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Nosocomial Infections

Nosocomial Infections. David M. Parenti, M.D. Definitions. sterilization : use of physical procedures or chemical agents to destroy all microbes, including spores, viruses, fungi disinfection : use of physical procedures or chemical agents to destroy most microbes

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Nosocomial Infections

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  1. Nosocomial Infections David M. Parenti, M.D.

  2. Definitions • sterilization: use of physical procedures or chemical agents to destroy all microbes, including spores, viruses, fungi • disinfection: use of physical procedures or chemical agents to destroy most microbes • high, intermediate, low level • antisepsis: use of chemical agents on skin or other tissue to inhibit or kill microbes

  3. Nosocomial Infections • Infection acquired in the hospital: > 48 hours after admission • $5 billion annually: increased hospital length of stay, antibiotics, morbidity and mortality • related to severity of underlying disease, immunosuppression, invasive medical interventions • frequently caused by antibiotic-resistant organisms: MRSA, VRE, resistant Gram-negative bacilli, Candida

  4. Sites of Nosocomial Infections Pneum SSI 11% 20% UTI Other 22% 36% BSI 11% Klevens. Pub Health Rep 2007;122:160

  5. Nosocomial InfectionTypes of Transmission • airborne • tuberculosis, varicella, Aspergillus • contact • S. aureus, enterococci, Gram-negative bacilli • common vehicle • food contamination • Salmonella, hepatitis A

  6. Patient 1 • A 67 yo female with poorly controlled hypertension was admitted because of a right-sided stroke. She had confusion, limitation of mobility of her left leg, and urinary incontinence. A urinary (Foley) catheter was placed and she was evaluated for rehabilitation. • 4 days later she developed a temp to 103º F and blood pressure of 90/60 and was transferred to the ICU. Blood and urine cultures grew resistant Klebsiella.

  7. Nosocomial UTI • Up to 25% of hospitalized patients are catheterized at some time during their hospital stay. • 15% colonized (bacteruria) • 5-10% per day of catheterization • 50% after 14 days • Gram-negative bacilli, VRE, Candida • frequent antimicrobial resistance

  8. Antibiotic-ResistantGram-Negative Bacilli • increasingly a problem in the ICU: UTI, pneumonia • selective pressure from high-level antibiotic usage in hospital and community • E. coli, Klebsiella, Enterobacter, Pseudomonas, Serratia, Acinetobacter • resistance to extended spectrum penicillins, cephalosporins, aminoglycosides, quinolones • colonization at multiple body sites: GI, skin, pharynx

  9. Nosocomial UTI Pathogenesis • external • most common • colonization of urethral meatus • movement of bacteria along fluid layer on external catheter surface • internal • colonization of urine in bag, ascend through catheter lumen

  10. Nosocomial UTI Prevention • *avoid catheterization • minimize duration of catheterization • intermittent (“in and out”) catheterization • aseptic insertion technique • closed system • dependent drainage • silver-coated catheters

  11. Patient 2 • A 45 yo male is admitted for community-acquired pneumonia. He has a long history of iv drug use, but has not used in several years. The intern has difficulty starting a peripheral iv so places a femoral venous catheter. His cough and fever begin to improve. • On hospital day 3 he has fever, chills and a WBC of 18,000. Blood cultures are positive for vancomycin-resistant Enterococcus.

  12. Vascular Device-Associated Bacteremia • major cause of morbidity and mortality in hospitalized patients • 150 million intravascular devices are purchased by hospitals yearly • estimated 50,000-100,000 intravascular device- related bacteremias in U.S./year • non-cuffed central venous catheters account for 90% of vascular catheter-related bacteremias

  13. CVC-Associated BacteremiasGWUH 2009 • Staphylococcusaureus, MRSA, S. epidermidis • Enterococcusfaecalis, VRE • Streptococcusagalactiae (group B strep) • Acinetobacter, Klebsiellapneumoniae, Enterobactercloacae • Candidaalbicans, C.parapsilosis

  14. Vascular Device-Associated Bacteremia: Pathogenesis • initial step is colonization of the insertion or access hub • biofilm formation allows attachment of bacteria • development of bacteremia

