6.2 enterobacteriae Flashcards
What are enterobacteriaecea as medically important pathogens?
large, heterogeneous group
enterobacteriaceae :
1. gram staining
2. shapes ?
- gram negative
- rods or bacilli
How many genera and species are included in the Enterobacteriaceae family?
more than 50 genera and over 150 species.
What percentage of Enterobacteriaceae species are responsible for the majority of infections, and what percentage of these infections do they account for?
Fewer than 20 species of Enterobacteriaceae are responsible for more than 95% of infections.
< 20 species of enterobacteriaceae responsible for > 95% infection such as… (give examples of most common forms of infections)
- UTIs
- septicemia
- intestinal infections
> 70% enterobacteriaecea responsible for what infections ?
urinary tract infections
where do infections with enterobacteriaceae originate from ?
- animal resevoir
- human carrier
- endogenous spread of organisms
Enterobacteriaceae physiology ?
1. grow … ?
2. nutritional requirements are … ?
3. type of anaerobes ?
- slowly
- simple
- facultative
what do enterobacteriacea ferment and reduce ?
- ferment glucose
- reduce nitrate
enterobacteriaceae:
1. catalase test result ?
2. unlike other gram-negative rods it’s oxidase status ?
3. pathogenic members don’t ferment …. ?
4. pathogenic members are resistant to …?
- positive
- negative
- lactose
- bile salts
Differences on solid medium colour between lactose fermenting colonies and non-lactose fermenting colonies ?
- fermenting = pink
- non-fermenting = colorless
List some enterobacteriaceae pathogenic to humans ? all end in spp
[Citrobacter and Enterobacter went to Escherichia’s Kitchen, Making Salad with Yummy Honey, Providing Perfect Satisfaction = simplify !]
- citrobacter
- enterobacter
- escherichia
- klebsiella
- morganella
- salmonella
- shigella
- yersinia
- hafina
- plesiomonas
- proteus
- serratia
Name some common medically significant enterobacteriaceae
SPECKY MESS
Morgana escorts salmonella and serratia (MESS)
She flex son
Protect vulgar mira
Enter aero cloud
Citro friendly kose
Klebsiella pneumoniae needs oxygen
Yes pseudo pests enter
- Citrobacter freundii, Citrobacter koseri
- Enterobacter aerogenes, Enterobacter cloacae
- Escherichia coli (opportunistic/pathogenic)
- Klebsiella pneumoniae, Klebsiella oxytoca
- Morganella morganii
- Proteus mirabilis, Proteus vulgaris
- Salmonella enterica (pathogenic)
- Serratia marcescens
- Shigella sonnei, Shigella flexneri (pathogenic)
- Yersinia pestis, Yersinia enterocolitica, Yersinia pseudotuberculosis (pathogenic)
Examples of only primary pathogen of enterobacteriaceae
shigella
salmonela
uersina
Examples of only opportunistic pathogen of enterobacteriaceae
- providencia
- enterobacter
- morganella
- serratia
- proteus
Example of an opportunistic / primary (mixed) pathogen of enterobacteriaceae
E. coli
K. pneumoniae
primary pathogens cause disease in ?
healthy host
opportunistic pathogen cause disease only in … ?
absence of normal host resistance (immunosuppressed host)
What are the virulence factors of enterobacteriaceae ?
O Core Lipid A has a resistance to 3 types of sides: Lips, Flag, Cap
or COSTAL LFC
- Flagellar H antigen
- Capsular K or Vi antigen
- Liposaccharide (LPS)
- O antigen
- Core polysaccharide (present in all E.)
- Lipid A (responsible for endotoxin activity)
- Siderophores
- Type III secretion system
- Antimicrobial resistance
E. coli is a major componenet of the … ?
normal intestinal floar
what does E. coli cause by at least 6 mechanisms ?
diarrhoea
E. coli causes diarrhoea by at least 6 mechanisms, identified by the adjectives used to describe the respective strains…
what are these 6 mechanisms ?
- STEC = shiga toxin producing strain
- ETEC = enterotoxigenic strains
- EIEC = enteropathogenic strains
- EPEC = enteropathogenic strains
- EAEC = enteroaggregative strains
- DAEC = diffusely adherent E.coli
Most clinically relevant salmonella pathogens belong to what ?
