10. Patho Digestive Tract

BACTERIA Morphology: - Gram (+) cocci in grapelike clusters - produce enterotoxin A to E (most common: A) - Exotoxin -Heat stable (resist boiling for 30 minutes) - stimulates peristalsis - resistant to gastric and jejunal enzymes

Reservoir: humans (skin, abscess, nasal secretions) - Occasionally cows, dogs, fowl Transmission: - ingestion of S. aureus contaminated food - contaminated milk, milk products, custards, cream-filled pastries, salad dressings (potato or egg), sandwiches, processed meats and fish

Incubation period: 30 minutes to 8 hours (usually 2 to 4 hours) Disease: FOOD POISONING - nausea, vomiting, crampy abdominal pain, and diarrhea - no fever - lasts for 24 hours Diagnosis: isolation of S. aureus from food, stool, vomitus

Treatment: fluid replacement Prevention and Control: - sanitation and cleanliness in kitchen - handwashing - keep perishable foods hot or cold - exclude people with boils and abscesses from handling foods

Morphology: - Gram (-) bacilli - facultative anaerobe, non-sporeforming - commensal strain ---- part of the normal flora - Nonpathogenic E. coli + virulence factors = Disease - Virulence factors: 1. Pili 2. Exotoxin production a. heat labile and stable toxin b. Shiga like toxin 3. Endotoxin: LPS 4. Iron binding siderophore

ENTEROVIRULENT STRAINS Enterotoxigenic E. coli (ETEC)

-Pili - Traveller’s diarrhea

(Montezuma’s Revenge) Enteroinvasive E. coli (EIEC)

-shiga-like toxin

Enteropathogenic E. coli (EPEC)

- destroy microvilli of the small intestine

Enterotoxin: a. Heat labile toxin b. Heat stable toxin plasmid --invades epithelial cells

Enteroadherent E. coli (EAEC) Enterohemorrhagic E. coli (EHEC)

-Pili --shiga like toxin (verotoxin)

-responsible for Hemolytic- Uremic syndrome (HUS)

Reservoir: Humans Incubation period: 10 to 72 hours Transmission: fecal-oral route - ingestion of fecally contaminated foods or water Disease: 1. Diarrhea a. ETEC--- Traveller’s Diarrhea -- profuse watery diarrhea, abdominal cramping, vomiting, dehydration -- no blood or mucus b. EHEC and EIEC – dysentery with blood or mucus

2. Urinary Tract Infection 3. Neonatal Meningitis 4. Gram negative sepsis Diagnosis: - isolation of organism from stool - DNA probe techniques - Immunodiagnostic procedure

TREATMENT: - Fluid and electrolyte replacement - Loperamide - Antibiotics: controversial - Co-trimoxazole - Tetracycline Prevention and Control: - avoid street foods - avoid salads and uncooked vegetables - drink boiled water - Proper waste disposal and water treatment - handwashing

Morphology: - Gram (-) curved bacilli with flagella - Subdivided by O antigen: 01 - Biotypes: El Tor Cholerae ( Classical) - Serological Subgroups: Ogawa, Inaba, Hikojima - Virulence due to: 1. Adhesiveness to intestinal epithelium 2. Choleragen - Enterotoxin - results in active secretions Reservoir: Humans, aquatic reservoir Incubation period: 2 to 3 days

Transmission: fecal oral route - ingestion of fecally contaminated water and food - high inoculum (infective dose) Disease: GASTROENTERITIS - abrupt vomiting and severe watery diarrhea ( colorless, odorless) - rice-watery stools - rapid dehydration shock Diagnosis: - rectal swab or stool specimens - culture: Thiosulfate-citrate-bile-sucrose (TCBS) agar

Treatment: - prompt fluid and electrolyte replacement - tetracycline Prevention and Control: - Purification of water - proper sewage disposal - avoid inadequately cooked fish and shellfish - vaccine ---- provide partial protection - Prophylaxis: tetracycline, doxycycline

