|Review Article (Open access)|
Int. J. Life. Sci. Scienti. Res., 4(4): 1858-1862, July 2018
Hospital Acquired Infections, Sources, Route of Transmission, Epidemiology, Prevention and Control
Taiyaba1*, Anurag Rai2, Farhat Tahira3
1Department of Microbiology, G.C.R.G Institute of Medical Sciences and Hospital Lucknow, India
2Department of Microbiology, Prasad Institute of Medical Sciences and Hospital Lucknow, India
3Department of Microbiology, Saraswati Medical College Unnao, India
*Address for Correspondence: Ms. Taiyaba, Tutor, Department of Microbiology, G.C.R.G Institute of Medical Sciences and Hospital Lucknow, India
ABSTRACT- Nosocomial infections are infections acquired in hospital or healthcare service unit that first appear 48 hours or more after hospital admission or within 30 days after discharge following in-patient care. The main routes of transmission of nosocomial infections are contact, airborne, common vehicle and vector borne. Common infections are urinary tract infections (UTI), surgical and soft tissue infections, gastroenteritis, meningitis and respiratory infections. The agents that are usually involved in hospital acquired infections are Streptococcus sp., Acinetobacter sp., Enterococci, Pseudomonas aeruginosa, Coagulase negative Staphylococci, Staphylococcus aureus, Bacillus cereus, Legionella and Enterobacteriaceae family members including Proteus mirablis, Klebsiella pneumonia, Escherichia coli, Serratia marcescens. Out of these Enterococci, P. aeruginosa, S. aureus and E. coli have a major role. Various infection control programmes and organizations help to lower the risk of an infection during and after the period of hospitalization.
Keywords- Urinary tract infections, Hospital Acquired Infections, Route of Transmission, Epidemiology, Prevention and Control
INTRODUCTION- According to the World Health Organization a Hospital-Acquired Infection is, “an infection acquired in hospital by a patient who was admitted for a reason other than that infection .” In other words nosocomial infections are those infections which are acquired in hospital or healthcare service unit that first appear 48 hours or more after hospital admission or within 30 days after discharge following in-patient care .‘Nosocomial’ or ‘healthcare associated infections’ (HCAI) can occur during healthcare delivery for other diseases and even after the discharge of the patients. They also comprise of occupational infections among the medical staff .
The situations in which infections are not believed as nosocomial are:
Increasing nosocomial infections have led to an increased antimicrobial resistance, increase in socio-economic disturbance, and increased mortality rate . The various aspects of nosocomial infections are the route of transmission, site of infections, common nosocomial bacterial agents, selected antibiotic-resistant pathogens along with their modes of transmission and control measures.
Routes of Transmission- The main routes of transmission include contact, airborne, common vehicle and vector borne .
Contact route-Direct Contact: It requires physical contact between the infectious individual or contaminated object and the susceptible host.
Indirect contact: This requires mechanical transfer of pathogens between patients through a health care worker or a medical kit.
Air borne route- Airborne transmission occurs by dissemination of airborne droplet nuclei (small particle) . Microorganisms inhaled by a susceptible host within the same room or over a long distance from the source patient depending on environmental factors. Examples include Mycobacterium tuberculosis, Legionella, and the Rubella and Varicella viruses.
Droplet route- Droplet particles, produced by coughing, sneezing and even talking, can settle either on surrounding surfaces or on the body mucosa which can be transferred to others. Examples include meningitis and pneumonia.
Common vehicle transmission- It applies to microorganisms transmitted to the host by contaminated items such as food, water, medications, devices and equipments.
Vector borne transmission- Vector-borne diseases are infections transmitted by the bite of infected arthropod species, such as mosquitoes, ticks, triatomine bugs, sandflies, and blackflies.
Types of Nosocomial Infections- National Healthcare Safety Network with Center for Disease Control (CDC) for surveillance has classified nosocomial infection sites into 13 types, with 50 infection sites, which are specific on the basis of biological and clinical criteria. The sites which are common include urinary tract infections (UTI), surgical and soft tissue infections, gastroenteritis, meningitis and respiratory infections .
