Infectious Diseases & Infection Prevention and Control & Critical Care & Internal Medicine
Healthcare-associated infections (HAIs)
Nosocomial infections - now called healthcare-associated infections (HAIs) to include infections occurring in any healthcare setting, including home care and long-term care - are defined by the CDC as infections occurring after 48 hours of admission to a healthcare facility, not present or incubating on admission. They represent a major public health problem: in the United States, 1.7 million HAIs occur annually, with 99,000 attributable deaths (Klevens 2007 - Public Health Reports). In Canada, data from the Public Health Agency of Canada (PHAC) estimate 220,000 HAIs annually, and 8,500 directly attributable deaths. The four most frequent types are Ventilator-Associated Pneumonia (VAP), Central Line-Associated Bloodstream Infection (CLABSI), Catheter-Associated Urinary Tract Infection (CAUTI) and Surgical Site Infection (SSI). In addition to these classic HCAIs, there is also Clostridioides difficile infection (CDI), the main cause of nosocomial diarrhoea in developed countries. The most dreaded pathogens are multi-resistant bacteria (MRB): MRSA (methicillin-resistant Staphylococcus aureus), VRE (vancomycin-resistant Enterococci), ESBL- or carbapenemase-producing Enterobacteriaceae (EPC), and multi-resistant Acinetobacter baumannii. HCAI prevention is based on a number of essential measures: hand hygiene, contact/drip/airborne precautions, structured care bundles for each type of HCAI, antimicrobial stewardship and active epidemiological surveillance.
Epidemiology, agents, and resistance mechanisms
- Epidemiology of HAIs and major nosocomial pathogens: global and Canadian epidemiological data: overall prevalence of HCAIs in Canadian hospitals: 10-15 % of hospitalized patients have at least one HCAI → Klevens 2007 - Public Health Reports: 1.7 million HCAIs/year in the USA + 99,000 deaths → PHAC 2020: 220,000 HCAIs/year in Canada → ECDC Cassini 2019 - Lancet Infectious Diseases: European meta-analysis → 3.2 million HAIs/year in EU countries + 37,000 directly attributable deaths → HAIs are preventable in 30-70 % of cases (depending on type); distribution by type of HAI: healthcare-associated urinary tract infections (CAUTI): 35-40 % of HCAIs → main risk factor: urinary catheter → healthcare-associated pneumonia (HAP + VAP): 15-25 % + CVC bacteremia (CLABSI): 10-15 % + surgical site infections (SSI): 15-25 % + C. difficile (ICD): 10-15 % → clearly increasing since 2000s → main nosocomial pathogens (CDC NHSN data 2021): E. coli (CAUTI + ISO) + S. aureus (MRSA + MSSA) (ISO + VAP + CLABSI) + coagulase-negative Staphylococcus (CLABSI on CVC) + Enterococcus spp. (VRE) (CAUTI + CLABSI) + Klebsiella pneumoniae (ESBL + KPC) (VAP + CLABSI + CAUTI) + Pseudomonas aeruginosa (VAP + ISO) + Acinetobacter baumannii (VAP + CLABSI → hospitals in tropical areas + intensive care) + C. difficile (ICD); antibiotic resistance mechanisms - BMR: MRSA (resistance to meticillin via mecA gene → PBP2a protein → reduced affinity for beta-lactams → resistance to all beta-lactams) + treatment: vancomycin + daptomycin + linezolid + ceftaroline → VRE (vancomycin-resistant Enterococcus - vanA + vanB genes → modification of peptidoglycan precursor D-Ala-D-Lac instead of D-Ala-D-Ala → vancomycin no longer binds) + treatment: linezolid + daptomycin + quinupristin-dalfopristin (VanA only) + carbapenemase-producing enterobacteria (EPC - KPC + NDM + OXA-48 + VIM + IMP) → carbapenem resistance → very limited options: ceftazidime-avibactam + meropenem-vaborbactam + imipenem-cilastatin-relebactam + colistin (nephrotoxic) + multidrug-resistant Acinetobacter baumannii (MDR-AB) : resistance to almost all antibiotics → colistin + tigecycline → often pan-resistant in some regions → surveillance data Quebec: MSSS + INSPQ publish annual surveillance data on MRSA + VRE + C. difficile by healthcare facility in Quebec
