Microbial Diseases - Digestive System

DISEASES OF THE DIGESTIVE SYSTEM

OVERVIEW

OVERVIEW

Many pathogens enter the body when we ingest water and food.

Defenses of the digestive system are very strong.

Digestive infections are a major cause of morbidity and mortality.

BACKGROUND

The mouth and large intestine are crowded with microorganisms. Part of the normal oral flora

Digestive diseases are usually associated with: Crowding Poor hygiene Contaminated food or water

BACKGROUND

Digestive infections in developed and undeveloped countries are associated with different pathogens.

Developed countries: Campylobacter Salmonella Shigella

Undeveloped countries: Vibrio cholerae

CLASSIFICATION OF INFECTION

Infections in the digestive system are classified in two groups: Exogenous infections – pathogens that come into

the body Endogenous infections – organisms that are part of

the normal microbial flora

EXOGENOUS INFECTIONS

Exogenous infections are brought in with contaminated food or water. C. difficile and other exogenous infections are

frequently acquired in hospital environments. Helicobacter pylori spreads through oral-oral or

fecal-oral contact.

EXOGENOUS INFECTIONS

ENDOGENOUS INFECTIONS

Endogenous infections are caused by organisms that are part of the normal flora. Streptococcus and Enterococcus are examples.

In the right circumstances they can cause: Dental diseases. DISEASES OF the bowel, appendix, and liver. Diverticular abscesses.

ENDOGENOUS INFECTIONS

CLINICAL SYMPTOMS OF GASTROINTESTINAL INFECTIONS

Most common symptoms are: Fever Vomiting Abdominal pain Diarrhea

The central feature in all cases is diarrhea

CLINICAL SYMPTOMS OF GASTROINTESTINAL INFECTIONS

The nature of the diarrhea is used to classify gastrointestinal infections into three categories: Watery diarrhea Dysentery Enteric fever

WATERY DIARRHEA

Caused by pathogenic mechanisms that attack the intestines

Symptoms are usually acute but brief (last 1 to 3 days).

DYSENTERY Caused by organisms that cause damage to the

colonic mucosa Either directly or production of toxins

Contain blood and pus Can be accompanied by cramps, abdominal pain

and little vomiting Not as much fluid loss as in watery diarrhea but

lasts longer Most cases resolve in 3 to 7 days.

ENTERIC FEVER

Systemic infection focused in the gastrointestinal tract.

Prominent features are fever and abdominal pain.

Pathogens spread to biliary (bile) tract, liver, and organs of the reticuloendothelial system.

Most investigated form is typhoid fever.

TYPES OF INFECTION

There are five major types of gastrointestinal infection: Endemic Epidemic Traveler’s diarrhea Food poisoning Nosocomial infections

ENDEMIC GASTROINTESTINAL INFECTIONS

Defined as infections that occur sporadically Some are worldwide. Some are geographically restricted. There can be seasonal variation. They can be age-related.

ENDEMIC GASTROINTESTINAL INFECTIONS

The major pathogens in developed countries are: Campylobacter Salmonella Shigella

Some organisms geographically restricted to warm climates: Vibrio cholerae

EPIDEMIC GASTROINTESTINAL INFECTIONS

Defined as infections involving regional, national, and international populations.

Most common epidemic infections are: Cholera Typhoid fever Shigellosis

All are directly related to failures in public health.

TRAVELER’S DIARRHEA

20-50% of travelers to undeveloped countries will get diarrhea in the first week.

Most studied cases are travelers from the US to Latin America. 50% of cases are caused by enterotoxigenic strains

of E. coli. 10-20% are caused by Shigella. The major source is ingestion of improperly

cooked food.

FOOD POISONING

Food poisoning is usually caused by: Failing to cook food adequately. Allowing undercooked food to sit. Improper storage is an additional factor.

FOOD POISONING

NOSOCOMIAL GASTROINTESTINAL INFECTIONS

Acquired in a hospital and usually traced to: Employees. Contaminated food prepared outside the hospital.

