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Nosocomial outbreaks Agnes Hajdu EpiTrain III, 24.08.2006 Jurmala, Latvia.

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Presentation on theme: "Nosocomial outbreaks Agnes Hajdu EpiTrain III, 24.08.2006 Jurmala, Latvia."— Presentation transcript:

1 Nosocomial outbreaks Agnes Hajdu EpiTrain III, Jurmala, Latvia

2 Content Nosocomial infections Health care setting Antimicrobial resistance Nosocomial outbreaks –History –Characteristics –Outbreak database –Detection, Investigation An example: Dent-O-Sept Summary

3 Nosocomial infection …hospital-acquired infection, health-care associated infection… Infection acquired in the hospital due to exposure to the pathogen in the hospital Development of infection after 48 hours of hospital admission (CDC)

4 Burden of nosocomial infections Increased morbidity, mortality –10% of in-patients acquire an infection in the hospital Increased costs –Prolonged hospital stay, additional medical procedures and treatment 30% preventable

5 Health care setting Devices: endoscope, catheter, ventilator.. Medical procedures: surgery.. Medical personnel: doctors, nurses.. Patient: immunocompromised, susceptible maybe the source as carrier of pathogen Dangerous residents: MRSA, VRSA, VRE, ESBL*, C. difficile ribotype 027 *methicillin-/vancomycin-resistant S.aureus; vancomycin-resistant Enterococcus; extended spectrum beta-lactamases

6 Patients at risk Immunocompromised patient –Malignancy, immunosuppressive treatment, HIV infection Other factors –Severe underlying disease, age, obesity Intensive care units –Medical, surgical, neonatal, burn units

7 Antimicrobial resistance 1945 – Penicillin 1948 – Penicillin-resistant S.aureus 1959 – Methicillin 1961 – Methicillin-resistant S.aureus 1998 – Vancomycin-resistant S.aureus Use, overuse and wrong use of antibiotics Possible to reverse, but it takes time Knowledge Attitude Behaviour

8 What can be worse than a nosocomial infection? A Nosocomial Outbreak!!! An unusual increase in the number of nosocomial infections (time, place, person)

9 History of nosocomial outbreaks First well-documented outbreak –Puerperal (child-bed) fever in a hospital in Vienna, 1847 –Ignác Semmelweis, Hungarian physician gathered and analysed mortality data –Autopsy room Maternity wards –Handwashing intervention (chlorine solution) Modern epidemiology –S. aureus hospital outbreaks worldwide, 1950s –CDC projects from 1970s –Intensive research from 1990s

10 1847

11 2006

12 Nosocomial outbreaks - examples Unusual transmission –ESBL Klebsiella pneunomiae – Maternity wards, contaminated ultrasonography gel (France, 1993) Rare pathogen –Malassezia pachydermatis – Neonatal ICU, associated with colonization of health care workers pet dogs (US, 1995) Emergence of more virulent strain –C. difficile ribotype 027 – Increased severity of diarrhoea, recent outbreaks in US, Canada, Netherlands, England

13 Nosocomial outbreak database Database providing information to facilitate interventions A learning tool –What kind of data to collect? Control selection? Search by pathogen, ward type etc. Osaka University, Japan


15 Characteristics of nosocomial outbreaks Location Type of infection Pathogens Source Mode of transmission Preventive/control measures Gastmeier et al. How Outbreaks Can Contribute to Prevention of Nosocomial Infections: Analysis of 1022 Outbreaks. Infection Control and Hospital Epidemiology; (4);

16 Location Hospital – 83% –50% in intensive care units Outpatient care – 12% Nursing home – 5% Special problems: –Hospital staff with part-time job in nursing homes (transmissing pathogens in both ways) –Nursing home: no infection control personnel, underreporting of outbreaks, gastroenteritis, scabies Gastmeier et al.

17 Type of infections Bloodstream – 37% Gastrointestinal* – 29% Pneumonia – 23% Urinary tract – 14% Surgical site – 12% Other lower respiratory – 10% Central nervous system – 8% Skin and soft tissue – 7% * Probable underreporting Gastmeier et al.

