EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS

					EPIDEMIOLOGY OF NOSOCOMIAL
   INFECTIONS (NCIs) PART-1


          Dr. A.K.AVASARALA MBBS, M.D.
          PROFESSOR & HEAD
          DEPT OF COMMUNITY MEDICINE &
          EPIDEMIOLOGY
          PRATHIMA INSTITUTE OF MEDICAL
          SCIENCES, KARIMNAGAR, A.P..
          INDIA: +91505417
          avasarala@yahoo.com
    DEFINITION
• Nosocomial infection is
  an infection that is not
  present or incubating
  when a patient is
  admitted to a hospital
  LEARNING OBJECTIVES
    LEARNER SHOULD LEARN

1. PUBLIC HEALTH IMPACT OF
   HOSPITAL ACQUIRED INFECTIONS.
2. EPIDEMIOLOGY, PREVENTION,
   SURVEILLANCE AND CONTROL
   STRATEGIES
3. INDIAN SITUATION OF THE
   PROBLEM
   PERFORMANCE OBJECTIVES
  LEARNER SHOULD BE ABLE TO
1. Estimate the extent and nature of nosocomial
  infections in his hospital
2. Identify the changes in the incidence of
  nosocomial infections and the pathogens that
  cause them.
3. Provide his hospital with comparative data on
  nosocomial infection rates.
4. Develop efficient and effective data collection,
  management and analysis methods for his
  hospital.
5. Conduct collaborative research studies on
  nosocomial infections in his hospital.
   TYPES BY ORIGIN
1.Endogenous:
 Caused by the organisms that are
 present as part of normal flora of
 the patient
2. Exogenous:
 caused by organisms acquiring by
 exposure to hospital personnel,
 medical devices or hospital
 environment
   TYPES OF NCI BY SITE

1. Urinary tract infections (UTI)
2. Surgical wound infections
   (SWI)
3. Lower respiratory infections
   (LRI)
4. Blood stream infections (BSI)
EPIDEMIOLOGICAL INTERACTION
                          Intrinsic host susceptibility
                          Age, Poor nutritional status,
                          Co morbidity, severity of
                          underlying disease



                          Environmental factors
                          hospital location,
                          diagn procedures,
Agent factors
                          immunosuppressive,
varieties of organisms
                          chemotherapy, antibiotics,
Institutional and human   med & surgical devices,
                          exposure to infected patients
Reservoirs & their
                          or health workers,
virulence
                          asymptomatic carriers
      DISEASE BURDEN
• 5-10% in developed countries
• 10-30% IN DEVELOPING COUNTRIES
• Rates vary between countries, within
  the country, within the districts and
  sometimes even within the hospital
  itself, due to
          1) complex mix of the patients
          2) aggressive treatment
          3) local practices
INDIAN SCENARIO
   HOSPITAL INFECTION
   SOCIETY (HIS), INDIA
• Ten to 30 per cent of patients
  admitted to hospitals and
  nursing homes in India, acquire
  nosocomial infection as against
  an impressive five per cent in
  the West, according to member
  of HIS, Rita Dutta – Mumbai.
  HINDUJA, HOSPITAL
Dr F D Dastur, Director, Medical
education, P D Hinduja, Hospital:

“nosocomial control programme is at
a nascent stage in Indian hospitals,
with some yet to establish a central
sterilization and supply department
(CSSD) and appoint an infection
control nurse”
ASIAN HEART INSTITUTE (AHI)

Dr Vijay D Silva, director, critical care,
 Asian Heart Institute (AHI):

“Suggestions to strengthen the
 infection control programme is turned
 down by the management of most
 hospitals as spending on infection
 control does not generate revenue.”
         INCIDENCE
• Average Incidence - 5% to 10%, but
  maybe up to 28% in ICU
• Urinary Tract Infection - usually
  catheter related -28%
• Surgical Site Infection or wound
  infection -19%
• Pneumonia -17%
• Blood Stream infection - 7% to 16%
       INCIDENCE
• Depends upon
1. Average level of patient risk
   depends upon intrinsic host
   factors and extrinsic
   environment factors
2. Sensitivity &specificity of
   surveillance programmes
   AGE RANKS OF NCIs
Ranks in   Ranks in   Ranks in
infants    children   adults