Two major pathogens responsible: E. coli C. difficile

C. difficile accounts for 90% of infections. Symptoms range from mild diarrhea to fulminant

pseudomembranous colitis. Colitis arises either during or after treatment with

antibiotics.

TREATMENT & MANAGEMENT OPTIONS FOR GASTROINTESTINAL INFECTIONS

Treatment involves supportive care with liquid replacement rest.

Infection with E. coli O157:H7 can result in renal failure.

BACTERIAL DISEASES OF THE DIGESTIVE SYSTEM

Most common causes: Escherichia coli (E coli), Salmonella, and

Shigella

Infections causes nausea with or without vomiting, diarrhea and other gastrointestinal symptoms.

May also cause bloody diarrhea, known as dysentery.

BACTERIAL DISEASES OF THE DIGESTIVE SYSTEM

Bacteria from drinking untreated, contaminated water or from eating raw, contaminated produce or undercooked meat, poultry or eggs.

DENTAL AND PERIODONTAL INFECTIONS

Many opportunistic pathogens reside in the mouth.

Most commonly seen infections in the mouth are: Dental caries. DISEASES OF the gum tissue.

In both cases, the major source of infection is plaque.

FORMATION OF DENTAL PLAQUE

Tooth surface is normally covered by pellicle. Bacteria adhere to the pellicle.

Facilitated by bacterial adhesion molecules Initial adherent is usually Streptococcus mutans

FORMATION OF DENTAL PLAQUE

FORMATION OF DENTAL PLAQUE

DENTAL CARIES

DENTAL CARIES (Cavity)

Caries are the single greatest cause of tooth loss.

Several factors are involved in its development. Tooth structure Types of microflora Types of substrate available

Saliva normally protects against carries.

DENTAL CARIES

Organisms that produce acid can cause dental caries. S. mutans is the major cause. Other organisms contribute.

Carbohydrates easily enter the plaque and are readily metabolized.

GINGIVITIS & PERIODONTITIS

There are two forms of plaque-induced periodontal disease. Gingivitis

Inflammatory condition

Limited to the marginal surfaces of the gingival

Does not involve loss of bone

Can be corrected

Will continue as long as dental plaque remains

GINGIVITIS & PERIODONTITIS

There are two forms of plaque-induced periodontal disease. Periodontitis

Infection of the gingival

Results in loss of supportive bone and ligaments

Responsible for most tooth loss in adults

Treatment

Dental Care Take antibiotics only when

prescribed by your dentist. Surgery for more severe cases Visit your dentist every 2 months

SALMONELLA TYPHI

TYPHOID FEVER

TYPHOID FEVER

Affecting an estimated 22 million people each year India, Southeast Asia, Africa, South

America Transmitted by food/water

PREDISPOSING FACTORS

Work in or travel to areas where typhoid fever is endemic

Work as a clinical microbiologist handling Salmonella typhi bacteria

Have close contact with someone who is infected or has recently been infected with typhoid fever

DIAGNOSIS

Blood culture Bone marrow culture

TREATMENT

Chloramphenicol Ciprofloxacin Ampicillin trimethoprim-sulfamethoxazole

VIBRIO CHOLERAE

CHOLERA

CHOLERA

Zero to five cases of cholera are seen in the United States in a given year

Worldwide, it affects 3-5 million and causes 100,000-130,000 deaths a year as of 2010.

Transmitted by food/water

INCIDENCE

Common in developing countries in the tropics and subtropics and most cases occur in Africa

DIAGNOSIS

Blood culture Stool culture “Rice-water sool”

TREATMENT

IV fluids Oral rehydration solution Antibiotics: tetracycline, Doxycline

LEPTOSPIRA INTERROGANS

LEPTOSPIROSIS

LEPTOSPIROSIS

Transmitted by rats and mice most farm animals dogs

India, China, Southeast Asia, Africa, Australia, Central and South America, The Carribean