Salmonella enterica spp
Most clinically relevant salmonella pathogens belong to salmonella enterica spp. with:
..1.. subspecies (I,II ,IIIa, IIIb, IV , VI)
over ..2… serovars differentiated based on the antignes ..3…
- 6
- 2500
- H,K,O
Salmonella:
1. Genus
2. Species
3. specific serovar / serotype designation of bacterium
- Salmonella
- Enterica
- Serotype Typhi
Salmonella enterica spp. causes …. ?
Give 2 examples of the types of what is caused ?
salmonellosis
- gastroenteritis
- enteric fever (typhoid fever)
Which Salmonella enterica serovars are commonly associated with gastroenteritis?
EW MOUNTAIN !
Salmonella:
* enteritidis
* wien
* montevideo
* typhimurium,
Which disease is commonly known as typhoid fever ?
enteric fever
salmonella typhi spp causes ?
typhoid fever
most common form of salmonellosis is ?
gastroenteritis
cause of salmonellosis ?
salmonella enteritidis
transmission of salmonellosis ?
- contaminated food (poultry, dairy, eggs) or water
- faecal-ocal route
symptoms (appear within 6-48 hours) of salmonellosis ?
- nausea
- vomiting
- diarrhoea
- fever
- abdominal cramps
diagnosis of salmonellosis ?
what agar or media ?
stool sample analysis
(MacConkey agar or selective media)
Treatment of salmonellosis ?
- rehydration
- if in bloodstream = Cephalosporins
Where in the body are peyer’s patches found ?
While they are most prominent and abundant in the ileum, Peyer’s patches can also be found in the jejunum and sometimes extend into the proximal part of the colon (ileocecal region).
Pathogenesis of gastroenteritis caused by salmonella (S. enterica)
- salmonella ingested in contaminated food / water
- bacteria attach to mucosa of small inestine and invade into the microfold (M-cells) of the peyer’s patches and endocytose into enterocytes
- bacterial invasion proteins are injected by type III secretion system
- production of salmonella enterotoxin which leads to local inflammation & diarrhoea
- pathogen kills host cells, triggering abdominal cramps & diarrhoea
Complication of salmonellosis (S. enterica) gastroenteritis ?
if bacteria enters the bloodstream, can lead to septicaemia
1 of the 4 key global causes of diarrhoeal disease is ?
salmonella
Enteric (typhoid) fever is a acute , ….. illness ? caused by ?
life-threatening
Salmonella Typhi
Transmission of enteric (typhoid) fever ?
- ingestion of contaminated food / water
- faecal-oral route
- contact without carriers
symptoms of enteric (typhoid) fever ?
occur within 10 - 14 days and persis for 3-4 weeks
- high fever
- headache
- constipation or diarrhoea
- abdominal pain
- malaise
Enteric (typhoid) fever has malaise within …1.. days following at least 1 week of ..2… ?
- 10 to 14 days
- constipation and abdominal cramping
Enteric (typhoid) fever symptoms persist for duration ?
3-4 weeks
diagnosis for enteric (typhoid) fever ?
- stool sample analysis
- blood
- bone marrow
- urine sample analysis
treatment for enteric (typhoid) fever ?
antibiotics e.g.
* fluoroquinolones
* chloramphenicol
* cephalosporins
Vaccination for enteric (typhoid) fever is recommended for people travelling to which countries ?
- asia
- africa
- latin america
Pathophysiology of S. Typhi infection (typhoid fever) ?
- ingestion of contaminated water / food
- Invasion of small intestine, enter bloodstream
- carried by WBC (phagocytosed NOT digested) to liver, spleen , bone marrow
- Bacteria multiply, re-enter bloodstream
- bacteria invade gallbladder, biliary system & lymphatic tissue of bowel
- bacteria pass into intestinal tract - can be identified for diagnosis in stool sample analysis (salmonella is shed in faeces) in lab
Untreated typhoid fever is broken down into how many different stages ?
4
In stage 1 of typhoid fever onset of symptoms is between …. days post-infection ?
5 - 14
what is epistaxis ?
acute hemorrhage from the nostril, nasal cavity or nasopharynx
what happens stage one of typhoid fever ?
- stepwise fever
- relative bradycardia
- malaise (discomfort or uneasiness)
- headache
- cough
- in 1/4 cases epistaxis can occur
Stage 2 of typhoid fever ?
