Gram-negative bacilli infection

Introduction Gram-negative bacilli are one of the major causes of infectious diseases in humans. It plays an important role in the pathogenic composition of infectious diseases. At the same time, Gram-negative bacilli are increasingly resistant to clinically commonly used antibiotics, and the clinical isolate rate of Gram-negative bacilli producing extended-spectrum -lactamase High, the infection is difficult to treat, is currently the most concerned drug-resistant bacteria. Gram-negative bacterial infections are common with meningococcal dysentery, dysentery, typhoid fever, paratyphoid fever, sammen, botulinum, etc., and common intestine infections such as the large intestine, Craybai, deformation, Pseudomonas aeruginosa and other rare legionella and Neisseria gonorrhoeae, etc.

Cause

Causes:

Gram-negative bacterial infections are common with meningococcal dysentery, dysentery, typhoid fever, paratyphoid fever, sammen, botulinum, etc., and common intestine infections such as the large intestine, Craybai, deformation, Pseudomonas aeruginosa and other rare legionella and Neisseria gonorrhoeae, etc.

an examination

Related inspection

Bacterial infection immunoassay bacterial morphology test method bacterial identification cerebrospinal fluid bacterial culture urine bacterial culture

The clinical manifestation period is generally 2 to 3 days, more common in winter and spring.

Laboratory inspection:

1, routine examination: blood, urine, stool routine.

2, bacterial culture: blood and cerebrospinal fluid culture can obtain meningococcal.

Differential diagnosis

Differential diagnosis of Gram-negative bacterial infections:

Common meningococcal, dysentery, typhoid, paratyphoid, sand, botulinum, etc., and common intestines in the hospital, intestinal, Cray white, deformation, Pseudomonas aeruginosa and other rare legionella and gonococcus.

(1) Epidemic cerebrospinal fluid meningitis (abbreviated as cerebral palsy) The pathogen of this disease is meningococcal, which is kidney-shaped and often arranged in pairs. Human beings are the only source of infection, especially in patients with nasopharynx. Through droplets, the rate of infection in the population is closely related to the prevalence of the disease. When meningococcal enters the nasopharynx, it is locally propagated. When the resistance of the person is reduced, the pathogen invades the blood to cause sepsis, and some pathogens enter the meninges to cause disease.

Clinical manifestation

The incubation period is generally 2 to 3 days, seen in winter and spring. The onset of illness is mainly chills, high fever, headache, nausea and vomiting. Physical examination showed visible spots or ecchymoses on the skin and mucous membranes, as well as obvious meningeal irritation. In severe cases, the condition is dangerous. In addition to convulsions and unconscious coma, skin and mucous membranes are fused into a piece, blood pressure drops, and more common in cerebral palsy or disseminated intravascular coagulation.

2. Laboratory examination

Peripheral blood leukocytes and neutrophils were significantly elevated, with nuclear left shift and poisoning particles. Cerebrospinal fluid pressure increased, white blood cells increased, mainly multinucleated, sugar decreased, protein significantly increased. Meningococcal can be obtained by culturing blood and cerebrospinal fluid. However, the bacteria is weak against the outside world and is prone to death. Therefore, the cerebrospinal fluid is sent to the culture immediately after the emergency lumbar puncture. In the routine examination of the cerebrospinal fluid, the smear should also be used for gram staining to find bacteria. There are methods for serological detection of antigens, such as immunofluorescence, latex agglutination, hemagglutination inhibition, and enzyme-linked immunosorbent assays, as well as methods for detecting specific antibodies in serum. But none of them can replace the results of bacterial culture. It is suspected that DIC should be measured by platelet count, 3P test, and prothrombin activity FDP.

3. Diagnosis

Mainly based on clinical manifestations and examination of cerebrospinal fluid. Need to identify with other purulent meningitis, the key is to find Gram-negative diplococcus.

4. Treatment

(1) general treatment: antipyretic sputum and blood volume, etc., those with high intracranial pressure should be given oxygen and dehydrated with 20% mannitol to reduce intracranial pressure.

(2) Antibiotics: Sulfadiazine (SD) and penicillin G are preferred, and the former can be taken orally. SD2g is immediately available, and every 1g every 4~6h. If the effect is not good, you can use penicillin G 1.2 million ~ 2.4 million u, dissolved in 100ml of liquid every 2 ~ 4h intravenously. For those who are allergic to penicillin, chloramphenicol can be used in an amount of 1 to 1.5 g/d, and dissolved in 500 ml of liquid instillation. It can also be combined with aminoglycosides (Qingda or amikacin), or cefazolin 4-6g/d, instillation or addition to Qingda.

