Bacillary dysentery in children

Introduction to pediatric bacterial dysentery Bacterial dysentery is referred to as bacillary dysentery. The pathogen is Shigella, also known as dysenteriae. The disease is a small intestinal infectious disease in children. It is characterized by fever, abdominal pain, diarrhea, pus and bloody stools, and urgency. Toxic bacillary dysentery is one of the most important clinical types, with frequent seizures, shock, respiratory failure, and prone to death. basic knowledge The proportion of illness: the probability of illness in infants and young children is 2.3% Susceptible people: children Mode of infection: digestive tract spread Complications: diarrhea, malnutrition, rickets

Pediatric bacillary dysentery

(1) Causes of the disease

Pathogen

Is a dysentery bacillus, belongs to the genus Shigella of Enterobacteriaceae, is Gram-negative, aerobic, no flagella, can not exercise, no capsule, no spore-forming bacilli, length of about 1 ~ 3m; water can survive for 5 to 9 days It can survive for 10 days in food. It is extremely sensitive to sunlight. It will die after 30 minutes of irradiation. At 60%, it will be killed immediately at 100 °C. In low temperature and humid place, it can survive for several months. , fruits, foods and contaminated items can survive for 1 to 2 weeks, using benzalkonium bromide (new chlorhexidine), bleaching powder, peracetic acid, lime milk, to Sushui can kill it, in 37% culture The substrate was well grown, and pure culture was obtained by using deoxycholate SS medium and eosin methylene blue medium, and the positive rate was higher with xylose lysine deoxycholate agar medium.

2. Grouping

According to the structure of the bacterial O antigen, it can be divided into four groups: A, B, C, and D. The group is further divided into 47 serotypes (including subtypes):

(1) Group A: Shigella, which is not fermented with mannitol, has no ornithine decarboxylase, and has no serological association with other groups. This group has 1 to 12 serotypes, group A. Type 1 is Shigella, Type 2 is Schmitz, and the rest is Shigella dysenteriae.

(2) Group B: Flexner, fermented mannitol, no ornithine decarboxylase, cross-agglutination between the various types, 13 serotypes (including subtypes and varieties).

(3) Group C: It is Boydii, fermenting mannitol, and has ornithine decarboxylase. There is no cross-aggregation between the various types, and there are 1 to 18 serotypes.

(4) Group D: Sonne, S. mannitol, fermented mannitol, ornithine decarboxylase, slowly fermented lactose, only one serotype, but in recent years, according to its ability to ferment lactose can be divided into two, According to its ability to produce colicin, it can be divided into 16 types.

3. Popular bacteria

Shigella has a large number of bacteria. Before the 1940s, group A was the main epidemic. In the early 1960s, it almost disappeared, but it suddenly broke out in Central America from 1969 to 1970. In 1972 to 1978 in South Asia, Bangladesh. The country has been popular in successive years, followed by India, Sri Lanka, Nepal, Bhutan, Myanmar, Thailand, etc., Group B has dominated in developing countries since the 1950s, and Group D has been in many developed countries since the 1960s. Among the 2,274 dysentery strains collected in 14 provinces and cities in China in 1984, B group accounted for 65.8%, followed by D group 25.1%, A1 group and C group accounted for 8.3% and 0.8% respectively. Group B and group D are still the main strains popular in Beijing from 1980 to 1992. In children, group D is more than group B. From 1986 to 1988, 113 children of dysentery bacillus were detected in children under 5 years old in the 7 provinces of maternal and child health demonstration counties. In group B, Freund's type 1, 2 is the most common account of 72.6%, followed by group D (Song) accounting for 11.5%, group A (Shiga) accounting for 5.3%; in the same period, children under 5 years old in Beijing detected dysentery bacillus 66 Strain, D group (in Song) most commonly accounted for 66.6%, B group (Fish) followed by 28.8%, C group (Bao) accounted for 4.5%, no A was found Group (Shigella).