- continuing high fever
- bradycardia continue
- extremely distended abdomen
- abdominal pain
- weight loss
- dicrotic pulse wave
- delirium is frequent, often calm and sometimes agitated
stage 3 of typhoid fever is when …. what occurs ? list some :
complications
* intestinal hemorrhage
* intestinal perforation
* encephalitis (inflammation of the brain)
* fever persistence
* dehydration (increases delirium)
* increased delirium
* motionlessness (eyes half-opened)
Stage 4 of typhoid fever ?
defervescence (very high fever) commences that continue into fourth week
Death can occur from complications which arise from Typhoid fever.
Name these complications
- overwhelming infection
- pneumonia
- intestinal bleeding (hemorrhage/perforation)
- kidney failure
- peritonitis (inflammation of peritoneum)
Who are asymptomatic disease carriers of S. Typhi ?
healthy people who have survived typhoid fever, but in whom the bacteria are able to survive without causing further symptoms
what’s the main source of chronic carriage of typhoid fever ?
infected gallbladders
How are carriers of chronic carriage of typhoid fever treated ? and cured
- long-term antibiotics
- can be cured via = gallbladder removal surgery
Shigella species are classified into four … ?
O - antigen-based serogroups
What are the 4 O-antigen based serogroups that shigella species are classified into ?
- A = S. dysenteriae
- B = S. flexneri
- C = S. boydii
- D = S. sonnei
Shigella spp. gram staining and shape ?
gram negative bacilli
All 4 species of shigella spp. cause what ?
bacillary dysentry or shigellosis
- Main mode
and 2. can also be mode of transmission of Shigella ?
- direct person-person
- contaminated food/water
symptoms of shigella ?
- bloody diarrhea
- intestinal pain
- intestinal cramps
- fever (sometimes)
What members of enterobacteriaceae result in shigella ?
non-motile and non-capsulated
Shigell only host is ?
human
Incubation period for shigella ?
1-3 days
Shigella spp. cause what illness ?
Shigellosis (baciliary dysentery)
* bacterial gastroenteritis
* caused by 4 shigella serogroups
* relatively few organisms can cause disease
Describe pathogenesis of shigellosis infection
- shigella proliferate rapidly in small intestine, reach colon and attach to M-cells in Peyer’s patches
- following endocytosis, shigella replicates in cytosol
- rearrangement of actin filaments of host cells - so shigella can enter adjacent cells (spread)
- shigella produce shiga toxin (exotoxin) which kills host cells leading to symptoms (local inflammation, disease manifestation)
- shigella are quickly phagocytosed in the bloodstream
Cause of shigellosis:
1. low/middle income countries =
2. high income countries =
1.Shigella flexneri
2.Shigella sonnei
Transmission of Shigellosis?
- faecal-oral route
- ingestion of contaminated food/water/fomites
- direct person-to-person contact
symptoms of shigellosis occur within …. of infection ?
1-3 days
symptoms of shigellosis ?
- abdominal cramps
- diarrhoea
- fever
- bloody stools
diagnosis for shigellosis ?
stool sample analysis
Treatment for shigellosis ?
Rehydration therapy
Antimicrobials
List the examples of antimicrobials for shigellosis treatment
FACTS
* fluoroquinolones
* azithromycin
* ciprofloxacin
* trimethoprim
* sulfamethoxazole
Yersinia infection leads to ?
enterocolitis (yersiniosis)
cause of yersiniosis ?
- Y. enterocolitica
- Y. pestis
- Y. pseudotuberculosis
Transmission of yersiniosis ?
- ingestion of contaminated foods (dairy, meat, poultry, fruits, vegetables, seafoods)
- blood transfusions (higher mortality rate)
symptoms of yersiniosis ?
- watery of bloody diarrhoea
- fever
- abdominal pain (lasting up to 2 weeks)
With yersinia symptoms present within …. days post-infection ?
4-6
Yersinia disease can become … ?
chronic
what can yersinia infection mimic ?
appendicitis
How can yersinia infection mimic appendicitis ?
it affects terminal ileum and mesenteric lymph nodes are enlarged
diagnosis of yersiniosis ?
stool sample analysis
Treatment of yersiniosis
antimicrobial drugs can be used if required
examples of antimicrobials that may be required for yersinia ?
- Cephalosporins
- Aminoglycosides
- Chloramphenicol
- Tetracyclines
- Trimethoprim
- Sulfamethoxazole
