Klebsiella michiganensis

Updated : November 28, 2023

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Klebsiella michiganensis infection, commonly known as donovanosis, presents a distinct epidemiological profile characterized by its relatively low global incidence yet pronounced impact in specific regions with conducive conditions for its transmission.

A comprehensive review published in 2018 estimated the worldwide occurrence of this sexually transmitted infection (STI) to be less than 0.5 instances per 100,000 individuals annually. The infection predominantly thrives in tropical and subtropical zones, with endemicity noted in regions such as India, Papua New Guinea, South Africa, Brazil, and Australia.  

Donovanosis exhibits a notable predilection for men over women, individuals with lower socioeconomic status, inadequate hygiene practices, and engagement in multiple sexual partnerships. The primary transmission mode is sexual contact, particularly involving genital-to-genital or oral-genital interactions.

The absence of protective measures and limited awareness regarding safe sexual practices contribute to its propagation, rendering individuals with multiple sexual partners and high-risk behaviors more susceptible. A compelling case report from 2019 further underscores the clinical presentation and management of K. michiganensis infection.

In this instance, a 32-year-old man from India displayed ulcerative lesions on his genital region, which were subsequently diagnosed through advanced techniques like PCR and DNA sequencing. Successful treatment with doxycycline over six weeks led to the complete resolution of the lesions. Significantly, this case marked the first documented Klebsiella michiganensis infection reported in India in the past decade, spotlighting its evolving epidemiological landscape.  

A surveillance report originating in 2020 further illuminates the current scenario of Klebsiella michiganensis infection within Australia. The report documented 20 cases in 2019, with the majority emerging from Queensland, followed by other regions. Most affected individuals were male, with a median age of 38 years. The infection was primarily localized in the genital region, yet instances involving the anal and oral areas were also reported. 

 

Kingdom: Bacteria 

Phylum: Pseudomonadota 

Class: Gammaproteobacteria 

Order: Enterobacterales 

Family: Enterobacteriaceae 

Genus: Klebsiella 

Species: Klebsiella michiganensis  

Klebsiella michiganensis, a gram-negative bacterium, appears as a short, plump, straight rod or bacillus. However, it can also display variations in shape, occasionally appearing as coccus or oval forms under specific environmental conditions. 

It exhibits a size range of approximately 1–2 µm in length and 0.5–0.8 µm in width.  

The cell wall of K. michiganensis is primarily composed of peptidoglycan, a mesh-like structure imparting rigidity. 

   

Characterizing antigenic types within Klebsiella michiganensis remains challenging due to its intricate growth requirements in standard laboratory settings and notable genetic variability. Researchers have turned to advanced molecular techniques like polymerase chain reaction (PCR) & DNA sequencing to elucidate these antigenic profiles.

By employing these methods, investigations have been conducted to identify and define the O and K antigens of K. michiganensis isolates derived from diverse geographic regions and distinct patient cases.  

In particular, the K antigen type has garnered attention for its potential influence on the immune response and susceptibility to antibiotic treatments. Varied K antigen types have been associated with differing degrees of resistance to complement-mediated killing and certain antibiotics like ciprofloxacin, ampicillin, and ceftriaxone. Illustrative instances include isolating specific strains from patients with donovanosis in different regions.

For instance, one strain was extracted from a patient experiencing donovanosis in Australia, while another strain was obtained from a case of genital ulceration in India. An in-depth examination of these strains revealed the presence of virulence-related genes such as mucoviscosity-associated gene A (magA), allantoin metabolism-related gene allS, capsule-associated gene A (K2A), Klebsiella ferric iron uptake (Kfu), and aerobactin. 

 

The pathogenesis of Klebsiella michiganensis involves a sequence of events that contribute to the development of granuloma inguinale or donovanosis, a sexually transmitted infection: Klebsiella michiganensis is primarily transmitted through sexual contact with a diseased person or exposure to contaminated objects or surfaces. Entry into the body occurs through skin or mucous membrane breaches, facilitating bacterial access to host tissues.  

The bacterium invades the epithelial cells and macrophages in the skin or mucous membranes. Klebsiella michiganensis can establish a sheltered environment for survival and replication within these cells. It incites an inflammatory response within the host tissue. This immune reaction manifests as localized swelling, redness, and discomfort. The ensuing inflammation attracts immune cells like neutrophils and lymphocytes to the site of infection. Unfortunately, these cells struggle to eliminate the bacterium and, instead, contribute to tissue damage and necrosis.  