1) SKIN    1) SKIN    1) UTI
2) LRI     2) LRI     2) LRI
3) BSI     3) BSI     3) SWI
4) UTI     4) UTI     4) BSI
5) SWI     5) SWI
   PEDIATRIC INFECTIONS
• Epidemiology is Unique
• Rates of infection by site and
  pathogen differ from those reported
  in adults
• Pathogen distribution is also
  different – S. aureus in children and
  E. Coli in adults
• Pediatric viral URI&LRI far exceeds
  that caused by bacterial ones.
    CONSEQUENCES OF
  NOSOCOMIAL INFECTIONS
1. Prolongation of hospital stay:
   Varies by site, greatest with
    pneumonias and wound infections
2. Additional morbidity
3. Mortality increases - in order - LRI, BSI,
    UTI
4. Long-term physical &neurological
    consequences
5. Direct patient costs increased-
  Escalation of the cost of care
     ECONOMICS OF NCIS
• Extra cost of NCI consequences
• Bed,
• Intensive care unit stay,
• Hematological, biochemical,
  microbiological and radiological tests,
• Antibiotics & other drugs,
• Extra surgical procedures
• Working hours
COMMON BACTERIAL
    AGENTS

                        (9%)

                      (10%)



                      (11%)

                 (12%)


                (13%)

              (45%)
KASTURBA MEDICAL COLLEGE, MANGALORE
• Drug resistance was more common with
  MRSA nosocomial strains.
• All MRSA strains were resistant to penicillin
  and sensitive (73.8 percent), ciprofloxacin
  (78.6 percent) gentamicin (84.7 percent) and
  trimethoprim-sulphamethoxazole (95.7
  percent).
• Bhat KG; Bhat MV
• Department of Microbiology, Kasturba Medical
  College, Light House Hill Road, Mangalore -
  575001, India
• Prevalence of nosocomial infections due to
  methicillin resistant staphylococcus aureus in
  Mangalore, India
• Biomedicine. 1997; 17(1): 17-20
  CHRISTIAN MEDICAL COLLEGE,
           VELLORE

• Says Dr J Kang, professor of
  microbiology at CMC:
 “ While MRSA is the troublemaker in
  most cases, at Vellore nosocomial
  infection due to MRSA is only five per
  cent because of genotyping.”
                 FUNGI
• Due to increased antibiotic use &host
  susceptibility
• Candida species– most common, causing
  BSI (38% mortality)
• Changing bacterial & fungal spectrum in
  the hospital reflects the increased use,
  particularly of the newer antibiotics
• Development of resistance (MRSA, VRE,
  MDRTB)
• Overcrowding & understaffing of nursing
  units increased the rates of infections
  (MRSA colonization)
           VIRUSES

•   CMV, HERPES SIMPLEX
•   V-Z VIRUSES
•   HEPATITIS VIRUSES- A, B ,C
•   HIV
•   INFLUENZA, PARA INFLUENZA,
    R.S.VIRUS, ROTAVIRUS
 EPIDEMIOLOGY OF VIRAL
      INFECTIONS
• Mostly affects Resp &
  Gastrointestinal tracts (90%)
  whereas bacterial infections attack
  these systems to about 15% only.
• Pediatric viral URI & LRI far
  exceeds that caused by bacterial
  ones.
    PLACE DISTRIBUTION
         ICU RISK

• PROLONGED ICU STAY
• MECHANICAL VENTILATION
• TRAUMA
• URINARY CATHETER,VASCULAR
  CATHETER
• STRESS ULCER PROPHYLAXIS
           RISK FACTORS
•   Malnutrition
•    Sex (females with UTI)
•   Extremes of age
•   Infections at remote site
•   Use of antibiotics, H2 blockers,
    sedatives
•   Diabetes, Renal Failure and causes of
    immunosuppression
•   Altered mental status
•   Surgery
•   ICU setting, endotracheal intubation
    with mechanical ventilation
    MODES OF TRANSMISSION
•   BY CONTACT
•  1) Direct - between Patients and between
      patient care personnel
   2) Indirect - contaminated inanimate objects
      in environment (Endoscopes etc)
   3) Droplet infections by large aerosols
B) THRO COMMON VEHICE like Food, Blood &
   blood products, Diagnostic reagents,
   Medications
C) AIRBORNE e.g. legionellosis, aspergillosis
D) VECTORBORNE – by flies
               UTI

• Contribute to one third of NCI s
• 80% due to catheter
• 5-10% due to urinary tract
  manipulation
• Prolongs hospital stay by 1-2 days
    BACTERIURIA (BU)

• PERIURETHRAL COLONIZATION
  WITH POTENTIAL PATHOGENS
  INCREASES BU BY THREE FOLD

• LATE CATHETERIZATION
  INCREASES BU
     RISK FACTORS FOR BU
• DURATION OF CATHETRIZATION

• MICROBIAL COLONIZATION

• NO PRIOR ANTIBIOTIC USE

• FEMALE GENDER

• DIABETES MELITUS

• ABNORMAL SERUM CREATININE

• FAILURE TO USE URINOMETER (DRIP CHAMBER)
       CATHETER & UTI
• Presence of catheter leads to
  increased incidence of Bacteriuria
• Short term catheter use (urinary
  output measurement, surgery )
  increase BU by 15%
  Long term catheter use (retention,
  obstruction, incontinence) increases
  BU by 90%
CATHETER USE COMPLICATIONS

