Nosocomial infection or Hospital acquired
infections is an infection acquired during
hospital care which are not present or
incubating at the time of admission.
Infection occurring more than 48 hours after
hospitalization are termed as hospital
They are major public health problem in
hospital through out the world
HAI are major cause of morbidity and
mortality in hospital.
Nosocomial infections not only involve
patients but also any one who come in
contact with hospital including staffs, visitors,
workers and volunteers.
Majority of HAI are clinically apparent during
hospitalization. However, the onset of
disease can be present after patient has been
It should not be confused with infection with
which patient has come to hospital for
treatment. They are community acquired,
unless they result from previous
They are the major cause of morbidity and
mortality among hospitalized patients and
are seen in both rich and poor countries.
A study done under WHO in 14 WHO regional
countries in 55 different hospital showed that
8.7% of hospitalized patient had nosocomial
infection. Highest frequency seen in East
Meditterian and South East Asian Countries
(11.8% and 10%)
Similarly the study done in Thailand
(2005),Albania (2007), and Tanzania (2003)
showed that the prevalence rate of HAI is 6-
According to Hospital Infection Society of
India, the incidence of HAI in India is 5-30%.
It has been found that because of HAI, the
patient occupy beds for an average of 15-20
days which results in increase in direct cost
and opportunity cost to patients.
Imbalance Between These Factors Leads to Disease Process
Agent Factor (Microorganisms)-Patients
are exposed to various microorganisms
during hospitalizations. Many different
Bacteria, virus, fungi and parasites cause HAI.
These infections can be endogenous or
exogenous. And some organisms may be
acquired from any substance/equipment
recently contaminated from another human
Large no. of HAI are due to gm—vet
Microorganisms like staphylococcus, e.coli,
salmonella, shigella, pseudomonas ,
kleibseilla are increasing in involvement and
are more cause of worry.
Host Factor(patient’s susceptibility) : It
includes patient’s age , immune status ,
underlying disease and different diagnostic
and therapeutic intervention which decrease
the host defense of patient.
Patient with chronic disease like leukemia,
malignant tumor, renal failure ,DM, AIDS are
at risk of infection with opportunistic
Other risk factor includes :
Immuno suppresive drugs
Patient with infection are potential source of
infection to other patients and staffs.
Crowded condition of hospital, frequent
transfer of patient and concentration of high
risk patient in one area ,contribute the
development of nosocomial infection.
In any epidemiological triad , the agent, host
and environment interacts and interplay, and
any imbalance between these factors lead to
The same phenomenon is applicable to
nosocomial infections also. where environment
plays as a fulcrum .
The balancing pore is within environment of the
The wide spread use of antimicrobials for
therapy and prophylaxis is major determinants
to the resistance.
Many strains of pneumococci,
staphyloococci,enterococci, TB are resistant to
antimirobials which were once not used to be
Critical problem in developing countries where
second line drugs are non-available or non-affordable.
1.Endogeneous infection – Bacteria from
normal flora cause infection because of
transmission outside to natural
habitat.eg.UTI,Damage to tissue cause
growth to c.difficle,yeast, Gm-ve patient
causing SSI in pt. with abdominal surgery and
pt. catheterized with UTI.
Exogenous Infection-Infections transmitted
through patient-patient or patient –staff or
staffs-patient through direct contact, air
droplets or during patient caring.
Also transmitted through contaminated
inanimate articles like
drinks,bed linen, hospital dust,equipment
Faulty design of ward, inadequate lightening,
Non avaibility of isolation ward
Non avaibility of separate dirty utility room
Crowding in hospital
Universal precaution not practiced well
Lack of inadequate hand washing
Poor hygiene practice of patients, staffs and visit
Poor housekeeping service ,dietary and waste
disposal service of hospital.