Infection Control 2024 PDF

Prevention of Infection: infection control Professor Michael Prentice 1 Learning objectives Define a Health Care Associated Infection (HCAI) List the leading health care associated infections in Ireland State adverse consequences of HCAI Describe how HCAI is detected Describe how HCAI can be prevent...

Prevention of Infection: infection control Professor Michael Prentice 1 Learning objectives Define a Health Care Associated Infection (HCAI) List the leading health care associated infections in Ireland State adverse consequences of HCAI Describe how HCAI is detected Describe how HCAI can be prevented – including the WHO 5 moments for hand hygiene Detailed aspects of infection control for airborne disease and SARSCoV2 2 Definitions : World Health Organisation (WHO) Infection control: a scientific approach and practical solution designed to prevent harm caused by infection to patients and health workers Healthcare associated infection (HCAI) is an infection occurring in a patient during the process of care in a hospital or other health care facility which was not present or incubating at the time of admission ("nosocomial" or "hospital" infection). Practical definition of HCAI is an infection acquired 48 hours or more after hospital admission, or within 30 days after having received health care (e.g.surgery, chemotherapy) 3 Transmission of infectious agents in a healthcare setting: requirements Source (reservoir) of infectious agents Susceptible host with portal of entry receptive to infectious agent Mode of transmission of infectious agent 4 Modes of transmission of Infection Contact Direct sweet sweet semen Blood/body fluids from infected person enter through mucous membrane or breaks in skin Cutaneous infection contact e.g. Herpes simplex, scabies Indirect Transfer of infectious agent via contaminated intermediate object (fomite) or person e.g. thermometer, blood pressure cuff, hands : MRSA, food (enteric infections), respiratory viruses *Droplet Respiratory droplets > 10 µm diameter of infected person from coughing/sneezing/talking or suctioning, endotracheal intubation reach susceptible mucosal surfaces (nose/eyes/mouth). Spread < 2m radius (approx) e.g. influenza, SARS and other Coronaviruses, Neisseria meningitidis *Airborne droplet nuclei/small particles < 10 µm (dessicated droplets) access lower respiratory tract and remain suspended in air for long periods, some pathogens can survive in these conditions Examples: M. tuberculosis, measles, chickenpox Less commonly influenza, SARS, rotavirus *Traditional medical distinction which is being replaced by a more scientific classification, hastened by COVID-19 5 Transmission of Infection Definitions of terms by example Salmonella gastro-enteritis Reservoir more commonly animal gut flora less commonly human cases & carriers Source or Vehicle food from affected animals contaminated food Mode of transmission Indirect contact 6 Transmission of Infection Definitions of terms by example S. aureus wound infection Reservoir Human nose & skin Source or Vehicle Hands of health care workers Mode of transmission Direct or indirect contact 7 Sources of infection Where do patients get their infections from...? …in the hospital Humans clinical case Cross-infection e.g. chickenpox streptococcal pharyngitis wound infection Humans Affect MRSA auto-infection symptomless carrier e.g. MRSA gent-resistant GNRs Staph aureus wound infections gram - rods food salmonellosis e.g. some IVI Environment ventilator e.g.Pseudomonas disinfectants, solutions etc eg. Pseudomonas e.g. Staph aureus, diphtheroids, staph epidermidis endoscopes e.g. mycobacteria H. pylori air/dust Staph aureus legionella , 8 Combination of risk factors for infection in hospital patients Many sources + Many entry points + Impaired immunity Source risks Point of entry risks Patient colonised (autoinfection) Other colonised or infected (Patient, staff, visitor) Contaminated equipment Contaminated environment (dust, air conditioning) Surgery/invasive procedure Other wounds (pressure sore) (Patient, staff, visitor) Initial insertion of medical device (drip, Feeding line, prosthesis) Continued presence of medical device (drip, Feeding line, prosthesis) Inhaled organism Ingested organism See: Healthcare associated infection: What else can the NHS do? July 2007. Healthcare Commission 9 Additional risk factor in hospital patients: failing immune system Disease, organ failure Trauma including surgery Extremes of age Malnourishment Medical treatment C. difficile and antibiotics, various infections and steroids or cytotoxic cancer drugs bacteria that wouldnt normally infect them will infect them 10 Impact of Healthcare associated infection (HAI) 6-8 % (1 in 16 to 1 in 12) patients acquire an infection in hospital they did not have when they arrived Causes pain and distress delay in discharge (cant go home due to infection) serious complications, even death Increases health care costs 11 Surveillance of Healthcare infection checking for numbers of organisms to see if they are going up or down Hospital laboratory records numbers of “alert