PREDISPOSING FACTORS

Camping in rural areas People who are working with

animals Sewage workers, farmers

DIAGNOSIS

CBC Creatine kinase Liver enzymes Urinalysis

TREATMENT

Ampicillin Ceftriaxone Doxycycline Penicillin

SHIGELLA

SHIGELLOSIS

SHIGELLOSIS

S. dysenteriae, S. boydii S. sonnei, and S. flexneri

Most cases occur in young children Transmitted by oral-fecal route

PREDISPOSING FACTORS

Living or traveling in areas that lack sanitation

Being a toddler Being a sexually active gay male

DIAGNOSIS

Stool culture

TREATMENT

Sulfamethoxazole Trimethoprim Ampicillin Ciprofloxacin Azithromycin

CAMPYLOBACTER JEJUNI

CAMPYLOBACTERIOSIS

CAMPYLOBACTERIOSIS

2.5 million cases per year in USA In developing countries, older

children and young adults have highest incidence of infection

Transmitted by : Contaminated milk Contaminated food Poultry, livestock or household pets

PREDISPOSING FACTORS

Consumption of poultry and poultry products

Drinking untreated water-consuming unpasteurized milk

DIAGNOSIS

Gram stain Stool culture

TREATMENT

Azitrhomycin

BACILLUS CEREUS

FRIED RICE SYNDROME

FRIED RICE SYNDROME

Common in Northern Europe and Canada

If the rice is not refrigerated properly after being steamed, the bacteria thrives and multiplies rapidly.

Transmitted by food

PREDISPOSING FACTORS

Storage of boiled rice Cooking frequency per dining session

DIAGNOSIS

Isolation of B. cereus organism

TREATMENT

Oral rehydration or intravenous fluid and electrolyte replacement

OTHER BACTERIAL DISEASES

Gastric ulcer Clostridial food poisoning Staphylococcal food poisoning Pseudomembranous colitis

FUNGAL DISEASE OF DIGESTIVE SYSTEM

Mycotoxins are toxins produced by some fungi.

It affects the blood, nervous system, kidneys, or liver.

CLAVICEPS PURPUREA

ERGOT POISONING OR ERGOTISM

ERGOT POISONING OR ERGOTISM

Produced due to fungal contamination of grains Cereal grains

Transmitted by: Ingestion of Claviceps purpurea Ingestion of fungus infected rye

INCIDENCE/PREVALENCE

Open-flowering and male-sterile cereals

Large reservoir of inoculum amongst grasses.

Prevalent throughout Britain

DIAGNOSIS

Stool exam

TREATMENT

Nifedipine

ASPERGILLUS FLAVUS

AFLATOXIN POISONING

AFLATOXIN POISONING They can colonize and contaminate

grain before harvest or during storage.

Peanuts are the crop most often contaminated

Toxin is carcinogenic in humans and can also cause other health effect, particularly liver problems

INCIDENCE

The condition is most common in poorly developed countries.

The American Food and Agriculture Organization estimates that 25% of the food crops in the world are affected by mycotoxins. Of these mycotoxins, aflatoxins are the biggest problem.

DIAGNOSIS

Stool exam Liquid chromatography-tandem mass

spectrometry

TREATMENT

Chemical treatment via ammoniation Reaction with sodium bisulfite

VIRAL DISEASES OF THE DIGESTIVE SYSTEM

Digestive system is an important portal of entry for viruses.

For some it is only an entry point Most common sign of viral infection is

diarrhea.

VIRAL DISEASES OF THE DIGESTIVE SYSTEM

Several groups of viruses cause gastrointestinal infections: Rotavirus Calicivirus Astrovirus Some serotypes of adenovirus Enterovirus

VIRAL DISEASES OF THE DIGESTIVE SYSTEM

Infections all have similar characteristics Brief incubation periods Fecal-oral routes of transmission Vomiting that either precedes or accompanies

diarrhea

VIRAL DISEASES OF THE DIGESTIVE SYSTEM

ROTAVIRUS

ROTAVIRUS

Not discovered until 1973 Now found around the world

Believed to account for 40 - 60% of cases of acute gastroenteritis

Can undergo genetic re-assortment Difficult to deal with immunologically

ROTAVIRUS

Most common cause of severe diarrhea among infants and young children

Outbreaks of rotavirus infections common in infants and children under 2. Adults are usually only minimally affected. Can affect the elderly or institutionalized Usually causes little or no clinical illness

ROTAVIRUS

Rotavirus infections kill more than 1 million infants worldwide each year. In the US there are fewer than 100 deaths

each year. Infection is still a major cause of

hospitalization early in life.

