BAC INFECTION Flashcards
(37 cards)
1
Q
- is a dehydrating diarrheal disease that rapidly leads to death in the absence of immediate initiation of appropriate treatment.
A
CHOLERA
2
Q
- 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.
A
Vibrio cholerae
3
Q
- A and C antigenic determinants
- A and B antigenic determinants
- produce all 3 antigenic determinants but are unstable and rare
A
- Inaba
- Ogawa
- Hikojima
4
Q
Mode of Transmission on Cholera
A
Consumption of contaminated water and ingestion of undercooked shellfish
5
Q
hallmark of CHOLERA
A
rice-water stools (suspended flecks of mucus) with a fishy smell
6
Q
• 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
A
CHOLERA GRAVIS
7
Q
Transported media of cholera
A
Transported media: thiosulfate-citrate–bile salts sucrose agar
8
Q
Result of cholera in Dark-field microscopy
A
typical darting motility in wet mounts
9
Q
Treatment of CHOLERA
A
• Rehydration
• Antibiotics (WHO)
> Tetracycline for children
> Erythromycin: alternative
10
Q
• an important cause of intraintestinal and extraintestinal infections.
• Intraintestinal infections present as different diarrheal illnesses.
A
Escherichia coli
11
Q
Characteristic of E. coli
A
- 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.
12
Q
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
A
ETEC
13
Q
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).
A
EIEC
14
Q
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.
A
EPEC
15
Q
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
A
STEC (EHEC/VTEC)
16
Q
MAJOR GROUPS OF E. coli
- risk for <2 y.o, HIV-infected px, and travelers
- watery stools
- acute, prolonged or persistent duration
- is the 2nd most common cause of traveler’s diarrhea after ETEC.’
• Typical illness is manifested by watery, mucoid, secretory diarrhea with low-grade fever and little or no vomiting.
• The watery diarrhea can persist for ≥14 days. In some studies, many patients have grossly bloody stools, indicating that it cannot be excluded on stool characteristics.
• strains are associated with growth retardation and malnutrition in infants in the developing world. - is associated with
(1) acute, prolonged and persistent pediatric
diarrhea in developing countries, most prominently in children <2 yr old and in malnourished children
(2) acute and persistent diarrhea in HIV-infected adults and children
(3) acute traveler’s diarrhea (secretort)
A
EAEC
17
Q
MAJOR GROUPS OF E. coli
- risk for >1 y.o and travelers
- watery stools
- acute duration
- produces acute watery diarrhea that is usually not dysenteric but is often prolonged
• strains produce diffuse adherence in cultured epithelial cells
• They express surface fimbriae,responsible for
the diffuse adherence phenotype in a prototype
strain
A
DAEC
18
Q
Tx for Groups of E. coli
- ETEC
- EIEC
- EPIC
- EAEC
- DAEC
- STEC1
A
- ETEC responds to antimicrobial agents such as TMP-SMX when the E. coli strains are susceptible.
- ETEC cases from traveler’s diarrhea trials respond to ciprofloxacin, azithromycin, and rifaximin.
- EIEC infections: TMP-SMX is an appropriatechoice.
- Although treatment of EPEC infection with TMP-SMX intravenously or orally for 5 days may be effective in speeding resolution,
- Ciprofloxacin or rifaximin is useful for EAEC traveler’s diarrhea, but pediatric data are sparse.
- Specific therapy for DAEC has not been defined.