4. Research on drug resistance

In recent years, studies at home and abroad have shown that the resistance of dysentery bacilli to various antibacterial drugs is increasing. Due to the different antibacterial drugs used in different places, the drug resistance reported in different places is also different. In 1988, the Capital Institute of Pediatrics took the lead in 7 provinces. Drug resistance monitoring showed that the resistance rate to tetracycline was 71.1%83.6%, sulfonamide 54.4%74.8%, chloramphenicol 33.9%35.8%, furazolidone ()53.6%100%, ampicillin ( Ampicillin) 49.1%-97.1%, the following antibiotics maintained a low resistance rate, gentamicin 29.2% ~ 32.9%, polymyxin E 20%, amikacin (butylamide kanamycin) 12.7% ~5.2%, kanamycin 21.2% ~ 33.6%, due to the application of neomycin in recent years, the resistance rate has dropped to 12.0% ~ 17.9%, quinolones have a good effect on intestinal pathogens, according to Beijing 302 The drug resistance test results in the hospital, the drug resistance rate is very low, pipermic acid 3.9% to 5.7%, norfloxacin 4.1%, enoxacin (fluidic acid) 0.7% to 0.9%, ciprofloxacin is 0, In recent years, due to the application, the resistance of quinolones has increased, the resistance rate of norfloxacin has increased to 26.5% to 39.5%, and ciprofloxacin has increased to 9.8% to 1 2%, the quinolone drug is still the drug of choice, and it is stable and moderately sensitive to diarrhea berberine. It has synergistic effect with other antibiotics to reduce drug resistance. The third generation cephalosporin has more Good sensitivity.

(two) pathogenesis

Pathogenesis

All Shigella bacilli can produce endotoxin, Shigella can also produce exotoxins. The above several dysentery bacilli can cause common and poisonous dysentery in clinical practice, identify the serotype of pathogens, help to trace the source of infection, and spread the route. And to judge the prognosis, but also contribute to the selection of antibacterial drugs.

After the dysentery enters the gastrointestinal tract by mouth, it must break through the defense of the gastrointestinal tract to cause disease. The dysentery bacterium has strong acid resistance, so it is easy to invade the intestine through the stomach, and it will quickly multiply in the alkaline environment of the intestinal fluid. Its own invasiveness directly invades and reproduces in the intestinal mucosal epithelial cells, then enters the lamina propria and continues to multiply, and causes inflammation of the colon. The dysentery bacterium is engulfed by phagocytic cells in the lamina propria, and a small amount of dysentery bacteria reaches the mesenteric lymph nodes. It is quickly eliminated by the mononuclear phagocytic system, and dysentery bacilli septicaemia is extremely rare.

2. Pathophysiological changes

In addition to the inflammation of the colon tissue, it can cause microcirculation disturbance of the lamina propria, degeneration and necrosis of epithelial cells, formation of superficial ulcers, resulting in abdominal pain, diarrhea, urgency and heavy, mucus and pus and blood.

(1) acute bacillary dysentery: acute dysentery often affects the entire colon, with the sigmoid colon and rectum most prominent. In severe cases, it can affect the lower ileum, mainly exudative inflammation, which can be divided into:

1 Congestive edema: catarrhal inflammation at the beginning, manifested as mucosal and submucosal hyperemia, edema and neutrophil infiltration mucus secretion increased, further developed into a large amount of fibrinous exudate covering the surface, followed by mucosal surface tissue and The exuded cells are necrotic, and the two are fused to form a gray-white sable-like attachment, which is a pseudomembrane. In the residual mucosa of the pseudomembrane, the blood vessels are dilated and congested, and there are many neutrophil infiltration, and the submucosa is extremely hyperemic. Edema.

2 ulcer formation period: mucosal epithelial pseudomembrane shedding after the formation of ulcers, this ulcer is generally small area, superficial, irregular edges, although invading into the submucosa, but rarely invade the muscle layer, so does not cause perforation.

3 ulcer healing period: As the treatment and the body's resistance increase, the inflammation dissipates, the ulcer gradually heals, and the small ulcer can heal through the regeneration of the mucosal epithelium. The large ulcer heals through the fibrous connective tissue hyperplasia to form a scar, and sometimes the mucosa proliferates around the scar. Polyps are presented. Intestinal lesions vary with the flora of the infection. The acute atypical sputum is not obvious, the lesions are mild, and some are only congestive edema of the intestinal mucosa.

