5. Hospital Acquired Infections Flashcards
3 terms for generality of hospital acquired infections
- Hospital acquired infections (HAI)
- Healthcare associated infections (HCAI)
- Nosocomial infections
Hospital accquired infections - definition
—> Infections arising as a consequence of providing healthcare
• Must be an infection that you didn’t have before hospital admission
• Neither present nor incubating at time of admission (Onset is at least 48 hours after admission)
• Also includes infections in hospital visitors and healthcare workers = people in hospitals
Consequences of hai s
Result in increase in: • Length of hospitalization = longer stay in hospital, treatment • Morbidity • Cost of care • Mortality (some cases)
Highest prevalence of HAIs
- generally in ICU (intensive care units)
• People in ICU may be immunocompromised – therefore more vulnerable
• Patients may be on ventilators, IV lines – exposed breakages of the skin
6 main types of HAIs
- Respiratory tract infections (pneumonia/other respiratory infections) - 22.8%
- Urinary tract infections - 17.2%
- Surgical site infections (SSI) - 15.7%
- Clinical sepsis - 10.5%
- Gastrointestinal infections - 8.8%
- Bloodstream infections - 7.3%
5 routes of infection transmission
Routes of entry of microbes:
- Skin: 10%
- Gastrointestinal (21%)
- Respiratory (14%)
- Urogenital (20%)
- Person to person transmission (respiratory/faecal-oral)
Predisposing factors in patients - for HAIs
- Extremes of age
- Young people<6 – not immunocompromised
- older people – low immune system
- Obesity/malnourished
- Diabetes
- Cancer
- Maybe due to drugs taken
- Immunosuppression
- e.g. HIV
- Smoker
- Surgical patient
- Emergency admission
- Prosthetic devices
Bacteria causing HAIs
• (Staphylococcus aureus including MRSA, Clostridium difficile, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa)
Viruses causing HAIs
• (Blood borne viruses hepatitis B, C, HIV, Norovirus, Rotavirus, SARSCoV-2)
Fungi causing HAIs
• (Candida albicans, Aspergillus species)
Parasites causing HAIs
• (Cryptosporidium spp - patient with cryptosporidiosis contaminated ice cubes through frequent use of the ice machines
Simple ventilator system
- Big tube goes right into their lung
* If anything enters this system it can easily enter lung and establish infection
Ventilator associated pneumonia (VAP)
Pneumonia develops in 5-20% of mechanically ventilated patients
- Mortality of ventilator associated infection is 10% = high
- Associated complication- pulmonary ARDS (acute respiratory distress syndrome) , pneumothorax, pulmonary oedema.
Pathogenesis of Ventilator associated pneumonia (VAP)
- Micro aspiration of oropharyngeal pathogens around the cuff
- Micro aspiration of gastro-enteric regurgitated secretion
- Bio film (sugar covering) within the endotracheal tube
- Cross contamination via respiratory equipment
Ventilator associated pneumonia
- Early causative pathogens
EARLY (<5 days) - less than 5 days on ventilator
• Streptococcus pneumoniae, Staphylococcus aureus, sensitive enteric Gram negative rods (GNR)
Ventilator associated pneumonia
- late causative pathogens
LATE (>5days) - after 5 days on ventilator
• MRSA, Pseudomonas species, multi-drug resistant organisms
Ventilator associated pneumonia - bundle
- Elevation of the head of the bed 30 degrees to prevent aspiration
- Sedation holiday to check for continued ventilation needs
- Weaning trials to indicate if the ventilator is still needed daily
- = assess if they still need ventilator at regular intervals
- Medication to prevent gastrointestinal bleeding (Stress-related mucosal disease is a typical complication of critically ill patients)
- DVT Prophylaxis (Thromboembolism is a major complication in these patients)
- Sub-glottal suctioning to prevent colonization and infection from pooling of secretions must be done every 4 hours
- Prevent buildup of secretions that allow microorganisms to grow
• Oral care to prevent accumulation of oral bacteria every 4 hours
Catheter related blood stream infections
→ how can they occur
- Introduction of skin pathogens at the time of insertion
- Contamination of the catheter hub(s)
- Contaminated infusate
- Migration of skin pathogens into the cutaneous catheter tract
- Hematogenous seeding from a distant infectious focus – spread microorganisms ?????
