Flashcards in Infections On Surfaces Deck (71):
What is meant by a surface?
Any interface between a solid and either a liquid or a gas
What does the microbiota consist of?
The microorganisms that are carried on the skin and mucosal surfaces
What is normally true of the microbiota?
They are normally harmless, or even beneficial
When can microbiota be harmful?
When they transfer to other sites
What are the categories of normal skin flora?
Gram positive coccus
Gram positive bacilli
What are the gram positive coccus found in the skin flora?
What are the gram positive bacilli found in the skin flora?
What are the mucosal flora found in the eye?
Coagulase negative staph
Saprophytic neisseria species
Viridans group streptococci
What are the mucosal flora found in the nares?
What are the mucosal flora found in the nasopharynx?
What are the mucosal flora found in the mouth?
What are the mucosal flora found in the stomach?
What are the mucosal flora found in the intestine?
Aerobic and anaerobic streptococci
What are the mucosal flora found in the urethra?
Alpha and non-haemolytic streptococci
What are the mucosal flora found in the vagina?
Microaerophilic and anaerobic streptococci
How is a coagulase test conducted?
By testing for coagulase in a test tube
How can you tell if coagulase is being produced in a coagulase test?
If plasma clots on addition of bacteria
What does a positive coagulase test indicate?
The staphylococcus in question is staph aureus- all other staphylococci are coagulase negative
What is the problem with surface infections?
They can be a major cause of hospital acquired infection
How can surface infections be acquired in hospitals?
Prosthetic surfaces that are implanted during surgeries
Infections of the mucosa or skin caused by procedures or invasive devices
What prosthetic surfaces implanted during surgery can cause a surface infection?
What invasive devices can result in a hospital acquired surface infection?
How can the majority of hospital acquired surface infections be prevented?
Proper sterilisation of surfaces
Care during the procedure
What is the problem with HAIs?
Cost a large amount of money
Have a large negative impact on the outcome of treatment, and can often even cause death
Why do HAIs cost a large amount of money?
Cost of investigations
Extended hospital stays
Loss of reputation and subsequent funding
Give 6 internal infections on natural surfaces
What pathogens can cause cellulitis?
What pathogens can cause pharyngitis?
What pathogens can cause conjunctivitis?
What pathogens can cause gastroenteritis?
What pathogens can cause UTIs?
What pathogens can cause pneumonia?
Give 5 external infections on natural surfaces
What pathogens can cause endocarditis?
What pathogens can cause vasculitis?
HTLV-1 (human T-cell lymphotrophic virus)
What does HTLV-1 cause?
What pathogens can cause septic arthritis?
What pathogens can cause osteomyelitis?
What is empyema?
Infection between pleural membranes
What pathogens can cause empyema?
What prosthetic surfaces can get infected?
Peritoneal dialysis catheters
What pathogens cause infection on prosthetic joints?
Coagulase negative staphylococcus
What are the categories of infection on cardiac valves?
Native valves and prosthetic valve endocarditis >1 year post op
Prosthetic valve endocarditis <1 year post-op
What pathogens can cause native valves and prosthetic valve endocarditis >1 year post op?
What pathogens can cause prosthetic valve endocarditis <1 year post-op?
Coagulase negative staph
What infection can occur on pacing wires?
Cardiac pacing wire endocarditis
What pathogens can cause cardiac pacing wire endocarditis?
Coagulase negative staph
What are the steps in the pathogenesis of infections at a surface?
Adherence to host cells or prosthetic surface
Invasion and multiplication
What enhance adherence to host cells or prosthetic surface?
Pili or fimbriae
How do biofilms form?
Bacteria excrete polymers which bind with water molecules to form a slimy matrix
The bacteria become embedded within the 'gel'
What polymers can bacteria excrete to produce biofilms?
Why do biofilms aid bacterial survival?
These bacteria have a slower turnover
Antibiotics don't work or attach as well
Nutrients can't diffuse into the matrix
Chemical gradients create microenvironments for different microbial species
What is the purpose of quorom secretion?
Intracellular communication between bacteria
What does intracellular communication between bacteria using quorom secretion involve?
Cell surface or cytoplasmic receptors
What signalling molecules are involved in quorom secretion?
What is the purpose of gene expression in quorom secretion?
Co-operative behaviours and more AI production
What does quorom secretion allow?
Bacteria to sense the number of nearby bacteria
What happens if, through quorom secretion, the bacteria can sense the number of bacteria is big enough?
Biofilm can be formed
What does quorum sensing control?
Virulence factor secretion
What can the host response to infections at surfaces involve?
What happens in a pyogenic response?
Neutrophils produce pus
What happens in a granulomatous response?
Fibroblasts, lymphocytes, and macrophages produce nodular inflammatory lesions
What are the main steps in managing infected surfaces?
What is the aim of diagnosis in the management of infected surfaces?
Identify infecting organism and its antimicrobial susceptibilities
How can an infected surface diagnosis be made?
Tissue/prosthetic material sonication and culture
What are the challenges in diagnosis of infected surfaces?
Low metabolic state/small colony variants
What is the aim of treatment of infected surfaces?
Sterilise tissue and reduce bioburden
How can infected surfaces be treated?
Remove prosthetic material
Surgery to resect infected material
What are the challenges in the treatment of infected surfaces?
Poor antibacterial penetration into biofilm
Low metabolic activity of biofilm microorganisms
Dangers/difficulties of surgery
How can infection on natural surfaces be prevented?
Maintain surface integrity
Prevent bacterial surface colonisation
Remove colonising bacteria