18 Most frequently reported pathogens* Nosocomial infections Staphylococcus aureus Enterococci E. coli Pseudomonas aeruginosa Streptococci Enterobacter spp. Nosocomial outbreaks Staphylococcus aureus Pseudomonas aeruginosa Klebsiella pneumoniae Serratia marcescens Hepatitis B, C virus Legionella pneumophila *Probable underreporting: Salmonella spp., Campylobacter spp., norovirus, rotavirus, respiratory viral infections Gastmeier et al.

19 Nosocomial outbreaks in Norway, 2005 Internet-based outbreak reporting system 47 outbreaks reported from hospitals with 622 cases OutbreaksNo. of cases Norovirus25463 MRSA1141 Gastroenteritis561 Listeria26 Influenza122 Other329 Grahek-Ogden et al. Varsler om mistenkte utbrudd av smittsomme sykdommer I Norge I MSIS rapport 2006;34:22 (in Norwegian)

20 Source of outbreak Patient – 26% Medical equipment / device – 12% Environment – 12% Medical personnel – 11% Contaminated drug – 4% Contaminated food – 3% Care equipment – 3% Unclear source – 37% Gastmeier et al.

21 Mode of transmission Contact – 45% Invasive technique – 16% Inhalation – 15% (droplet, airborne) Ingestion – 4% Unclear mode of transmission – 28% Gastmeier et al.

22 Managing hospital outbreaks Patient, health personnel screening, surveillance Isolation, cohorting Handwashing, hand disinfection Sterilisation, disinfection (Change) antibiotic therapy Modification of care / equipment Protective clothing Restriction of work load Vaccination Gastmeier et al.

23 CDC guidelines Standard Precautions Contact / Droplet / Airborne Precautions standard.html

24 Detection of nosocomial outbreaks Alert from an effective surveillance system Alert from – the physician – the nurse – the hospital microbiologist – the hospital epidemiologist

25 Nosocomial transmission? Similar cases at one department / among similar patients Cases associated with invasive device Health personnel and patients with same infection Nosocomial pathogen


27 Problems with detecting outbreaks No detection –2-3 patients with pneumonia in intensive care unit Detection No investigation –Nursing homes Detection Investigation No reporting –If sanctions against reporting doctors, nurses False detection: pseudo-epidemics (artefacts) –E.g. consequent laboratory contamination –May lead to unnecessary antibiotic treatment

28 A method for early detection Reports from antibiotic susceptibility tests from each medical ward (at least 85% culturing proportion) Baseline data: frequency of each pathogen isolated from specimens over a 26-week observation period Threshold: –I solates ranked from the lowest to highest –Divide the distribution into quintiles (fifths), and set the cut-off between the 4th and 5th quintile –The number of isolates represented by the 22nd week item becomes the threshold value 80% (4/5)

29 Proteus mirabilis isolates Threshold (80%) Baseline data

30 Evaluation of the method Early warning mechanism for potential outbreaks Either unusual and common pathogens Minimum effort and time Hospitals with limited infection control personnel Establishing endemic nosocomial infection rates Sensitive if organisms are routinely tested Epidemics involving several locations might go undetected Epidemics with prolonged incubation might go undetected

31 Investigation of nosocomial outbreaks Asset –Diagnosis can usually be made rapidly –Direct access to medical care, laboratory –Patients records are available –Easy cohorting of the cases Disadvantage –Multidrug-resistent pathogens –Complex environment –Intra – interhospital transfer –Temporary staff, working in shifts Steps of an outbreak investigation..