(3) 5% sodium bicarbonate can be used in the case of metabolic acidosis 100 ~ 200ml / time.

(4) severe symptoms of poisoning can be short-term use of small amounts of hormones, hydrocortisone 100mg added to the intravenous infusion, or dexamethasone 2 ~ 5mg intravenous injection.

(5) Heparin and fresh blood are used as appropriate in DIC.

(two) gonorrhea

It is a sexually transmitted disease caused by Gram-negative gonococcus, which does not penetrate the squamous epithelium but has affinity for the columnar epithelium. In the male urethra, prostate, female vestibular gland, urethra, cervix, etc. are susceptible to infection.

(3) Bacterial dysentery

Caused by Shigella, a total of Shihe, Fu Shi, Song Nai and Bao Shi four groups. Domestic dysentery bacillus is more common, followed by Song Nai. In recent years, due to the transfer of drug resistance factors between lycobacteria and dysentery bacilli by phage and plasmid, the resistance of dysentery bacilli is becoming more and more serious. The dysentery has a disease all year round, which is more common in summer and autumn. Patients and intestinal carriers are the source of infection and are infected by contaminating food. Most of the bacteria enter the gastrointestinal tract and are killed by gastric acid. A few enter the intestine. When the body's defense function is low, the dysentery bacillus breeds in the intestinal tract and invades the intestinal mucosa and causes disease. The dysentery bacillus has endotoxin, which is absorbed into the body to cause symptoms of toxemia such as chills and fever; it can also produce enterotoxin and cause diarrhea.

Clinical manifestation

The incubation period is several hours to two days, and the general onset is acute, with fever, abdominal pain, nausea, and vomiting. Typical dysentery is urgency, heavy, and pus. The number of diarrhea is large, the symptoms of poisoning are often mild, and those without diarrhea are more severe, sometimes combined with septic shock. Physical examination is soft, only mild tenderness in the left lower abdomen, active bowel sounds; severe cases have shock hypotension, cold limbs, skin spots, shortness of breath, cyanosis or confusion.

2. Laboratory examination

Blood leukocytes and neutrophils were significantly elevated, stools were routinely red, white blood cells were full of vision, and stools were cultured with Shigella. Sigmoidoscopy showed mucosal congestion, edema, a large amount of purulent exudate and multiple superficial ulcers.

3. Diagnosis

According to the onset season, it is not difficult to diagnose fever, abdominal pain, diarrhea, urgency, and pus and blood. Need to be identified with amoebic dysentery. In addition, in the case of toxic dysentery without diarrhea, attention should be paid to the identification of epidemic encephalitis and cerebral malaria.

4. Treatment

Light fungus can be taken orally with berberine 0.3g, 3 times / d, or TMPco 2 tablets, 2 times / d, the course of treatment is 7 to 10 days. After 3 days of taking the medicine, the effect is not good and other antibiotics can be exchanged. It can also be changed according to the susceptibility test of bacteria obtained from stool culture. In recent years, norfloxacin 0.2 g, 3 times/d has been widely used.

Severe bacteria need infusion, supplement blood volume, correct electrolyte imbalance; antibiotics should be combined and intravenously administered, optional ampicillin or oxypiperazine penicillin plus Qingda or amikacin, such as chloramphenicol for allergic to penicillin Or cefazolin, cefoperazone plus an aminoglycoside.

(4) Cholera

It is caused by Gram-negative Vibrio, which is divided into classical Vibrio cholerae and ELTor Vibrio, which are more common in the future. Patients and carriers (healthy, latent and recovery patients) are the source of infection. The disease is mainly transmitted through contaminated water sources, which can cause outbreaks. In recent years, the incidence rate has been significantly reduced due to the use of epidemic prevention measures and vaccines. However, due to frequent international exchanges, it is still possible to re-enter them from abroad, so it is still necessary to be vigilant. Vibrio cholerae invades the human body through the mouth, reaches the small intestine through the stomach, rapidly multiplies in an alkaline environment, and produces a large amount of enterotoxin. The enterotoxin stimulates cAMP of intestinal epithelial cells, causing intestinal secretion to cause diarrhea.

