Shriveled fingerprints

Introduction Cholera (cholera) is a potent intestinal infectious disease caused by Vibrio cholerae. It is an acute and rapid spread. It is an important cause of diarrhea in most parts of Asia and Africa. It is an international quarantine infectious disease. In China, it belongs to Class A infectious diseases. Typical patients can cause dehydration, muscle spasm due to severe diarrhea and vomiting, and severe peripheral circulatory failure and acute renal failure. Generally speaking, it is more common in mild cases, and there are more carriers, but severe cases and typical patients can cause death if not treated in time. The performance is thirsty, the eye socket is deep, the voice is hoarse, the abdomen sinks into a boat, the skin shrinks, the fingerprint folds, the severe gastrocnemius and rectus abdominis tendon, blood pressure drops, oliguria or anuria, unconsciousness.

Cause

(1) Causes of the disease

Classification

The pathogen of cholera is Vibrio cholerae, a moving, curved, curved Gram-negative bacterium. According to the cell wall surface antigen component, the pathogen is divided into 139 serogroups, of which only O1 and O139 can cause cholera epidemics. The WHO Diarrhea Control Center divides Vibrio cholerae into three groups based on the biochemical traits of Vibrio, specificity and pathogenicity of O antigen.

(1) O1 group Vibrio cholerae: including the classical biotype Vibrio cholerae classical (CVC) and Vibrio cholerae E1 Tor biotype (EVC). The former is a Vibrio isolated from the patient's feces in the 19th century; the latter is the Vibrio hemolyticus found in the quarantine station in El Tor, Egypt, in the early 20th century. This group of Vibrio cholerae is the main pathogen of cholera.

(2) Non-O1 group Vibrio cholerae: The group of Vibrio flagella antigens is the same as the O1 group, while the bacteria (O) antigens are different, and are not agglutinated by O1 group Vibrio cholerae multivalent serum, also known as non-aggregation arc Non-agglutinable group vibrio (NAG vibrio). According to the O antigen, the Vibrio can be divided into 137 serogroups (ie O2O138), some of which can produce toxins like cholera enterotoxin, while others produce heat-resistant enterotoxin similar to Escherichia coli. A small number of serogroups can also cause gastroenteritis. In the past, non-O1 Vibrio cholerae was thought to cause only gastrointestinal inflammatory diarrhea, which did not cause outbreaks. Therefore, such Vibrio infections were not treated with cholera.

However, in 1992, cholera outbreaks occurred in India and Bangladesh. It was confirmed that this epidemic group was not agglutinated by O1 Vibrio cholerae and 137 non-O1 Vibrio cholerae diagnostic sera, not the 138 serums previously confirmed. Group, but a new serogroup. Shimada et al. named O139 Vibrio cholerae and thought it might replace O1 Vibrio cholerae in countries around the world, especially in Asia, Africa, Latin America and regions. These epidemics may mark the beginning of the eighth cholera pandemic. . The O139 cholera vibrio has only one serotype. Since the new strain isolated is from the city along the Bay of Bengal, it is also known as the Bengal type. These names have been recognized by the International Center for Diarrheal Disease Research.

Recently reported, O27, O37, O53 and O65 serogroups have O1 gene backbones, each of which has different pathogenic genes. O53 and O65 have a cluster of pathogenic genes of El Torque, and non-O1 non-O139 serum. The potential pathogenicity of the population suggests that attention should be paid to these serogroups that may lead to new cholera outbreaks in the future.

(3) Atypical O1 Vibrio cholerae: This group of Vibrio cholerae can be agglutinated by multivalent O1 group serum, but this group of Vibrio does not produce enterotoxin in vivo and in vitro, so there is no pathogenicity.

2. Morphology and dyeing

Vibrio cholerae is negative for Gram staining and is curved or punctate. Generally, it is 1.5-3.0 m long and 0.3-0.4 m wide. There is a flagella at the end of the bacteria, and the movement is lively. The shuttle-like movement can be seen in the dark field. The direct smear of the patient's stool shows that the Vibrio column is "fish". O139 Vibrio cholerae is a Gram-negative Vibrio, which does not have the typical characteristics of 138 serogroups of non-O1 Vibrio cholerae. The bacterium is 2 to 3 m long and 0.5 m wide, and has a flagella at one end.

