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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 – high, intermediate, low level antisepsis: use of chemical agents on skin or other tissue to inhibit or kill microbes 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 Gramnegative bacilli, Candida Sites of Nosocomial Infections Pneum 11% SSI 20% UTI Other 22% 36% BSI 11% Klevens. Pub Health Rep 2007;122:160 Nosocomial Infection Types of Transmission airborne – tuberculosis, varicella, Aspergillus contact – S. aureus, enterococci, Gram-negative bacilli common vehicle – food contamination – Salmonella, hepatitis A 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. 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 Antibiotic-Resistant Gram-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 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 Nosocomial UTI Prevention *avoid catheterization – minimize duration of catheterization – intermittent (“in and out”) catheterization aseptic insertion technique closed system dependent drainage silver-coated catheters 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. 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 catheterrelated bacteremias CVC-Associated Bacteremias GWUH 2009 Staphylococcus aureus, MRSA, S. epidermidis Enterococcus faecalis, VRE Streptococcus agalactiae (group B strep) Acinetobacter, Klebsiella pneumoniae, Enterobacter cloacae Candida albicans, C. parapsilosis Vascular Device-Associated Bacteremia: Pathogenesis initial step is colonization of the insertion or access hub biofilm formation allows attachment of bacteria development of bacteremia IV Catheter Biofilm 24 hours after Insertion Coagulase Negative Staphylococci Slime-producing, Catheter Surface Vascular Catheter Infections Risk 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 Vascular Catheter Infections Clinical 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 Vascular Catheter Infections Diagnosis 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 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 Groshong catheter CVC-Associated Bacteremia Prevention (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 Chlorhexidine/Silver SulfadiazineCoated CVCs 158 hospitalized patients with 403 triplelumen, polyurethane venous catheters chlorhexidine/silver sulfadiazine-coated vs uncoated catheters-external surface uncoated coated p colonization 24.1% 13.5% < 0.005 bacteremia 4.7% 1% < 0.03 Maki DG; Ann Intern Med 1997;127:257 VRE RFLP GWUH 2004 * * * * * * * * 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 Enterobacter cloacae. 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 4872 h post endotracheal intubation organisms may originate from endogenous flora, other patients, visitors, or environmental sources Ventilator Associated Pneumonia GWUH 2009 Staphylococcus Proteus aureus, MRSA mirabilis, Serratia marcescens, Pseudomonas aeruginosa, Stenotrophomonas maltophilia Nosocomial Pneumonia Klebsiella, Enterobacter S. aureus P. aeruginosa S. pneumoniae E. coli anaerobes Episodes 30% Mortality 40% 27% 15% 12% 10% 2% 33% 72% 43% 31% 0% Bryan CS. Am Rev Resp Dis 1984;129:668-671 Gram-Negative Bacilli Colonization Risk Factors severity of underlying illness duration of hospitalization prior or concurrent use of antibiotics advanced age intubation major surgery achlorhydria ? Ventilator-Associated Pneumonia Prevention *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 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 postop 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 Staphylococcus aureus. Patient 4 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 preoperative antibiotics 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 MRSA Isolates Pulse Field Gel Electrophoresis (PFGE) MRSA Mechanism of Resistance chromosomal mecA gene *altered PBP 2´ or 2a in cell wall low affinity for all ßlactam antibiotics Hospital-acquired MRSA BSI pneumonia osteomyelitis endocarditis cellulitis skin abscess/necrosis mortality 76% 13% 6% 3% 4% 1% 2.5% www.cdc.gov/abcs 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 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 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. HCW Blood/Body Fluid Exposure Risk Factors needlestick/sharp>>mucosal>>non-intact inoculum: viral titer, volume of blood needle type – hollow-bore needles > solid-bore – large bore > small bore decreased risk with glove use skin GWU Health Care Workers Percutaneous Exposures: 2007-09 Occupation – Hospital staff – Residents – Students 38-49%* 39-56%* 6-11% Location – – – – – ER ICU OR other floors Pathology 7-14% 7-21%* 31-52%* 24-27%* 3-8% 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 HCW Blood/Body Fluid Exposure Management 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 HCW Blood/Body Fluid Exposure Prevention SLOW DOWN do not recap needles dispose of sharps in the proper receptacle use needleless systems whenever possible heptitis B immunization Isolation to protect both patients and personnel Standard Precautions – routinely consider all body fluids and moist surfaces as potentially infectious airborne precautions droplet precautions contact precautions Isolation Airborne Precautions transmission of pathogen via inhalation of droplet nuclei – tuberculosis, varicella, ? influenza private room negative pressure > 10 air exchanges per hour Staff: particulate respirators Isolation Droplet Precautions respiratory secretions via close personal contact group A strep, influenza private room particulate respirator do not need negative pressure or increased air exchanges Isolation Contact Precautions transmitted via hands of personnel, inanimate surfaces MRSA, VRE, highly resistant GN rods private room gloves with patient contact handwashing Michael Jackson Approach Handwashing most important means to prevent spread of nosocomial pathogens hand cultures of medical personnel GN bacilli S. aureus random sample 45% 11% serial sample 100% 64% persistent carrier 16% 16% Puerpural Sepsis Ignaz Semmelweis Ignaz Semmelweis (1847) observed differences in the incidence of puerpural sepsis (group A strep) on 2 different wards one ward was staffed by obstetricians, medical students: mortality 8% one ward was staffed by midwives: mortality 2% Puerpural Sepsis Ignaz Semmelweis Observation #1: lower mortality when students were on vacation Observation #2: pathologist cut during autopsy developed similar illness Solution: HAND HYGIENE in the autopsy room prevented transmission of organisms to the delivery suite Ignaz Semmelweis Decreased Mortality with Improved Hand Hygiene Chlorinated lime hand antisepsis Ignaz Semmelweis (1818-65)