Progression of the infection leads to tissue ulceration and erosion. The affected tissue undergoes breakdown, exposing underlying blood vessels and tissue layers. Ulceration may result in bleeding and the discharge of pus. Additionally, the ulcer can extend to neighboring regions or disseminate to distant sites via lymphatic or bloodstream pathways.  

Klebsiella michiganensis infection can precipitate a range of complications, amplifying the severity of the ailment. These complications encompass secondary infections, anemia, scarring, the formation of fistulas and strictures, genital mutilation, lymphedema, elephantiasis, and even the potential development of cancer. 

 

Inflammasomes, another critical defense mechanism, are multiprotein platforms formed by NLR protein family members like NLRP1, NLRP3, and NLRC4. These inflammasomes induce the activation of caspase-1, leading to the processing and secretion of mature forms of cytokines IL-1β and IL-18. Caspase-1 activation can also initiate pyroptosis, a form of cell death that may contribute to the clearance of bacteria through pore-induced intracellular traps and efferocytosis.  

The retinoic acid-inducible gene I or (RIG-I)-like receptor (RLR) family, including proteins like RIG-I and MDA5, detects viral RNA and initiates immune responses. These receptors collaborate with other pattern recognition receptors (PRRs) to activate mitogen-activated protein kinases (MAPKs) and transcriptional factors such as IRF3, IRF7, and NF-κB. These factors collectively trigger gene transcription, influencing immune responses.  

In the context of Klebsiella michiganensis infections, boosting pro-inflammatory signaling has shown promise. Strategies involving the expression of chemokines and cytokines like CCL3, KC, IL-12, and IFNγ, either intrapulmonarily or via treatments like cyclic di-GMP stimulation, enhance bacterial clearance. These treatments also lead to increased recruitment of immune cells, including neutrophils, T cells, and γδ T cells, contributing to a more effective defense against K. michiganensis infections. 

Klebsiella michiganensis can lead to diverse human infections, encompassing pneumonia, urinary tract infections, bloodstream infections, wound infections, and eye infections. The symptoms associated with these infections are distinct:  

Pneumonia: Patients often exhibit symptoms like fever, chills, productive cough with mucus or even blood, chest pain, and shortness of breath, signifying the respiratory nature of the infection.  

Bloodstream Infections: Manifestations comprise fever, chills, reduced blood pressure, confusion, rapid heart rate, and potential organ failure, reflecting the systemic nature of the infection. 

Urinary Tract Infections: Typical signs include painful or burning sensations during urination, frequent or urgent urination, pus or blood in the urine, & discomfort or pain in the lower abdomen. 

 

Culture method: Although challenging to cultivate in standard laboratory conditions, Klebsiella michiganensis can be cultured for research purposes using peripheral blood mononuclear cells cultivated with fetal calf serum or Hep-2 cell monolayers treated with cycloheximide. This culture method necessitates specialized precautions to prevent contamination. The culturing process can extend over several weeks.  

Microscopy: A tissue crush preparation or lesion biopsy is subjected to staining with Wright, Giemsa, or Leishman stain. Microscopic examination under a microscope allows for identifying Donovan bodies, distinctive Gram-negative bacilli characterized by a safety-pin appearance and surrounded by a capsule. The presence of these structures is indicative of Klebsiella michiganensis infection.  

Serology: Serological testing evaluates the patient’s antibody response to the bacterium. It can be executed through indirect immunofluorescence or enzyme-linked immunosorbent assay (ELISA). While serology contributes to epidemiological assessments, it should be noted that it possesses lower sensitivity and specificity and may exhibit cross-reactivity with other bacterial species.  

PCR assay: A molecular technique, PCR amplifies and detects specific DNA sequences of the bacterium. PCR can be performed on fluid or tissue samples extracted from the lesion or blood samples collected from the patient. In comparison to microscopy, PCR offers heightened sensitivity and specificity. Additionally, PCR can facilitate the identification of the bacterium’s antigenic types. 

 

Preventing Klebsiella michiganensis infection involves avoiding sexual contact with infected individuals. While condoms offer some protection, they may not provide complete coverage due to the potential for lesions beyond the condom-protected areas. In addition to condom use, practicing good hygiene is essential. It includes washing hands and genital areas before and after sexual activity.   

To further reduce the risk of transmission, it’s advisable to refrain from sharing personal items like towels or razors, which could contribute to the spread of the infection. Individuals can take proactive steps to lower their risk of developing K. michiganensis infection and protect their sexual health by following these preventive measures. 