Clinical manifestation

The incubation period is 1 to 3 days, and asymptomatic recessive infection accounts for 75%. Typical cases can be divided into three phases, one vomiting and diarrhea: most patients have acute onset, severe vomiting and diarrhea, stools are rice-like watery, and there is also a washing water sample. 2 Dehydration period: Due to frequent vomiting and diarrhea, a large amount of water and electrolytes are lost in a short period of time. The patient has a thirsty lip dry, the eye socket is invaginated, the skin loses elasticity, blood pressure drops, urine is low or urine is closed. 3 recovery period: After active infusion and electrolyte supplementation, the patient's vomiting and diarrhea stopped, the symptoms gradually disappeared and returned to normal; there was also fever in the recovery period, and it improved after 2 to 3 days. Complications are more common in renal dysfunction.

2. Laboratory examination

Take the stool for hanging drop test, such as the rapid movement of bacteria, can be inhibited by specific anti-serum, usually within 2 to 5 minutes to make a diagnosis, but the diagnosis still needs to be cultured. Peripheral blood leukocytes and hemoglobin can be elevated by dehydration.

3. Diagnosis

In addition to epidemiological history and clinical manifestations, stool suspension test and culture can help diagnose. Clinical needs are differentiated from food poisoning and bacillary dysentery.

4. Treatment

(1) Mainly infusion and supplemental electrolytes. Light and moderate patients can take oral rehydration (20g of glucose per 1000ml, NaCl 3.5g, NaHCO3 2.5g and KCl 1.5g), a small amount of multiple doses, the rehydration rate can be calculated according to the amount of vomiting and diarrhea. Severe cases require internal venous catheter rehydration. These patients are often difficult to find blood vessels. They can be infused through the femoral vein or subclavian vein. The speed depends on the patient's dehydration. You can enter 50-100ml per minute. When the blood pressure rises, the pulse is powerful and then slows down.

(2) Antibiotics can be taken orally with tetracycline 0.5g, 4 times / d, for 3 days. It can also be intravenously infused with 1g/d, and other doxycycline or TMPco is also effective.

(3) As there are few diseases in China, once it is found that in addition to active treatment, isolation and reporting are required to control the spread of the disease.

(5) Typhoid fever and paratyphoid fever

Acute infectious diseases caused by Salmonella typhimurium and paratyphoid A, B, and C. The incidence of typhoid bacillus is higher, and paratyphoid fever is second. The pathological changes and clinical symptoms of typhoid and paratyphoid are very similar and difficult to identify, mainly by bacterial culture and serology. Patients and carriers are the source of infection. Feces containing typhoid bacilli can contaminate water or food and can cause epidemics. Bacteria enter the human body through the mouth, some are not killed by gastric acid into the small intestine, and grow in the intestinal mucosa and mesenteric lymph nodes. Salmonella typhimurium (or paratyphoid bacillus) and its toxins invade the blood circulation through the lymphatic vessels, causing the first transient bacteremia, and the patient has clinical symptoms. Thereafter, the bacteria are engulfed by the reticuloendothelial cells in the liver, spleen, bone marrow, and lymph nodes, and re-invade the blood circulation after breeding therein, resulting in a second long bacteremia. At this time, the symptoms of clinical poisoning are aggravated, and a large number of typhoid bacilli are discharged to the small intestine with bile, and then enter the intestinal lymphoid tissue to form the hepatic and intestinal circulation. The intestinal lymphatic tissue lesions are aggravated, and complications such as ulcers, hemorrhage and perforation can occur.

Clinical manifestation

The incubation period is 7 to 14 days, and the symptoms can be divided into four phases.

1 Initial: Slow onset, mainly fever, headache, fatigue, body temperature gradually increased, visible rose rash, splenomegaly and relatively slow pulse.

2 pole phase: in the second week of onset, the body temperature showed heat or relaxation heat, ambiguity, hearing loss, lethargy or paralysis, check thick and greasy tongue, abdominal distension, hepatosplenomegaly, and relatively slow pulse.

3 remission period: for the third to fourth week of the disease, a small number of symptoms of poisoning, continue to high fever, intestinal bleeding or intestinal perforation. Most patients have gradually decreased their body temperature and their symptoms improved.

4 recovery period: normal body temperature, sweating, and appetite is getting better. At present, typhoid fever in China is often not typical, and the symptoms of clinical manifestations of poisoning are mild. Relatively slow veins and rose rash are also rare, which may be related to antibiotics in the early stage of the disease. There is recurrence and re-ignition in typhoid fever. Recurrence refers to the typhoid bacillus that lurks in the body after the body temperature returns to normal. The cause of recurrence is not clear and may be related to abnormal immune function. Reburning refers to a decrease in body temperature but not rising to normal. Typhoid fever can also cause toxic myocarditis, toxic hepatitis or demyelinating encephalopathy, and immune complex nephritis.

