EPIDEMIOLOGY OF NOSOCOMIAL INFECTIONS (NCIs) PART-1

Dr. A.K.AVASARALA MBBS, M.D.PROFESSOR & HEADDEPT OF COMMUNITY MEDICINE & EPIDEMIOLOGYPRATHIMA INSTITUTE OF MEDICAL SCIENCES, KARIMNAGAR, A.P..INDIA: +91505417avasarala@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

• PUBLIC HEALTH IMPACT OF HOSPITAL ACQUIRED INFECTIONS.

• EPIDEMIOLOGY, PREVENTION, SURVEILLANCE AND CONTROL STRATEGIES

• 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 INTERACTIONIntrinsic host susceptibility Age, Poor nutritional status, Co morbidity, severity of underlying disease

Agent factors varieties of organisms

Institutional and human

Reservoirs & their virulence

Environmental factors hospital location, diagn procedures, immunosuppressive, chemotherapy, antibiotics, med & surgical devices, exposure to infected patients or health workers, 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

1. Depends upon

2. Average level of patient risk depends upon intrinsic host factors and extrinsic environment factors

3. Sensitivity &specificity of surveillance programmes

AGE RANKS OF NCIs

Ranks in children

1) SKIN 2) LRI3) BSI4) UTI5) SWI

Ranks in adults

1) UTI2) LRI3) SWI4) BSI

Ranks in infants

1) SKIN2) LRI3) BSI4) UTI5) 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 infections2. Additional morbidity3. Mortality increases - in order - LRI, BSI,

UTI4. Long-term physical &neurological

consequences5. 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

Pseudomonasaeruginosa

Enterococcus

Coag-neg staphylococcl

E-coli

Staphylococcus aureus

Other

(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 DISTRIBUTIONICU 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.

1. It can be classified as

2. Superficial incisional SWI

3. Deep incisional SWI and

4. 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

1. BY CLOSTRIDIUM DIFFICILE

2. OLD AGE

3. SEVERE UNDERLYING DISEASE

4. HOSPITALISATION FOR >1 WEEK

5. LONG STAY IN ICU

6. 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