- Most common pathogens: S. epidermidis, S. aureus, Candida albicans
Catheter related blood stream infections
- prevention measures
- Fill out central line insertion check list – before inserting catheter iv line etc
- Hand Hygiene prior to insertion
- Use standardized supply kit that is all inclusive for the insertion of central venous catheter
- Use maximal barrier precautions (Full body drape, wearing of cap, mask, gown and gloves) = PPE
- Clean Skin with Chlorhexidine and allow to air dry = remove microorganisms
- Need for continuation of catheter is evaluated on a daily bases = evaluate IV lines look for signs of infection
- Central line dressings are changed every 7 days
- Positive pressure caps are used on all central line (IV line) posts and changed every 7 days
What are Surgical site infections (SSI)
• occur within 30 days postop, or within 1year if an implant is left (e.g. hip or knee), and infection appears to be related to the operation
○ As some microorganisms may be slow growing, or go to sleep at the site so no signs til later
• Most SSIs occur between 5-10 days post-operation
3 types of Surgical site infections (SSI)
- Superficial incisional SSI: skin + subcutaneous tissue
- Deep incisional SSI: deep soft tissue(fascia + muscle)
- Organ/space SSI: organs, body cavities, sub-integumental spaces
Organisms causing SSIs
Enterobacterales (mainly present in bowel but can be disloged) -caused SSI are most prevalent in large bowel surgery, contributing 48.5% of superficial SSIs and 55.7% of deep or organ/space SSIs.
Infecting organisms in hip and knee surgery
• Methicillin Sensitive Staphylococcus aureus – Hip 32%, Knee 40.7% (MOST COMMON IN HIP AND KNEE)
• Methicillin Resistant Staphylococcus aureus – Hip 4%, Knee 3.1%
• Coagulase-negative Staphylococci – Hip 25.1%, Knee 23.9%
Infections can also be caused by a mixture of organisms
Prevention measures for Surgical site infections (SSI)
• Screened (patient and staff) prior to surgery for MRSA
• chlorhexidine washes/ shower
– pre operation to steralise them
- Alcohol containing skin prep (2% chlorhexidine gluconate in 70% isopropyl alcohol solution)
- Preoperative antibiotics
• Appropriate hair removal
– microorganisms at base of hair
• Euglycemia
– anyone with diabetes has it controlled
- Optimise tissue oxygenation
- Wound care
- Best practice checklist
- Surveillance for SSI
- Educate providers, patient regarding SSI
CAUTI - Catheter Associated Urinary Tract Infection
• Urinary Catheter Associated Infections are defined as an infection occurring 48 hours after insertion of a urinary catheter, signs and symptoms of infection (fever, pain, frequency, urgency, increased white count, etc.) and a positive urine culture of ≥ 103 cfu/ml
CAUTI – causative organisms
• Multidrug resistant Enterobacteriaceae (MDRE)
– Escherichia coli
– Klebsiella, Proteus and Pseudomonas species
• Candida albicans
Prevention of CAUTI
- Evaluation of catheter need prior to insertion
- Hand Hygiene should be done immediately before and after any manipulation of the catheter site
- Closed Catheter System
- Catheter securement system
- Urinary collection bag not to be higher than the bladder
- Urinary collection bag not to rest on the floor – but should be at a lower level than the patietn
- The catheter and collecting tube should be free of kinking
- The collecting bag should be emptied regularly
Multiresistant organisms
Definition
- MRO’s are bacteria that have become resistant to many of the antibiotics used to treat infections caused by them
- In hospitals a lot of antibiotics used, easier for resistance to spread
3 multiresistant organisms
• Multidrug resistant organisms of concern are
– Methicillin Resistant Staphylococcus aureus (MRSA).- glycomyacin, titroplanin
– Vancomycin resistant Enterococci (VRE)
– Multidrug resistant Enterobacteriaceae (
Antimicrobial resistance
—> Antimicrobial resistance is the ability of a microbe to resist the effects of medication that once could successfully treat the microbe.
Antibiotic resistance
- The term antibiotic resistance is a subset of anti-microbial resistance, as it applies only to bacteria becoming resistant to antibiotics.
- Only need one resistant bacteria for resistance to spread
Antimicrobial resistance - factors to consider
- Duration of antibiotics
- Use of broad spectrum antibiotics (also have side effects tho)
- Hygiene
4 ways Antibiotic resistance can occur
Bacteria can cause
- Inactivation of antibiotic (eg. beta - lactamase)
- Alteration of target- or binding site
- Alteration of metabolic pathway
- Reduced drug accumulation
Methicillin Resistant Staphylococcus aureus (MRSA)
—-> Methicillin-resistant Staphylococcus aureus (MRSA) refers to a group of Gram-positive bacteria that are genetically distinct from other strains of Staphylococcus aureus.
– mecA gene codes for PBP2a which has low affinity for beta lactam antibiotics
• Resistant to methacilin
Methicillin Resistant Staphylococcus aureus (MRSA)
Prevention and management
- Prevention: Screening/Handwashing/Isolation - isolate patients who have MRSA in chest causing coughing
- Management: Antibiotics (Vancomycin), dependent on site of infection
Norovirus
- Norovirus is a non-enveloped, ss +ve strand RNA virus
- Spread by fecal-oral route
- Norovirus infection is characterized by nausea, vomiting, watery diarrhea, abdominal pain, and in some cases, loss of taste. A person usually develops symptoms of gastroenteritis 12 to 48 hours after being exposed to norovirus.
