OVERVIEW
Pseudomonas spp. are a group of gram-negative non-bacteriophageous bacteria. There are many species of bacteria in this genus, up to more than 200 species. Pseudomonas aeruginosa pneumonia is an acute or chronic inflammation of the lower respiratory tract of horses, mules, donkeys and other single-hoofed animals caused by Pseudomonas aeruginosa, and the infection occurs in human beings due to contact with diseased animals. The acute cases die in 1 to 2 weeks, and the chronic cases remain untreated for a long time.
Causes
Pseudomonas nosocomialis is a gram-negative bacillus with bluntly rounded ends, elongated and slightly curved rods, which is the causative agent of Pseudomonas nosocomialis pneumonia.
Symptoms
With different infection routes, it can be categorized into 3 types: cutaneous gangrene, nosocomial gangrene and pulmonary gangrene. The incubation period is generally from a few hours to 3 weeks, with an average of 4 days, and even delayed to as long as 10 years.
1. Acute nosocomial gangrene
Acute nosocomial gangrene is usually accompanied by chills and high fever, chest pain, cough, sputum (sputum can be bloody), generalized myalgia, headache and other symptoms. Wet rales or signs of pulmonary solid changes and corresponding signs of pleural effusion can be heard in the lungs. If the damage is confined to the site of skin infection, acute cellulitis may develop, with localized swelling, followed by necrosis and ulceration, resulting in an ulcer with irregular margins and a grayish base, and covered with grayish-yellow exudate. It may be complicated by lymphangitis or lymphadenitis of the lymph nodes to which it belongs, and occasionally by cervical lymph nodes and splenomegaly. In severe cases, nodular abscesses are formed, and fistulas can be formed after rupture, discharging red or gray-white pus. Pathogenic bacteria can also enter the bloodstream from the lesion, causing a generalized papular rash, which then develops into a pustule, with an umbilical concavity in the center and the size of a pea grain. The pustules gradually crust over and leave a scar after molting. If the damage originates in the nose, there may be nasal cellulitis and necrosis, perforation of the nasal septum, ulcer formation in the palate and pharynx, often discharging bloody secretion first, followed by purulent secretion, developing into extensive ulcerative granuloma.
2. Chronic nosocomial gangrene
Systemic symptoms may not be obvious, only low fever or prolonged irregular fever, joint pain of limbs, lung symptoms are not obvious, with sepsis or septicemia episodes. Abscesses appear in the skin or soft tissues, and the nearby lymph nodes are enlarged, sometimes the abscess breaks down and exudes a large amount of pus, and fistulas that do not heal for a long time can also be formed. Joints, bone marrow, liver, spleen, eyes and central nervous system can be involved, and the course of the disease extends from several months to several years. Patients often gradually lose weight and become malignant, and often die due to gradual exhaustion, but there are also reports of spontaneous recovery.
Examination
1. Laboratory examination
The total number of white blood cells may be normal or elevated, and the nucleus may be left shifted. The positive rate of complement binding test can be more than 95%.
2. Other auxiliary tests
X-ray chest radiograph shows patchy shadows in the lung field with blurred edges, and sometimes cavities can be seen. In sepsis combined with pneumonia, it shows irregular nodular changes, which are diffusely disseminated in both lungs, and may fuse with each other or form cavities. Pleural effusion may also be present as well as pleural fibrosis later in the course of the disease.
Diagnosis
A history of epidemiologic exposure, including direct or indirect contact with diseased horses; positive blood, sputum, or pus cultures; positive Strauss reaction of isolates; and a serum agglutination titer of 1:160 or higher, or a complement binding test titer of 1:20 are helpful in the diagnosis of the disease.
Differential diagnosis
This disease should be differentiated from nosocomial gangrene, disseminated tuberculosis, streptococcal cellulitis, staphylococcal infections, and typhoid fever.
Treatment
1. General treatment
Patients should be isolated. Secretions, excretions and dressing gauze should be thoroughly sterilized. Symptomatic and supportive therapies should be given to acute infections, and chronic suppurative foci should be incised and drained, but the spread of infection should be avoided.
2.Antibacterial treatment
Sulfonamides, tetracyclines, chloramphenicol and aminoglycosides have some efficacy. Sulfadiazine has good efficacy. Streptomycin and sulfadiazine or tetracycline are generally recommended for joint application until the symptoms disappear. In recent years, with the increasing number of antibacterial drugs, ceftazidime, ciprofloxacin, piperacillin, tobramycin, imipenem (imidopenem) and other antibacterial drugs have better anti-pseudomonas effects.