肠道杆菌

Enterobacteriaceae Enterobacteriaceae (( 肠杆菌科肠杆菌科 ))

•肠杆菌科目前有 44个菌属、 170多个种。•多为肠道正常菌群，但可成为条件致病菌；少数为致病菌。

A. All bacilli belonging to Enterobacteriaceae are short gram-negative rods, either mobile or non-mobile.

B. All bacilli belonging to Enterobacteriaceae are facultative anaerobes. They grow in common media. Most of the enteric bacilli form round, convex, smooth colonies with distinct edges.

LactoseLactose （乳糖） （乳糖） fermentationfermentation•Mechanism: Non-pathogenic enteric bacilli can ferment lactose while pathogenic enteric bacilli such as Shigella and Salmonella can not.

•Media: SS-plate or EMB plate , TSI agar slants

•Basic components: lactose and a pH indicator

C. The identification of Enterobacteriaceae is largely depend on biochemical reactions

• ResultsResults

SS plate

red coloniesred coloniesnon-pathogenic/non-pathogenic/ 非致病菌非致病菌

white colonieswhite colonies pathogenic/pathogenic/ 致病菌致病菌

D. Enterobacteriaceae have complex antigenic structures.H Ag (flagella)

somatic O Ag (lipopolysacchari

de)

K/Vi Ag (capsule)

E.E. Common pathogenic materials for Common pathogenic materials for Enterobacteriaceae include:Enterobacteriaceae include:

bacterial structures (pili, capsule)bacterial structures (pili, capsule) toxins (enterotoxin, endotoxin)toxins (enterotoxin, endotoxin)

Infections outside the intestines caused by bacterial translocation Opportunistic infection

including septicemia, pneumonia, meningitis and urinary tract infections

Community-acquired infection

urinary tract infections

E. coli associated urinary tract infection

E. coli causes urinary tract infections such as acute cystitis （ 急 性 膀 胱炎 ） and pyelonephritis （ 肾 盂 肾炎） .

Infections inside the intestines caused by pathogenic E. coli

Common symptoms include Gastroenteritis （肠胃炎） , diarrhea （腹泻） and dysentery （痢疾） . Disease transmission is by fecal-oral route （粪口途径） .

EnteroEnterottoxigenic oxigenic E. coli E. coli ((ETEC/ETEC/ 肠产毒性大肠杆菌肠产毒性大肠杆菌 ))

EnteroEnteroppathogenic athogenic E. coli E. coli ((EPEC/EPEC/ 肠致病性大肠杆肠致病性大肠杆菌菌 ))

EnteroEnteroiinvasive nvasive E. coli E. coli ((EIEC/EIEC/ 肠侵袭型大肠杆菌肠侵袭型大肠杆菌 ))

EnteroEnterohhemorrhagic emorrhagic E. coli E. coli ((EHEC/EHEC/ 肠出血性大肠肠出血性大肠杆菌杆菌 ))

EnteroEnteroaaggregative ggregative E. coli E. coli ((EAEC/EAEC/ 肠集聚性大肠杆肠集聚性大肠杆菌菌 ))

•Cause "traveller’s diarrhea".

•Two types of plasmid-encoded toxins are produced: Heat labile toxins (LT/ 耐热肠毒素 )

activate adenyl cyclase （腺苷环化酶） which catalyze ATP to cAMP Heat stable toxins (ST/ 不耐热肠毒素 )

activate guanyl cyclase （ 鸟 苷 环 化 酶 ） to catalyze GTP to cGMP

•cAMP/cGMP are the intracellular second messagers. The former increases the secretion of water and ions, and the latter inhibits ionic uptake.

•Clinical signs: watery diarrhea, fever and nausea.

EnteroEnterottoxigenic oxigenic E. coli E. coli ((ETEC/ETEC/ 肠产毒性大肠杆菌肠产毒性大肠杆菌 ))

• Commonly associated with infant diarrhea.

• Characteristic lesion with destruction of microvilli without invasion

• Clinical signs: fever, diarrhea with non-bloody stools, vomiting and nausea.

EnteroEnteroppathogenic athogenic E. coli E. coli ((EPEC/EPEC/ 肠致病性大肠杆菌肠致病性大肠杆菌 ))

• Associated with elder children and adult diarrhea.

• Without flagella

• High virulence: a small number of EIEC can cause serious

illness

• Clinical signs: Acute inflammatory responses and tissue

destruction. Produce diarrhea with little fluid, much blood

and mucus containing polymorphonuclear cells.

EnteroEnteroiinvasive nvasive E. coli E. coli

((EIEC/EIEC/ 肠侵袭型大肠杆菌肠侵袭型大肠杆菌 ))

•EHEC produces bacteriophage-mediated exotoxin. This

toxin is called Vero toxin (VT) because of its cytotoxicity to

cultured Vero cells.