- General lethargy, weakness, muscle aches, headaches, and low-grade fevers may occur.
- Most who contract it make a full recovery within two to three days
Rotavirus
Rotavirus is a non-enveloped ds RNA virus
• Rotavirus (RV) is considered as the most important viral agent of acute gastroenteritis worldwide in children less than 5 y.
• Vaccines available for prevention of Rotavirus infections
• 48 hours after the admission in hospital to 72 hours after hospital discharge
Clostridium difficile (c.difficile)
- Clostridium difficile Gram positive spore forming rods
- c.difficile goes to spore form and goes to sleep, spores are very resistant
• Pathogenic strains produce 2 toxic polypeptides Toxin A and Toxin B (causing signs and symptoms)
– Toxin A is an endotoxin, stimulates inflammatory response and causes fluid secretion
– Toxin B is s cytotoxin which disrupts protein synthesis
- Symptoms include watery diarrhea, fever, nausea, and abdominal pain. It makes up about 20% of cases of antibiotic-associated diarrhea.
- Can cause more serious problems colitus ??
Clostridium difficile (c.difficile)
2 toxins
– Toxin A is an endotoxin, stimulates inflammatory response and causes fluid secretion
– Toxin B is s cytotoxin which disrupts protein synthesis
3 Clostridium difficile associated problems
Antibiotic associated diarrhoea:
Antibiotic associated colitis:
Antibiotic associated pseudomembranous colitis:
Antibiotic associated diarrhoea:
• benign, self limited after use of antimicrobials, Clostridium difficile implicated in 10-25%
Antibiotic associated colitis:
• worse diarrhoea , fever, abdominal pain, leukocytosis, Clostridium difficile implicated in 50-75%
Antibiotic associated pseudomembranous colitis:
• typical pseudomembranes, high leukocytosis, profuse diarrhoea, abdominal pain + distension, can progress to toxic megacolon, sepsis and death(6-30%). Clostridium difficile implicated in 90-100%
Clostridium difficile - risk factors
• Antibiotic use and Clostridium difficile infection
– (High risk: Cephalosporins, Clindamycin, Co-amoxiclav, Ciprofloxacin)
– Intermediate risk: Amoxicillin, Carbapenems,Erythromycin
– Low risk: Nitrofurantoin, Penicillin V, Trimethoprim, Vancomycin
Clostridium difficile - management
- Healthcare environment
- Acid suppression medication (may help Clostridium difficile proliferate by altering gut flora)
- Management: Isolation measure, treatment of dehydration and Vancomycin.
Infection prevention
—> The discipline concerned with preventing nosocomial or healthcare-associated infections
• Can also include community acquired infections e.g. care homes
• Any place that looks after vulnerable people
• Focuses on evidence-based practices and procedures that can prevent or reduce the risk of transmission of microorganisms
3 sources of infection
Patient
Healthcare workers
Contaminated environments
Examples of spread of infection
- Patient to patient
- Patient to care worker
- Care worker to patient
- Patient contaminating environment (e.g. oral fecal route) contaminate water, air, surfaces, food
- Patients can transmit infections to themselves e.g. self commensals carried by patient can infect patient when skin surface is broken or catheter
4 routes of transmission
- Blood and body fluids (pass person to person)
- Fecal/oral route
- Airborne
- Contact
Pathogens transmitted by Blood and body fluids (pass person to person)
○ Hep B and C and HIV
Pathogens transmitted by Fecal/oral route
○ Rotavirus, salmonella, shigella, camplyobacter
Pathogens transmitted by Airborne
○ Tb, chickenpox
Pathogens transmitted by contact
○ Multi resistant gram negative, wound/line infections
Basic reproduction number R0
the average number of cases one case generates over the course of its infectious period, in an otherwise uninfected, non-immune population
Relationship between R0 and cases
- If Ro >1 → increase in cases
- If Ro =1 → stable number of cases
- If Ro <1 → decrease in cases
Factors determining transmissibility (causing infection)
Infectious dose – number of microorganisms required to cause infection
– Varies by:
• micro-organism = e.g. virulence factors
• immunity of potential host
Preventing infections in healthcare
- Distancing / separation (of beds in wards) / restriction of movement and of visitors
- PPE: gloves, gowns, masks, eye-protection (where appropriate)
- Hand hygiene
- Cleaning, disinfection and sterilization
- Waste management – dispose contaminated material properly
- Staff health management: Exposure prophylaxis, health monitoring (Occupational Health)
- Discharge of patients – ideally when free of infection and cured
- Care of the deceased – if they died from infectious microorganism
Goals of infection prevention
To prevent the spread of infections from
• patient-to-patient
• patients to health care providers
• health care providers to patients
• health care providers to health care providers and to visitors and others in the health care environment
Desired outcomes of infection prevention
- improved survival rates
- reduced morbidity associated with infections
- shorter length of hospital stay
- a quicker return to good health
4 Ps of infection prevention and control
Patient
Pathogen
Practice
Place
Infection prevention- patients
General
Optimise patient’s condition
– Immunosuppressed patientscosiderations?