  15. IV Catheter Biofilm 24 hours after Insertion

  16. Coagulase Negative StaphylococciSlime-producing, Catheter Surface

  17. Vascular Catheter InfectionsRisk Factors • type of catheter: plastic > steel • multiple > single lumen • location of catheter • central > peripheral • internal jugular, femoral > subclavian • duration of placement: > 72 hours • emergent placement > elective • skill of venipuncturist: others > i.v. team

  18. Vascular Catheter InfectionsClinical Clues • local inflammation or phlebitis at catheter insertion site • bacteremia caused by associated organisms: MRSA, CNS, VRE, Candida above waist 38% hand or arm 29% inguinal area 86% Bonten MJM . Lancet 1996; 348:1615

  19. Vascular Catheter InfectionsDiagnosis • Maki rollplate technique • catheter tip or intracutaneous segment is rolled on agar plate • colonies are counted • > 15 colonies correlates with colonization and potential source of bacteremia Maki DG. NEJM 1977;296:1305

  20. Semipermanent Tunneled Catheters (Groshong, Hickman, Mediport) • long term i.v. therapy • much lower rate of infection • dacron cuff incites inflammatory response, fibrosis at insertion site • prevents bacteria from migrating along external catheter surface • locations of infection: exit site, tunnel, tip • tunnel infection always requires catheter removal • septic thrombophlebitis/pulmonary emboli

  21. Groshong catheter

  22. CVC-Associated BacteremiaPrevention (Bundles) • *minimize duration of catheterization • use single vs multiple lumen catheters • site placement • meticulous insertion technique • drapes, gown/gloves/mask • antibiotic impregnated catheters • impregnated dressing (Biopatch) • outbreak/cluster control

  23. Chlorhexidine/Silver Sulfadiazine-Coated CVCs • 158 hospitalized patients with 403 triple-lumen, polyurethane venous catheters • chlorhexidine/silver sulfadiazine-coated vs uncoated catheters-external surface uncoatedcoatedp • colonization 24.1% 13.5% < 0.005 • bacteremia 4.7% 1% < 0.03 Maki DG; Ann Intern Med 1997;127:257

  24. VRE RFLP GWUH 2004 * * * * * * * *

  25. Patient 3 • A 52 yo male is admitted with a severe headache and is found to have a subarachnoid hemorrhage from a ruptured aneurysm. The neurosurgeons evacuate the hematoma and clip his aneurysm. Post-op he remains on a ventilator. • On hospital day 5 he spikes a fever to 102º F and is noted to have copious secretions from his endotracheal tube. Increasing amounts of inspired O2 are required. Blood and sputum cultures grow highly resistant Enterobactercloacae.

  26. Nosocomial Pneumonia • 300,000 cases/year in U.S. • 10-15% of nosocomial infections • leading cause of death from nosocomial infection • crude mortality 35-50% • ventilator-associated pneumonias occur 48-72 h post endotracheal intubation • organisms may originate from endogenous flora, other patients, visitors, or environmental sources

  27. Ventilator Associated Pneumonia GWUH 2009 • Staphylococcusaureus, MRSA • Proteusmirabilis, Serratiamarcescens, Pseudomonasaeruginosa, Stenotrophomonasmaltophilia

  28. Nosocomial Pneumonia EpisodesMortality Klebsiella, 30% 40% Enterobacter S. aureus 27% 33% P. aeruginosa 15% 72% S. pneumoniae 12% 43% E. coli 10% 31% anaerobes 2% 0% Bryan CS. Am Rev Resp Dis 1984;129:668-671

  29. Gram-Negative Bacilli ColonizationRisk Factors • severity of underlying illness • duration of hospitalization • prior or concurrent use of antibiotics • advanced age • intubation • major surgery • achlorhydria ?

  30. Ventilator-Associated PneumoniaPrevention • *limit duration of ventilation • handwashing/gloves • closed ventilator circuits • semi-recumbent positioning • avoid large gastric volumes • avoid prolonged nasal intubation • prevent sinusitis • ? maintain gastric acidity

  31. Patient 4 • A 73 yo male is admitted with chest pain and severe coronary artery disease. He has emergent 3-vessel coronary artery bypass grafting. He recovers fairly well from the surgery but on post-op day 10 develops fever and purulent drainage from the inferior aspect of the wound. • He returns to the operating room for extensive debridement of sternal osteomyelitis. Cultures grow methicillin-resistant Staphylococcusaureus.