(2) Pathological changes of chronic bacillary dysentery: the rectum is the most common in the rectum, the sigmoid colon, followed by the ascending colon and the lower ileum. The thickening of the intestinal mucosa can also form ulcers. The ulcer often prolongs and heals, sometimes it gradually heals, but because of ulcers Large area, can form a concave scar, surrounded by polyps, sometimes scar tissue contraction, can cause intestinal stenosis, some ulcers are not completely healed, mucous cysts can be seen on the mucosa, and the dysentery can be continuously discharged from the cyst. Repeat the disease.

Pediatric bacillary dysentery prevention

Prevention of dysentery should fully mobilize the masses, carry out extensive health education, and take comprehensive preventive measures: strengthen the health management of children, pay attention to personal hygiene, care for people and children before and after meals, wash hands with soap, improve drinking water hygiene, prevent water sources Contaminated, do not drink raw water, strengthen the management of manure, the patient's feces should be soaked with 1% bleaching powder or poured with boiling water or sprinkled with quicklime before being poured into the sewer or septic tank. The diapers and underpants of the sick children should be cooked or used. After soaking in boiling water, wash it again, strengthen the food hygiene, do not eat spoiled food, eat raw fruits and wash, strengthen environmental sanitation, kill fly, kill cockroaches, food storage should be covered to prevent insect pollution, for patients to find early, early diagnosis Early isolation and early treatment are the key to controlling the epidemic of dysentery. For atypical children, asymptomatic carriers (rare in childhood) and chronic dysentery are important sources of infection. Early detection, isolation, and treatment must be taken care of. Acute dysentery turns into a chronic cause, such as rickets, malnutrition and other complications should be treated in a timely manner.

For the cooks of the collective children's institution, the nurses should regularly check the feces and, if necessary, do bacterial culture, and find that the carriers should be treated in time.

Pediatric bacterial dysentery complications Complications, diarrhea, malnutrition, rickets

Children with acute dysentery such as vomiting, severe diarrhea, can be complicated by water and electrolyte disorders (dehydration, acidosis, low potassium, low sodium, low calcium, etc.), chronic dysentery has more complications, mainly malnutrition and Caused by low immune function, the most common are malnutrition and dystrophic edema, lack of multivitamins and trace elements, manifested as dry eye disease, malnutrition anemia, rickets, severe cases of beriberi and scurvy, The latter is rarely seen in China. Intestinal ulcers can cause massive intestinal bleeding. Frequent diarrhea can cause rectal prolapse. Prolonged use of antibiotics can cause intestinal flora disorder or fungal infection. Individual severe malnutrition children Intestinal ulcers can not be repaired for a long time, and intestinal perforation can occur.

Symptoms of bacterial dysentery in children Common symptoms Diarrhea, nausea, loss of appetite, fatigue, mucus, loose stools, severe abdominal pain, high fever, low fever

Incubation period

It ranges from a few hours to 8 days, most of which are 1-3 days.

2. Clinical classification of bacterial dysentery

According to the course of the disease and the condition, it can be divided into acute bacillary dysentery, chronic bacillary dysentery and poisoning dysentery. Due to the special case of poisoning sputum sputum, the following is a general discussion of acute bacillary dysentery and chronic bacillary dysentery.

(1) Acute bacterial dysentery:

1 typical dysentery: typical cases of acute onset, fever, body temperature is low fever or high fever, diarrhea, stool 10 to 30 times a day, feces with mucus and pus, nausea, vomiting, paroxysmal abdominal pain, mild tenderness in the abdomen, sometimes The left lower abdomen can touch the sigmoid colon intestines, and the bowel sounds are hyperthyroidism. After the urgency, the patient feels weak and the appetite is diminished. Infants and young children sometimes have febrile seizures. Most children with acute dysentery can be treated with reasonable treatment within a few days. Gradually relieved and healed, the prognosis is good, the stools of older children are quickly formed, and infants and young children can continue to be loose for several days, which is related to the slow recovery of intestinal function in infants and young children.

2 atypical dysentery: no fever or only slight heat, no symptoms of poisoning, mild diarrhea, loose stools, only mucus in the stool without pus, only the stool culture is positive to confirm the diagnosis, in the epidemic, the number of such cases may exceed The typical number of cases, because it is similar to general enteritis, is easily overlooked and often becomes a spreader of dysentery.