3. Culture characteristics

Vibrio cholerae grows well in common medium and belongs to facultative anaerobic bacteria. It grows and grows quickly in an alkaline environment. Generally, 1% alkaline protein water with a pH of 8.4 to 8.6 is commonly used for enrichment culture, which can inhibit the growth of other bacteria. O139 Vibrio cholerae can grow in water without sodium chloride and 30 g/L sodium chloride peptone, but not at 80 g/L sodium chloride concentration. The colonies were yellow on the thiosulfate citrate bile salt sucrose agar medium (TCBS) plate, and the colonies were light gray on the TTG plate with black hearts in the colonies.

4. Biochemical reaction

O1 Vibrio cholerae and atypical O1 Vibrio cholerae can ferment sucrose and mannose without fermenting arabinose. Non-O1 Vibrio cholerae has different fermentation conditions for sucrose and mannose. In addition, the Elto biotype decomposes glucose to produce methyl acetate (ie, the VP test). O139 Vibrio cholerae can ferment glucose, maltose, sucrose and mannose, produce acid without gas, and not ferment inositol and arabinose. The oxidase test and gelatin test were positive, the sputum matrix test was positive, and the results of sheep erythrocyte hemolysis test were uncertain (/-), for polymyxin (50u), compound sulfamethoxazole, azole and DADP (deoxyadenosine diphosphate) ( 50 and 150 g) insensitive, positive for chicken red blood cell agglutination test, insensitive to IV and V phage of O1 Vibrio cholerae Murkherjee.

5. Antigenic structure

Vibrio cholerae has a thermotolerant bacterial (O) antigen and a thermolabile flagellum (H) antigen. H antigen is shared by Vibrio cholerae; O antigen is highly specific, and there are two antigens of group specificity and type specificity, which is the basis of Vibrio cholerae grouping and typing. The group has more than 100 specific antigens. The specific antigens of the O1 group Vibrio type are A, B, and C. Among them, the A antigen is shared by the O1 group Vibrio, and the A antigen combined with other B or C antigens can be divided into three types.

Ogawa type (Ogawa) contains AB antigen; rice leaf type (prototype, Inaba) contains AC antigen; Yanda type (intermediate type, Hikojima) contains three antigens of A, B, and C. The BC antigen contained in Vibrio cholerae can be transformed into each other by the variation of Vibrio, for example, the Ogawa type and the rice leaf type can be transformed with each other. The O139 group of Vibrio cholerae did not cross-agglutinate the multivalent diagnosis serum of Vibrio cholerae O1, and did not react with the monoclonal antibodies specific to the O1 group Vibrio cholerae specific for A, B and C factors. Vibrio cholerae can produce enterotoxin, neuraminidase, hemagglutinin, and endotoxin can be released after cell lysis. Among them, cholera toxin (CT) can be produced in classical type, Elto biotype and O139 Vibrio cholerae, and it is difficult to distinguish between them. CT is a thermolabile toxin that is destroyed at 56 ° C for 30 min. It is synthesized in the log phase of Vibrio and released in vitro.

The antigenic specificity of Vibrio cholerae O1 and non-O1 Vibrio cholerae enterotoxin is approximately the same. CT is a multimeric active protein that is non-covalently bound by two subunits. The molecular weight of A subunit is 27.2×103, consisting of 240 amino acids, containing 18 amino acid signal peptides, which are enriched by proteolytic enzymes during maturation. A1 (having a molecular weight of 21.8 x 103, composed of 194 amino acids) and A2 (having a molecular weight of 500, composed of 53 amino acids) are linked to each other by a disulfide bond. The B subunit has a molecular weight of 11.6×103 and is composed of 103 amino acids, and its secretion signal peptide is 21 amino acids. CT-B consists of five oligomers containing six peptides (CTP1-CTP6, of which (CTP3 has important biological activity). Enterotoxin is immunogenic, non-toxic cholera enterotoxin obtained after formaldehyde treatment Known as choleragenoid, it is an antibody against CT that is produced by immunizing the human body. Neuraminidase is an enzyme in the secreted polysaccharide complex of Vibrio cholerae, and its activity is regulated by neuraminidase. The antibody IgG is neutralized, the neuraminidase structure gene product has a molecular weight of 76×103, and the N-terminal has 24 amino acid secretion signal peptides. It is presumed that its function is to promote the binding ability of CT to the receptor, thereby improving the virulence of the bacterial strain. .