 

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Klebsiella michiganensis

Updated : November 28, 2023

Mail Whatsapp PDF Image



Klebsiella michiganensis infection, commonly known as donovanosis, presents a distinct epidemiological profile characterized by its relatively low global incidence yet pronounced impact in specific regions with conducive conditions for its transmission.

A comprehensive review published in 2018 estimated the worldwide occurrence of this sexually transmitted infection (STI) to be less than 0.5 instances per 100,000 individuals annually. The infection predominantly thrives in tropical and subtropical zones, with endemicity noted in regions such as India, Papua New Guinea, South Africa, Brazil, and Australia.  

Donovanosis exhibits a notable predilection for men over women, individuals with lower socioeconomic status, inadequate hygiene practices, and engagement in multiple sexual partnerships. The primary transmission mode is sexual contact, particularly involving genital-to-genital or oral-genital interactions.

The absence of protective measures and limited awareness regarding safe sexual practices contribute to its propagation, rendering individuals with multiple sexual partners and high-risk behaviors more susceptible. A compelling case report from 2019 further underscores the clinical presentation and management of K. michiganensis infection.

In this instance, a 32-year-old man from India displayed ulcerative lesions on his genital region, which were subsequently diagnosed through advanced techniques like PCR and DNA sequencing. Successful treatment with doxycycline over six weeks led to the complete resolution of the lesions. Significantly, this case marked the first documented Klebsiella michiganensis infection reported in India in the past decade, spotlighting its evolving epidemiological landscape.  

A surveillance report originating in 2020 further illuminates the current scenario of Klebsiella michiganensis infection within Australia. The report documented 20 cases in 2019, with the majority emerging from Queensland, followed by other regions. Most affected individuals were male, with a median age of 38 years. The infection was primarily localized in the genital region, yet instances involving the anal and oral areas were also reported. 

 

Kingdom: Bacteria 

Phylum: Pseudomonadota 

Class: Gammaproteobacteria 

Order: Enterobacterales 

Family: Enterobacteriaceae 

Genus: Klebsiella 

Species: Klebsiella michiganensis  

Klebsiella michiganensis, a gram-negative bacterium, appears as a short, plump, straight rod or bacillus. However, it can also display variations in shape, occasionally appearing as coccus or oval forms under specific environmental conditions. 

It exhibits a size range of approximately 1–2 µm in length and 0.5–0.8 µm in width.  

The cell wall of K. michiganensis is primarily composed of peptidoglycan, a mesh-like structure imparting rigidity. 

   

Characterizing antigenic types within Klebsiella michiganensis remains challenging due to its intricate growth requirements in standard laboratory settings and notable genetic variability. Researchers have turned to advanced molecular techniques like polymerase chain reaction (PCR) & DNA sequencing to elucidate these antigenic profiles.

By employing these methods, investigations have been conducted to identify and define the O and K antigens of K. michiganensis isolates derived from diverse geographic regions and distinct patient cases.  

In particular, the K antigen type has garnered attention for its potential influence on the immune response and susceptibility to antibiotic treatments. Varied K antigen types have been associated with differing degrees of resistance to complement-mediated killing and certain antibiotics like ciprofloxacin, ampicillin, and ceftriaxone. Illustrative instances include isolating specific strains from patients with donovanosis in different regions.

For instance, one strain was extracted from a patient experiencing donovanosis in Australia, while another strain was obtained from a case of genital ulceration in India. An in-depth examination of these strains revealed the presence of virulence-related genes such as mucoviscosity-associated gene A (magA), allantoin metabolism-related gene allS, capsule-associated gene A (K2A), Klebsiella ferric iron uptake (Kfu), and aerobactin. 

 

The pathogenesis of Klebsiella michiganensis involves a sequence of events that contribute to the development of granuloma inguinale or donovanosis, a sexually transmitted infection: Klebsiella michiganensis is primarily transmitted through sexual contact with a diseased person or exposure to contaminated objects or surfaces. Entry into the body occurs through skin or mucous membrane breaches, facilitating bacterial access to host tissues.  

The bacterium invades the epithelial cells and macrophages in the skin or mucous membranes. Klebsiella michiganensis can establish a sheltered environment for survival and replication within these cells. It incites an inflammatory response within the host tissue. This immune reaction manifests as localized swelling, redness, and discomfort. The ensuing inflammation attracts immune cells like neutrophils and lymphocytes to the site of infection. Unfortunately, these cells struggle to eliminate the bacterium and, instead, contribute to tissue damage and necrosis.  

