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A 10- year-old, previously healthy child came to the emergency room for the evaluation of bloody diarrhea and diffuse 弥弥弥 abdominal pain for 24 hours’. His mother said him eaten an hamburger at a fast food restaurant beside the school yesterday. • Your diagnosis are …you must find the child’s…

Your diagnosis are …you must find the child’s…

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A 10- year-old, previously healthy child came to the emergency room for the evaluation of bloody diarrhea and diffuse 弥漫性 abdominal pain for 24 hours’. His mother said him eaten an hamburger at a fast food restaurant beside the school yesterday. Your diagnosis are …you must find the child’s…. - PowerPoint PPT Presentation

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A 10- year-old, previously healthy child came to the emergency room for the evaluation of bloody diarrhea and diffuse 弥漫性 abdominal pain for 24 hours’. His mother said him eaten an hamburger at a fast food restaurant beside the school yesterday.

• Your diagnosis are …you must find the child’s…

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questionsName four genera of enterobacteriaceae that

can cause gastrointestinal disease.Name two genera that can cause hemorrhagic

colitis 出血性结肠炎Name the group of E.coli that can cause

gastroenteritis 胃肠炎what are the forms of salmonella 沙门菌

infection ?

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Suggested reading: your textbookChapters 10 of zhengren zhou

Enteric Bacilli, Vibrio, Campylobacter and HelicobacterEnteric Bacilli, Vibrio, Campylobacter and Helicobacter

EscherichiaShigellaSalmonella

Enteric Bacilli associated with diseassEnteric Bacilli associated with diseass

Suggested reading: your textbookChapters 10 of enjie luo

Suggested reading: your English Textbook Chapters 15-17

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ClassificationClassification~29 genera, over 100 species.

– Escherichia 埃希杆菌属– Shigella 志贺菌 ( 属 )

– Edwardsiella 爱德华 ( 氏 ) 菌属

– Salmonella 沙门氏菌– Citrobacter 柠檬酸细菌属– Klebsiella 克雷白 ( 氏 ) 杆菌属– Enterobacter 肠道细菌 ( 属 )

– Hafnia 哈夫尼菌属– Serratia 灵杆菌 , 粘质沙雷 ( 氏 )

– Proteus 变形菌– Providencia 普罗威登斯菌

– Morganella 摩根 ( 氏 ) 菌属

– Yersinia 耶尔森菌属

– Erwinia 欧文 ( 氏 ) 菌属

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General Information:General Information:

• gram-negative bacilli.

• peritrichous flagella (most)--- motile.

• pili --- associated with attachment.

• non-spore forming.

1. Similar shape

肠外感染株常有微荚膜

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2. culture : EMB agar

contain lactose and two dyes (eosin and methylene blue 亚甲蓝 )

+: purple colonies with green metallic sheen 金属光泽

E. coli -: colorless pathogenic bacteria Salmonella

Shigella

facultative anaerobes. form circular, convex 凸的 , and smooth colonies with distinct edges.

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4. Colonies color

3. Isolated from fecal matter on agar containing lactose and a pH indicator (中性红)

•E. coli ferments lactose

•Shigella, Salmonella and Yersinia are non-fermenters•"Non-pathogenic" strains of E. coli (and other

lactose-positive enterics) are often present in normal feces.

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• Oxidase 氧化酶 test: negative

• They ferment glucose, often with gas

production.

• lactose fermentation is an important test for

differentiating pathogenic enteric bacilli from non-pathogenic strains.

Biochemical reactions -- active and diverse

+ -

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All Enterobacteriaceae isolated from other sites•which contain low numbers of bacteria [e.g. urine],sterile [e.g. blood]• are identified biochemically [e.g. the API 20E system]

Important serotypes can be differentiated by their:

However, serotyping is generally not performed in the Routine 常规 clinical laboratory.

• O (lipopolysaccharide) • H (flagellar) antigens • K (capsular) antigens

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Antigenic StructureAntigenic Structure– Most are motile by peritrichous flagellaMost are motile by peritrichous flagella -- --HH

antigens. antigens.

– Capsule –Capsule – KK antigen antigen (( ViVi for Salmonella).for Salmonella).

– Cell envelope (wall)Cell envelope (wall)

– LPS (endotoxin) –LPS (endotoxin) – OO antigen. antigen.

– various outer membrane proteins.various outer membrane proteins.

