EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS (NCIs) PART-1

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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_at_yahoo.com
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DEFINITION

• Nosocomial infection is an infection that is not
  present or incubating when a patient is admitted
  to a hospital

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LEARNING OBJECTIVES

• LEARNER SHOULD LEARN
• PUBLIC HEALTH IMPACT OF HOSPITAL ACQUIRED
  INFECTIONS.
• EPIDEMIOLOGY, PREVENTION, SURVEILLANCE AND
  CONTROL STRATEGIES
• INDIAN SITUATION OF THE PROBLEM

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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.

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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

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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)

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EPIDEMIOLOGICAL INTERACTION
Intrinsic host susceptibility Age, Poor
nutritional status, Co morbidity, severity of
underlying disease
Environmental factors hospital location,
diagn procedures,
immunosuppressive, chemotherapy, antibiotics, med
surgical devices, exposure to infected patients
or health workers, asymptomatic carriers


Agent factors
varieties of organisms Institutional and human
Reservoirs their virulence
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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

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• INDIAN SCENARIO

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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.

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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

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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.

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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

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INCIDENCE

• Depends upon
• Average level of patient risk depends upon
  intrinsic host factors and extrinsic
  environment factors
• Sensitivity specificity of surveillance
  programmes

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AGE RANKS OF NCIs

Ranks in children 1) SKIN 2)
LRI 3) BSI 4) UTI 5) SWI
Ranks in adults 1) UTI 2) LRI 3) SWI 4) BSI
Ranks in infants 1) SKIN 2) LRI 3) BSI 4) UTI 5)
SWI
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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 URILRI far exceeds that caused
  by bacterial ones.

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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

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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

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COMMON BACTERIAL AGENTS
(9)
(10)
(11)
(12)
(13)
(45)
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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

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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.

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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)

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VIRUSES

• CMV, HERPES SIMPLEX
• V-Z VIRUSES
• HEPATITIS VIRUSES- A, B ,C
• HIV
• INFLUENZA, PARA INFLUENZA, R.S.VIRUS, ROTAVIRUS

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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.

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PLACE DISTRIBUTIONICU RISK

• PROLONGED ICU STAY
• MECHANICAL VENTILATION
• TRAUMA
• URINARY CATHETER,VASCULAR CATHETER
• STRESS ULCER PROPHYLAXIS

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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

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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
• THRO COMMON VEHICE like Food, Blood blood
  products, Diagnostic reagents, Medications
• AIRBORNE e.g. legionellosis, aspergillosis
• VECTORBORNE by flies

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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

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BACTERIURIA (BU)

• PERIURETHRAL COLONIZATION WITH POTENTIAL
  PATHOGENS INCREASES BU BY THREE FOLD
• LATE CATHETERIZATION INCREASES BU

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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)

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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

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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

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SURGICAL WOUND INFECTIONS (SWI)

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

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EPIDEMIOLOGY OF SWI

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

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SOURCES OF INFECTION

1. DIRECT INOCULATION FROM PATIENTS FLORA
2. CONTAMINATED HOST TISSUES
3. HANDS OF SURGEONS
4. AIRBORNE TRANSMISSION
5. POST- OPERATIVE DRAINS/CATHETERS

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LOWER RESPIRATORY INFECTIONS (LRI)

• MOSTLY SEEN IN ICU
• RISK FACTORS
• TRACHEOSTOMY,
• ENDOTRACHEAL INTUBATION, VENTILATOR,
• CONTAMINATED AEROSOLS, BAD EQIPPMENT,
• CONDENSATE IN VENTILATOR TUBING,
• ANTIBIOTICS,
• SURGERY,
• OLD AGE ,
• COPD,
• IMMUNO SUPPRESSION

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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

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COHORT STUDY

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

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RISK FACTORS FOR DIARRHEAS

• BY CLOSTRIDIUM DIFFICILE
• OLD AGE
• SEVERE UNDERLYING DISEASE
• HOSPITALISATION FOR gt1 WEEK
• LONG STAY IN ICU
• PRIOR ANTIBIOTICS

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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

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BACTEREMIA (BSI)

• BSI ARE INCREASING PRIMARILY DUE TO INCREASE
  IN INFECTIONS WITH GMVE BACTERIA FUNGI
• MOST COMMON IN NEONATES IN HIGH RISK NURSERIES
• MORTALITY RATE FOR NOSOCOMIAL BACTEREMIA IS
  HIGHER THAN FOR COMMUNITY ACQUIRED BACTEREMIA

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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 gt72 HOURS