- Hand hygiene and standard precautions — fundamental prevention measures: hand hygiene - the most effective and least costly preventive measure: WHO (2009) - My 5 Moments for Hand Hygiene: 5 key indications: before touching the patient + before an aseptic procedure + after a risk of exposure to a biological fluid + after touching the patient + after touching the patient's environment → hydroalcoholic friction (FHA) : ethanol-based hydroalcoholic solution (SHA) (62-80 %) → 20-30 seconds + bactericidal efficacy superior to handwashing with soap and water unless hands visibly soiled + or C. difficile (sporulation - SHA ineffective → washing with soap and water mandatory) → Pittet 2000 - Lancet: improved hand hygiene compliance → 50 % reduction in HAIs → Génève → HH-Success program → Pittet 2001 - Annals of Internal Medicine: hand hygiene improvement program → MRSA reduction of 32 % → target compliance: ≥80 % in intensive care units + standard precautions: applicable to all patients systematically → blood + secretions + biological fluids → gloves + mask + goggles if projection risk → additional precautions protocols: contact (MRSA + VRE + C. difficile + Norovirus + RSV): room only + apron + gloves → droplets (influenza + COVID-19 + meningococcal meningitis + mumps + influenza): surgical mask + gloves → airborne (tuberculosis + chickenpox + measles + aerosol-generating SARS-CoV-2): negative pressure chamber + N95/FFP2 mask + gloves + gown → Cohen 2006 - SHEA/IDSA Practice Recommendations: additional precautions in HAIs → Siegel 2007 - CDC/HICPAC Guidelines: isolation precautions → international reference + MSSS Quebec + INSPQ: provincial infection prevention and control (IPC) protocols → regular updates
Specific IAS, prevention, and treatment
| IAS Type | Prevention, diagnosis, and treatment | Key studies and recommendations |
|---|---|---|
| Clostridioides difficile infection (CDI) C. difficile — oral vancomycin — fidaxomicin — bezlotoxumab — fecal transplant — recurrence — contact precautions — hypochlorite |
Clostridioides difficile - epidemiology and pathogenesis: spore-forming Gram-positive anaerobic bacterium → spores resistant to alcohol + heat + most disinfectants → only chlorine (sodium hypochlorite - dilute bleach) destroys them + antibiotics → dysbiosis of the intestinal microbiota → C. difficile spores germinate → colonization + toxin production A (enterotoxin) + B (cytotoxin) → pseudomembranous colitis. difficile spores germinate → colonization + production of toxins A (enterotoxin) + B (cytotoxin) → pseudomembranous colitis → watery diarrhea + fever + abdominal pain → hypervirulent strain BI/NAP1/027: binary toxin producer + hyperproducer of toxins A + B + resistant to fluoroquinolones → epidemics in North America since 2001 → risk factors for CDI : recent antibiotics (especially clindamycin + quinolones + cephalosporins + broad-spectrum penicillins) + prolonged hospitalizations + PPIs + age >65 + immunosuppression + digestive surgery; diagnosis of CDI: criteria: ≥3 soft stools/24h + EIA (Enzyme Immunoassay) for A/B toxins: rapid + specific (95 %) + but sensitivity 70-75 % → PCR (NAAT) on stool: sensitivity 90-97 % + specificity 97 % → screen asymptomatic carriers → risk of overdiagnosis → optimal algorithm: glutamate dehydrogenase (GDH - antigen C. difficile) in screening → if positive → EIA toxins → if negative → PCR (2- or 3-step algorithm) → Crobach 2016 - Clinical Microbiology and Infection (meta-analysis): GDH + EIA + PCR algorithm → better performance + avoids overdiagnosis; CDI treatment: initial non-severe episode: fidaxomicin (Dificid) 200 mg × 2/d × 10 days → superior to oral vancomycin in reducing recurrence → Louie 2011 - NEJM (RCT): fidaxomicin vs vancomycin → similar cure rates + recurrence rate: 15 % vs 25 % → recommended as 1st-line (IDSA 2021 + SHEA 2022) + or oral vancomycin 125 mg × 4/d × 10 days → less costly alternative → severe initial episode (leukocytosis >15 × 10⁹/L or creatinine >1.5 × normal or albumin antibiotics for recurrent CDI → Van Nood 2013 - NEJM: TMF via nasoduodenal probe → 81 % vs 31 % vancomycin → trial stopped → TMF = reference treatment for multiple recurrent ICD + Ribaxamase and SYN-004: antibiotic-degrading enzymes in the digestive tract → reduction of dysbiosis → clinical trials; specific precautions C. difficile precautions: strict contact precautions + room only + hand washing with soap and water (SHA ineffective on spores) + wearing gloves and gown → surface disinfection with sodium hypochlorite 1000-5000 ppm (bleach diluted 1:10) → maintain precautions until 48-72h after resolution of symptoms → no treatment of asymptomatic carriers → INSPQ + MSSS Quebec: protocols for controlling C. difficile epidemics. | Louie 2011 — NEJM (RCT): fidaxomicin vs vancomycin → similar cure rates + 15% % vs 25% % recurrence → fidaxomicin superior + Wilcox 2017 — NEJM (MODIFY I + II trials): bezlotoxumab → 40% % reduction in recurrence → indicated if high risk of recurrence + Van Nood 2013 — NEJM: FMT vs vancomycin → 81% % vs 31% % → trial stopped + Paramsothy 2017 — Lancet: FMT > antibiotics for recurrent CDI → Crobach 2016 — CMI: GDH + EIA + PCR algorithm → best diagnostic performance → + McDonald 2018 — Clinical Infectious Diseases (IDSA/SHEA Guidelines): CDI treatment 2018 → vancomycin + fidaxomicin first-line → metronidazole abandoned first-line + Kelly 2021 — IDSA/SHEA 2021 update: fidaxomicin = first-line + bezlotoxumab for high-risk recurrence + INSPQ Quebec: C. difficile control protocols in healthcare facilities → mandatory epidemiological surveillance + reporting to MSSS |
| Ventilator-associated pneumonia (VAP) and hospital-acquired pneumonia (HAP) Definition VAP — criteria — prevention bundle VAP — head of bed at 30–45° — oral hygiene — cuff pressure — VAP antibiotic therapy — cultures — de-escalation |
VAP - definition and epidemiology: pneumonia occurring ≥48h after endo-tracheal intubation → incidence: 10-25 % of mechanically ventilated patients → attributable mortality: 10-25 % → prolongs VM duration by 7-9 days + ICU length of stay by 5-7 days → high cost → pathogens: early (<5 days): S. aureus + H. influenzae + S. pneumoniae + susceptible enterobacteria → late (≥5 days): P. aeruginosa + S. aureus MRSA + Klebsiella ESBL/KPC + Acinetobacter → mechanism: micro-inhalation of colonized oro-pharyngeal secretions around intubation tube balloon → biofilm on tube → VAP bundle (ventilator bundle) - prevention: head of bed elevated at 30-45° (unless contraindicated - reduction of micro-inhalations) + oral hygiene with chlorhexidine 0,12 % × 2-4/d + control of intubation tube cuff pressure (20-30 cmH₂O) → insufficient pressure → micro-inhalations + excessive pressure → tracheal necrosis + daily interruption of sedation + evaluation of extubation → reduce duration of VM + prefer nasogastric route to gavage if enteral feeding → prefer semi-sitting position + continuous subglottic suction (intubation tube with suction channel) → Coffin 2008 - Infection Control and Hospital Epidemiology : VAP bundle → 50-70 % reduction in incidence + CDC / Institute for Healthcare Improvement (IHI): VAP bundle → standard recommendation + Institute for Safe Medication Practices (ISMP) + Pronovost 2006 - NEJM: Keystone Project - Michigan → application of CVC bundle → 66 % reduction in CLABSI → applicable to VAP bundle; diagnosis of VAP: clinical + radiological + microbiological criteria → fever + leukocytosis + purulent secretions + radio → infiltrates but : low specificity → cultures: bronchoalveolar lavage (BAL) + tracheal aspiration → quantitative if possible (threshold: BAL ≥10⁴ UFC/mL + tracheal aspiration ≥10⁵ UFC/mL) + semi-quantitative culture + Gram direct → biomarkers: procalcitonin + CRP → guide treatment duration + treatment of APV: empirical antibiotic therapy according to risk of multi-resistant germs and local data: early APV (≤5 days) without resistance FdR: cefazolin 1 g × 3/d IV → or amoxicillin-clavulanate 1.2 g × 3/d IV → or ceftriaxone 2 g/d IV → late APV (≥5 days) or resistance FdR (recent antibiotic therapy + prolonged hospitalization + prolonged VM + previously documented