Agents of Nosocomial infections- Bacteria are responsible for about ninety percent infections. Protozoans, fungi, viruses and mycobacteria are less contributing compared to bacterial infection . The agents that are usually involved in hospital acquired infections include Streptococcus sp., Acinetobacter sp., Enterococci, Pseudomonas aeruginosa, Coagulase Negative Staphylococci, Staphylococcus aureus, Bacillus cereus, Legionella and Enterobacteriaceae family members including Proteus mirablis, Klebsiella pneumonia, Escherichia coli, Serratia marcescens. Out of these Enterococci, P. aeruginosa, S. aureus and E. coli play a major role . UTIs are usually caused by E. coli, while it is uncommon in other infection sites. Contrarily, S. aureus is frequent at other body sites and rarely causes UTI. Coagulase-Negative S. aureus is the main causative agent in blood borne infections. Surgical-site infections contain Enterococcus sp. which is less prevalent in respiratory tract. One tenth of all infections are caused by P. aeruginosa, which is evenly distributed to the entire body sites . Nosocomial infections are being elevated by excessive and improper use of broad-spectrum antibiotics especially in healthcare settings. Penicillin-resistant pneumococci, multi-drug-resistant tuberculosis, methicillin-resistant S. aureus (MRSA), vancomycin-resistant S. aureus (VRSA) are common examples of drug-resistant bacteria. The distribution of bacteria in nosocomial infections is changing over periods of time. For example, Proteus sp., Klebsiella sp. and Escherichia sp. were responsible for nosocomial infections in the 1960s, but from 1975 to 1980s, Acinetobacter sp. with P. aeruginosa created clinical difficulties . Lately, streptococci along with coagulase-negative staphylococci and coagulase-positive staphylococci reemerged and incidence level of K. pneumonia and E. coli declined from 7% to 5% and 23% to 16%, respectively .
S. aureus, out of many species of Staphylococcus genusis is considered one of the most important pathogens, responsible for nosocomial infections .
E. coli is an emerging nosocomial pathogen causing problems in health care settings. E. coli is responsible for a number of diseases including UTI, septicemia, pneumonia, neonatal meningitis, peritonitis and gastroenteritis [15,16]. The second leading cause of hospital acquired infections worldwide is Enterococci . Three to seven percent of hospital-acquired bacterial infections are related to K. pneumonia, which is the eighth significant pathogen in healthcare settings. It gets involved in diseases such as neonatal septicaemia, pneumonia, wound infections and septicemia  P. aeruginosa contributes to 11% of all nosocomial infections, which result in high mortality and morbidity rates. It is a cause of surgical and wound infections, UTI, pneumonia, cystic fibrosis and bacteremia . C. difficile is an important nosocomial pathogen which mainly causes diarrhea .
High-risk situations for acquiring hospital-acquired infections- Numerous risk factors are there which predispose a host to acquire HAIs which include low body resistance as in infancy and old age, serious underlying illnesses, major surgeries , immune deficiency states  and prolonged hospital stay .Various areas are there in the hospital which carry a greater risk of patients acquiring HAI’s [24,25]. These include intensive care unit, dialysis unit, organ transplant unit, burns unit, operation theatres, delivery rooms, post-operative wards.
Prevention of Nosocomial Infections- Various measures that should be taken for prevention of Nosocomial infections are:
Routine cleaning and precautionary measures in most hospitals, effective environmental decontamination methods are still in demand. Disinfectants are commonly used to minimize the risk of Methicillin-resistant Staphylococcus aureus (MRSA) . Resistance to Methicillin is documented in 8 (50%) of 16 Staphylococcus isolates .
Hospital Infection Control Programme- In the 1960s infection prevention and control programmes were initially implemented in hospitals in the US. The main aim of the infection control programme is to lower the risk of an infection during the period of hospitalization .
Infection Control Organizations
Infection Control Committee (ICC) - Representatives of medical, nursing,, pharmacy, CSSD and Microbiology departments are the members of the ICC. The committee formulates the policies for the prevention and control of infection . The role of the Infection Control Committee is very multi-faceted. It should be involved in planning, monitoring, evaluating, updating and educating.
Infection Control Team (ICT)- Infection Control Team is responsible for establishing infection control policies and procedures, providing advice and guidance regarding infection control matters, regular audits and surveillance, identification and investigation of outbreaks, awareness and education of staff.
Infection Control Officer (ICO)- Secretary of Infection Control Committee are responsible for recording minutes and arranging meetings. When notified of an exposure incident, the infection control officer should ensure that notification, verification, treatment and medical follow-up occur.
Infection Control Nurse (ICN)- To cooperate between microbiology department and clinical departments for detection and control of HAI. ICN works in close assistance with the ICO on surveillance of infection and detection of outbreaks of infection. ICN also increases the awareness among patients and visitors about infection control and various measures that needs to be taken.
CONCLUSIONS- Increasing nosocomial infections have led to an increased antimicrobial resistance, increase in socio-economic disturbance, and increased mortality rate Nosocomial infections are uncontrollable even in this age of advanced antibiotics. Measures must be taken at the Hospitals to come up with an in-house awareness programme where staff members, patients and their relatives can be educated and well equiped on maintaining hygiene.
ACKNOWLEDGMENT- Authors thank to the G.C.R.G. Institute of Medical Sciences and Hospital, Lucknow for their assistance where this study took place.
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