(2) Chronic bacillary dysentery: Chronic dysentery is called more than 2 weeks, and chronic dysentery is more than 2 months. The cause is mainly due to physique, malnutrition, rickets or anemia, or because of this. The sick children are not treated properly, because the course of disease is long, they are getting thinner, the stool contains a lot of mucus, not necessarily with pus, or the mucus and pus and blood will alternate, the feces can still produce dysentery, but the positive rate is significant Less acute dysentery, children with chronic dysentery, such as severe malnutrition, are prone to some crises, sick children may be due to electrolyte imbalance (low sodium, low potassium, low calcium), severe myocardial damage and accidental death, such diseases Children are rarely seen in China, but it is often seen in other developing countries. Sometimes symptoms of acute dysentery suddenly increase, showing an acute attack.

Examination of bacterial dysentery in children

1. Blood routine examination In the acute, the total number of white blood cells, neutrophils increased, chronic mild anemia.

2. Fecal examination

(1) Fecal routine: appearance of mucus and pus and blood, see more red, white blood cells, and phagocytic cells under the microscope.

(2) Fecal culture: About 70% of the bacteria can be cultured. The pus and blood part of the feces should be cultured before applying antibiotics. The specimens should be fresh, and the positive ones should be tested for drug sensitivity.

(3) Detection of fecal bacterial antigen: using fluorescent antibody staining method, immunofluorescence surface method, latex agglutination test, synergistic agglutination test, direct PCR detection method, etc., is a rapid, sensitive and simple diagnostic method.

Sigmoidoscopy and barium enema X-ray examination, generally used for chronic dysentery.

Diagnosis and diagnosis of bacterial dysentery in children

diagnosis

Common sputum sees pus and blood, the diagnosis is not difficult, should pay attention to the following points to help diagnose:

1. Summer and Autumn Festival: Summer and autumn diarrhea with fever, feces with mucus pus and blood.

2. History of exposure: Patients with dysentery have recently been arrested at home or in the same room.

3. Stool examination: Beijing standard: Each high-powered field of view pus cells>15 and see red blood cells, the clinic can diagnose the bacteria and fill the infectious disease card.

4. Fecal culture: Strictly speaking, accurate diagnosis depends on feces culture. Fresh pus and bloody stools should be taken for culture. It is best to inoculate the culture at the bedside. If it can not be done immediately, the specimen can be stored in buffered glycerin saline solution. Send the bacteria room culture as soon as possible, and collect the stool specimen before treatment with antibacterial drugs, which can increase the positive rate of culture.

5. Rapid PCR diagnosis Recently, a rapid PCR diagnosis method has been developed, but multiple specimens need to be collected together for examination, which is not widely used in clinical practice.

Differential diagnosis

Bacterial dysentery is characterized by pus and blood, but the diagnosis of bacillary dysentery is only by pus and blood, and the misdiagnosis rate can reach about 30%, which is most likely to be confused with the following enteritis:

1. Invasive Escherichia coli (EIEC) enteritis: The disease season and the disease are very similar to bacillary dysentery, but also manifested as fever, diarrhea, pus and bloody stools, and also found similar symptoms of poisoning dysentery, identification should be based on fecal culture, Culture results: dysentery bacillus was negative, Escherichia coli was found, and the Escherichia coli droplets were injected into the conjunctival sac of guinea pig eyes for 24 hours. If the guinea pig conjunctival hyperemia had an inflammatory reaction, the invasive Escherichia coli could be diagnosed. Bacillus.

2. Campylobacter jejunum enteritis: The disease season and clinical process are similar to bacillary dysentery, more common in children over 3 years old, symptoms of fever, diarrhea, first loose stools, can be expressed as pus and bloody stools, similar to dysentery, identification needs to be based Fecal culture, using a micro-aerobic 43 ° C culture method, can be cultured Campylobacter jejuni.

3. Salmonella enteritis: It is more common in small babies and diversified in feces. It begins with loose stools. It can be expressed as mucus, pus and blood, and is easily misdiagnosed as bacillary dysentery. The first age of onset is different. The dysentery is more common in 3 years old. The above children, small infants are rare, accurate identification needs to be based on fecal culture.

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