organisms” of a type likely to have been acquired in hospital- meticillin-resistant S. aureus (MRSA),E.coli, C. difficile + various other antimicrobial resistant bacteria over set periods Inherent bias - what about non-meticillin resistant S. aureus, wound infections with no clear isolate Point prevalence surveys All infected patients diagnosed on day x Expensive, need many assessors who can apply complex case definitions -> done every few years 12 Infection control Surveillance (direct or proxy measure of healthcare associated infection) fed back to hospital to monitor change over time and allow inter-hospital comparison Infection Control Service Infection control doctor (Consultant microbiologist) and infection control nurses Oversight of surveillance Education of clinical staff outbreak management ( eg. moving patients to another room) antibiotic control formulation of policies Hospital infection control committee HICC directs the Hospital response to infections and to ensure that the relevant elements of national policies and guidance are addressed Minuted committee, Chaired by Hospital Chief Executive or deputy. 13 List of statutorily notifiable diseases and their definitions 14 Antimicrobial Resistance and Hospital Infection Antimicrobial resistance occurs when an antimicrobial has lost its ability to control bacterial growth or kill bacteria Resistant bacteria continue to multiply in the presence of therapeutic levels of an antimicrobial Increasing levels of antimicrobial resistance in bacterial pathogens infecting humans and domestic animals result from production and use of antimicrobials using antibiotics can cause increased resistance More antimicrobial resistant organisms in hospitals than at home so risk of acquisition is higher in hospital Easier to detect antimicrobial resistant bacteria, record their numbers as in indication of hospital infection control 15 EARS-Net Established as European Antimicrobial Resistance Surveillance System (or EARSS) in 1998 by EC DG-SANCO o organised by § Dutch public health institute (RIVM) = Europe-wide co-ordination § HPSC in Ireland health protection surveillance centre Transferred to European Centre for Disease Prevention and Control (ECDC) in 2010 o An international network of national surveillance systems with laboratories and hospitals from 29 EU/EEA countries participating in 2016 o Aims to collect comparable & reliable antimicrobial resistance (AMR) data for public health action 16 EARS-Net case definition EARS-Net collects antimicrobial resistance data on the first invasive isolate (specimen types indicated below) per patient per year for eight key pathogens (arranged in order of frequency reported): Escherichia coli (blood or CSF) Staphylococcus aureus (blood only) (% Meticillin-resistant Staphylococcus aureus MRSA counted) Enterococcus faecium (blood only) Klebsiella pneumoniae (blood or CSF) Streptococcus pneumoniae (blood or CSF) Enterococcus faecalis (blood only) Pseudomonas aeruginosa (blood or CSF) Acinetobacter spp. (blood or CSF) MRSA is an indicator organism for good/bad infection control because generally hospital acquired 17 Trends in S. aureus bloodstream infections showing %MRSA methicillin resistant. 1400 25% 1200 20% 800 15% 600 10% %MRSA Number of cases 1000 400 5% 200 0 0% 2011 2012 2013 2014 2015 2016 2017 2018 2019* Year Total SAU cases MRSA %MRSA * 2019 data to the end of Q2 only 18 Distribution of MRSA in EARS-Net countries percentage of S.A caused by in 2018 Antimicrobial resistant strain Map downloaded from ECDC’s Surveillance Atlas on 11/11/2019 IE rank: 14/29 (12.4%) EU/EEA: 16.4% (population-weighted mean) 2018 trends 0 countries 8 countries increasing/decreasing trends 2015-2018 19 Distribution of MRSA in EARS-Net countries in 2018 Ireland about average For Europe EARS-Net data on Antimicrobial Resistance in Ireland, Q1-2 2019 20 Multi-drug resistant organism (MDRO) other than MRSA in Ireland identified by HPSC/HSE Resistant Enterobacteriaceae e.g. Extended Spectrum Beta Lactamase producers (ESBLs), Carbapenemase Producing Enterobacterales (CPE) Multi-drug Resistant Acinetobacter spp. and Pseudomonas aeruginosa Vancomycin Resistant Enterococci VRE HPSC = Health Protection Surveillance Centre 21 Enterobacterales/ Enterobacteriaceae Gram negative bacteria Escherichia coli, commonest Klebsiella pneumoniae, Enterobacter cloacae, Citrobacter freundii Resident in the gut Cause UTI, bacteraemia (most frequent cause of bacterial infections in patients of all ages) Readily exchange DNA Can easily acquire and spread antimicrobial resistance 22 23 Overall result of 2017 Europe-wide prevalence survey in Ireland The overall rate of HCAI in Ireland was 6.1 % i.e. 1 in 16 patients surveyed on one day had acquired an infection in hospital that they did not have on arrival The rate varied depending on the type of hospital 8.7% in regional/tertiary hospitals 7.6% in primary/general hospitals 3.4% in specialist hospitals. 