MRSA or Pseudomonas): piperacillin-tazobactam 4.5 g × 4/d IV + and/or meropenem 1-2 g × 3/d IV + MRSA: vancomycin IV + or linezolid → de-escalation as soon as culture results are available → duration: 7-8 days in general (Chastre 2003 - JAMA: 8 days = 15 days for APV except Pseudomonas + Acinetobacter → shorter course recommended) | Coffin 2008 — Infection Control and Hospital Epidemiology : VAP bundle → réduction 50–70 % de l'incidence + Pronovost 2006 — NEJM (Keystone Michigan) : application des bundles → réduction 66 % CLABSI → principe applicable aux bundles VAP + Chastre 2003 — JAMA (RCT) : 8 jours vs 15 jours de traitement VAP → mortalité identique + 8 jours = durée standard + ATS/IDSA 2016 (Kalil — Clinical Infectious Diseases) : guidelines HAP/VAP → diagnostic + traitement → désescalade + durée 7–8 jours + CDC/NHSN 2023 : définitions actualisées des IAS → VAP + CLABSI + CAUTI + ICS 2017 + INSPQ Québec : protocoles de prévention VAP en réanimation + déclaration des IAS obligatoire dans les établissements québécois (MSSS) |
| Central Line-Associated Bloodstream Infections (CLABSI) and Catheter-Associated Urinary Tract Infections (CAUTI) Bundle CVC — aseptic insertion — chlorhexidine — early catheter removal — CLABSI prevention — antibiotic therapy — CVC duration — DTP infection vs. contamination |
CLABSI - prevention and treatment: CVC insertion bundle (Central Line Bundle - IHI): rigorous hand hygiene + skin disinfection with alcoholic chlorhexidine 2 % (superior to povidone iodine) → Mimoz 2015 - Lancet (RCT): alcoholic chlorhexidine 2 % vs alcoholic povidone iodine → reduced CLABSI and colonization → chlorhexidine = standard + maximum sterile barriers (gown + gloves + mask + large sterile sheet) + subclavian or internal jugular route preferred to femoral route (less contamination) + remove catheter as soon as no longer essential + chlorhexidine-impregnated sutures (Biopatch) + transparent dressings + catheter maintenance: disinfection of taps before each manipulation + antiseptic caps (Curos) → Pronovost 2006 - NEJM (Keystone Michigan): bundle CVC → reduction 66 % CLABSI (from 2.7 to 0 episodes/1,000 catheter-days in some units) → seminal publication + CLABSI diagnosis: sepsis + catheter in place + positive blood cultures with unknown starting point → DTP (Differential Time to Positivity): if blood culture on CVC becomes positive ≥2h before peripheral blood culture → infection on catheter + Blot 2004 - Lancet ID: DTP >2h → sens. 89 % + spec. 87 % → CLABSI treatment: remove or change CVC → control blood cultures → depending on germ: SCN on CVC in place uncomplicated → vancomycin IV × 14 days + catheter removal recommended → S. aureus on CVC: remove CVC + vancomycin (MRSA) or cloxacillin (SAMS) × 14 days (uncomplicated bacteremia) → ETT/ETO to exclude IE + Candida on CVC: remove CVC + echinocandin IV × 14 days after last negative blood culture; CAUTI - prevention and treatment: main preventive measure: avoid unnecessary bladder catheterization + remove urinary catheter as soon as no longer essential → Gould 2010 - Infection Control and Hospital Epidemiology (CDC HICPAC guidelines): CAUTI recommendations → strict catheter indications + removal reminder systems → antimicrobial-coated catheters (silver + antibiotic): mixed data in recent studies → Cochrane 2013: inconsistent efficacy → no universal recommendation + meatus hygiene + sterile closed circuit + never break the circuit → CAUTI diagnosis: if catheter in place → bacteriuria ≥10³ CFU/mL + symptoms → treatment: removal or change of catheter + antibiotic therapy guided by antibiogram × 7 days → asymptomatic bacteriuria on catheter → DO NOT TREAT (Nicolle 2019 - CIDP IDSA) except before a urological procedure + clean intermittent catheterization (SIP): preferable to indwelling catheterization if chronic retention. | Pronovost 2006 — NEJM (Keystone Michigan): CVC bundle → 66% reduction % CLABSI → foundational publication Mimoz 2015 — Lancet (RCT): alcoholic chlorhexidine 2% % vs. povidone-iodine → chlorhexidine superior → new standard Blot 2004 — Lancet ID: DTP >2h → catheter infection → sens. 89 % + spec. 87 % + IDSA 2009 (Mermel — Clinical Infectious Diseases): CLABSI guidelines → treatment according to pathogen + duration + catheter removal + Gould 2010 — ICHE (CDC HICPAC guidelines CAUTI): strict indications + early removal → recommendations Nicolle 2019 — CID IDSA: BA on catheter → DO NOT TREAT + CDC NHSN 2023: updated CLABSI + CAUTI definitions + INSPQ Quebec: mandatory CLABSI + CAUTI surveillance → MSSS reporting → Quebec Intensive Care Safety program |