Morphology: -Gram (-) bacilli, non lactose fermenting, non motile - Virulence factors: 1. Invade epithelial cells and proliferate within 2. Shiga toxin 3. LPS - Others species: S. flexneri, S. boydii, S. soneii Reservoir: Humans

Transmission: - transmitted by person to person via 4 F’s ( fingers, flies, foods, feces) - fecal-oral - ingestion of contaminated food and water - homosexual transmission - carrier: convalescent carrier ---- last within 4 weeks of onset chronic carriers (rare) --- more than 1 year

Incubation period: 2 to 4 days Disease: DYSENTERY 1. Mild Shigella infection – watery or loose with minimal or no constitutional symptoms 2. Small bowel infection – abrupt onset of fever, systemic toxicity, headache, profuse watery diarrhea 3. Bacillary dysentery– abdominal cramps with tenderness and tenesmus; mucus stool with or without blood

Diagnosis: - fecalysis: leukocytes - Culture: MacConkey agar Treatment: Fluid and electrolyte replacement - Quinolone, antimotility agent (ex.Loperamide) is contraindicated Prevention and Control: - Strict handwashing, prevention of food contamination - sanitary water supply, food processing and sewage disposal - exclusion of infected persons as food handler

Morphology: - Gram (-) bacilli, non- lactose fermenting but produce H2S - Motile --- peritrichous flagella - Pathogens: S. typhi --- typhoid fever S. Chlerasius --- septicemia S. enteritidis --- S. typhimurium, S. paratyphi - Virulence factors: 1. Surface antigens: O antigen, Vi antigen 2. Invasiveness (epithelial lining) 3. Exotoxin --- diarrhea 4. Cytotoxin --- cell invasion and destruction -Reservoir: Humans

Transmission: fecal oral route - food and water contaminated by feces or urine - carriers: for more than 1 year Incubation period: Gastroenteritis – 6 to 72 hours Invasive disease – 9 to 14 days Disease: 1. Typhoid fever or enteric fever– fever, headache, malaise, anorexia, cough, abdominal pain, diarrhea, rose spots 2. Carrier state– carry bacteria in gallbladder 3. Sepsis– infect lungs, brain, bone 4. Gastroenteritis –nausea, abdominal pain, watery diarrhea Diagnosis: -- isolation of bacteria from blood, urine, stool or bone marrow -- biochemical test (Widal test) -- Immunodiagnostic procedures (Typhidot)

Treatment: -- fluid and electrolyte replacement -- Quinolone or Ceftriaxone -- Chloramphenicol Prevention and Control: -- Handwashing -- Hygienic measures: -- good water supply and effective sewage disposal -- careful food preparation -- vaccine ( polysaccharide vaccine)

Morphology: -Gram (-) bacilli, microaerophilic, comma shaped (“seagull”) - motile --- single polar flagellum - invades lining of small intestine Toxins: 1. Enterotoxin– similar to LT toxin of E. coli 2. Cytotoxin - Reservoir: animals especially raw poultry

- Transmission: - ingestion of contaminated food or water - contaminated cutting boards - Incubation Period: 2 to 5 days - Disease: > fever, headache, crampy abdominal pain, nausea, vomiting, profuse bloody diarrhea > self-limited (usually 5 to 8 days)

Diagnosis: - isolation of organism in stools - culture: Campy blood agar Treatment: - fluid and electrolyte replacement - fluoroquinolone or erythromycin Prevention and Control: - Handwashing - properly prepare and cook food

-Recognized species: B. abortus (8 biovars) --- cattle B. melitensis --- goat B. suis ( 4 biovars) --- swine B. canis – dogs B. ovis --- sheep

Morphology: - gram (-) coccobacilli - Non motile, non spore forming, obligate aerobe Reservoir: cattle, goat, pigs, dogs, sheep