– Pili - various antigen types, some encoded by Pili - various antigen types, some encoded by plasmids plasmids

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鞭毛抗原( H )

菌体抗原 (O)

K 或 Vi 抗原

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Summary

• G- rod bacilli

• Habitat is the intestinal tract

• Facultative anaerobes or aerobes

• Ferment a wide range of carbohydrates

• Possess complex Ags structure

• Produce a variety of toxins and other virulence factors

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Genera Disease

Escherichia

(E.coli)

extraintestinal infections

diarrhea 腹泻

Shigella bacillary dysentery 菌痢

Salmonella enteric fever 肠热症 , septicemia 败血症 and enterocolitis 小肠结肠炎 .

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• important properties: ferment lactose

• laboratory diagnosis: MacConkey’ agar, EMB agar

At some level, E. coli and Shigella are indistinguishable.

((i) i) Escherichia coli Escherichia coli 埃希菌属

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Pathogenesis of E. coli

• Transmission is by the fecal-oral route.• Pili (fimbriae) allow the bacteria to colonize the

ileal mucosa.• Cytotonic enterotoxins watery diarrhea.

tissue damage• Vero toxin• Hemolytic toxin• Others LPS, K Ag

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pathogenesis

• intestinal tract infection– gastroenteritis 胃肠炎

• systemic infection– septicemia 败血症 ,– meningitis 脑膜炎

• urinary tract infection 泌尿道感染– Uropathogenic E.coli. UPEC

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E. coliE. coli fimbriae fimbriae

mannosemannose

Type 1 Type 1

• galactose galactose – glycolipids glycolipids – glycoproteins glycoproteins

P P

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E.coli-urinary tract infection E.coli-urinary tract infection Is the leading cause of urinary tract infections which can lead to

acute cystitis 急性膀胱炎 (bladder infection) and pyelonephritis 肾盂肾炎(kidney infection).

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E.coli-Meningitis and SepsisE.coli-Meningitis and Sepsis

• Neonatal meningitis – is the leading cause of neonatal meningitis and septicemia with a high mortality rate. Usually caused by strains with the K1 capsular antigen.

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Clinical Manifestations of gastroenteritis 胃肠炎

• Depending on the virulence factors they possess, virulent Escherichia coli strains cause – noninflammatory diarrhea (watery diarrhea) – inflammatory diarrhea (dysentery with stools

usually containing blood, mucus, and leukocytes 粘液脓血便 ).

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Strains Virulence factors Disease

ETECLT: ATP → cAMP

ST: GTP → cGMP

infant and traveler’s diarrhea similar to cholera

EIECEndo-toxin Infant and adult diarrhea

similar to dysentery

EPECadherence factor Newborn and infant

watery diarrhea

EHEC

Shiga-like toxin

O157: H7

Children and adults diarrhea

Hemorrhagic colitis

Hemolytic uremic syndrome

EAEC adherence

Enterotoxins (EAST)

Persistent, watery diarrhea

In infant

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Summary of E.coli strains that cause gastroenteritis.

肠产毒型大肠埃希菌肠产毒型大肠埃希菌

肠侵袭性大肠埃希菌肠侵袭性大肠埃希菌

肠致病性大肠埃希菌肠致病性大肠埃希菌

肠出血性大肠埃希菌肠出血性大肠埃希菌

肠集聚型大肠杆菌肠集聚型大肠杆菌

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Enteropathogenic E. coli (EPEC).Enteropathogenic E. coli (EPEC).

• fever• infant diarrhea• vomiting • nausea • non-bloody stools • Destruction of surface microvilli 微绒毛1. loose attachment mediated by bundle

forming pili (Bfp); 2. Stimulation of intracellular calcium

level; 3. rearrangement of intracellular actin,

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Enterohemorrhagic Enterohemorrhagic E. coliE. coli (EHEC). (EHEC).

• These are usually serotype O157:H7.

Transmission electron micrograph of Escherichia coli O157:H7

CDC/Peggy S. Hayes

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• These organisms can produce a hemorrhagic colitis (characterized by bloody and diarrhea with few leukocytes in afebrile 无热的 patients).

• However, they are taking increasing importance with the recognition of outbreaks caused by contaminated hamburger meat.

• The organisms can disseminate 播散 into the bloodstream producing systemic hemolytic-uremic syndrome (hemolytic anemia, thrombocytopenia 血小板减少 ( 症 )

and kidney failure 肾衰竭 ).