Progression of the infection leads to tissue ulceration and erosion. The affected tissue undergoes breakdown, exposing underlying blood vessels and tissue layers. Ulceration may result in bleeding and the discharge of pus. Additionally, the ulcer can extend to neighboring regions or disseminate to distant sites via lymphatic or bloodstream pathways.  

Klebsiella michiganensis infection can precipitate a range of complications, amplifying the severity of the ailment. These complications encompass secondary infections, anemia, scarring, the formation of fistulas and strictures, genital mutilation, lymphedema, elephantiasis, and even the potential development of cancer. 

 

Inflammasomes, another critical defense mechanism, are multiprotein platforms formed by NLR protein family members like NLRP1, NLRP3, and NLRC4. These inflammasomes induce the activation of caspase-1, leading to the processing and secretion of mature forms of cytokines IL-1β and IL-18. Caspase-1 activation can also initiate pyroptosis, a form of cell death that may contribute to the clearance of bacteria through pore-induced intracellular traps and efferocytosis.  

The retinoic acid-inducible gene I or (RIG-I)-like receptor (RLR) family, including proteins like RIG-I and MDA5, detects viral RNA and initiates immune responses. These receptors collaborate with other pattern recognition receptors (PRRs) to activate mitogen-activated protein kinases (MAPKs) and transcriptional factors such as IRF3, IRF7, and NF-κB. These factors collectively trigger gene transcription, influencing immune responses.  

In the context of Klebsiella michiganensis infections, boosting pro-inflammatory signaling has shown promise. Strategies involving the expression of chemokines and cytokines like CCL3, KC, IL-12, and IFNγ, either intrapulmonarily or via treatments like cyclic di-GMP stimulation, enhance bacterial clearance. These treatments also lead to increased recruitment of immune cells, including neutrophils, T cells, and γδ T cells, contributing to a more effective defense against K. michiganensis infections. 

Klebsiella michiganensis can lead to diverse human infections, encompassing pneumonia, urinary tract infections, bloodstream infections, wound infections, and eye infections. The symptoms associated with these infections are distinct:  

Pneumonia: Patients often exhibit symptoms like fever, chills, productive cough with mucus or even blood, chest pain, and shortness of breath, signifying the respiratory nature of the infection.  

Bloodstream Infections: Manifestations comprise fever, chills, reduced blood pressure, confusion, rapid heart rate, and potential organ failure, reflecting the systemic nature of the infection. 

Urinary Tract Infections: Typical signs include painful or burning sensations during urination, frequent or urgent urination, pus or blood in the urine, & discomfort or pain in the lower abdomen. 

 

Culture method: Although challenging to cultivate in standard laboratory conditions, Klebsiella michiganensis can be cultured for research purposes using peripheral blood mononuclear cells cultivated with fetal calf serum or Hep-2 cell monolayers treated with cycloheximide. This culture method necessitates specialized precautions to prevent contamination. The culturing process can extend over several weeks.  

Microscopy: A tissue crush preparation or lesion biopsy is subjected to staining with Wright, Giemsa, or Leishman stain. Microscopic examination under a microscope allows for identifying Donovan bodies, distinctive Gram-negative bacilli characterized by a safety-pin appearance and surrounded by a capsule. The presence of these structures is indicative of Klebsiella michiganensis infection.  

Serology: Serological testing evaluates the patient’s antibody response to the bacterium. It can be executed through indirect immunofluorescence or enzyme-linked immunosorbent assay (ELISA). While serology contributes to epidemiological assessments, it should be noted that it possesses lower sensitivity and specificity and may exhibit cross-reactivity with other bacterial species.  

PCR assay: A molecular technique, PCR amplifies and detects specific DNA sequences of the bacterium. PCR can be performed on fluid or tissue samples extracted from the lesion or blood samples collected from the patient. In comparison to microscopy, PCR offers heightened sensitivity and specificity. Additionally, PCR can facilitate the identification of the bacterium’s antigenic types. 

 

Preventing Klebsiella michiganensis infection involves avoiding sexual contact with infected individuals. While condoms offer some protection, they may not provide complete coverage due to the potential for lesions beyond the condom-protected areas. In addition to condom use, practicing good hygiene is essential. It includes washing hands and genital areas before and after sexual activity.   

To further reduce the risk of transmission, it’s advisable to refrain from sharing personal items like towels or razors, which could contribute to the spread of the infection. Individuals can take proactive steps to lower their risk of developing K. michiganensis infection and protect their sexual health by following these preventive measures. 

 

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