Transmission: 1. By direct contact – most common - with contaminated livestock or aborted placentas thru skin break 2. Ingestion of infected milk, milk products and meals 3. Airborne spread– occurs in heavily contaminated area (slaughter house and lab) Incubation Period: few days to several months

Disease: Brucellosis (Undulant Fever) - Undulating fever- fever peaks in evening and returns to normal in morning - chills, weakness, loss of appetite, athralgia, myalgia, abdominal pain, hepatomegaly, splenomegaly. Diagnosis: - Culture of blood, bone marrow, liver or lymph nodes (3-4 weeks) - Serological tests - standard tube agglutination - mercaptoethanol test - Skin test --- indicates exposure

Treatment: tetracycline, strpetomycin, Cotrimoxazole Prevention and Control: -eradication of brucellosis in animals - milk pasteurization

Morphology: - gram (+), motile, spore forming bacilli, aerobe - produce enterotoxin Disease: FOOD POISONING Reservoir: soil & vegetation Transmission: Ingestion of contaminated food

Diagnosis: Isolation of B.cereus in food (infective dose=>105 ) Treatment: Fluid replacement Prevention & control: - cooked food must be exposed to high temperature &/or refrigerated

Morphology: Gm(+) bacilli, unencapsulated, subterminal pores - obligate anaerobe, motile - with 7 types (A to G) – most common is type A - produce neurotoxin (Botulinum toxin) – results to flaccid (relaxed) paralysis, symmetric & descending - toxin heat-labile - spores  heat-stable Reservoir: soil, dust, food

Transmission: 1. Adult botulism – home-canned foods, vegetables, smoked fish 2. Infant botulism – fresh honey contaminated w/ spores of C. botulinum Incubation period: 18-36 hours Disease: BOTULISM 1. Adult botulism (food-borne botulism) - weakness of the mouth & pharynx - no fever - cranial nerve palsiesdiplopia, dysphagia, dysarthria - generalized muscle weakness - respiratory (diaphragmatic & pharyngeal) paralysis & death (w/n 72 hrs after ingestion)

2. Infant botulism - constipation, generalized weakness, cranial nerve defects, w/ suckling ability, sudden apneic episodes - “floppy” babies Diagnosis: culture from gastric aspirate or stool Treatment: antitoxin; supportive therapy Prevention & control: - boil foods for 15-20 minutes - careful processing of foods - don’t give raw honey to infants

(aka C. welchii) Morphology: - gm(+), spore foring, anaerobic bacilli - produce enterotoxin Reservoir: - soil, GIT of animals (cattle, swine, poultry, fish) Incubation period: 6-24 hrs (usually 10-12 hrs) Transmission: ingestion of food (usu. recooked meat & gravies) contaminated by dirt & feces Disease: FOOD POISONING - colic, diarrhea, nausea, mild dse. lasting <1 day (self limiting)

Diagnosis: - demonstration of organism in food or patient’s stool - detection of enterotoxin in patient’s stool Treatment: None Prevention & control: - cook food well esp. meats - proper preparation of meat & poultry - hot foods should be served while hot

Quiz time Please prepare ¼ paper and number it 1 to 10

1. Produce Food Poisoning EXCEPT

Bacillus cereus Salmonella typhi Closrtidium botulinum 2. This is avoided to prevent Infant Botulism breastmilk honey

3. Escherichia coli Gram (+) Gram (-) 4. Shiga-like toxin EXCEPT EIEC EHEC ETEC

5. Cause Gastroenteritis Vibrio cholera Brucella 6. Cause Dysentery Shigella Salmonella

7. Produce neurotoxin Clostridium botulinum Clostridium perfringens 8. “Rice water stools” Vibrio cholera Salmonella typhi

9. Produce Undulating Fever Bacillus cereus Brucella species 10. Found in pigs Brucella mellitensis Brucella suis

II. VIRUS A. Herpes Simplex Type 1 (HSV–1) - linear, double-stranded DNA virus, herpes virus Resevoir: humans Transmission: contact with active lesions - carriers (latent infection) Incubation period: 1-26 days (usu. 6-8 days)