MODE OF TRANSMISSION

Fecal-oral route Contact with contaminated hands,

surfaces and objects Possibly by the respiratory route.

DIAGNOSIS

Enzyme-linked immunosorbent assay (ELISA)

Electron microscopy PCR (polymerase chain reaction)

TREATMENT

Maintenance of hydration low-osmolarity oral rehydration

solution and zinc supplementation

ENTEROVIRUS

ENTEROVIRUS

Enteroviruses are members of the picornaviridae.

Very resistant to acidic environments Humans are the natural hosts.

ENTEROVIRUS

Transmission is by direct or indirect fecal-oral route.

Virus will normally spend 1 to 4 weeks in the oropharynx.

ENTEROVIRUS INFECTION:Pathogenesis

60% of infections occur in children of 9 and younger.

Incubation time is 2 to 10 days. Virus is brought into the host cell by

envelopment in the host membrane.

ENTEROVIRUS INFECTION:Pathogenesis

Enteroviruses are lytic. End result is destruction of host

cell Primary infection in the digestive

system Spreads to other sites

TREATMENT OF ENTEROVIRUS INFECTION

None of the currently available antiviral agents is effective.

HEPATITIS VIRUSES

HEPATITIS VIRUSES

Hepatitis describes any disease that affects the hepatocytes of the liver.

At least 6 different viruses cause hepatitis

HEPATITIS VIRUSES

Humans are the most common natural host. Transmission is usually via the fecal-oral

route. Infections are common where there is crowding

and poor hygiene. Rates of infection are higher in lower

socioeconomic groups. Up to 90% of the population of developing nations

show evidence of previous infection.

HEPATITIS INFECTION:Pathogenesis

Infection often results from poor personal hygiene in food handlers.

Virus is believed to replicate initially in intestinal mucosa

HEPATITIS INFECTION:Pathogenesis

Multiplication in the intestines is followed by spread to liver

Extent of necrosis correlates to the severity of infection.

HEPATITIS INFECTION:Pathogenesis

Immune response is protective. Patients with antibodies cannot be reinfected.

Incubation times vary from 10 to 50 days, followed by: Fever Anorexia Nausea Pain in the abdomen Jaundice

HEPATITIS INFECTION:Pathogenesis

In infected patients with jaundice: Urine becomes dark. Stool can become clay-colored 1 to 5 days before

onset of jaundice.

HEPATITIS INFECTION:Treatment

No drugs are effective – supportive measures are recommended.

There is an active immunization protocol for those who are repeatedly exposed to hepatitis A virus.

Mumps

Oral herpes

Viral gastroenteritis

PARASITIC DISEASES OF THE DIGESTIVE SYSTEM

Several protozoan and helminthic diseases of the human digestive system

Common parasitic diseases are caused by: Giardia Cryptosporidium Whipworms Hookworms

HELMINTHIC DISEASE OF DIGESTIVE SYSTEM

ASCARIS LUMBRICOIDES

ASCARIASIS

ASCARIASIS

Large Intestinal Roundworm The disease is acquired by ingesting

Ascaris eggs. The eggs can remain viable in the

soil for several months or even years.

ASCARIASIS

More than 2 billion people are affected by this infection.

One study indicated that the prevalence of ascariasis in the United States at about 4 million (2%)

PREVALENCE

Perhaps as many as one quarter of the world's population are infected, with a prevalence of 45% in Latin America and 95% in parts of Africa.