  32. Patient 4

  33. Surgical Site Infection (SSI) • usually introduction of skin organisms into the wound • S. aureus, Gram-negative bacilli • risk factors • underlying disease • skill of the operator • duration of operative procedure • may not become clinically apparent until after discharge • risk may be decreased by appropriately timed pre-operative antibiotics

  34. MRSA • 1960 methicillin-resistant S. aureus identified • MRSA 60% of S. aureus isolates at GW are MRSA (2007) • Community-acquired: recent increase in incidence • Hospital-acquired: > 48 h after admission • Healthcare-associated community-onset: • previous positive MRSA culture • history of hospitalization, surgery, dialysis or residence in long term care facility in the last year • indwelling catheter/percutanous device

  35. MRSA IsolatesPulse Field Gel Electrophoresis (PFGE)

  36. MRSAMechanism of Resistance • chromosomal mecA gene • *altered PBP 2´ or 2a in cell wall • low affinity for all ß-lactam antibiotics

  37. Hospital-acquired MRSA • BSI 76% • pneumonia 13% • osteomyelitis 6% • endocarditis 3% • cellulitis 4% • skin abscess/necrosis 1% • mortality 2.5% www.cdc.gov/abcs

  38. Hospital-acquired MRSA • Risk factors: • prolonged hospitalization • prolonged antimicrobial therapy • location in an intensive care unit • proximity to a known MRSA case • Persistent colonization up to 4 years: nares • Contamination of environmental surfaces • up to 30%: bed rails, table, BP cuff

  39. SSI Prevention • no shaving of operative site: clippers or no hair removal • hand hygiene; fastidious aseptic technique • surgical site antisepsis with chlorhexidine • prophylactic antibiotics • single dose 30-60 minutes prior to incision • second dose for prolonged surgeries • laminar air flow or HEPA filtration; limit traffic in the operating room • pre-operative screening for S. aureus

  40. Patient 5 • A 26 yo medical student draws blood from a patient for a classmate. He is in a hurry and sticks his thumb while recapping (?) the needle. The patient has been tested positive for HIV and hepatitis C. The student has received the hepatitis B immunization series.

  41. HCW Blood/Body Fluid ExposureRisk Factors • needlestick/sharp>>mucosal>>non-intact skin • inoculum: viral titer, volume of blood • needle type • hollow-bore needles > solid-bore • large bore > small bore • decreased risk with glove use

  42. GWU Health Care WorkersPercutaneous Exposures: 2007-09 • Occupation • Hospital staff 38-49%* • Residents 39-56%* • Students 6-11% • Location • ER 7-14% • ICU 7-21%* • OR 31-52%* • other floors 24-27%* • Pathology 3-8%

  43. Risk of Transmission following Percutaneous Exposure • HIV 0.3% • Hepatitis C 1.9% • HBeAg - < 6% • HBeAg + 30% • estimated US transmission for yr 2000* • 390 cases of HCV • 40 cases of HBV • 5 cases of HIV Henderson DK. Clin Microbiol Rev.2003;16:546 * Prüss-Üstün A. Am J Ind Med 2005;48:482

  44. HCW Blood/Body Fluid ExposureManagement • baseline serologies, including the patient if necessary • assessment of risk • HIV: antiretroviral therapy • hepatitis B: hepatitis B immune globulin and hepatitis B vaccine if non-immune • hepatitis C: close follow up

  45. HCW Blood/Body Fluid ExposurePrevention • SLOW DOWN • do not recap needles • dispose of sharps in the proper receptacle • use needleless systems whenever possible • heptitis B immunization

  46. Isolation • to protect both patients and personnel • StandardPrecautions • routinely consider all body fluids and moist surfaces as potentially infectious • airborne precautions • droplet precautions • contact precautions

  47. IsolationAirborne Precautions • transmission of pathogen via inhalation of droplet nuclei • tuberculosis, varicella, ? influenza • private room • negative pressure • > 10 air exchanges per hour • Staff: particulate respirators

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