Overview
Nosocomial gangrene is a human-animal co-morbidity caused by Burkholderia cepacia. Clinical manifestations are diverse and may be acute or chronic, localized or generalized, symptomatic or asymptomatic. Most of them are accompanied by multiple suppurative foci. It is mainly found in the tropics and is endemic in Southeast Asia. People are infected mainly through contact with water and soil containing the causative agent, via broken skin. The population is generally susceptible to B. anthracis-like bacteria. The incubation period of the disease is generally 4 to 5 days, but there are cases where the disease develops months, years or even 20 years after infection, which is known as “latent bacillus nosocomialis”, and such cases are often triggered by trauma or other diseases.
Causes of the disease
The causative agent of this disease is Burkholderia pseudomallei, which is usually disseminated, but can also be an epidemic.
1. Source of infection
Water and soil in endemic areas often contain the bacterium. The bacteria can grow naturally in the external environment and do not require any animals as storage hosts. The bacterium can infect or even cause disease in many kinds of animals, but it is not the main source of infection, and human transmission is rare.
2.Transmission
People are infected by contact with water and soil containing the bacteria and through broken skin. Ingestion, nostril drip or inhalation of germ contaminants can also cause disease. Generally, arthropod-derived infections do not occur.
3. Susceptible people
People are generally susceptible. Newly entering the infected area, diabetes, alcoholism, splenectomy, HIV infection, etc. are susceptible factors.
Symptoms
The incubation period of the disease is 4~5 days, and there are cases that last for several months or years. The clinical manifestations are diverse and very similar to nosocomial gangrene. The disease can be classified into 7 types such as insidious infection, asymptomatic pulmonary infiltration, acute localized purulent infection, acute pulmonary infection, acute sepsis, chronic purulent infection and recurrent infection.
1. Localized purulent infection
The manifestations are nodule formation at the skin break, enlarged lymph nodes in the drainage area and lymphangitis, often accompanied by fever and general discomfort, which can quickly develop into acute sepsis.
2. Acute lung infection
It is the most common type of infection in nosocomial gangrene, which can be primary or bloodstream disseminated pneumonia, besides high fever and chills, there are cough, chest pain, shortness of breath and so on, and the symptoms are disproportionate to the chest signs. Inflammation in the lungs is mostly seen in the upper lobe, which is solid, and there are often thin-walled cavities, which can be easily misdiagnosed as tuberculosis, and this type can also develop into sepsis.
3. Acute sepsis
It can be primary or secondary, and is the most serious clinical type of pyoderma gangrenosum. Sudden onset of disease, sepsis symptoms are obvious, often rapidly appear the manifestations caused by multi-organ involvement, such as lung involvement, may appear dyspnea, double lung wet rales.
4. Central nervous system infection
Symptoms and signs of encephalitis or meningitis may appear in time. Some patients may die due to the rapid progression of the disease to the point where it is too late to save them.
5. Chronic suppurative infection
Chronic suppurative infections are mainly characterized by multiple abscesses, which may involve multiple tissues or organs, and patients may not have fever. Recurrent infections may manifest as acute localized septic infection, acute pulmonary infection, acute sepsis, or chronic septic infection. Surgery, trauma, alcoholism, and radiation therapy are often triggers for recurrence.
Examination
1. Peripheral blood picture
Most of them have anemia. The total number of leukocytes increases in the acute stage, and the increase of neutrophils is dominant. However, the white blood cell count can be within the normal range.
2. Pathologic examination
Smear (methylene blue staining) and culture of exudate, pus, etc. Suspension test can observe the power, which can be used to distinguish from Burkholderia mallei.
3. Serologic examination
There are mainly two kinds of indirect hemagglutination test and complement binding test. The former appears earlier, but the specificity is poor. Dynamic observation of antibody potency is more than 4 times higher than the diagnostic value; single potency of the former is more than 1:80, the latter is more than 1:8, also has a certain reference value. The strain-specific antigen is used in indirect enzyme-linked immunosorbent assay, which has higher sensitivity and specificity.
4. Molecular biology test
Designing specific primers for the bimA (Bm) gene of Burkholderia pseudomallei can be used for rapid diagnosis, and adopting real-time polymerase chain reaction (PCR) method to design specific probes can be used to differentiate Burkholderia pseudomallei from Burkholderia pseudomallei.
Diagnosis
The disease should be considered in anyone who has traveled to an infected area and develops fever or septic illness of unknown origin. Clinical manifestations and microbiologic examination can be used to confirm the diagnosis.
Differential diagnosis
In the acute phase, the disease should be differentiated from acute nosocomial gangrene, typhoid fever, malaria, staphylococcal septicemia and pneumonia. In the chronic stage, it should be distinguished from tuberculosis and chronic nosocomial gangrene.
Treatment
The drugs commonly used clinically for the treatment of nosocomial infections are penicillin, streptomycin, chloramphenicol, tetracycline, gentamicin and so on. Surgical incision and drainage is appropriate for those with abscesses, and surgical excision of diseased tissues or organs can be used in chronic cases where internal medicine treatment is ineffective.