Exam 1 - Waterborne Pathogens

Chapters 1 - 3

Types of Waterborne Diseases

• Cholera

• Diarrhoea

• Malaria

• Typhoid Fever

• Salmonella

• Hepatitis

• Giardiasis

• Filariasis

• Amoebiasis

• Dysentry

• Campylobacter

Waterborne pathogens have continued appearing because

• Increase in population density

• Changes in water usage

• Increase in agricultural, industrial and other development

• Globalization of commerce and travel

• Increase in sources and routes of water contamination

Life Strategy: Not So Host-Dependent Pathogens

• Well adapted to water conditions

• Examples: Legionella spp, Pseudomonas aeruginosa, Naegleria fowleri

Life Strategy: Host-Dependent (obligate) Pathogens

• Propagation occurs only in the host

• Replication typically occurs inside the intestines of an infected host

• Depend on being shed by the host to reach another host, “environmentally-transmitted pathogens”

• Examples: Campylobacter, Salmonella, Giardia, Cryptosporidium

Sources of Waterborne Infection

• Potable water used for drinking and cooking (from nonregulated sources or treated improperly)

• Recreational water from public ponds, lakes, swimming pools, etc.

Non-point source pollution sources

Urban

• oil, gas, battery acid, household chemicals

Agriculture

• manure, nutrients, pesticides

Forests

• sediment and pathogens from animal fecal matter

Point source pollution sources

• Sewage

• Chemicals

• Carcinogens

Acinetobacter

Bacteria

Acinetobacter Taxonomy

Domain: Bacteria

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Pseudomonadales

Family: Moraxellaceae

Genus: Acinetobacteria

Acinetobacter Biology

• Aerobic, catalase-positive, oxidase-negative

• Gram- positive, non-motile, non-fermentative

• Minimal pigmentation

• Most common human pathogen is A. baumannii

• Found in different environments like soil, water, sewage, food and human skin

Acinetobacter Health Effect

• Low-grade pathogen, can remain in the body without causing illness

• Very opportunistic and can colonize endotracheal tubes, intravascular, ventricular and urinary catheters

• Common inhabitant of intensive care units

• May cause various infections including bacteremia, secondary meningitis, UTI’s and pneumonia

Acinetobacter Pathogenicity and Virulence

• Developed the ability to resist desiccation, main reason for persistence in hospitals

• Virulence factors depend on the production of receptors and iron-regulated catechol siderophores, which favor bacterial growth and virulence factors

• Exopolysaccharide production is a major virulence factor and protects bacteria from host defenses

Acinetobacter Antibiotic Resistance

• Currently innate resistant to many antibiotics

• Imipenem is the most effective drug currently for treating infections, but has begun to show signs of resistance

Acinetobacter Habitats and Routes of Transmission

• Isolated in freshwater, estuaries, sewage, seawater and biofilms in drinking water systems

• Primarily spread person to person, medical equipment, aerosols in water environments

Acinetobacter Methods of Detection

• Selective medium is Herellea agar containing bile salts, sugars and bromocresol purple. Colonies are pale lavender in color

• Gel electrophoresis, random amplified polymorphic DNA (RAPD) analysis with a set of primers amplifying random DNA fragments

Enterococcus Taxonomy

Domain: Bacteria

Division: Firmicutes

Class: Bacilli

Order: Lactobacillales

Family: Enterococcaceae

Genus: Enterococcus

Enterococcus Biology

• Gram-positive

• Facultative anaerobes

• Catalase negative

• Coccus. Some are known to be motile

• Can survive in extreme environments

• Two most common species: E. faecalis & E. faecium

Enterococcus Health Effect

• One of the most common agents of nosocomial infection

• Hepatobiliary sepsis

• UTI

• Surgical wound infection

Enterococcus Sources and Habitats

• Vary from environmental to human and animal sources

• E. faecalis and E. faecium are most common in the human GI tract

• These species have also been isolated from cheese, fish, sausages, minced beed and pork

• Very common in all types of aquatic environments

Escherichia Coli Taxonomy

Domain: Bacteria

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Enterobacteriales

Family: Enterobacteriaceae

Genus: Escherichia

Species: E. coli

Closely related to Shigella

E. coli Biology

• Gram-negative

• Produce indole from the amino acid tryptophan

• Non-spore forming, motile, facultative anaerobes, fermenting carbohydrates

• Many have capsule

• Reside in digestive tract of warm-blooded animals

E. coli Health Impact

• Classified as harmless, often profitable producing B12 but can go bad

• Can cause: diarrhea, urinary tract sepsis, acute renal failure

E. coli Occurrence in the Environment and Routes of Transmission

• Cattle

• Chicken

• Drinking water

• Cross contamination

• Food exposed to fecal content

• Person-to-person

Francisella tularensis

Domain: Bacteria

Phylum: Proteobacteria

Class: Gammaproteobacteria

Order: Thiotrichales

Family: Francisellaceae

Genus: Francisella

Species: F. tularensis

F. tularensis Biology

• Gram-negative coccobacillus

• Facultative intracellular bacterium

• Replicates in amoebas and in the cytosol of macrophages

• 10% of genes are pseudogenes or gene fragments

F. tularensis Health Effects

• Highly infectious pathogen

• Subsp. tularensis and subsp. holarctica cause disease in humans

• Causes zoonosis tularemia (ulcers, tender lymph nodes, fever)

F. tularensis Pathogenicity

Type A

• found in North America

Airborne form is the deadliest

• 35% mortality in humans

• Biological warfare

Attacks macrophages

F. tularensis Occurence and Routes of Transmission

Rodents are usual hosts

• skinning game

• eating contaminated meat

• bites

• mosquitoes and ticks

• airborne

• contaminated water supply

F. tularensis Antibiotic Treatment

Aminoglycosides

Chloramphenicol

Imipenem

Fluoroquinolones

• well tolerated by patients

• achieve adequate blood levels

• intracellular penetration

• 100% clinical cure