaccharides, which contribute to its virulence and resistance mechanisms. It also serves as a protective barrier against the host immune system and antimicrobial agents. The peptidoglycan layer supports the cell wall and plays a role in cell division.
Acinetobacter pittii possesses pili and fimbriae on its outer surface, which aid in adherence to host tissues and facilitate the formation of biofilms. Biofilms are complex communities of bacteria that are notoriously difficult to eradicate and can contribute to the persistence of Acinetobacter infections.
The genome of Acinetobacter Pitti has been sequenced, revealing the presence of numerous resistance genes and virulence factors. This species has demonstrated a remarkable ability to acquire and disseminate antibiotic resistance determinants, making it a significant concern in healthcare settings.
Antigenic types of bacteria are different antigens that bacteria can express on their surface to evade the host immune system. Antigens are molecules that an immune system can detect.
The host antibodies trigger an immune response. Some bacteria can change their antigens through gene conversion, DNA inversion, hypermutation, or recombination.
Acinetobacter pittii may have different types of antigens, such as O or somatic antigens, K or capsular antigens, and H or flagellar antigens. O antigens are part of the lipopolysaccharide (LPS) layer covering gram-negative bacteria’s outer membrane. LPS is also known as endotoxin and can trigger a robust immune response in the host. O antigens are composed of repeating units of sugars that vary in number, composition, and arrangement among different bacteria. K antigens are polysaccharides that form a capsule around some bacteria and protect them from phagocytosis and complement-mediated lysis. K antigens are also composed of repeating units of sugars that vary among different bacteria. H antigens are proteins that form the flagella, long whip-like structures that help bacteria move and attach to surfaces. Flagella also have different types and arrangements among different bacteria.
The antigenic types of Acinetobacter pittii have yet to be well studied, but some studies have suggested that they may vary depending on the source and location of the isolates. For example, one study found that Acinetobacter pittii isolates from China had different O antigen profiles than those from Europe. Another study found that Acinetobacter pittii isolates from clinical specimens had different K antigen profiles. The antigenic variation of Acinetobacter pittii may have implications for its diagnosis, typing, and vaccine development.
Acinetobacter pittii strains are bacteria isolated from different sources and locations and have different genetic and phenotypic characteristics. Some of the strains of Acinetobacter pittii that have been reported in the literature include:
Strain sw-1: A strain isolated from 7619-m seawater of the Mariana Trench and efficiently utilized long-chain n-alkanes (C18–C36) as carbon sources.
Strain RUH 2206: A strain isolated from a patient with bacteremia in the Netherlands and resistant to multiple antibiotics.
Strain 320: A strain isolated from a patient with pneumonia in China with a different O antigen profile than European strains.
Strain NIPH 519: A strain isolated from a patient with wound infection in Norway with a different K antigen profile than other clinical isolates.
These are some examples of strains of Acinetobacter pittii that have been studied for their genetic and phenotypic diversity, pathogenicity, and antibiotic resistance. More strains may be discovered and characterized in the future, as Acinetobacter pittii is an emerging nosocomial pathogen.
Pathogenesis of Acinetobacter pittii is the process by which Acinetobacter pittii causes infection and disease in humans. Acinetobacter pittii is a gram-negative bacterium that belongs to the Acinetobacter calcoaceticus-baumannii complex, a group of closely related species that can cause nosocomial infections, especially in immunocompromised patients. Some of the pathogenic mechanisms of Acinetobacter pittii include:
Adherence and invasion: Acinetobacter pittii can adhere to and invade various human cells and tissues, such as epithelial cells, endothelial cells, fibroblasts, and macrophages. It can also form biofilms on biotic and abiotic surfaces, such as wounds, catheters, or medical devices. Adherence and invasion are mediated by various factors, such as pili, fimbriae, outer membrane proteins, lipopolysaccharide (LPS), and extracellular polysaccharide (EPS).
Resistance and persistence: Acinetobacter pittii can resist and persist in hostile environments, such as desiccation, oxidative stress, nutrient limitation, pH changes, and antimicrobial agents. It can also evade or modulate the host immune system by altering its surface antigens, producing capsule or biofilm, inhibiting phagocytosis or complement activation, or inducing apoptosis or cytokine production in host cells.
Toxins and enzymes: Acinetobacter pittii can produce toxins and enzymes that can damage the host cells and tissues, such as hemolysins, phospholipases, proteases, lipases, siderophores, and endotoxins. These factors can cause cell lysis, membrane disruption, tissue necrosis, iron acquisition, inflammation, and septic shock.
Acinetobacter pittii host defenses are the mechanisms the human body uses to protect itself from infection by this bacterium.
Some of the host defenses of Acinetobacter pittii include:
Intact skin and mucosal surfaces: The skin and mucous membranes act as physical barriers that prevent the entry of Acinetobacter pittii and other microorganisms into the body. They also secrete antimicrobial substances such as lysozyme, defensins, and lactoferrin that can kill or inhibit the growth of bacteria.