Disease: Initial infection occurs during 1st 2 yrs

- reactivation due to UV light, immunosuppresion, trauma to skin, menstruation, emotional stress - gingivostomatitis & pharyngitis - most common - cold sores blisters, fever

Diagnosis: Tzanck test; Culture; Immunodiagnostic procedures Treatment: Acyclovir Prevention & control: Handwashing; good personal hygiene

B. Rotavirus - Reovirus, segmented, double-stranded RNA virus - group A strains  majority of illness - infects & kills mature villus tip cells of small intestine  osmotic diarrhea Reservoir: humans Transmission: Fecal-oral route Incubation period: 1-4 days

Disease: GASTROENTERITIS - diarrhea, fever, abdominal pain, vomiting, dehydration Diagnosis: Immunoassay; DNA probe, PCR will detect the virus Treatment: F/E replacement Prevention & control: Water sanitation; Vaccine; Sewage management

C. NORWALK-like VIRUS - Viral Gastroenteritis, Viral enteritis, Viral diarrhea - Endemic or epidemic - Nausea, vomiting, diarrhea - Abdominal pain, myalgia, headache, malaise, low-grade fever - Self-limiting: 24 – 48 hrs Etiologic Agents: adenovirus astrovirus ( 5-6 star-shaped morphology) calicivirus (Norwalk-like virus)

Reservoir: humans, shellfish, food, fomites, water Transmission: fecal-oral, airborne, contact with fomites Diagnosis : clinical, electron microscope of stool, immunodiagnostic procedures Treatment: supportive

D. POLIOVIRUS - Poliomyelitis, polio, infantile polio Abortive case: - non-specific febrile illness, malaise, anorexia, N/V, headaches, sorethroat, constipation, abd pain Non-paralytic or Aseptic meningitis - S/Sx of abortive case, with nuchal/spinal rigidity, increase or decrease in superficial/deep tendon reflexes Paralytic - with flaccid paralysis and absent deep tendon reflexes

Etiologic agent: RNA virus, family Picornaviridae Poliovirus ( type 1, 2, 3 ) Reservoir: feces and oropharyngeal secretions of man - virus is present in the throat about a week after onset of clinical illness - excreted intermittently in feces for several weeks Mode of transmission: fecal to oral, oral to oral (respiratory) routes - patients are potentially contagious as long as fecal excretion persists

POLIOVIRUS Incubation period: 3-6 days for abortive poliomyelitis 7-21 days in Paralytic poliomyelitis Diagnosis: - clinical : patient with flaccid paralysis - isolation of virus from 2 stool specimens taken 24-48 hrs apart within 14 days of onset of paralysis Treatment : symptomatic and supportive Prevention: immunization - OPV, IPV

HEPATITIS A - Infectious hepatitis, Epidemic hepatitis Etiologic Agent: non-enveloped linear RNA genus – hepatovirus; family - Picornaviridae Type of Disease: Pre-icteric phase: abrupt onset of fever, malaise, N/V, anorexia, abdominal discomfort Icteric phase: RUQ pain, jaundice, dark urine Mild – 1-2 wks only Severe – several months

HEPATITIS A Reservoir and Mode of Transmission: - contaminated food and water - fecal-oral route, person to person, handler

infected food

Diagnosis: IgM antibody to HAV – acute infection Prophylaxis: Immune globulin : for susceptibles with no anti HAV - Newborn of symptomatic mothers Treatment: supportive Prevention: Hepatitis A vaccine : at 12 mos of age, 2 doses 6 months apart

HEPATITIS B - Serum hepatitis Etiologic agent: enveloped circular DNA Genus – Orthohepadnavirus, Family – Hapadnaviridae Type of Disease - asymptomatic carrier – majority - symptomatic illness - jaundice, constitutional S/Sx - chronic form - fulminating – include extrahepatic manifestations - cirrhosis and hepatocellular carcinoma

