复旦大学：《医学微生物学 Medical Microbiology（MBBS）》课程讲义_讨论稿_01 Microorganisms that cause Gastroenteritis Respiratory infection

Microorganisms that cause Gastroenteritis Respiratory infection Cheng Ling How,Tai Lily,Peach Subannaphong, Priyanka Hingorani Stella Muloongo

Cheng Ling How, Tai Lily, Peach Subannaphong, Priyanka Hingorani & Stella Muloongo

Contents Bacteria that cause: Gastroenteritis and Respiratory Infection e Viruses that cause Gastroenteritis and Respiratory Infection Fungi that cause: Respiratory Infection

Contents — — — Bacteria that cause: Gastroenteritis and Respiratory Infection Viruses that cause: Gastroenteritis and Respiratory Infection Fungi that cause: Respiratory Infection

Bacteria That Cause Gastroenteritis Signs symptoms Pathogenesis Clinical Features Staphylococcus aureus Nausea and Enterotoxin acts Very common, abrupt onset, intense vomiting on receptors for up to 24 hours, regular recovery in 24-48 in the gut that hours. Occurs in persons eating the same food transmit impulse No treatment usually necessary except to to medullary restore fluids and electrolytes ters that control Bacillus cereus Vomiting or Enterotoxin formed in Witn incubation period of 2-8 hours, mainly diarrhea food or in gut from vomiting With incubation period of 8-16 growth of B cereus. hours, mainly diarrhea Clostridium perfringens Watery Enterotoxin produced Abrupt onset of profuse diarrhea: vomiting during sporulation occasionally Recovery usual without treatment in gut, causes in 1-4 days. Many clostridia in cultures of faod d feces of patients Clostridium botulinum Paralysis Toxin absorbed Diplopia, dysphagia, dysphonia, difficulty from gut blocks eathing Treatment requires ventilatory acetylcholine at support and antitoxin Diagnosis confirmed by neuromuscular finding toxin in blood or stool Junction DIAGNOSTICS 1)Staphylococcus aureus Gram stain-(+), in clusters; Culture- beta-hemolytic, golden yellow pigment 2)Bacillus cereus Culture specimen from suspected food source 3)Clostridium perfringens: Culture( anaerobic ) Gram stain-(+) 4)Clostridium botulinum Culture(anaerobic ) Gram stain -(+)

Bacteria That Cause Gastroenteritis DIAGNOSTICS : Staphylococcus aureus : Bacillus cereus : Clostridium perfringens : Clostridium botulinum : 1) Gram stain – (+), in clusters ; Culture- beta-hemolytic, golden yellow pigment 2) Culture specimen from suspected food source 3) Culture ( anaerobic ) , Gram stain – (+) 4) Culture (anaerobic ) , Gram stain – (+)

Organism Symptoms Pathogenesis Clinical Features Escherichia coli Watery ETEC in the gut Usually abrupt onset of diarrhea; vomiting rare enterotoxigenic; diarrhea produces heat-labile Serious infections in newborns. In adults ETEC (HL)or heat-stable usually self-limiting in 1-3 days (HSJenterotoxins Toxins cause hypersecretion in small intestine Escherichia coli Dysentery Inflammatory invasion Acute bloody diarrhea with malaise, headache, enteroinvasive of the colonic high fever, and abdominal pain. Severe disease ElEC) mucosa: similar to in poorly nourished children. WBC presentin o shigellosis. EIEC is stool ely related to Shi Escherichia coli Watery, STEC produces shi Causes bloody diarrhea, hemorrhagic colitis, and (Shiga-toxin like toxins. Ofte the majority of causes of hemolytic-uremic produ cing: STEC) diatrhea serotype 0157: H7 yndrome Culture stool for sorbitol-negative E coli and serotype isolates with antisera for 0157: 1-17. Other serotypes may be detected by toxin production using enzyme mmunoassays that contain antibodies to the Shiga-like toxins

Clinical Features Organism Symptoms Pathogenesis Escherichia coli Watery EPEC attaches to mucosal Insidious onset over 3-6 days with listlessness, (enteropathogenic; diarrhea thelial cells and poor feeding, and diarrhea. Usually lasts 5-15 EPEC) roduces cytoskeletal days. Dehydration, electrolytic imbalance changes; may invade and other complications may cause death cells Different from Antimicrobial therapy is important other Ecoli that are enteroadherent o enteroaggregative and cause diarrhea VIbrio parahaemolyticus Watery Toxin causes Abrupt onset of diarrhea in groups consuming hypersecretion; vibrios same food, especially crabs and other seafood. Recovery is usually complete in tools may be days. Food and stool cultures are positive Diagnostics: D)E coli: Gram stain-(); Pink colonies on MacConkey agar; Dark purple to black on EMB agar 2)Vibrio parahaemolyticus: Blue colonies on TCBS agar(non- sucrose fermenting)

