BAC INFECTION Flashcards
- is a dehydrating diarrheal disease that rapidly leads to death in the absence of immediate initiation of appropriate treatment.
CHOLERA
- a gram-negative, comma-shaped bacillus, subdivided into serogroups by its somatic O antigen.
- > 200 serogroups, only serogroups O1 and O139 have been associated with epidemics, although some non-O1, non-O139
- V. cholerae strains (e.g., O75, O141) are pathogenic and can cause small outbreaks.
- O1 serogroup is further divided into its biochemical characteristics
• classical
• El Tor biotypes based on its.
Vibrio cholerae
- A and C antigenic determinants
- A and B antigenic determinants
- produce all 3 antigenic determinants but are unstable and rare
- Inaba
- Ogawa
- Hikojima
Mode of Transmission on Cholera
Consumption of contaminated water and ingestion of undercooked shellfish
hallmark of CHOLERA
rice-water stools (suspended flecks of mucus) with a fishy smell
• most severe form of the disease
• purging rates of 500-1,000 mL/hr occur
• decreased urine output, a sunken fontanel (in infants), sunken eyes, absence of tears, dry oral mucosa, shriveled hands and feet (“washerwoman’s hands”), poor skin turgor, thready pulse, tachycardia, hypotension, and vascular collapse
• Patients with metabolic acidosis can present with typical Kussmaul breathing
• progress to obtundation and coma -> death can occur within hours
CHOLERA GRAVIS
Transported media of cholera
Transported media: thiosulfate-citrate–bile salts sucrose agar
Result of cholera in Dark-field microscopy
typical darting motility in wet mounts
Treatment of CHOLERA
• Rehydration
• Antibiotics (WHO)
> Tetracycline for children
> Erythromycin: alternative
• an important cause of intraintestinal and extraintestinal infections.
• Intraintestinal infections present as different diarrheal illnesses.
Escherichia coli
Characteristic of E. coli
- facultative anaerobic,
- gram-negative bacilli
- ferment lactose.
-most are commensal, are ubiquitous among humans starting in the 1st mo of life, and do not cause diarrhea.
MAJOR GROUPS OF E. coli
- risk for >1 y.o and travelers
- watery stools
- acute duration
- detection of enterotoxins (LT & ST)
- accounts for a sizable fraction of dehydrating
infantile diarrhea in the developing world (10–30%) and of traveler’s diarrhea - is the most common cause of traveler’s diarrhea
- explosive watery, nonmucoid, nonbloody diarrhea; abdominal pain; nausea; vomiting; and little or no fever.
- self-limited and resolves in 3-5 days but occasionally lasts >1 wk
ETEC
MAJOR GROUPS OF E. coli
- risk for >1 y.o
- watery stools
- bloody diarrhea
- acute duration
- present either with watery diarrhea or a dysentery syndrome with blood, mucus, and leukocytes in the stools, as well as fever, systemic toxicity, crampy abdominal pain, tenesmus, and urgency.
• resembles bacillary dysentery
• shares virulence genes with Shigella spp.
• Sequencing of multiple housekeeping genes indicates is more related to Shigella than to noninvasive E. coli .
• diarrhea occurs mostly in outbreaks
• disease resembles shigellosis .
• cause colonic lesions with ulcerations, hemorrhage, mucosal and submucosal edema, and infiltration by polymorphonuclear leukocytes (PMNs).
EIEC
MAJOR GROUPS OF E. coli
- risk for <2 y.o
- watery stools
- acute, prolonged or persistent duration
- causes acute, prolonged, and persistent diarrhea
- primarily in children <2 yr old in developing countries, where the organism may account for 20% of infant diarrhea.
- Profuse watery, nonbloody diarrhea with mucus, vomiting, and low-grade fever are common symptoms.
- Prolonged diarrhea (>7 days) and persistent diarrhea (>14 days) can lead to malnutrition , a potentially mortality-associated outcome infection in infants in the developing world.
- Studies show that breastfeeding is protective against diarrhea caused by
- colonization causes blunting of intestinal villi, local inflammatory changes, and sloughing of superficial mucosal cells
- induced lesions extend from the duodenum through the colon.
EPEC
MAJOR GROUPS OF E. coli
- risk for 6-10 y.o and the elderly
- watery stools
- acute duration
- causes a broad spectrum of diseases
- may be asymptomatic
- Patients who develop intestinal symptoms can have mild diarrhea or severe hemorrhagic colitis
- Abdominal pain with initially watery diarrhea that may become bloody over several days
- Infrequent fever differentiates from the otherwise similar appearance of shigellosis or EIEC disease
STEC (EHEC/VTEC)