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Sanitary significance 卫生学指标

• Totoal bacterial numberTotoal bacterial number 细 菌 总 数 : : number of bacteria contained per ml or number of bacteria contained per ml or gm of the sample; the standard of gm of the sample; the standard of drinking water is less than 100.drinking water is less than 100.

• Coliform bacteria indexColiform bacteria index 大肠菌群指数 the number of coliform bacteria detected the number of coliform bacteria detected

out per 1000 ml sample; the standard of out per 1000 ml sample; the standard of drinking water is less than 3drinking water is less than 3

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Structure, Classification, and Antigenic Types

• Shigellae are Gram-negative,

• nonmotile,

• facultatively anaerobic,

• non-spore-forming rods.

(ii) ShigellaShigella

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CASE STUDY AND • A 25-year-old, previously healthy woman came to

the emergency room for the evaluation of bloody diarrhea and diffuse abdominal pain of 24 hours’duration. She complained of nausea and had vomited twice. She reported no history of inflammatory bowel disease, previous diarrhea, or contact with other people with diarrhea. The symptoms began 24 hours after she had eaten an undercooked hamburger at a local fast food restaurant. Rectal examination 直肠检查 revealed watery stool with gross blood. Sigmoidoscopy 乙状结肠镜检查 ( 术 ) showed diffuse mucosal erythema 红斑 and petechiae 瘀点 with a modest exudation 渗出物 but no ulceration or pseudomembranes 假膜 , 伪膜 .

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QUESTIONS

• Name four genera of Enterobacteriaceae that can cause gastrointestinal disease. Name two genera that can cause hemorrhagic colitis.

• What virulence factor mediates this disease ?• Name the five groups of E. coli that can cause

gastroenteritis. What is characteristic of each group of organisms?

• What are the four forms of Salmonella infection ?• Differentiate between disease caused by S.typhi

and that caused bu S.sonnei?

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ShigellaShigella

4 Species; S. flexneri, S. boydii, S. sonnei,

S. dysenteriae

All cause bacillary dysentery or shigellosis.

Shigellosis is Shigellosis is bloody fecesbloody feces associated with associated withintestinal pain. intestinal pain. ““pus”pus” feces : mucusmucus and bloodblood ,leukocytes into the bowel.

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Shigella are differentiated from the closely related Escherichia coli

• failure to ferment lactose

• The genus is divided into four serogroups with multiple serotypes: – A (S dysenteriae, 12 serotypes); – B (S flexneri, 6 serotypes); – C (S boydii, 18 serotypes); and – D (S sonnei, 1 serotype).

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Pathogensis substance

• All species are able to invade and multiply inside a wide variety of epithelial cells, including the enterocyte

• Endotoxin• Shiga toxin, STShiga toxin, ST (( exotoxinexotoxin ))

Chromosomally encodedNeurotoxic, Enterotoxic and Cytotoxic

EnterotoxicityEnterotoxicity can make the disease clinicallyappear as a diarrheadiarrhea. The toxin inhibits protein synthesistoxin inhibits protein synthesis (acting on the 60S ribosome and lysing 28S rRNA).

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Shigella attachment and penetration

• WWithin 2-3 daysithin 2-3 days• EEpithelial cell pithelial cell

damagedamage

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ShigellaShigella Clinical Manifestations

• Symptoms of shigellosis include – abdominal pain, – Tenesmus 里急后重 , 下坠 ,

• watery diarrhea, and/or dysentery (multiple scanty, bloody, mucoid stools).

• Other signs may include abdominal tenderness, fever, vomiting, dehydration.

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Treatment

• Patients with severe dysentery are usually treated with antibiotics (e.g. ampicillin 氨苄西

林 ).

• Mild diarrhea is often not recognized as shigellosis.

• Managing dehydration is of primary concern.

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Prevention It can be transmitted by fecal-oral contact.

Adults can catch this disease from children.

Food hands contaminating food.

The source in each case is unwashed handsunwashed hands. Man is the only "reservoir".

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Only a few types that are commonly associated with characteristic human diseases -

1. 1. S. enteritidisS. enteritidis

2. 2. S. cholerae-suisS. cholerae-suis

3. 3. S. typhiS. typhi

(iii) SalmonellaSalmonella 沙门氏菌

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Salmonella typhiSalmonella typhi• The organism is transmitted from:

1. 1. a human reservoir a human reservoir

2. 2. in the water supply (if sanitary conditions in the water supply (if sanitary conditions are poor)are poor)

3. 3. in contaminated foodin contaminated food

• It initially invades the intestinal epithelium and during this acute phase, gastrointestinal symptoms are noted.