Diagnostics : 1) E. coli 2) Vibrio parahaemolyticus : Gram stain- (-) ; Pink colonies on MacConkey agar ; Dark purple to black on EMB agar. : Blue colonies on TCBS agar. ( non￾sucrose fermenting )

Signs Organism Symptoms Pathoger Clinical Features Vibrio cholerae Abrupt onset of iiquid alarmed in enc diarrhea Toxincauses hypersecretion in small area Needs prompt replacement of fluid intestine. Infective and electrolytes IV or orally, Stool cultures dose >10 organisms positive Use selective media Shigella species(mild ot onset of diarrhea: can hav cases) Dysentery Organisms invade epithelial cells; blood pus in stools, cramps, tenesmus, and lethargy mucus, and PMNs in mild and self-limiting. Restore fluids 10 positive. No antimicrobials unless systemic organisms immuno-compromised. Prolonged carriage s frequent sidious onset of malaise, anorexia. Salmonella Typhi Enteric fever evades intestinal mucosa myalgias, and headache; high remittent Is pororyph/A and B and multiplies in macrophages in fever may have constipation or diarrhea. Hepatosplenomegaly in about 50% of patient, Diagnosis by culture of s typhi from

Signs and Clinical features Organism Symptoms iogel Yersinia enterocolitica Enteric fever stroenterris or Severe abdominal pain, diarrhea, fever; PMNS and blood in stool: polyarthritis, erythema Occasional bacteremia. nodosum, especially in children. Keep stool Toxin produced occasionally specimen at 4 C before culture Clostridium difficile Makes enterotoxin Abrupt onset of bloody diarhea and fever. Toxin (toxin A) and cytotoxin in stool. Patient typically received antibiotics (toxin B), which cause hea and epithelial cell necrosis Campylobacter jejuni Dysentery nvas,on of mucous membrane Toxin Fever, diarrhea; PMNs, and fresh blood in stools, production uncertain especially in children. Usually selfF-limited. special media needed for cultures at 42C

Lab diagnosis Shigella Dysenteria Stool culture Salmonella Typh Culture: blood. stool or urine Non-typhi groups of Culture: blood stool or urine Salmonella Yersinia enterocolitica .Stool or blood cultures ° colonscopy Vibrio cholerae .Dark field microscopy grows as fiat yellow colonies on selective media: thiosulfate-citrate-bile-salts sucrose agar Campylobacter jejuni .Microscopic exam of stool .Selective media with antibiotics at 42(c

Lab Diagnosis Salmonella Typhi Culture: blood,stool or urine Non-typhi groups of Salmonella Culture: blood,stool or urine Yersinia enterocolitica Stool or blood cultures colonscopy Vibrio cholarae Dark fieldmicroscopy Grows as fiat yellow colonies on selective media: thiosulfate-citrate-bile-salts￾sucrose agar Campylobacterjejuni Microscopic exam of stool Selectivemedia with antibiotics at 42 Shigella Dysenteriae Stool culture • • • • • • Gc

Viruses that Cause gastroenteritis signs and Organism Symptoms Pal athogenesis Clinical Features Rotavirus Watery Induces histopathologic Fever and vomiting usually precede abdominal diarrhea changes in intestinal distress and diarrhea, Death in infants in vomiting mucosal cells develaping countries follows dehydration. mild fever and electrolyte imbalance. Typical course is 3-9 days. Diagnosis by immunoassay detection of rotavirus antigen in stool Norovirus Watery Induces histopathologic Abrupt onset of abdominal pain followed by diarrhea change in intestinal nausea, vomiting and diarrhea. Low-grade vomiting mucosa such as fever may occur: malaise, myalgias, and blunting of microvilli eadache are described. Typical course is 2-3 days. Diagnosis requires RT-PCR or other assays not readily available Diagnosis Rotavirus: Enzyme immunoassay( ElAs)and PCr from stool Norovirus: rt-PCr from stool

Viruses That Cause Gastroenteritis Diagnosis: Rotavirus: Enzyme immunoassay ( EIAs) and PCR from stool Norovirus: RT- PCR from stool

The experiment used to isolate and identify bacteria from feces sample IS

The experiment used to isolate and identify bacteria from feces sample is