BIOL 2044 - Healthcare infections

pathophysiology

• within hours bacteria colonise patients

• 3 types of risk factors

IATROGENIC

• invasive procedures (intubation, indwelling vascular lines, catheters

• antibiotic/prophylaxis use

ORGANISATIONAL

• contaminated water supplies, contaiminated air conditioning systems

• staffing and physicaly patient layout

PATIENT RISK FACTORS

• how severe the illness is

• underlying immuneocompromised state

surface cleaning problem

• most surfaces are not smooth - will have draw marks, scratches where pathogens can colonise

• stainless steel is not so easy to clean

• terminal cleaning (filling the room with hydrogen peroxide gas) is not actually effective against MRSA

superbugs

• bacteria which are resistant to antibiotcs

• many braod spectrum antibiobic resistances

  • MRSA

  • BRE - resistant to vancomycin

  • C. diff spores hard to kill

gram negative reistant bacteria (ESBL) - extended spectrum beta lactamase

• beta lactamase is the enzyme produced by bacteria which gives them resistance to a range of beta lactam antibiotics

• bacteria that have the enzyme:

  • acinobacterium baumanii

  • E. coli

  • P. aeruginosa

  • klebsiella pneumonia

  • new dehli metallo beta lactamase class B

ESKAPE group

the following can survuve days and weeks on surfaces and are the major pathogens prioritised by WHO:

Enterococcus faecium

Staphylococcus aureus

Klebsiella pneumoniae

Actinobacter

Pseudomonas aeruginosa

Enterobacter

KPC

• klebsiella pneumonia carbopenemes

• resistant to lots of antibiotics

copper as an antimicrobial

• used to sterilise drinking water and wounds

• outer electron very reactive - mobilises this electron in redox reactions

• supresses helicobacter pylori, legionella pneumophilia

• antifungal, antiviral properties

• on copper MRSA is completely killed within 40 mins

• kill times on dry surfaces are a lot more rapid than on wet surfaces

antibiotic resistance

• some bacteria have beta lactamases which cleave the lactam ring

• cephalosporin was produces as broad spec antibiotic is a last resort —> as a result, bacteria modified BS beta lactamases which break down cephalosprins

• then a 3rd gen cephalosporin was produced —> bacteria then evolved resistance to theres

• carbapenemes developes which have modified rings/side chains and are used as a last resort —> KPC, NDM1 bacteria are now resistant

New Dehli Metallolactase 1

• namy people in india had these resistant pathogens which survived very well on surfaces

E. coli plasmid

• CtxM which gives cephoxatine resistance

• other resistant genes around it

• if the plasmid is mibilised then the spread of more than one resistance gene

• cells exposed to sstainless steel have in tact plasmids but those exposed to copper have broken plasmids

can we demonstrate transferred resistance?

• pathogen with resistance gene and resident E. coli on surface together, then culture bacteria of residents on antibiotic covered plates

• if capable of horizontal gene transfer you will get conjugates which rea resistant

  • transfer is good in suspension but not on copper

  • copper abolishes gene transfer

• plasmid material is destroyed on copper

cell wall of bacteria

• cell walls degrade when placed on copper

• can measure metabolic state - stainless steel bacteria from ETC can measure metabolic activity

  • on copper respiratory activity is stopped

  • copper also disrupts membrame electrical potential in gram negative bacteria

• when bacteria lands on copper surface it directly interacts with copper, particularly Cu1 and destroys

  • membrane

  • nucleic acid material

  • respiratory chain

• H2O2 from side metabolism of bacteria converts Cu1—>Cu2 and generates oxygen radicals which accelerates copper kill

• in a dry state kill is faster due to more hydroxyl radicals produced