Nosocomial infections

Nosocomial infections

Nosocomial Infections



The World Health Organisation (WHO) has declared the year 2006 as the year for creating awareness on “Nosocomial infections”. People working in the health care sector have doubled their efforts globally, towards prevention and containment of nosocomial infections. In the early days, hospitals were the refuge of the destitute and dying – avoided by the wealthy. They were used for the treatment of infectious diseases like small pox at a time when there was no vaccine available. From those days to now, the early twenty first century, hospitals have undergone a lot of transformation. Hospitals vie with each other to become showcases for medicine’s miracles and technology. As a result, hospitals have the potential of becoming dangerous places, in part because of the complexity of medical knowledge — multiple drugs and interventions, multiple specialists and multiple, complex systems of care delivery. With so many factors, mistakes are made and systems do break down.

Nosocomial bloodstream infections are a leading cause of death in Argentina, United States and in other Central American countries. In India, nosocomial infections rate at over 25 per cent and are responsible for more mortality than any other form of accidental death. According to Dr Rosenthal, Director and Co-coordinator of the International Nosocomial Infection Control Consortium (NICC), a multinational research network of 200 researchers from 60 cities in 15 countries, one third of such episodes are preventable.

What is Nosocomial infection? 
Nosocomial or Hospital-acquired infections include almost all clinically evident infections that do not originate from patient’s original admitting diagnosis. Within hours of admission, a patient’s flora begins to acquire characteristics of the surrounding bacterial pool. Most infections that become clinically evident after 48 hours of hospitalization are considered hospital-acquired. Infections that occur after the patient’s discharge from the hospital are also considered to be nosocomial in origin if the organisms were acquired during the hospital stay.

Frequency: 

The incidence of nosocomial infection or hospital-acquired infections is about 5-10% in most developed nations, while in India, one in four patients admitted into hospital acquire a nosocomial infection.

Socio-economic Impact

According to a study carried out by London School of Hygiene and Tropical Medicine, London, United Kingdom 

  • Adult hospitalised patients remain in hospital 2.5 times longer 
  • Incur hospital costs almost three times higher 
  • Incur higher hospital costs post hospital discharge than uninfected patients. 

Mortality/Morbidity: The risk of mortality or morbidity is more than doubled in any patient who develops a nosocomial infection.
Pathophysiology: Within hours of admission, colonies of hospital strains of bacteria develop in the patient’s skin, respiratory tract, and genitourinary tract. Risks factors for the invasion of colonizing pathogens can be categorized under 4 main areas: iatrogenic, organizational, and patient and microbial related. 

  • Iatrogenic risk factors include invasive procedures (eg, intubation, indwelling vascular lines, urine catheterization) and antibiotic use and prophylaxis. 
  • Organizational risk factors include contaminated air-conditioning systems, contaminated water systems, and staffing and physical layout of the facility (eg, nurse-to-patient ratio, open beds close together). 
  • Patient risk factors include the severity of illness, underlying immuno-compromised state, age of patient, nutritional status, co-existing illnesses and length of stay. 
  • Microbial factors – Nosocomial infections are influenced by the microbes’ intrinsic virulence as well as its ability to colonize and survive within institutions. 

Types and Distribution of Nosocomial Infections
A. Urinary Tract Infections
B. Surgical Wound infections
C. Lower Respiratory Infections
D. Blood stream infections
A) Urinary Tract Infections (UTI) represent the most common (34%) type of nosocomial infection caused mainly by indwelling catheters followed by genito-urinary procedures.
Risk Factors specific for nosocomial UTI:

  • Length of time of catheterization
  • Colonization of the drainage bag
  • Absence of antibiotics
  • Female gender
  • Diabetes mellitus
  • Uremia
  • Improper catheter care
  • Failure to use a drip chamber
  • Indications other than drainage during surgery or measurement of output

Complications
Bacteriuria caused by catheters may lead to bacteremia or surgical wound infections by the same organism.
Prevention
Nosocomial UTIs can be prevented by 

  • Eliminating or restricting catheterization. 
  • Usage of condom catheters, intermittent catheterization, supra-pubic catheterization and urinary diversion. 
  • If a catheter is definitely indicated, a time limit should be set for using an indwelling catheter and a closed drainage system is the preferred method.