MODE OF TRANSMISSION

Ingestion of Embryonated egg through contaminated food or water

DIAGNOSIS

Concentration methods and Direct Fecal Smear: Kato-Katz

TREATMENT

Albendazole Mebendazole Pyrantel pamoate

TRICHURIS TRICHIURA

TRICURIASIS

TRICURIASIS

Infects a human large intestine Found in Tropical Areas There is a worldwide distribution of

Trichuris trichiura, with an estimated 1 billion human infections.

PREVALENCE

50 to 80 percent in some regions of Asia (noted especially in China and Korea) and also occurs in rural areas of the southeastern United States.

Infection is most prevalent among children, and in North America, infection occurs frequently in immigrants from tropical or sub-tropical regions.

MODE OF TRANSMISSION

Fecal-oral contamination

DIAGNOSIS

Stool ova and parasites exam Kato-Katz thick-smear technique Colonoscopy

TREATMENT

Mebendazole Albendazole Ivermectin

ENTEROBIUS VERMICULARIS

ENTEROBIASIS

ENTEROBIASIS

Human parasitic disease and one of the most common childhood parasitic worm

Infection usually occurs through the ingestion of pinworm eggs, either through contaminated hands, food, or less commonly, water.

PREVALENCE

Pinworms are particularly common in children, with prevalence rates in this age group having been reported as high as 61% in India, 50% in England, 39% in Thailand, 37% in Sweden, and 29% in Denmark.

MODE OF TRANSMISSION

Human-to-human By ingesting (swallowing) infectious

pinworm eggs.

DIAGNOSIS

Diagnostic Exam: Scotch Tape Swab

TREATMENT

Mebendazole Albendazole

FASCIOLA HEPATICA

FASCIOLOSIS

FASCIOLOSIS

Human fasciolosis has been reported from countries in Europe, America, Asia, Africa and Oceania. The incidence of human cases has been increasing in 51 countries of the five continents.

In addition, fasciolosis is now recognized as an emerging human disease: the World Health Organization (WHO) has estimated that 2.4 million people are infected with Fasciola, and a further 180 million are at risk of infection

MODE OF TRANSMISSION

Intermediate snail hosts, Domestic herbivorous animals,

DIAGNOSIS

Stool examination ELISA Western blot.

TREATMENT

Nitazoxanide Triclabendazole Bithionol

TAPEWORMS

TAPEWORMS

Taenia Solium - pork Taenia Saginata- beef Diphyllobothrium latum- fish

TAENIASIS

TAENIASIS Most occurrences are found in areas

which lack adequate sanitation Southeast Asia West Africa East Africa

Usually cause no symptoms Some people experience upper

abdominal discomfort, diarrhea, and loss of appetite.

MODE OF TRANSMISSION

Blood to blood contact Eating the raw meat of an animal

infected with tapeworms

DIAGNOSIS

Stool examination Inject gravid proglottid with India ink Scotch tape test for the eggs

TREATMENT

Mebendazole Praziquantel Niclosamide

OTHER HELMINTHIC DISEASE

Schistosomiasis Paragonimiasis Clonorchiasis Strongyloidiasis Cysticercosis Diphyllobothriosis Intestinal capillariasis

PROTOZOAN DISEASE OF DIGESTIVE SYSTEM

Giardiasis Amoebiasis Balantidiasis Isosporiasis Cryptosporidiosis

GIARDIA LAMBLIA

GIARDIASIS

GIARDIASIS

Common cause of gastroenteritis in humans, infecting approximately 200 million people worldwide.

One of the most common water borne gastrointestinal diseases in the United States.

PREVALENCE

Areas with inadequate sanitary conditions

Among people living in developed countries

Tropics and subtropics area

MODE OF TRANSMISSION

Fecal-oral route Personal contact Contaminated water and food By not washing their hands after

touching something contaminated with Giardia cysts

MODE OF TRANSMISSION

DIAGNOSIS

Stool microscopy

TREATMENT

Metronidazole Tinidazole Quinacrine Paromomycin

ENTAMOEBA HISTOLYCTICA

AMOEBIASIS

AMOEBIASIS

A gastrointestinal infection that may or may not be symptomatic and can remain latent in an infected person for several years, amoebiasis is estimated to cause 70,000 deaths per year world wide

Can cause severe diarrhea with blood.

