Vibrio cholerae

Asiatic or Epidemic Cholera

Readings Question #1

• Describe the Vibrio cholerae bacterium. Where is it found?

Outbreaks

• no major outbreaks in U.S. since 1911• sporadic: 1973-1991• 1991: South America – Peru– 1,099,882 cases and 10,453 deaths (1991-95)

• 1992: new strain – Bangladesh and India– 1 case in U.S.

Symptoms of Cholera

• “rice-water” stools• viscous blood• sudden onset, incubation: 6 hrs- 5 days• violent vomiting• No fever• abdominal cramps, nausea, dehydration,

shock• 1 million organisms

Progression of Disease

Diagnosis

• isolated from feces• recovered from foods• pathogenic and non-pathogenic forms exist• test for presence of cholera enterotoxin

Treatment of Cholera

• water and electrolyte replacement– oral rehydration therapy– sodium chloride, sodium bicarbonate, potassium

chloride and dextrose– intravenous rehydration

• tetracycline• untreated – 50% mortality rate• death occurs from dehydration and loss of

essential electrolytes

Bacillus anthracis

• 1877 isolated by Robert Koch

Readings question #2:List 5 characteristics of the Bacillus anthracis

bacterium.

People at Risk

• handle animals, hides, wool, and other animal products

• goat hair and handicrafts containing animal hides from the Middle East

• infection initiated by endospores• 2 exotoxins: edema toxin and lethal toxin• capsule does not stimulate a protective response

Readings Question #3

What are the 3 forms of anthrax that affect humans?

Treatment of Anthrax

• antibiotics• ciprofloxacin and doxycycline• preventive doses of antibiotics (60 days)• vaccination of livestock– live attenuated

• human vaccine: inactivated form– 6 injections over 18 months– Annual boosters

Diagnosis of Anthrax

• isolation and identification from a clinical speciman

Biological Weapons

• “the use of living pathogens for hostile purposes”

• 14th century: 1346 Tartar army at Kaffa– began the plague pandemic for 1348 - 1350

• 1925: 100 countries– Sino-Japanese War (1937-1945)– canisters of fleas carrying Yersinia pestis dropped

on China

U.S. Epidemic Intelligence Service

• formed in 1951 (after start of Korean War)• early warning system• important role in combating epidemics and

tracking outbreaks of disease

• 1940s-1960s: research on biological weapons– develop vaccines or treatments

“Operation Sea-Spray”

• September 27 and 27, 1950• Serratia marcescens over San Francisco and

Florida (Panama City and Key West)• non-pathogenic, reddish coloration• September 29: 11 patients (1 died)• Pneumonia• January 2008: recall of pre-filled heparin-lock

flush solution

Serratia marcescens

• production of red pigment• damp conditions: bathrooms• complete eradication is difficult• dirt, “sterile places”, biofilm of teeth• hospital settings: catheters, saline irrigation solutions,

sterile solutions• urinary and respiratory tract infections in hospitals• conjunctivitis, keratitis, endophthalmitis, tear duct

infections• resistant to several antibiotics

Biological Weapons

• 1972: 100 countries• 1979: Bacillus anthracis in Sverdlovsk– explosion resulting in 100 deaths in 2 weeks

• 1984: The Dalles, Oregon– Salmonella enterica

• 2001: U.S. Postal Service– Bacillus anthracis– “bioterrorism”

Bordetella• Whooping Cough (Pertussis)– 2 basic toxins: 1) tracheal cytotoxin

- damages ciliated cells 2) pertussis toxin

- systemic symptoms• small children: violence of coughing can break

ribs• infants: irreversible damage to the brain

occasionally occurs• adults: misdiagnosed as bronchitis

Diagnosis of Pertussis

• clinical signs and symptoms• throat swab culture• culture on special media• rapid tests available

Treatment of Pertussis

• Erythromycin• Antibiotics render the patient noninfectious• Immunity following recovery is good

• DTap Vaccine: 1996, minimal side effects– lowered annual cases– fewer than 10 deaths/year– effectiveness wanes after 12 years of age– elderly and infants

Enterics(Enterobacteriaceae)

• Genera: Escherichia, Klebsiella, Proteus, Salmonella, Shigella

• straight rods, simple nutritional requirements• intestinal tracts of humans and animals• fermenters of glucose and carbohydrates• fimbriae• sex pili• proteins: lysis of closely related species

Readings Question #4

What is the most significant opportunistic pathogen of all the enterics? Where is it found?

• traveler’s diarrhea

Klebsiella pneumoniae

• normal flora of mouth and skin• naturally occurs in soil• new antibiotic resistant strains• nosocomial infection: invasive treatments

Pathogenesis• bacterial pneumonia• severe, rapid onset• high fever, chills, flu-like symptoms, cough• “currant jelly” sputum• mortality fairly high• lung destruction and abcesses• empyema• bronchitis• urinary tract and wound infections• feces and contaminated instruments

Treatment

• resistant to penicillin and its derivitives• two or more powerful antibiotics• susceptible to aminoglycosides and

cephalosporins• culture: sputum, blood, and urine samples and swab of surgical site

Proteus

• Hospitals: colonizes skin and oral mucosa• Rod-shaped, gram-negative bacilli• Soil, stagnant and standing water, fecal

matter, raw meats, dust• Proteus mirabilis: 90% (community-acquired)• highly motile, does not form regular colonies

Proteus “Swarming Colonies”

Pathophysiology

• Fimbriae attach to uroepithelial cells • bloodstream: sepsis• Long-term indwelling urethral catheters• UTIs most common clinical manifestationReadings question #5:What is the significance of Proteus vulgaris to

the embalmer?

Salmonella

• all members potentially pathogenic• biochemical and serological tests• common inhabitants of the intestinal tract of

many animals, especially poultry and cattle• contaminate food: unsanitary conditions• gram-negative, facultatively anaerobic, non-

endospore-forming rods

Salmonella enteritidis• intestinal mucosa• lymphatic and cardiovascular system• less than 1% mortality rate• normal recovery in a few days• shed in feces for up to 6 months• 40-50,000 reported cases; 2-4 million cases• Sources: intestinal tracts of animals

1 in 20,000 eggspet reptiles (90%)

Treatment

• antibiotic therapy is not useful• oral rehydration therapy

Shigella• facultatively anaerobic gram-negative rods• pathogenic E. coli• many cases of “traveler's diarrhea” may actually

be mild forms of shigellosis• small infective dose• primary site: large intestine• toxins, destroy tissue, dysentery• rarely invade the bloodstream• diagnosis: rectal swabs• fluoroquinolones

Yersinia pestis

• Scratches and bites from domestic cats• Flea bite – bloodstream- lymph and blood• Survive and proliferate in phagocytic cells• Fever• “buboes”

“Septicemic Plague”

• septic shock• “pneumonic plague”: 100% mortality rate• spread by airborne droplets• diagnosis: isolating bacterium• treatment: streptomycin, tetracycline• recovery confers reliable immunity• vaccine