| Surgical site infections (SSIs), MRSA, and antimicrobial stewardship programs Surgical prophylaxis — cefazolin — MRSA — preoperative decolonization — ISO classification — rational antibiotic therapy — judicious use of antibiotics — audit — de-escalation |
Surgical site infections (SSI) - prevention and classification: classification of SSI (CDC): superficial SSI (skin + subcutaneous tissue) + deep SSI (fascia + muscles) + organ/space SSI (cavity + prosthesis) → risk factors for SSI: duration of surgery + colorectal surgery + field contamination + obesity + diabetes + smoking + corticoids + MRSA carrier + inadequate antibiotic prophylaxis; surgical antibiotic prophylaxis: cefazolin 2 g IV (3 g if >120 kg) within 60 minutes before incision → booster dose if surgery >3 h or >1,500 mL losses → algorithm: Bratzler 2013 - American Journal of Health-System Pharmacy (ASHP/IDSA/SIS/SHEA guidelines): cefazolin = antibiotic of choice for most clean-contaminated surgeries → clindamycin + gentamicin if beta-lactamine allergy + vancomycin if preoperative MRSA carrier → no prolonged prophylaxis >24h (with cardiac + orthopedic exceptions) → prevention of SSI by preoperative decolonization: screening for MRSA nasal carriage before high-risk scheduled surgery (cardiac + orthopedic + prosthesis) → if MRSA: nasal mupirocin 2 % × 5 days + chlorhexidine baths × 5 days → Bode 2010 - NEJM (RCT): preoperative MRSA decolonization → 58 % reduction in SSI to S. aureus → maintenance of blood glucose <11 mmol/L intraoperatively + normothermia + adequate oxygenation + normvolemia → reduction in SSIs; MRSA - hospital control measures: active screening of nasal carriers on admission to certain departments (intensive care + orthopedics) → nasal swab + perineum/week → contact precautions if carrier: room only + apron + gloves → decolonization if scheduled surgery + reinforced cleaning and disinfection of surfaces + Edgeworth 2017 - Lancet: universal MRSA screening in the ICU → 50 % reduction in MRSA + Huang 2013 - NEJM (REDUCE MRSA RCT): universal decolonization in ICU (nasal mupirocin + chlorhexidine baths) vs targeted screening → 44 % reduction in MRSA infections → 37 % reduction in all ICU infections → major result → universal decolonization in ICU feasible; Antimicrobial Stewardship Program (ASP): objectives: optimize clinical outcomes by using appropriate antibiotics + reduce resistance + reduce adverse effects + reduce costs → components: prospective audit + feedback to prescribers + list of antibiotics with prior authorization + de-escalation period (48-72h after microbiological results) + standardized treatment duration according to diagnosis → bio-markers guiding duration (procalcitonin → Schuetz 2012 - Cochrane: procalcitonin-guided → reduced duration of antibiotic therapy without increased mortality + benefits for respiratory infections ++ ) + prescriber education + Barlam 2016 - Clinical Infectious Diseases (IDSA/SHEA): guidelines for ASPs → multidisciplinary program → infectiologist + pharmacist + microbiologist + Canadian data: CNISP (Canadian Nosocomial Infection Surveillance Program - ASPC): national surveillance of BMRs and HAIs + INSPQ Québec: annual provincial assessment of HAIs + publication of indicators by establishment. | Bratzler 2013 — American Journal of Health-System Pharmacy (ASHP/IDSA/SIS/SHEA): surgical prophylaxis → cefazoline = standard + duration <24h + Bode 2010 — NEJM (RCT): preoperative MRSA decolonization → −58 % SSI from S. aureus + Huang 2013 — NEJM (REDUCE MRSA RCT): universal decolonization ICU → −44 % MRSA infections → −37 % all infections → Edgeworth 2017 — Lancet: universal MRSA screening ICU → −50 % MRSA + Schuetz 2012 — Cochrane: procalcitonin-guided → reduced antibiotic duration without increased mortality + Barlam 2016 — CID (IDSA/SHEA ASP guidelines): ASP program → multidisciplinary + audit + de-escalation + INSPQ Quebec + MSSS 2023: HAI report + mandatory declaration + CNISP ASPC: national surveillance HAIs + ARMs in Canada + CDC 2020: Core Elements of Hospital Antibiotic Stewardship Programs |
