View
233
Download
0
Category
Tags:
Preview:
Citation preview
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
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
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
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
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%)
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”
Recommended