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

Transcription

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 Gramnegative bacilli, Candida

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

5 Nosocomial Infection Types 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-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

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 intravascular device- related bacteremias in U.S./year non-cuffed central venous catheters account for 90% of vascular catheterrelated bacteremias

13 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

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 Staphylococci Slime-producing, Catheter Surface

17 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

18 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% inguinal area 86% hand or arm 29% Bonten MJM. Lancet 1996; 348:1615

19 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

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 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

23 Chlorhexidine/Silver Sulfadiazine- Coated 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% < 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 O 2 are required. Blood and sputum cultures grow highly resistant Enterobacter cloacae.

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

28 Ventilator Associated Pneumonia GWUH 2009 Staphylococcus aureus, MRSA Proteus mirabilis, Serratia marcescens, Pseudomonas aeruginosa, Stenotrophomonas maltophilia

29 Nosocomial Pneumonia Episodes Mortality 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:

30 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?

31 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

32 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.

33 Patient 4

34 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

35 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

36 MRSA Isolates Pulse Field Gel Electrophoresis (PFGE)

37 MRSA Mechanism of Resistance chromosomal meca gene *altered PBP 2 or 2a in cell wall low affinity for all ß- lactam antibiotics

38 Hospital-acquired MRSA BSI 76% pneumonia 13% osteomyelitis 6% endocarditis 3% cellulitis 4% skin abscess/necrosis 1% mortality 2.5%

39 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

40 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 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

41 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.

42 HCW Blood/Body Fluid Exposure Risk 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

43 GWU Health Care Workers Percutaneous Exposures: 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%

44 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

45 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

46 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

47 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

48 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

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52 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

53 Isolation Contact Precautions transmitted via hands of personnel, inanimate surfaces MRSA, VRE, highly resistant GN rods private room gloves with patient contact handwashing

54 Michael Jackson Approach

55 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%

56 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%

57 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

58 Ignaz Semmelweis Decreased Mortality with Improved Hand Hygiene Chlorinated lime hand antisepsis Ignaz Semmelweis ( )