B) Surgical Wound Infections (SWIs) represent 17% of nosocomial infection and are the second most common hospital-acquired disorder. The classification of wound infections is based on the degree of bacterial contamination. Co-existing conditions contributing to increased morbidity and contamination of the surgical site contribute to the infection rate.
Risk Factors for SWIs:

  • Age 
  • Obesity 
  • Concurrent infection 
  • Prolonged hospitalization 

Sources of infection include direct inoculation from a host’s residual flora, cross-contamination, the surgeon’s hands, air-borne contamination, and devices such as drains and catheters.
Prevention:
Surgical wound infections can be prevented by 

  • Not shaving off the operative site. 
  • Cleansing the skin with a disinfectant and using antibiotics.
  • Peri-operative antibiotics given before surgery and up to 24 hours post-surgery are effective prophylaxis. 
  • Good surgical techniques, limiting the duration of the procedure and the judicious use of drains contribute to reduction of SWIs. 
  • Aseptic and sterile techniques should be used to change the post-operative wounds. 
  • Education on proper methods and self-awareness of the individual infection rate may minimize events of surgical wound infections 

C) Lower Respiratory Infections (LRIs) or pneumonias represent 13% of nosocomial infections but have a fatality of almost 30%. Nosocomial LRI manifest in the intensive care unit or post-surgical recovery room.
Certain procedures such as endotracheal intubation and tracheostomy increase the risk of acquiring nosocomial LRI, as they dry the lower respiratory tract mucous and provide entry for microbes. Other agents that cause nosocomial LRI are ventilators and nebulizers.

Risk factors for LRI

  • Previous use of Antibiotics. 
  • Surgery 
  • Chronic Obstructive Pulmonary Disease 
  • Advanced age 
  • Immunosuppression 

Prevention

  • Hand washing
  • Barrier isolation materials
  • Decontamination of respiratory equipment. 
  • Gastric acidity reduces colonization of the upper GI tract and is hence protective. Some hospitals prefer avoiding the usage of H2 blockers and antacids in intubated patients, rather than using topical antibiotics for the upper GI tract as this may lead to emergence of resistant strains of bacteria.

D) Nosocomial blood stream infections (BSIs) represent 14% of nosocomial infections. Nosocomial bacteremia can be classified as primary or secondary.

Primary nosocomial bacteremia occurs without any infection in other sites while secondary bacteremia occurs when there is infection in a site such as urinary tract. SWI or LRI that can lead to a blood stream infection with the same organism. Mortality from nosocomial bacteremia is greater than if it is community-acquired.

Primary bacteremia or fungemia usually occurs due to intravenous catheters, intravenous fluid contamination and multi-dose parenteral medication lines. Most BSIs are associated with vascular catheter related infections. The usual sources of infection are contaminated antiseptics used to clean the skin, contaminated hands of health care personnel, and infections following hematogenous seeding or external colonization.

Risk factors for peripheral IV catheters:

  • IV catheters placed for longer than 72 hours, 
  • The location of cut down site, lower extremity site
  • Placement of catheter in an emergency 
  • Poor hand washing.

Prevention
Prevention of BSIs basically addresses the factors that increase the likelihood of infection. IV catheters should be observed for signs and symptoms of infection.

Microbes responsible for Hospital acquired infections 
In UTI microbes responsible

  • Gram-negative enteric bacteria (50%) 
  • Fungi (25%) 
  • Enterococci (10%) 

In surgical-site infections (SWI) microbes include the following:

  • S.aureus, 20% 
  • Pseudomonads, 16% 
  • Coagulase-negative staphylococci, 15% 
  • Enterococci, fungi, Enterobacter species, and Escherichia coli, less than 10% each 

Microbial etiologies in bloodstream infections (BSI) include the following:

  • Coagulase-negative staphylococci, 40%
  • Enterococci, 11.2%
  • Fungi, 9.65%
  • Staphylococcus aureus, 9.3%
  • Enterobacter species, 6.2%
  • Pseudomonads, 4.9%

Nosocomial etiologies in fever include the following: 

  • Viral infections are most common causes of nosocomial fevers. 
  • Phlebitis is the second most common cause of nosocomial fevers in the hospitalized child. 