- Antibiotics should not be given for STEC infection because they can increase the risk of HUS
19
Q
• Small, aerobic gram-negative coccobacilli that colonizes only ciliated epithelium
• Extremely contagious
• Transmission: aerosol droplets
A
Bordetella pertussis
20
Q
Stages of Bordetella pertussis
- May last 1-2 weeks
- Symptoms:
> runny nose
> low-grade fever
> mild
> occasional cough
> highly contagious
A
- Catarrhal stage
21
Q
Stages of Bordetella pertussis
- May last 2-3 weeks; susceptible to other respi infections for many
- Symptoms:
> recovery is gradual
> coughing lessens but fits of coughing may return
A
- Convalescent stage
22
Q
Stages of Bordetella pertussis
- May last 1-6 weeks
- Symptoms:
> fits of numerous
> rapid coughs followed by “whoop” sound
> vomiting & exhaustion after coughing fits
A
- Paroxysmal stage
23
Q
Suspect pertussis if ➞ pure or predominant complaint of cough especially if the ff features are absent:
A
- Fever
- Malaise or myalgia
- Exanthem or enanthem
- Sore throat
- Hoarseness
- Tachypnea
- Wheezes
- Rales
24
Q
Clinical case definition of pertusis
A
- cough of ≥ 14 days’ duration + at least 1
associated symptom of paroxysms, whoop, or post-tussive ➞ 81% sensitivity and 58% specificity for culture confirmation - Older children: cough illness escalating at 7-10 days and whose coughing episodes are not continuous
- <3 mos: gagging, gasping, apnea, cyanosis
25
gold standard for Dx for pertusis
Culture
26
Admit px if
- Infants <3 months: admit to hospital
- Infants 3-6 months: may not admit unless witnessed paroxysms are not severe
27
Px with Bordetella pertussis may discharge if:
• disease severity unchanged or diminished over 48 hr period
• no intervention needed during paroxysms
• Adequate nutrition
• No complication has occurred
• Parents prepared for care at home
28
Antibiotic choice for pertusis
Macrolides: Azithromycin
29
Bordetella pertussis Complications in Infants <4 months:
90% of fatal pertussis
30
• Motile, nonsporulating, nonencapsulated gram-negative rods
• Possess somatic O antigens & flagellar H antigens
• May survive for weeks in sewage, dried food stuffs, pharmaceutical agents, fecal material
•major cause of childhood diarrhoea illness
•incidence proportional to the standards of hygiene, sanitation availability of safe water, and food preparation practices
•may also be related to intensive animal husbandry practices
•incidence peaks: young infants & elderly
• 2 important serotypes:
> Salmonella Enteritidis
> Salmonella Typhimurium
Non-typhoidal Salmonellosis
31
- most common manifestationg of salmonella
- IP: 6-72 hours
- Nausea, vomiting, crampy abdominal pain, mild to severe diarrhea
- Subsides in 2-7 days in healthy children
- mild leukocytosis, S/E: moderate PMN and occult blood
1.Acute Enteritis
32
TREATMENT for Gastroenteritis in Salmonella
- correction of dehydration and electrolyte disturbances
- supportive care
- antibiotics generally not recommended for isolated uncomplicated cases
33
• antibiotics given to infants with salmonella
- -infants <3 months old
- high risk groups with immune compromise (HIV, malignancies, immunosuppressive therapy, sickle cell anemia, immunodeficiency states)
- cefotaxime
34
Transmission fo Typhoid Fever (Salmonella enterica, serovar Typhi)
ingestion of food/water contaminated with
S. typhi from human feces
35
DIAGNOSIS for Typhoid Fever
- culture:
> Blood (positive 40-60% early in the course)
> Stool & urine positive after 1st week
- Widal test
> Measures antibodies against O and H Ag
> Lacks specificity and sensitivity
36
TREATMENT for Typhoid Fever
• Supportive
- Rest
- Hydration
- Antipyretic
• Antibiotic
- chloramphenicol
- amoxicillin
- fluoroquinolones
• 7Dexamethasone
37
PREVENTION of Typhoid Fever
1.Oral live attenuated Ty21a
• Oral
• Given every 5 years
• good efficacy (67-82%)
2. Vi capsular polysaccharide vaccine
• can be used in ≥ 2 years of age
• IM
• Given every 2-3 years
• efficacy: 70-80%