2. Laboratory examination

The white blood cells are normal or decreased, the eosinophils are reduced or disappeared, and the urine has a small amount of protein and cast. The blood culture has the highest positive rate at the first weekend. It is best to take blood before the antibiotics, and the urine and feces culture have more positive chances in the third to fourth weeks of the disease. The blood-fat reaction cell "O" antibody 1:160 (microdrop method) has diagnostic significance; the flagellar "H" antibody titer can be affected by past typhoid infection or injection vaccination, for reference only.

3. Diagnosis

Typical typhoid diagnosis is not difficult, but for some atypical or mild typhoid, sometimes rely on serology and blood culture results to help diagnose.

4. Treatment

In addition to general supportive therapies including cooling, antispasmodic and infusion, the preferred antibiotic is still chloramphenicol 1 ~ 1.5g / d, divided intravenous infusion, body temperature after normal reduction, treatment for about 10 days. For patients with low white blood cells, ampicillin 4 ~ 6g / d can be used, divided into intravenous infusion. Oral TMPco and aminoglycosides such as Qingda or amikacin intramuscular injection, other penicillin 0.4g, 3 times / d orally, norfloxacin 0.2 ~ 0.4g, 3 times / d orally. Carriers can be treated with oral TMPco, amoxicillin or norfloxacin.

5. Prevention

The patient's stool should be disinfected with 20% bleach and poured into the septic tank. After contact with the patient, pay attention to the disinfection of the hands, soak for 1min in 0.2% peracetic acid. For those engaged in the catering industry, regular fecal culture should be carried out to detect the carriers in the early stage. It is best to vaccinate 3 times (0.5, 1.0, 1.0ml subcutaneous) for outings or going to an infected area with typhoid fever, each time between 7 and 10 days, and then every 2 to 3 years.

(6) Salmonella infection

It refers to Salmonella infections of non-typhoid bacillus, such as Salmonella typhimurium, Enterobacter bacillus and Cholera cholerae. The main source of infection is livestock, poultry and rats, as well as eggs. Because Salmonella can survive for several months in meat with a salt content of 10% to 15%, it can also get sick by eating contaminated meat. In addition, water pollution can cause pollution. It is not always the case that the same contaminated food is involved. It depends on the body condition, the immunity is poor, and the infection is more likely to occur. The production of large amounts of endotoxin by Salmonella in food is an important condition for disease.

Clinical manifestation

Divided into two types

(1) Acute gastroenteritis type: The incubation period can be as short as several hours after eating, also known as food poisoning. Acute onset, chills, fever, headache, body aches, vomiting, diarrhea. The frequency of bowel movements is mostly watery stools, sometimes dehydration and electrolyte disturbances occur. The mild cases have a course of 2 to 4 days, and the severe cases last for more than 1 week.

(2) Typhoid type: the incubation period is the same as typhoid fever, other fever, abdominal distension, hepatosplenomegaly, relatively slow pulse and low white blood cell are similar to typhoid fever.

2. Laboratory examination

Low blood white blood cells, blood, stool, vomit bacteria culture can be found in Salmonella.

3. Diagnosis

It is necessary to pay attention to the identification of other food poisoning, typhoid fever and paratyphoid fever. The key point is that the disease has a history of contaminated food, or an epidemiological history of the majority.

4. Treatment

Acute gastroenteritis type infusion to correct electrolyte imbalance, oral TMPco, amoxicillin, norfloxacin or fluazilic acid, slightly heavier can be given ampicillin 4 ~ 6g / d, divided intravenously, can also be used chloramphenicol Wait.

5. Typhoid treatment is the same as typhoid fever.

(7) Legionella is caused by Legionella pneumophila. In 1976, the United States Veterans Organization held its 58th annual meeting at the Philadelphia Hotel. A pneumonia epidemic broke out among the participants. A total of 149 people were affected. Among the people who had contact with the hotel, 72 people were infected at the same time, and 221 cases were involved. 34 deaths. After 6 months of investigation and research, it was confirmed that the epidemic was related to the cooling tower water source of the hotel. A large number of Gram-negative bacilli were separated from the water. The bacteria floated in the airflow in the hall through the air conditioner, and the susceptible person inhaled and became sick. The bacterium is named Legionella pneumophila and 12 serotypes are known to date. Pontiac fever occurred in July-August 1968 in an unidentified illness in the Health Office building in Pontiac, Michigan, involving 144 people, characterized by fever, headache, and muscle pain. , diarrhea and vomiting, no death, later called Pontiac fever. The retrospectively detected serum of this epidemic found that the antibody titer of Legionella pneumophila increased, which proves that Legionnaires' disease and Pontiac fever are two different clinical manifestations caused by the same pathogen, collectively referred to as Legionella infection.