Hemagglutinin is divided into two types according to the arrangement pattern, one is connected to cells, the other is soluble hemagglutinin (SHA), and the refined SHA is filamentous polymer under electron microscope, which is a zinc-containing polymer. Ionic metal endopeptidase, whose activity is inhibited by the chelate zincor (inhibition of oxyacid derivatives containing zinc protease activity), during the recovery period, the patient's SHA titer can be increased, and the antibody specifically inhibits Vibrio cholerae Hemagglutination and adhesion, but does not show protective effects on animals, but also kills Vibrio activity. Vibrio cholerae can produce hemolysin, Elt type produces heat-labile hemolysin, molecular weight is 20×103, it is a monomeric protein. Besides hemolytic activity, it also has cytotoxicity, heart toxicity and lethal toxicity. Vibrio cholerae has a pili structure, classical strains have three kinds of pili, A, B, and C, and Elt type produces only type B and C pili. The expression of type A pili is simultaneously affected by Vibrio cholerae enterotoxin. ToxR regulation, named toxin coregulated pilus (Tcp). Tcp fimbriae gene synthesis involves at least nine genes involved in the production of Tcp synthesis enzymes, from Tcp A ~ Tcp I, mainly Tcp A, Tcp G and settlement, known as "settling factor." Tcp B, Tcp I is involved in protein regulation, and Tcp H is a protein that determines the length of the pili. The role of other genes is still under investigation.

O139 serogroup Vibrio cholerae produces toxins similar to cholera enterotoxin (CT) produced by O1 Vibrio cholerae, O139 serogroup Vibrio cholerae and specific et gene probes and ZOT genes isolated from O1 cholera The result of the hybridization of the needle was positive. However, the hybridization with the heat-resistant enterotoxin (ST)-specific gene probe isolated from non-O1 Vibrio cholerae was negative. The O139 serogroup Vibrio cholerae produced a cholera-like toxin yield of 80 ng/ml or higher. It can be neutralized by specific IgG antibody and anti-CT polyclonal antibody. The effect of this cholera-like toxin on YI adrenal cells is consistent with CT. Using CT gene operon-specific primers, PCR can be used from O139 Vibrio cholerae strains. The toxin gene is amplified in the genome. The cholera-like toxin can cause intestinal effusion in the intestine ligation test in rabbits, producing watery diarrhea similar to O1 Vibrio cholerae.

6. Resistance

Vibrio cholerae is sensitive to drying, heating and disinfectants. Generally boiled for 1 to 2 minutes to kill. A 0.2% to 0.5% peracetic acid solution can be killed immediately. It can only survive for 5 minutes in normal gastric acid. However, it takes longer to survive in the natural environment. For example, Elto vibrio cholerae can survive for 1 to 3 weeks in rivers, rivers, wells or seawater, and can survive for 1 to 2 weeks in fish, shrimp and shell foods. . Islam believes that Vibrio cholerae O139 survives in water longer than O1 Vibrio cholerae. After detailed research, Albert synthesized the pathogenic features of Vibrio cholerae O139 as follows:

1 is Gram-negative Campylobacter, size (2 ~ 3) m × 0.5 m, single-ended flagella.

The 2O1 group of Vibrio cholerae antiserum could not be braked.

3 Colony yellow on TCBS plate, gray on TTG A, opaque, black at center.

4 oxidase, gelatinase test positive.

5 fermented glucose, malt extract, sucrose, mannose, but not gas, do not ferment inositol and arabinose; 6 lysine, ornithine dehydrogenase positive, arginine dehydrogenase negative.

7 can produce .

8 grows without sodium chloride or 3% sodium chloride, but does not grow under 8% sodium chloride.

9 Hemolysis of sheep red blood cells, chicken red blood cell agglutination test was positive.

10 pairs of polymyxin B, compound sulfamethoxazole and p-chlorobenzene (O139 Vibrio cholerae inhibitors, 10g and 150g), not mutated to Murkherjee and V phage; ? to tetracycline, ampicillin , erythromycin, ciprofloxacin sensitive.

