Lecture 11: chronobacter Flashcards
Chronobacter is a gram ___, ___, ____ bacteria
negative, non spore forming, straight, rod shape bacteria
the group most vulnerable-at risk for chronobacter infection is
immunocompromised and neonates younger than 28 days old, also low birth weight neonates
what makes premature neonates more susceptible to chronobacter?
secrete less gastric acid than older infants and this may be important in the long term survival of chronobacter
incidence of disease is very (high/low) for chronobacter
low
cronobacter infection may cause severe ___ &____ in survivors
neurological and developmental disorders
infected infants suffer from
- necrotizing enterocolitis
- septicaemia
- meningitis
neurological sequelae are common and include
- brain abscess
- necrosis of brain tissue
- liquefaction of white cerebral matter
foods found to harbour chronobacter include;
milk powder, cheese, herbs, spices and rice
chronobacter has also been reported from clinical sources, including cerebrospinal fluid, blood, intestinal and respiratory tracts, bone marrow and skin wounds.
cerebrospinal fluid, blood, intestinal and respiratory tracts, bone marrow and skin wounds
T or F: current processing technology is unable to completely eliminate the potential for microbial contamination without affecting organoleptic and nutritional requirements
True
why is the elimination of chronobacter in PIF very hard
PIF is highly regulated in terms of nutritional requirements and based on our current knowledge sterilization of PIF seems to only be possible using irradiation. However, the doses required to kill all cronobacter are not feasible due to organoleptic deterioration.
explain the process of cronobacter pathogenesis in terms of manufacturer, infant, and organism
- the organism survives on the equipment, may survive via biofilm formation and improper temp in facility/storage areas.
- infants who then have a high stomach pH, low GI microbiome complexity and may also be immunocompromised allow for a suitable growth environment for chrono.
- the organism can then cross the blood brain barrier, OmpA facilitates invasion of brain cells and the enterotoxins produced can also cross the GI barrier.
name the 4 ways in which crono may cause virulence
- apical attachment
- apical invasion
- basolateral invasion
- disruption of tight and adherens junction.
name 9 virulence factors associated with crono
- outer membrane proteins
- enterotoxin
- outer membrane protease
- stalic acid utilization
- iron aquisition system
- efflux system
- proteolytic enzymes
- lipopolysaccharides
- type 3 hemolysin
which virulence factor is of greatest interest and why?
- the outer membrane proteins because of their cell surface exposure and contribution in export of extracellular virulence factors and in anchoring the structures that mediate adhesion and motility.
- OmpA helps cells adhere to GI epithelial cells.
- only OmpA positive Cronobacter breech the blood brain barrier.
- OmpX helps invasion on the apical side of GI epithelial cells, but also helps crono survive on the basolateral side as well.
what does cpa stand for
presence of a plasmid (pESA3) encoding an outer membrane proteases (cpa)
what is special about cpa
This protease has an ability to render serum resistance by cleaving complement components, activating plasminogen and inactivating a plasmin inhibitor.
the pESA3 also encodes….
a type 6 secretion system and some adhesion factors
sialic acid is found in ____ in the form of ___
human milk and infant formulae in the form of sialyloligosaccharides
the intestinal microvilli of neonates contain (increased/decreased) levels of sialic acid
increased
T or F: is plausible that there is a linkage between sialic acid metabolism and the pathogenicity of C. sakazakii as it is the only Cronobacter species possessing the nanAKT gene cluster encoding for sialic acid utilization
True
how may cronobacter be prevented
- refrigerate prepared infant formula to 4 deg C within 1 hour of prep
- prepare only small volumes of IF to reduce the “hang time” at room temp before consumption. the hang time should never exceed 4 hours.
- use only chilled, sterile water for IF preparation.
- discard any IF remaining in the bottle after feeding
- use the PIF within 4 weeks of opening
- sterilize bottles.
what are the strains of cronobacter associated with neonatal infection?
C sakazakii, C turicensis and C malonaticus.
why are cronobacter infections under reported?
due to being diagnosed as SIDs
what is critical in the pathogenesis of cronobacter?
the outer membrane proteins
mortality rates associated with crono infection are very ___ and even survivors will likely have ___
high, permanent brain damage