Clinical manifestation

Pontiac has an incubation period of 1 to 2 days with fever, headache, myalgia, diarrhea and vomiting. The latency of Legionella pneumonia is 2 to 10 days. There are fever, shortness of breath, difficulty in breathing, coughing, wetness in the lungs, and consolidation in the chest. Sometimes it is like flu, gastroenteritis or meningoencephalitis. Individual severe cases may have shock and coma.

2. Laboratory examination

The white blood cells are normal or elevated, and the classification is mainly neutrophils. There may be a small amount of protein and red blood cells in the urine. The detection period of serum indirect fluorescent antibody is 4 times higher than that in the initial stage of the disease, and the antibody is also detected by enzyme immunosorbent assay. Legionella can also be isolated by direct fluoroscopy of the antigen from the sputum smear or by culture of the tracheal aspirate.

3. Diagnosis

Clinical diagnosis is difficult because it is difficult to distinguish it from other lung infections caused by other pathogens, and Pontiac is quite like the flu. Therefore, the diagnosis must be separated by serology or etiology.

4. Treatment

Legionella bacteria can produce -lactamase, which has poor effect on penicillin and cephalosporins. It is best to choose erythromycin 1.2-1.8g/d in divided intravenous drip. Or oral rifampicin 450 ~ 600mg / d. Also useful for gentamicin.

(8) Botox Poisoning Botox is an anaerobic Gram-negative bacillus that lives in the soil of nature or in the feces of livestock. It is divided into 7 types (A, B, C, D, E, F, G). China is mainly based on type A and type B, and is more common in Xinjiang, Tibet and Qinghai. The main cause of the disease is its exotoxin. In contaminated sausages, canned foods, and kippers, bacteria multiply in an anaerobic environment, producing large amounts of exotoxin. Exotoxin is highly toxic, and 1 g can kill people. After eating, the exotoxin can not be destroyed by gastric acid and digestive enzymes, absorbed into the blood through the intestinal mucosa, and enters the nervous system, mainly acting on the neuromuscular junction of the striated muscle. Block the conduction of nerves and develop symptoms. A small number can be caused by wound contamination of botulinum.

Clinical manifestation

The incubation period is 18 to 36 hours, and the elderly are 8 to 14 days. It is inversely proportional to the amount of toxins. Typical symptoms are headache, fatigue, dizziness, and visual impairment. Nervous system spasm occurs within 1 to 2 days of onset, first eyelids appear, blurred vision, eyelid drooping, difficulty swallowing, drinking water and cough. Individuals have gastrointestinal symptoms, showing nausea, vomiting and diarrhea.

2. Laboratory examination

The patient's vomit or feces are cultured under anaerobic conditions to isolate Botox, and toxins can be detected from vomit, contaminated food or wound secretions.

3. Diagnosis

According to the collective or a food contaminated with the same food, there are visual impairment, individual respiratory muscle paralysis, and laboratory tests can make a diagnosis. It needs to be differentiated from other food poisoning and nervous system diseases. Due to wound infection, it should be distinguished from tetanus.

4. Treatment

Use specific anti-toxins, type A, B or E, each type is injected 40,000 to 100,000 u, half of the muscle and vein are used after the skin test is negative, and can be repeated once more after 6 hours if necessary.

For those who eat fast, 5% sodium bicarbonate or 1:4000 potassium permanganate is used for gastric lavage, because the exotoxin is easily destroyed in an alkaline solution, and the virulence is weakened by the oxidant. It can also be used for catharsis such as magnesium sulfate.

For patients with dyspnea, throat or respiratory muscle paralysis, tracheotomy should not be considered, and sputum hydrochloride can be used to promote the recovery of phrenic nerve.

(9) Gram-negative bacilli sepsis

It is common in the large intestine, Cray white, deformation and Pseudomonas aeruginosa, and patients with long-term hospitalization and low hospitalization have a high mortality rate in hospital infections. In the United States, an average of 40 million people are hospitalized each year, and hospital infections account for 5% to 10%, with an average of 2 million to 4 million patients. There was no infection before hospitalization, and it was not an incubation period. An infection occurred 48 hours after hospitalization, which was called a hospital infection. If you transfer from one hospital to another, the hospital stays are added together and calculated over 48 hours. The incidence of nosocomial infections is directly related to the date of hospitalization, and the long-term hospitalization rate is high. Regardless of how strict the infection control measures are in the hospital, infections still occur because some bacteria are intrinsic, especially those with primary disease and low immune function.

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