• MORE SEEN IN MEN (BACTEREMIA DUE
  TO UTI 15%)
• SHORT TERM USE - EVERS,
  SYMPTOMATIC UTI, BACTEREMIA
• LONG TERM CATHETER USE - ABOVE +
  CATHETER OBSTRUCTION, URINARY
  STONES, PERIURINARY INFECTIONS,
  RENAL FAILURE, BLADDER CANCER
SURGICAL WOUND INFECTIONS
          (SWI)

 Incidence varies from 1.5 to 13 per
   100 operations.
• It can be classified as
1. Superficial incisional SWI
2. Deep incisional SWI and
3. Organ/Space SWI.
    EPIDEMIOLOGY OF SWI

• HOST FACTORS
• OLD AGE
• OBESITY
• CURRENT INFECTION AT ANOTHER
  SITE
• PROLONGED POST OPERATIVE
  HOSPITALIZATION
SOURCES OF INFECTION

1. DIRECT INOCULATION FROM
   PATIENT’S FLORA
2. CONTAMINATED HOST TISSUES
3. HANDS OF SURGEONS
4. AIRBORNE TRANSMISSION
5. POST- OPERATIVE
   DRAINS/CATHETERS
     LOWER RESPIRATORY INFECTIONS
                              (LRI)
MOSTLY SEEN IN ICU
RISK FACTORS
1.   TRACHEOSTOMY,
2.   ENDOTRACHEAL INTUBATION, VENTILATOR,
3.   CONTAMINATED AEROSOLS, BAD EQIPPMENT,
4.   CONDENSATE IN VENTILATOR TUBING,
5.    ANTIBIOTICS,
6.   SURGERY,
7.   OLD AGE ,
8.    COPD,
9.   IMMUNO SUPPRESSION
   LOGISTIC REGRESSION OF
   CONTRIBUTING FACTORS
• TIME FROM ADMISSION TO PNEUMONIA
  +++++++
• PROLONGED HOSPITAL STAY +++++
• NASOGASTRIC INTUBATION +++
• AGE ++
• PRIOR USE OF MECHANICAL
  VENTILATORS++
• POST TRACHEOSTOMY STATUS++
• IMMUNOSSUPPRESSION OR
  LEUKOPENIA++
• NEOPLASTIC DISEASE +
      COHORT STUDY

• ON PNEUMONIA PATIENTS WITH
  VENTILATORS
• ATTRIBUTABLE RISK 27%
• DEATH RISK 2%
• LRI IS DIRECTLY RELATED TO THE
  LENGTH OF STAY
        RISK FACTORS FOR
           DIARRHEAS

•    BY CLOSTRIDIUM DIFFICILE
1.   OLD AGE
2.   SEVERE UNDERLYING DISEASE
3.   HOSPITALISATION FOR >1 WEEK
4.   LONG STAY IN ICU
5.   PRIOR ANTIBIOTICS
BLOOD STREAM INFECTIONS
         (BSI)
• PRIMARY = ISOLATION OF BACTERIAL
  BLOOD PATHOGEN IN THE ABSENCE OF
  INFECTION AT ANOTHER SITE

• SECONDARY = WHEN BACTERIA ARE
  ISOLATED FROM THE BLOOD DURING
  AN INFECTION WITH THE SAME
  ORGANISM AT ANOTHER SITE i.e. UTI,
  SWI OR LRI
      BACTEREMIA (BSI)
BSI ARE INCREASING PRIMARILY DUE TO
INCREASE IN INFECTIONS WITH GM+VE
BACTERIA & FUNGI

MOST COMMON IN NEONATES IN HIGH
RISK NURSERIES

MORTALITY RATE FOR NOSOCOMIAL
BACTEREMIA IS HIGHER THAN FOR
COMMUNITY ACQUIRED BACTEREMIA
        SOURCES OF BSI
• IV CATHETERS, INTRINSIC IV FLUID
  CONTAMINATION
• MULTIDOSE PARENTERAL MEDICATION
  VIALS
• VASCULAR CATHETER RELATED
  INFECTIONS, CONTAMINATED
  ANTISEPTICS, CONTAMINATED HANDS OF
  HEALTH CARE WORKERS
• AUTOINFECTION FOLLOWING
  HEMATOGENOUS SEEDLING - RISK
  INCREASES WITH LONGER DURATION >72
  HOURS

				
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