Lab Studies: 
A detailed physical examination and review of systems most likely reveal the involved organs or systems. Workup should be focused on infections of the bloodstream, UTI, and pneumonia, unless an obvious source (eg, surgical-site infection) is readily identified.
If a nosocomial urinary tract infection is suspected in a catherterised patient, the following measures could help: 

  • Efforts should be made to differentiate colonization, cystitis, and frank pyelonephritis by means of urinalysis, urine Gram staining, and culturing.
  • Early removal of the urinary catheter is always helpful in the treatment of catheter-associated UTI

If Pneumonia is suspected, 

  • Radiography, oxygenation, and hemodynamic status determination 
  • Examination of the sputum, endotracheal aspiration material, and pleural effusion fluid with Gram staining and culturing may be useful.
  • A serological confirmation if indicated.

In Bloodstream infections

  • Quantitative blood cultures with samples from the intravenous line and peripheral vein are recommended to aid in differential diagnosis of line-associated bacteremia.
  • Fungal cultures should be requested, if they are suspected. The laboratory should incubate cultures longer for fungus detection than for other pathogens.
  • In immunocompromised patients, special studies such as cultures for nocardia and atypical mycobacteria, cytomegalovirus, and antigenemia detection, occasionally are requested.

In Colitis

  • A stool Gram stain should be performed to detect white blood cells.
  • Tests for Clostridium difficile toxin are useful in the workup for nosocomial fevers and loose stool. In infants, colonization with C difficile often does not cause problems
  • Rotavirus spreads among susceptible infants during local epidemics in cold months.

General investigations 

  • General viral cultures from the throat and rectum can be helpful in management.
  • Acute and convalescent titers against viral agents also can be helpful.
  • Urine direct examination or for antigen detection depending on clinical suspicion 

Imaging Studies: 

  • Special imaging techniques (eg, sonography, CT, or MRI) may be helpful in some infections. 

Treatment
Medical Care: 

  • Symptomatic treatment of shock, hypoventilation, and other complications is provided, along with the administration of empiric antibacterials, antifungals, and antivirals.
  • Appropriate usage of antibiotics , antivirals, antifungals based on causative organism.
  • Indwelling catheter removal in case of nosocomial UTI if feasible. 
  • Line removal should be considered if the line is suspected in the cause of sepsis. 

Surgical Care: 

  • Surgical debridement is an integral part of management of surgical-site infections or super infected decubitus ulcers. 

Special Concerns: 

  • Bacterial agents: Multiple-resistant organisms, such as vancomycin-resistant enterococci, glycopeptide-resistant S aureus, and inducible beta-lactamase gram-negative organisms, are a constant threat. 
  • Viral agents: The rapid spread of respiratory syncytial virus (RSV) among pediatric patients during an RSV epidemic poses a threat to susceptible children who require hospitalization during winter months. 

Prevention and Control of Hospital Acquired Infections

  • Infection control practices need to be integrated into the nursing procedures of each hospital.
  • Nursing care must be planned with an awareness of the measures that increase infection risk and the use of these techniques balanced against the possible benefits.
  • Emphasis on hand-washing, use of aseptic techniques in invasive procedures, care of catheters, intravenous sites, surgical wounds and improvement of disinfection and sterilization procedures in respective areas.
  • Routine cleaning of environment including floors, toilets, bathrooms, washbasins, locker tops and other furniture by adequately trained and supervised staff.
  • The importance of barrier protection nursing measures such as wearing a gown, cap and mask in high risk areas such as ICU’s etc must be stressed. 
  • No brooming. Only wet mopping and damp dusting must be done.
  • Periodic screening of health care workers must be instituted to identify nasal carriers, followed by appropriate management of nasal carriers.
  • Regular screening of kitchen staff and food handlers for carriage of pathogens.
  • Proper waste disposal management.
  • Compliance and adherence to infection control practices by everyone.
  • Isolation of patients constituting an infection risk eg patients with smear positive for pulmonary tuberculosis.
  • A continuous training programme  for all health care workers.

The three issues which face any patient contemplating treatment in India, namely, how safe is the blood at the hospital, what’s the state of nursing and post-operative care and what’s the rate of infection needed to be addressed and it is proof of adherence to these infection control policies that India is now gaining world wide acceptance as a main player in the field of Medical Tourism. An effective hospital infection control programme would benefit patients and their caregivers, and release considerable resources for alternative use. In India, results from many studies conducted by private hospitals conclude the rate of HAIs at 20-25%, in agreement with WHO figures. The issue of HAIs is now being given priority worldwide. Most of the big hospitals in India have set up elaborate protocols to check the infection rate and thereby contain the risk of community acquired as well as hospital acquired infections so as to limit the spread of antimicrobial resistance.
 


Dr Saranya Nandakumar
Consultant Microbiologist
[email protected]

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