7. Vibrio cholerae typing

The most widely used typing method is O serotyping. At present, Vibrio cholerae has been divided into 155 serogroups according to different O antigens. Only O1 group CVC, EVC and O139 groups can cause pandemics, mainly because they contain virulence factors such as CT and pili, respectively, by CT gene clusters. And the virulence gene coding such as TCP, the difference between the epidemic strain and the non-epidemic strain lies in the difference in virulence (the epidemic strain must be a virulent strain). Both O1 and O139 can produce cholera enterotoxin and contain corresponding virulence genes, which can cause cholera epidemics. It has been found that more than 99% of the non-O1 and non-O139 strains do not contain virulence genes such as CT and TCP, but there are still very few non-O1 and non-O139 groups containing the above virulence genes.

(two) pathogenesis

Pathogenesis

Whether the human body is infected with Vibrio cholerae depends on the immunity of the body and the amount of Vibrio ingestion. If the human body can secrete normal gastric acid and is not diluted, it can kill a certain amount of Vibrio cholerae without disease. If oral live vaccine is used, the presence of specific IgM, IgG and IgA antibodies in the intestine can also prevent Vibrio from adhering to the intestinal wall without disease. However, if most of the stomach is removed to reduce gastric acid secretion, or a large amount of drinking water, a large amount of food to dilute the stomach acid, or the amount of Vibrio cholerae ingested more than 108 to 109, can cause disease. After reaching the intestine through the stomach, Vibrio cholerae passes through the flagellar movement and the protease produced by Vibrio, passes through the mucus layer on the intestinal mucosa, and adheres to the upper part of the small intestine under the action of Tcp A and Vibrio cholerae hemagglutinin (HA). The intestinal mucosal epithelial cells do not invade the intestinal mucosa on the brush border.

Vibrio cholerae multiplies in the alkaline environment of the small intestine and produces cholera enterotoxin. When enterotoxin is contacted with the intestinal mucosa, its B subunit recognizes and binds to receptors on intestinal mucosal epithelial cells, which are gangliosides. The enzymatically active A subunit enters the intestinal mucosal cells, wherein the A subunit can transfer ADP (adenosine diphosphate) ribose from the nicotinamide adenine dinucleotide (NAD) to the target protein guanosine triphosphatase. Medium (GTPase), combined with it, inhibits GTPase activity, resulting in the continuous activation of adenylate cyclase, which continuously converts adenosine triphosphate into cyclic adenosine monophosphate (cAMP). When the intracellular cAMP concentration is increased, the intestinal mucosal crypt cells are stimulated to excessively secrete water, chloride and carbonate. At the same time, it inhibits the absorption of sodium ions and chloride ions by intestinal villus cells, causing water and sodium chloride to accumulate in the intestinal lumen, thus causing severe watery diarrhea (Fig. 1).

Cholera enterotoxin can also promote the secretion of mucus in the goblet cells of the intestinal mucosa, so that the diarrhea water sample contains a lot of mucus. In addition, the loss of water caused by diarrhea, so that bile secretion is reduced, so the diarrhea feces can become "rice water". In addition to enterotoxin, endotoxin and Vibrio cholerae produce hemolysin, enzymes and other metabolites, which also have a certain pathogenic effect.

2. Pathophysiology

(1) Water and electrolyte disorders: In cholera patients, due to severe vomiting and diarrhea, a large amount of water and electrolytes are lost in the body, resulting in dehydration and electrolyte imbalance. Circulatory failure can occur in patients with severe dehydration. If the correct water loss is not timely, the shock time is too long, which can further cause acute renal failure. Although the fluid lost by cholera patients is an isotonic liquid, the amount of potassium contained therein is 4-6 times that of serum potassium. Sodium and chlorine are slightly lower than serum, so when rehydration treatment, potassium should be added in time in the case of urine. Otherwise, severe hypokalemia can lead to arrhythmia; it can also cause degeneration of renal tubular epithelial cells, further aggravating renal failure.

(2) Metabolic acidosis: A large amount of bicarbonate is lost due to diarrhea. In addition, peripheral circulation failure caused by water loss, tissue anaerobic metabolism due to hypoxia, so excessive production of lactic acid can aggravate metabolic acidosis. Acute renal failure, which cannot excrete metabolic acid, is also the cause of acidosis.