Reservoir - patients with chronic HBV infection - blood, semen, serous exudates, saliva, vaginal fluid and breastmilk Mode of Transmission: - sexual; household contact with infected person - mother to infant - drug user, tattooing, needle stick, nosocomial (blood transfusion)

HEPATITIS B Diagnosis: HBsAg – acutely or chronically infected people anti-HBs – resolved infections, immunization HBeAg - infected people at increased risk of transmitting HBV Anti-HBe - infected people at lower risk of transmitting HBV Anti-HBc – acute, resolved or chronic HBV, not present after immunization IgM anti-HBc - acute or recent HBV infection Treatment: no specific treatment Interferon, lamivudine, adefovir dipivoxil Liver transplantation

HEPATITIS B Prophylaxis: - Newborn w/ HBsAg (+) mother: HBIg + Hepatitis B at birth or w/n 12hrs, followed by hepatitis B vaccine 6 wks after then after 6 mos - sexual contact w/ HBsAg (+) partner, acute or exposure to blood that may contain HBsAg  Hepatitis B vaccine + HBIg not later than 14 days from sexual contact and w/in 7 days for percutaneous exposure - household/sexual contact with chronic carrier : Hepatitis B only

Prevention: Hepatitis B vaccine : ( EPI of WHO ) 1st dose: at birth

1st dose: 6wks old

2nd dose: 6wks old

2nd dose: 10wks old

3rd dose: 14 wks old

3rd dose: 14wks old

HEPATITIS C

nonA nonB hepatitis (previous name) Etiologic agent: enveloped linear RNA, Genus – Hepacivirus, Family – Flaviviridae Type of disease : insidious, 50-80% chronic, - may develop cirrhosis and hepatocellular carcinoma - asymptomatic illness : majority

Mode of transmission: parenteral - blood (drug users) hemodialysis patients, sexual contact ( rarely ) Diagnosis : IgG antibody to HCV Treatment: Interferon Prevention: screening of blood products, avoidance of needle stick injuries, safe sex

HEPATITIS D - Delta hepatitis Etiologic agent: - enveloped circular RNA, viral satellite – defective RNA virus Genus – deltavirus Type of Disease: abrupt onset >>chronic and severe - co-infection with Hepa B needed

Mode of Transmission: infected blood and body fluids, needles, sexual contact, intrafamilial or intimate contact Diagnosis: IgM antibody to Hepa D Treatment: supportive Prevention: immunization against Hepatitis B

HEPATITIS E Etiologic agent: spherical, non-enveloped RNA virus Type of Disease: similar to HAV but more severe, no chronic form Mode of Transmission: fecal-oral route, fecally contaminated food and water, person to person, mother to fetus

Diagnosis: IgM antibody to HEV Treatment: supportive Prevention: good sanitation

HEPATITIS G - cause chronic hepatitis Etiologic agent: Hepatitis G virus or Hepatitis GB virus linear RNA, Genus: Hepacivirus, Family : Flaviviridae Transmission: blood transfusion – primary route - parenteral, organ transplantation, blood, sexual contact, vertical, - IV drug users, hemodialysis

Type of Disease: mild illness or no disease Diagnosis: immunodiagnostic; detection of HGV RNA, HGV antibody Treatment: supportive

FUNGI Aspergillus flavus Produce mycotoxin Contributes to liver cirrhosis and carcinoma Disease: Aflatoxin poisoning Transmission: ingestion of fungi esp. peanuts, corn

Quiz Time Please prepare ¼ paper and number it 1 to 10

Hepatitis C Hepatitis B • • • • •

Hepatitis A Hepatitis D

Epidemic hepatitis Co-infection with Hepatitis B Hepacivirus Serum hepatitis Hepatovirus

Hep B Ig + Hep B vaccine Hep B only 6. Sexual contact with chronic carrier 7. Newborn with Hepatitis B 8. Acute exposure with Hepatitis B 9. non-reactive anti-HBs 10. Healthy newborn