PREVALENCE/ INCIDENCE

Amoebiases occurs worldwide, although much higher rates of incidence are found in the tropics and subtropics. About 5,000 to 10,000 cases are diagnosed each year in the US, leading to about 20 deaths annually.

MODE OF TRANSMISSION

Contaminated food/water Fecal-oral route Anal-oral contact

PREDISPOSING FACTORS

Poor sanitary conditions Commonly affects active homosexual

men Immigrants from developing

countries

DIAGNOSIS

Fecal microscopic analysis

TREATMENT

Metronidazole Paromomycin Amoebicide

BALANTIDIUM COLI

BALANTIDIASIS

BALANTIDIASIS

The first case of Balantidiasis in the Philippines, where it is the most common, was reported in 1904.

Currently, Balantidium coli is distributed worldwide but less than 1% of the human population is infected.

BALANTIDIASIS Symptoms can be local due to

involvement of the intestinal mucosa, or systemic in nature and include either diarrhea or constipation.

MODE OF TRANSMISSION

Contaminated food/water When a patient has diarrhea

combined with a probable history of current exposure to amoebiasis Travel contact with infected persons Anal intercourse.

DIAGNOSIS

Fecal analysis

TREATMENT

Tetracycline Metronidazole Iodoquinol

ISOSPORA BELLI

ISOSPORIASIS

It is found worldwide, especially in tropical and subtropical areas.

Infection causes acute, non-bloody diarrhea with crampy abdominal pain, which can last for weeks and result in malabsorption and weight loss.

ISOSPORIASIS

In immunodepressed patients, and in infants and children, the diarrhea can be severe.

MODE OF TRANSMISSION

Contaminated food/water

DIAGNOSIS

Fecal analysis Typical laboratory analyses include:

Microscopy Morphologic comparison with other

intestinal parasites Bench aids for Isospora

TREATMENT

Trimethoprim-sulfamethoxazole

CRYPTOSPORIDIUM

CRYPTOSPORIDIOSIS

CRYPTOSPORIDIOSIS

Affects the intestines and is typically an acute short-term infection

the main symptom is self-limiting diarrhea in people with intact immune systems.

CRYPTOSPORIDIOSIS

It is found worldwide. It causes 50.8% of water-borne diseases that are attributed to parasites.

The age group most affected is children from 1 to 9 years old.

MODE OF TRANSMISSION

By the fecal-oral route Directly from person to person Contaminated drinking water and

swimming pools and to petting infected animals

Contaminated food

PREVALENCE/ INCIDENCE

0.5 to 2 million undiagnosed cases each year

DIAGNOSIS

Examination of stool samples Stool microscopy

TREATMENT

Nitroxonide Paromonomycin Clarithromycin Azithromycin

OTHER PROTOZOAN DISEASE

Sarcosporidiosis Gum disease

POP QUIZ!

1. CHOLERAA.CAMPYLOBACTER JEJUNIB. VIBRIO CHOLERAE

2. Organisms that are part of the normal microbial floraA. ENDOGENOUS INFECTIONSB. EXOGENOUS INFECTIONS

3. FRIED RICE SYNDROMEA.SHIGELLAB. BACILLUS CEREUS

4. ASCARIASISA. ASCARIS LUMBRICOIDESB. ASCARIS LUMBERICOIDE

5. TAENIA SOLIUMA. BEEFB. PORK

6. TREATMENT FOR ERGOT POISONINGA. NIFEDIPINEB. MEBENDAZOLE

7. Treatment for Ascariasis is SCOTCH TAPE SWAB? Y/N

8. ERGOT POISONING A. CLAVICEPS PURPUREAB. ASPERGILLUS FLAVUS

9. TREATMENT FOR AMOEBIASIS IS NIFEDIPINE?

Y/N

10. A. ROTAVIRUSB. HEPATITIS VIRUS