3. Pathological anatomy

The main pathological changes of this disease are severe dehydration, and the organ damage is not serious. It can be seen that the skin is dry, the subcutaneous tissue and muscles are dehydrated, and the organs such as heart, liver and spleen are reduced due to dehydration. The glomerular and renal interstitial capillaries are dilated. The renal tubules may have degeneration and necrosis. Non-specific infiltration was seen only in the small intestinal mucosa.

an examination

Related inspection

Vibrio cholerae detection of blood electrolytes

[clinical manifestations]

The incubation period of the disease is several hours, and the elderly are 3 to 6 days, usually 1 to 3 days. The diseases caused by classical biotypes and O139 Vibrio cholerae are more serious; the symptoms caused by El Tortox's Vibrio cholerae are more frequent, and there are more asymptomatic pathogen carriers. A typical patient has a sudden onset of illness. A small number of patients may have symptoms such as dizziness, fatigue or mild diarrhea 1 to 2 days before onset.

1. The stage of the disease, the typical case can be divided into three stages.

(1) vomiting and diarrhea: start with severe diarrhea, followed by vomiting. Generally no fever, only a few have low fever.

1 diarrhea: diarrhea is the first symptom of the onset, characterized by no urgency and heavy feeling, most without abdominal pain, consciously light after defecation. A small number of patients have abdominal pain, and in some cases there may be paroxysmal abdominal cramps. The discharged feces are initially yellow and thin, followed by watery stools, which are more common with yellow water. Severe diarrhea discharges white turbid "rice water" stool. Those who have intestinal bleeding discharge the water-like stool. Those with more bleeding were tar-like, and more common with Erto biotypes of Vibrio cholerae. The number of diarrhea varies from several times a day to dozens of times, and in severe cases, the stool is incontinent.

2 vomiting: generally occurs after diarrhea, without nausea, mostly jet vomiting. The vomit is initially a food in the stomach, followed by a watery sample. In severe cases, it can also vomit the "rice water" sample, which is similar in nature to feces. Lighter can be vomiting.

(2) Dehydration period: due to severe vomiting and diarrhea, a large amount of water and electrolytes are lost in the body, resulting in dehydration, electrolyte imbalance and metabolic acidosis, and severe circulatory failure. The length of the disease in this period depends mainly on whether the treatment is timely and correct. Usually hours to 2 to 3 days.

1 dehydration: can be divided into light, medium and heavy three degrees. Mild dehydration, visible skin mucous membrane dry, skin elasticity is poor, generally about 1000ml of water loss, children 70 ~ 80mL / kg body weight; moderate dehydration, see poor skin elasticity, eye socket depression, mild hoarseness, blood pressure drop and urine output Reduce, lose 3000 ~ 3500ml of water. Children 80 ~ 100ml / kg body weight; severe dehydration, dry skin wrinkles, no elasticity, hoarseness, and visible eyelid depression, cheeks deep, ambiguous or unclear "cholera face". Those who have circulatory failure and acidosis can be life-threatening if they are not actively rescued. For patients with severe dehydration, about 4,000 ml of dehydration and 100 to 120 ml/kg of body weight for children.

2 Circulatory failure: water loss shock caused by severe water loss. Clinical manifestations: When the blood volume is significantly reduced, the extremities are cold, the pulse is fine, and even cannot be touched, and the blood pressure drops or cannot be measured. Then, due to insufficient blood supply to the brain, cerebral hypoxia and disturbance of consciousness, began to be irritated, followed by sluggishness, lethargy and even coma.

3 uremia acidosis: clinical manifestations of increased breathing, severe cases in addition to Kussmaul (Kussmaul) breathing, may have consciousness disturbances, such as lethargy, feeling dull and even coma.

4 muscle spasm: This is vomiting, diarrhea causes a lot of salt loss, severe hyponatremia causes gastrocnemius and rectus abdominis. The clinical manifestations are pain in the ankle area and rigidity of the muscles.

5 hypokalemia: diarrhea causes a large loss of potassium salt, and blood potassium can be significantly reduced. The clinical manifestations are weakened muscle tone, weakened or disappeared knee reflexes, and abdominal distension.