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Pathogenesis Virulence factors

a. Invasiveness: -pili

-Vi antigens, anti-phagocytosis

b. Endotoxin:

c. Exotoxin: (some)-enterotoxin, like ETEC’s.

The antigenic The antigenic structures of structures of salmonellae salmonellae used in used in serologic typingserologic typing

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Clinical disease

a. Enteric fever

b. Enteritis (or food poisoning)

c. Septicemia

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S. typhi → small intestine ↓

penetrate across the mucosa ↓ multiplication in phagocytes

↓ the first bacteremia

↓ multiplication in phagocytes of some organs

↓ the second bacteremia (carrier state) gall bladder high fever, leukopenia, low pulse ↓ reinvasion of the gut mucosa ↓ hypersensitivity intestinal hemorrhage or perforation 穿孔

bloodstream

bloodstream

S. typhi

rose rash

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胆囊 --- 肠道 --- 粪排菌 /肠 壁淋巴组织肾 ----- 尿肝脾 ----- 肿大骨髓 ------ 受抑制皮肤 ---- 血栓出血 -- 玫瑰疹 rose rash

伤寒和付伤寒的致病过程

伤寒和付伤寒沙门菌

小肠上部粘膜

肠系膜淋巴结

固有层淋巴结

进入血液 再次进入血液

第一次菌血症 第二次菌血症

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TyphoidTyphoid

•acute phase, gastroenteritis acute phase, gastroenteritis

gall bladdergall bladder–shedding, weeksshedding, weeks

SepticemiaSepticemia-occurs 10-14 days-occurs 10-14 days– lasts 7 dayslasts 7 days

gastrointenteritisgastrointenteritis

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Enteric fever

S. typhi - typhoid fever

S. paratyphi - paratyphoid fever

incubation period: 1 ~ 2 weeks

typical duration: 3 ~ 5 weeks

Enteric fever

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the most common Salmonella infection.

common causative agents:

S. typhimurium, S. enteritidis and S. choleraesuis.

manifestations:

low fever, nausea, vomiting, diarrhea.

a self-limited disease, lasting for 3 ~ 5 days.

Enteritis (Food poisoning)

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the common causative agent:

S. choleraesuis S. typhimurium S. enteritidis. S.schottmuelleri

manifestations: fever, chill, and some local infection.

intestinal symptoms : little or no

Septicemia

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LaboratoryLaboratory D Diagnosisiagnosis

A. SpecimensA. Specimensa) Enteric fever: blood, bone a) Enteric fever: blood, bone

marrow, stool, urine.marrow, stool, urine. b) Food poisoning: stool, b) Food poisoning: stool,

vomitus, suspected food.vomitus, suspected food.c) Septicemia: blood. c) Septicemia: blood.

B. Culture and identificationB. Culture and identification C. Widal testC. Widal test

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Bacteriologic Methods

Serologic diagnosis ---- Widal test

Definition

A quantitative agglutination test for enteric fever, which

detects a patient’s antibodies to the specific O antigen

of S. typhi and H antigens of S. typhi, S. paratyphi A,

S. schottmuelleri, and S. hirschfeldii.

菌体抗原凝集试验

鞭毛抗原凝集试

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Typhoid -TherapyTyphoid -Therapy

AntibioticsAntibiotics VaccinesVaccines

Vi (capsular) Vi (capsular) antigen antigen ::protectiveprotective

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防治原则

口服减毒活菌苗TYPHOID MARY

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This chapter will focus on Definitions

Widal test Questions

1. What are the common properties of the Enterobacteriaceae?2. What are the medically important genera of the

Enterobacteriaceae? What diseases are caused by them?3. What is the importance of lactose fermentation in distinguishing

between certain genera of the Enterobacteriaceae?4. What are the 5 serotypes of E. coli causing diarrhea? What is the

pathogenesis of them?5. What are the medically important species of Salmonella? What

diseases are caused by them?6. What is the pathogenesis of typhoid?7. what is the medical significance of Widal test? How to interpret the

results of the test?

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Isolation Rate for Salmonella enteritidisSalmonella enteritidis by Region, United States, 1974-1994 CDC