– Comorbidities (diabetes) - biggern chance of infection
– Nutrition is good to prevent infection
– Smoking - more liekly to get infection
Antimicrobial prophylaxis = minimize chance of infection after surgery
Skin preparation
Hand hygiene
Specific
MRSA screens – before surgery - eradicate MRSA with Mupirocin nasal ointment
Disinfectant body wash beofre operations, minimise commensals entry
Infection prevention - pathogen
Reduce/eradicate pathogen using
– Antibacterials including disinfectants
– Decontamination
– Sterilisation of equipment
• Reduce/eradicate vector
– Eliminate vector breeding sites
Infection prevention - practice
– Awareness = amongst all visitors, workers, patient
– Policies = clear guidance
– Training = of those involved in patient care
– Leadership (at all levels)
– Engagement at local and national level
Infection prevention - place
Ensuring all premises delivering healthcare are infection control compliant
- Building – consider not just medical wards (including kitchens, cafes, shops)
- Wards
- Consulting rooms
- Communal areas
- Toilets
- Furnishing (including movable items)
- Flooring
- Air conditioning/heating system
Examples of ppe
Gloves, aprons, long sleeved gowns, surgical masks, eye goggles, face visors and respirator masks
Uses of PPE
- create a barrier between healthcare workers and an infectious agent from the patient and to reduce the risk of transmitting micro-organisms from healthcare workers to patient(s) or vice versa
- PPE may sometimes be used by the patient’s family / visitors, e.g. assisting patient with toileting, visiting patient who has a contagious infection, visiting vulnerable patients
- Visitors must be fully inducted in the use of PPE and Hand Hygiene
Choice of ppe
—> should be based on a risk assessment of potential exposure to blood / body fluids / infectious agents
Care with blood and bodily fluids
- Safe handling of blood, bodily fluids and spillages
- Handling and labelling of specimens
- Use of solidifying agents = when there is a spillage to prevent it leaking
- Taking blood
Decontamination of the environment
- General environment
- Ventilation (maintenance)
- Air conditioning
Safe management of sharps (infection can be transmitted with sharps)
- All sharps must be disposed of into a designated BS 7320 approved sharps container.
- All sharps must be removed prior to sending any trays/instruments to HSSU
- Needles must NOT be resheathed
Decontamination of equipment
- All equipment used in the clinical environment should have the ability to be decontaminated or be single patient use. (ideally should be single use)
- Infection Control should be consulted if the equipment being purchased cannot be decontaminated in line with infection control guidelines
Key items of equipment/practices
- Ventilators
- Suction
- Incubators
- Humidifiers
what to do in an innoculation accident
• First Aid
• Report to person in charge of the area
• Attend Occupational Health Department (OHD) or A&E out of hours
• Completion of incident report form.
Never ignore this accident
Prevention of innoculation accidents
- Safe handling
- Disposal = of everything
- Only competent practitioners should take blood and give injections to patients with known or suspected blood borne viruses
Key times to wash hands
- Before touching patient
- Before any clean or aseptic treatment
- After body fluid exposure
- After touching patient
- After touching patient surroundings
Preventing patient to patient transmission of infection
- Physical barriers - separate rooms
- Isolation of infected patients
- Protection of susceptible patients – sperate them from others
Health care workers interventions
– must be Healthy
• Disease free
• Vaccinated
– ensure Good practice • Good clinical techniques (e.g. sterile non-touch) • Hand hygiene • PPE • Antimicrobial prescribing
Environmental interventions
—> minimsie spread of infection from environment to patient
Built environment = build environment to ensure
– good Space/Layout
– clean Toilets
– Wash hand basins – wash dry touch door handles
• Furniture and furnishings = must be able to be cleaned and sterilized
Environmental interventions cleaning
- Disinfectants
- Steam cleaning
- Hydrogen peroxide vapour – to decontaminate
Environmental interventions - operating theatres
- Very sterile to prevent infections
- Decontaminate
- Positive or negative pressure in rooms
Environmental interventions - medical devices
- Single use equipment
- Sterilization
- Decontamination