(3) Recovery period or reaction period: diarrhea is stopped. After the dehydration is corrected, the symptoms of most patients disappear, the amount of urine increases, and the physical strength gradually recovers. However, in a few cases, due to the improvement of blood circulation, endotoxin remaining in the intestinal lumen is absorbed into the bloodstream, which can cause fever of different severity. Generally, the patient's body temperature is as high as 38-39 ° C, and it disappears after 1 to 3 days.

2. The clinical type can be divided into light, medium and heavy according to the degree of water loss, blood pressure and urine volume.

(1) Light type: slow onset, diarrhea no more than 10 times / d, for loose or dilute watery stools, generally without vomiting, continuous diarrhea after 3 to 5 days to recover. No significant dehydration performance.

(2) medium (typical): typical diarrhea and vomiting symptoms, diarrhea up to 10 to 20 times / d. For the water sample or "rice water" sample, the amount is large. Therefore, there are obvious signs of water loss. The blood pressure drops, the systolic blood pressure is only 9.31 to 12 kPa (70 to 90 mmHg), the urine volume is reduced, and the urine volume is 500 ml/24 h or less.

(3) Heavy: In addition to the typical symptoms of diarrhea and vomiting, the patient has severe water loss and thus circulatory failure. The pulse is fine or inaccessible, the blood pressure drops significantly, and the systolic blood pressure is lower than 9.31 kPa (70 mmHg) or cannot be measured. The urine volume is 50 mL/24 h or less.

In addition to the above three clinical types, there is a rare type of violent or poisonous type, also known as "cholera sicca". This type of onset is rapid, and there are no symptoms of diarrhea and vomiting, that is, rapid entry into toxic shock and death.

diagnosis

In areas where cholera is endemic, any patients with diarrhea and vomiting during the epidemic season should be suspected of having cholera and cholera screening for cholera. Anyone with typical symptoms should be treated as cholera first.

1. Diagnostic criteria, one of which can be diagnosed as cholera.

(1) There are symptoms of diarrhea, and the culture of feces is positive for Vibrio cholerae.

(2) During the cholera epidemic, there are typical symptoms of cholera diarrhea and vomiting in the affected area, and severe dehydration, circulatory failure and muscle spasms occur rapidly. Although Vibrio cholerae was not found in fecal culture, there are no other reasons to investigate. If the condition can be used as a double serum lectin test, the titer of 4 times increase can be diagnosed.

(3) Those with diarrhea symptoms within 5 days before the fecal culture is found to be positive in the source search can be diagnosed as mild cholera.

2. Suspected diagnosis has one of the following

(1) The first case with typical cholera symptoms, the pathogen examination has not been confirmed before.

(2) During the epidemic of cholera, there is a clear history of contact with cholera patients, and symptoms of vomiting occur, but no other reason can be investigated. Suspected patients should be isolated, disinfected, reported as suspected cholera epidemic, and do fecal culture every day. If the fecal culture is negative for 2 consecutive times, a negative diagnosis can be made and a revised report on the epidemic situation.

Differential diagnosis

First, the identification of bacterial diarrhea

Bacterial diarrhea is generally caused by non-OI group Vibrio and enterotoxin-producing E. coli (ETEC). Most of the former patients had diarrhea with severe abdominal pain and fever; 1/4 of the patients had bloody stools. Diarrhea caused by E. coli is generally short-lived. The identification of both and cholera depends on the pathogen examination.

Second, cholera should be differentiated from various bacterial food poisoning, such as Staphylococcus aureus, Proteus, Bacillus cereus and accessory hemolysis such as Staphylococcus aureus, Proteus, Bacillus cereus and Vibrio parahaemolyticus A variety of food poisoning onset, acute convulsions often occur collectively, often vomiting and diarrhea, there is paroxysmal abdominal pain before defecation, feces often yellow water, occasionally pus.

Third, if part of the feces is washed with water or dysentery, it needs to be differentiated from bacterial dysentery. The latter is often associated with abdominal pain and urgency, and the amount of feces is small.

Fourth, the identification of acute arsenic poisoning. Acute arsenic poisoning is mainly characterized by acute gastroenteritis. The stool is yellow or gray water, often with blood, severe urine output, and even urinary closure and circulatory failure. Checking the arsenic content of feces or vomit can be clearly diagnosed.

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