•The illness is characterized by serious abdominal pain and

diarrhea which is initially watery but then becomes bloody.

•In children, the disease may be progressed to a systemic

stage called as hemolytic uremic syndrome (kidney injury)

with 10% death rate.

EnteroEnterohhemorrhagic emorrhagic E. coli E. coli ((EHEC/EHEC/ 肠出血性大肠杆菌肠出血性大肠杆菌 ))

• A dominant serotype of EHEC is E. coli O157:H7

It causes a persistent, mucus-watery diarrhea with

vomiting and dehydration in infants.

It produces enteroaggregative heat-stable toxin

(EAST) similar to the heat stable toxins of ETEC.

It produces mucous associated autoagglutinin which

causes aggregation of the bacteria and formation of

biofilm.

EnteroEnteroaaggregative ggregative E. coli E. coli

((EAEC/EAEC/ 肠集聚性大肠杆菌肠集聚性大肠杆菌 ))

E. coli

Enterobacter Aerogenes

IMViC testIndole testMethyl red (MR) testVoges-Proskauer (VP) testCitrate utilization test

枸橼酸盐试验吲哚试验 甲基红试验

产气肠杆菌

微生物学检测微生物学检测

防治原则防治原则菌毛疫苗

QUIZ 1主要引起婴儿和旅行者腹泻的大肠埃希菌是：A.肠产毒型大肠埃希菌B.肠致病型大肠埃希菌C.肠侵袭型大肠埃希菌D.肠出血型大肠埃希菌

•人类细菌性痢疾的最常见病原菌人类细菌性痢疾的最常见病原菌（急性细菌性痢疾，慢性细菌性痢疾）（急性细菌性痢疾，慢性细菌性痢疾）•痢疾发病总数在前五位，死亡在前十位（传染病）•革兰氏阴性短小杆菌，无鞭毛，有菌毛，无芽胞，无荚膜•O 抗原是分类依据，可以分为 4 群（种）， 40 余个血清型（包括亚型）•致病性：黏附、侵袭、胞内繁殖、细胞间扩散

ShigellaShigella志贺菌属

SalmonellaSalmonella 沙门菌属

• 急性消化道传染病，我国乙类传染病 • Enteric fever (typhoid fever) is the most serious form of salmonella infection which only occurs in human • Carrier state is common • In untreated patients, the death rate is 7% to 14%• Antibiotic therapy is essential, vaccines are not effective and not widely used

肠热症 肠热症 (( 伤寒、副伤寒伤寒、副伤寒 ))

1. The microbe initially invades intestinal mucosal epithelium and propagate at the local.

2. The microbe penetrates into the bloodstream to cause the first round of bacteremia with symptoms of fever, general discomfort and pain.

3. The microbe enters many organs such as liver, spleen, kidney, gall and marrow for further propagation.

4. The microbe penetrates into the bloodstream again to cause the second round of bacteremia with serious symptoms of high fever, swell of spleen and liver, rose-colored spots in skin, and tissue injury.

enteric fever developmententeric fever development

1. 致病菌S. typhi （伤寒沙门菌）S. paratyphi A （甲型副伤寒杆菌）S. schottmuelleri （肖式沙门菌）S. hirschfeldii （希式沙门菌）

enteric fever Diagnosis

2. 标本采集 Blood @ first week Stool and urine @ from the second week on Marrow can be considered because of its high and permanent positive results.

enteric fever diagnosis

3. Widal test （肥达试验）a quantitative agglutination test using the known O antigen of S.typhi , and H antigens of S. typhi and S. paratyphi A/B to detect specific serum antibodies. • For one single serum sample, The titers of anti-O antigen IgM 1:80 and/or anti-H antigen IgG 1:160. • For two serum samples that collected with an interval of 5~7 days, 4-fold increase in titers of specific antibody.

沙门菌引起的其它疾病沙门菌引起的其它疾病急性胃肠炎 ( 食物中毒， Gastroenteritis /food-poisoning)

败血症It is the most common Salmonella infection and usually transmitted from contaminated food. However, only a few of food poisoning-causing salmonella serotypes can produce enterotoxin.

Many Salmonella serotypes can cause septicemia. This disease is commonly found in children or adult with low immunity.

QUIZ 2肠热症发病一周内，进行病原性诊断应选择：A.尿培养B.血培养C.粪便培养D.肥达试验

Helicobacter pylori                                                  

幽门螺杆菌

慢性胃炎，消化性溃疡，胃癌2005诺贝尔奖获得者Barry M arshall，Robin W arren于1983年，从胃炎组织标本中分离出幽门螺杆菌，并证实该菌是胃炎及消化道溃疡的病原菌

一端有 2-6根鞭毛，运动活泼的革兰氏阴性螺杆菌主要生化鉴定依据：脲素酶、过氧化氢酶、氧化酶均为阳性