32 Case ascertainment The investigation is dependent on clearly defined case definitions and case ascertainment strategies Molecular diagnostics –PFGE, PCR.. – Demonstrating clonality among epidemic isolates Combinative approach –Epidemiological study –Genetic typing method

33 Steps of an outbreak investigation Have an outbreak control plan Confirm outbreak diagnosis Define a case Identify cases and obtain information Descriptive data collection and analysis Develop hypothesis Analytical studies to test hypothesis Communication (outbreak report) Control measures


35 A Norwegian example: Dent-O-Sept Antiseptic non-sterile single-use swab for mouth hygiene Largest Pseudomonas outbreak ever recorded in Norway 231 confirmed cases, 34 deaths Genotypically identical strains in production plant, swabs and patients

36 Alert to NIPH Late February 2002 Notification from the infection control personnel (not quantified by lab statistics) Impression of possible increase in the number of pseudomonas infections in clinical wards of Norwegian hospitals (ICU) outbreak investigation

37 Outbreak investigation Objectives: –Describe the outbreak –Identify the cause –Make recommendations for future prevention Outbreak Control Team: –Members from NIPH and the hospitals

38 Initial investigation March 2002: identical outbreak strain is shown in patients in 3 different hospitals No national surveillance system for P. aeruginosa in Norway Inquiry for increased awareness in regional centers for infection control Patient interviews/case notes with trawling questionnaires in the affected hospitals (common exposure?) Suspect: fluids and moist products samples

39 Environmental investigation April 2002: laboratory identifies genotypically identical strains of P. aeruginosa in swabs control measures: information to the producer, hospitals, authorities and the public, product recalled, production ceased Hospitals were asked to report which batches of the product they had in store samples Inspection and sampling at the production plant –Outbreak strain found in packing machine spraying moisturizing liquid into the bags –Violation of regulations (no documented quality assurance system with microbiological testing..)

40 Case finding and descriptive study Norway: routine storage of all clinical bacterial isolates from blood and cerebrospinal fluid Isolates of P. aeruginosa from to reference labs for genotyping (PFGE) For patients with P.aeruginosa (outbreak strain or other) questionnaire: –Demographic and clinical data

41 Descriptive results 231 patients with outbreak stain from 27 health care institutions –Median age: 65 yrs, 61% men –87 pneumonia, 42 sepsis, 70 colonization –31% died (all had severe underlying disease) –31% had not or probably not used the swab

42 Dent-O-Sept outbreak – epidemic curve

43 Analytical study 1. Case-control study Case definition: person with the outbreak strain isolated from blood or CSF during Oct 2001-Dec 2002 Control definition: person with another strain of P. aeruginosa isolated from blood or CSF in the same period To identify risk factors for having the outbreak strain

44 Results – CC study Risk factor OR (95% CI) P-value Use of Dent-O- Sept swab 5.3 (2.0-14) Been on ventilator 6.4 (2.3-17) <0.001 Patients with the outbreak strain were more likely to be on ventilator / use the swab

45 Analytical study 2. Cohort study Including all patients in the CC study To identify risk factors for a fatal outcome during hospital stay for patients with invasive pseudomonas infection

46 Results – Cohort study Risk factors for dying RR (95% CI) Use of Dent-O-Sept 2.2 ( ) Patients with fatal outcome were more likely to be exposed to the swab Confounding? (severely ill patients –> mouth swab instead of tooth brush)

47 Lessons learned Direct transmission from swabs and indirect transmission through health personnel and contaminated environment Need to strengthen infection control routines and standard precautions –E.g. for patient with severe underlying disease should only use sterile products Adherence to regulations in production of medical equipment

48 Oakland Daily Evening Tribune, 06 Nov 1939

49 Media The outbreak may cause serious damage to the hospitals reputation Tool for education: message –Public: antibiotics = anti-cold drugs –Professionals: every hospital need a plan for antibiotic use Increased awareness: time to evaluate routines, existing guidelines (local/national/international level)

50 Summary Detection –Effective surveillance system, vigilant hospital personnel Investigation –Skilled hospital infection control practicioner, epidemiologist, microbiologist Prevention / Control –Appropriate infection control practices –Strategies to prevent and control antimicrobial- resistent pathogens (antibiotic-plan)

51 The ultimate goal: patient safety

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