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Hand washing with soap and water (not alcohol-based hand rubs) is MANDATORY for patient care with Clostridioides difficile — C. difficile spores are resistant to alcohol: The prevention of healthcare-associated infections relies on three inseparable pillars: hand hygiene (alcohol-based hand rub for most situations + soap and water for C. difficile and visibly soiled hands), structured care bundles for each type of HAI, and stewardship programs to limit the emergence of multidrug-resistant bacteria. Reporting HAIs to the MSSS is mandatory in Quebec for all healthcare facilities.
Situations requiring urgent care
Hospitalized patient with profuse diarrhea (>3 stools/24h) + abdominal pain + fever + massive leukocytosis (>30 × 10⁹/L) + elevated creatinine after recent antibiotic therapy Severe or fulminant ICD → isolation in single room + contact precautions + hand washing with soap and water + GDH + EIA toxins + PCR on stool → if severity criteria met → oral vancomycin 500 mg × 4/day + abdominal CT scan → if megacolon or perforation → emergency surgery.
Patient in intensive care on mechanical ventilation with onset of fever, purulent tracheobronchial aspiration, and new infiltrates on chest X-ray after 5 days of mechanical ventilation → Late VAP → cultures (BAL + tracheal aspiration + blood cultures) → empirical broad-spectrum antibiotic therapy covering MRSA (piperacillin-tazobactam + vancomycin) → de-escalation at 48–72h according to antibiogram → reinforced VAP bundle.
Sudden fever + chills + hypotension in the hours following central venous catheter manipulation → Probable bacteremia on central venous catheter → Blood cultures x2 (on CVC + peripheral vein) → DTP → if MRSA or S. aureus → removal of CVC + IV vancomycin + TTE/TEE → if uncomplicated SCN on CVC and difficult to remove → treatment without removal can be discussed with the infectious disease specialist → monitoring of control blood cultures.
Enterobacterales producing carbapenemase (EPC) carrier identified on admission or during the hospital stay → Enhanced contact precautions + private room + disinfection and sanitization of surfaces with a virucidal product + reporting to INSPQ and MSSS (mandatory declaration) + contact tracing + no treatment for asymptomatic colonization → treatment for invasive infection: ceftazidime-avibactam +/- meropenem-vaborbactam depending on the resistance mechanism.
Consult at Clinique Omicron
Clinique Omicron physicians provide follow-up care for patients with a history of HAIs on an outpatient basis, prescribe and interpret post-hospitalization microbiological assessments, manage community-acquired HAIs (particularly recurrent UTIs in the outpatient setting), refer complex cases or carriers of MDROs requiring decolonization to infectious disease specialists, and participate in the implementation of local infection prevention and control programs. Consultations are available at several service points across Quebec and via telemedicine. To book an appointment, visit cliniqueomicron.ca.
The content of this page is for informational purposes only and does not substitute for professional medical advice from an infectious disease specialist or infection prevention and control professional. Infection prevention protocols vary by facility and must be adapted to local epidemiological data.
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