30 (4.4 % of all HCAI) patients had infection with Clostridium difficile 24 Overall results of 2017 survey Leading HCAI as % of inpatients 1.9% Pneumonia 1.2% Surgical site infection 0.9% Urinary tract infection 0.6% Blood stream infection (82% had indwelling IV lines) 0.4% Systemic infections 0.3% C. difficile 25 2017 Survey Health Associated Infection by Organism 64% E.coli, 11% Klebsiella, 8% Proteus 8% Enterobacter26 Clostridium difficile C. difficile is the major cause of diarrhoea following antibiotic therapy. Most of those affected are elderly patients with underlying illnesses Hyper-toxin producing PCR Ribotype 027 strains causing severe disease, identified in UK, Dublin, Canada. 27 Hospital-acquired COVID-19 Estimates based on dates of onset England @ 20% of hospital cases acquired in hospital in first wave Germany: 14.7% Wildtype period (first wave) 3.5% Alpha 8.8% Delta 10.1% Omicron 28 Practices to Control Infection in Health Care Traditional Hierarchy from 1970s onwards Standard Precautions Contact Precautions Droplet Precautions Increasing Stringency Airborne Precautions Data from COVID-19 pandemic has suggested Droplet/Airborne division should be revised 29 Standard Precautions Underlying principle all blood, body fluids, secretions, excretions except sweat, nonintact skin, and mucous membranes may contain transmissible infectious agents Standard Precautions comprise hand hygiene Respiratory hygiene/cough etiquette use of gloves (if blood/body fluid exposure likely) safe injection practices (sterile, single-use, disposable needle and syringe) gown (if body fluid splashes expected) Mask (if body fluid splashes or respiratory aerosol expected) eye protection, or face shield (if body fluid splashes expected) https://www.cdc.gov/infectioncontrol/index.html 30 Tools of the trade Sharps disposal bin Alcohol hand rub Long-sleeved disposable gown Hand wash sink Eye protection and mask Non-sterile glooves 31 World Health Organisation: 32 Evidence base from Centers for Disease Control USA Internationally practiced USA/Europe/Australia etc use chopsticks 33 Transmission-based precautions Additional to Standard Precautions for patients who may be infected/colonized with infectious agents requiring additional precautions to prevent infection transmission Contact Precautions – infections spread by direct contact only Droplet precautions (often + Contact)- infections spread by respiratory droplet in the close vicinity of patients Airborne precautions (often + Contact) – infections spread many metres through the air COVID-19 has shown the distinction between droplet and airborne spread of respiratory viruses is based on a misunderstanding of physical properties of respiratory particles A continuum of transmission risk is present highest with close contact but still occurring at longer distances 34 Contact Precautions Patient placement in a single room (preferably en suite with hand hygiene facilitiy) if available in acute care hospitals Use personal protective equipment (PPE) including gloves and gown for all interactions that may involve contact with the patient or the patient’s environment. Limit transport and movement of patients outside of the room to medically-necessary purposes. Use disposable or dedicated patient-care equipment (e.g., blood pressure cuffs). If common use of equipment for multiple patients is unavoidable, clean and disinfect such equipment before use on another patient Prioritize cleaning and disinfection of the rooms of patients on contact precautions For e.g. MRSA carriage, diarrhoea, fever of unknown origin, medical repatriation from hospital abroad 35 Medical Early 20th Century Paradigm: Droplet vs aerosol transmission Droplet Large particles (? > 10microns, >100 microns) Settle on ground within 1 m and < 5 minutes Contaminate immediate environment Transmission: ballistic particle lands in mouth,nose,eyes Countermeasure: stay 2 m away, cover mouth,nose,eyes Clean contaminated surfaces Big list of organisms (most respiratory infections) Aerosol/Airborne Small particles 1000 frames per second images Sneeze Particles fragmented before exit Particles fragmenting and propagating after exit Sneeze:Multiphase Buoyant cloud Distance of droplet spread from sneeze can be >2 metres according to MIT Physics lab Respiratory etiquette essential Speaking produces respiratory particles and projects air jets Video of particles visualized by laser fluorescence when speaking the phrase “stay healthy” Coughing and sneezing not required to spread respiratory particles Stadnytskyi V, Bax CE, Bax A, Anfinrud P. Proc Natl Acad Sci USA. 2020;117:11875–7. Speaking Jets Human Thermal Plume Abkarian et al PNAS 2020 https://www.pnas.org/content/117/41/25237.short https://www.mae.ncsu.edu/cfd/contaminant-transport/ Unmasked speakers project particles > 2m Emitted Particles convected upwards don’t fall to ground Low humidity (indoor air in winter, meat plant) rapidly dries out large 100 µm liquid particles To 2 metres Speaking/ singing produces air jets which travel > 1 metre faster than ambient air currents indoors Human thermal plumes lift respiratory particles upwards and stop them falling Particles are not of fixed sizes: Low humidity (e.g. indoor air in winter, meat plant, aircon) dries out 100 µm liquid particles to