Nosocomial infections, that develop as a result of a stay in hospital or are produced by micro-organisms and viruses acquired during hospitalisation may have several different transmission routes: contact, droplet, air, water, food, or disease vector carrying and transmitting an infectious pathogen, or blood.
The transmission routes are divided into two: direct or indirect transmissions. The direct transmission route of an infectious agent present within a patient's body, through skin contact or mucous membrane is a human to human transmission. In addition to patient-to-patient spread, other sources for contaminants may be involved, including hospital staff, medical students, or visitors.
In indirect transmission, where the contaminant is transmitted from another source within the hospital, is transferred to patient. The source can be contaminated water, food or poorly disinfected structures, furniture or supplies & accessories that are used from patient to patient. One source of contamination can also be a vehicle, that is a carrier transmitting the contaminant to a patient. One of these is the contaminated indoor air. Contaminants can origin from humans within the premises, or even from the structures of building, such as poorly cleaned air ventilation shafts.
Contacts between patients, patients and health care workers and among healthcare workers represent one of the important routes of transmission of hospital-acquired infections (HAI). The other, not so recognised transmission route is the air. A detailed description and quantification of transmission routes in hospitals provides key information for HAIs epidemiology.
Nano size particles can stay in the air for a long time, resulting significant nosocomial problems
In airborne contamination, microbes are transmitted in small droplets – especially when coughing, or sneezing, dust or dandruff particles. By air circulation small-particle-size micro-organisms remain suspended in the air for long periods of time, and they can spread quickly. Microbes can spread within air circulation for long distances, ending up into people’s mucous membranes. Respiratory viruses are increasingly recognized as significant pathogens, as their transmission routes are not based on contact transmission, and they are readily transmitted over considerable distances. Long distance transmission occurs via spread of small (median diameter, <5 μm) droplets.
Given the relative ease, with which they spread, and their relatively short incubation times, these viruses can result in significant nosocomial problems.
A patient with a known or suspected infection that spreads within air, may present a potential risk to other patients and staff and could serve as the point source of a nosocomial outbreak, as the microparticles can stay in the air for a long time, and can travel long distances. Awareness of the potential risk and knowledge of the nature of the contaminant concerned and its likely transmissibility may lead to the need for immediate single-room isolation. While nosocomial outbreaks being rather impossible to forecast, causes the suspected infections varying needs for isolation rooms. In these cases, it is essential, that a vacuum room with a negative pressure is available, so that the microbes can be stopped from spreading, and eliminated.
In an ideal world, the infected patients would be accommodated in separate rooms, with own dedicated nursing staff. In reality, shortage of beds and staff usually necessitates compromise. This may involve selecting different sections of a single ward for use, causing the situation where ensuring that infection control protocols are strictly adhered to, is difficult. Especially, what comes to airborne pathogens.
The importance of prevention strategies and guidelines for precautions of airborne infections
The control of hospital-acquired infections (HAI) is largely based on preventive procedures derived from the best available knowledge of potential transmission routes. The accurate description of contact patterns and possible sources of infections is crucial to recognise, as it can help to understand the possible transmission dynamics and the design principles for appropriate control measures.
Therefore, environmental infection control measures are primary methods to protect the patient from transmission of airborne micro-organisms and viruses. The importance of an approach to reduce transmission of contaminants through airborne spread with detailed guidelines in hospitals should not be ignored. The use of personal protective equipment protects the healthcare workers from exposure to micro-organisms in the healthcare settings, but it is not adequate, as it does not protect the immunocompromised patients from airborne infections.
An air decontamination is the most effective way for airborne infection control, to stop the transmission and nosocomial outbreak. If a comprehensive approach is adapted, both modes of operations should be considered when creating preventive procedures for precautions of airborne infections in critical areas.
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