Neutrophil activity: Neutrophils are white blood cells, part of the innate immune system. They can recognize and phagocytose (engulf and digest) Acinetobacter pittii and other bacteria. They also release reactive oxygen species (ROS) and antimicrobial peptides that can damage the bacterial cell wall and membrane.
Complement system: A complement system is a group of proteins that circulate in the blood and can be activated by Acinetobacter pittii and other bacteria. The complement system can enhance the phagocytosis of bacteria by neutrophils and macrophages, opsonize (coat) bacteria for clearance by the spleen and liver, and form membrane attack complexes (MACs) that can lyse (burst) bacterial cells.
Antibody production: Antibodies are proteins produced by B cells, a white blood cell part of the adaptive immune system. Antibodies can bind to specific antigens (molecules) on the surface of Acinetobacter pittii and other bacteria. It can neutralize the bacteria, prevent their attachment to host cells, or activate the complement system and phagocytosis.
T cell activation: T cells are another white blood cell part of the adaptive immune system. T cells can recognize antigens presented by antigen-presenting APCs, including macrophages and dendritic cells that have phagocytosed Acinetobacter pittii and other bacteria.
Clinical manifestations of Acinetobacter pittii infections:
Pneumonia: Acinetobacter pittii can cause pneumonia, particularly in individuals who are critically ill or have compromised immune systems. Symptoms may include cough, fever, chest pain, shortness of breath, and productive sputum.
Urinary tract infections (UTIs): UTIs caused by Acinetobacter pittii can present with symptoms such as frequent urination, burning sensation during urination, cloudy or bloody urine, and pelvic pain.
Wound infections: Acinetobacter pittii is known to cause wound infections, especially in individuals with surgical wounds or open injuries. Symptoms may include redness, swelling, pain, pus discharge, and delayed wound healing.
Bloodstream infections: Acinetobacter pittii can enter the bloodstream, leading to a severe condition known as bacteremia. Symptoms of bloodstream infections may include fever, chills, rapid heart rate, low blood pressure, and general signs of sepsis.
Meningitis: Although less common, Acinetobacter pittii can also cause meningitis, an infection of the membranes surrounding the brain and spinal cord. Meningitis may present with symptoms such as severe headache, neck stiffness, fever, sensitivity to light, altered mental status, and seizures.
The diagnosis of Acinetobacter pittii infection typically involves several steps, including:
Clinical evaluation: The healthcare provider will assess the patient’s symptoms, medical history, and risk factors for infection. Common Acinetobacter pittii infections include bloodstream infections, pneumonia, urinary tract infections, wound infections, and infections associated with medical devices like catheters or ventilators.
Sample collection: To confirm the presence of Acinetobacter pittii, samples from the suspected infection site are collected. The sample type depends on the suspected infection but may include blood, sputum, urine, wound swabs, or other relevant specimens.
Laboratory testing: The collected samples are sent to a microbiology laboratory for analysis. The laboratory will perform various tests to isolate and identify the bacteria. These tests may include:
Gram staining: This initial test helps classify the bacteria as gram-negative and provides a preliminary assessment of its morphology.
Culture: The sample is plated on specific culture media that promote the growth of Acinetobacter species. The bacteria are then isolated and allowed to grow for further analysis.
Biochemical tests: Various biochemical tests, such as oxidase test, catalase test, and others, are performed to identify the bacteria as Acinetobacter pittii. These tests help differentiate it from other species within the Acinetobacter genus.
Antibiotic susceptibility testing: The isolated bacteria are tested against different antibiotics to determine their susceptibility patterns. This information helps guide appropriate treatment choices.
Molecular identification: In some cases, further molecular testing PCR, for example, is a procedure that may be used or sequencing techniques to confirm the species as Acinetobacter pittii and rule out other closely related species.
Acinetobacter pittii infection can be prevented by practicing proper hygiene and avoiding exposure to contaminated environments or equipment. Some of the preventive measures include:
Limiting your exposure to hospitals or other healthcare settings where Acinetobacter pittii may be present, especially if you have a weakened immune system or a chronic medical condition.
Frequently wash your hands with soap and water or use an alcohol-based hand sanitizer, especially before and after touching any wounds, catheters, or medical devices.
Do not touch your mouth, nose, or eyes with unclean hands, as this can introduce bacteria into your body.
Requesting caregivers wash their hands before and after touching you or any of your belongings.
Insisting caregivers practice aseptic techniques when inserting or removing any catheters, tubes, or needles from your body.
Taking antibiotics only when necessary and precisely as your doctor prescribes and completing the entire course of treatment to avoid antibiotic resistance.
Cleaning and covering wounds or skin lesions with sterile dressings and changing them regularly.
Acinetobacter pittii biofilm formation on inanimate surfaces after long-term desiccation – ScienceDirect
Phenotypic Variation and Carbapenem Resistance Potential in OXA-499-Producing Acinetobacter pittii – PubMed (nih.gov)
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