Nosocomial infections are a major issue to the health care systems and result in a significant mortality, morbidity and economic burden. Intensive care unit patients face an extremely elevated tendency to be infected due to breaches of host defense mechanisms as a result of traumatic medical conditions, corticosteroid therapies and invasive medical devises. [1] Additionally ICU patients usually have coexisting organ system or metabolic dysfunction. Drug- resistant bacteria arise due to antibiotic stress thereby making the infections extremely hard to control or eradicate. [2] ICU patients essentially require high standards of hygiene. Many studies show that healthcare workers’ [1], medical devices such as stethoscopes [3] portable radiograph equipment [4, 5] catheters [6] canulas, surgical equipment and many common surfaces act as major sources of contamination.

Sites of most common nosocomial infections include the urinary tract, lower respiratory tract, surgical sites, skin and soft tissue, GI tract, ENT, eyes and catheter sites. [2] Considering the microbial diversity of contaminations, fungi are less commonly found than bacteria as causative agent of ICU infections [7] while commensal bacteria such as E.coli, and human pathogens; Clostridium spp., Staphylococcus aureus, Proteus, Klebsiella, Enterobacter, Serretia marcescens, Pseudomonas spp., Acinetobacter spp., and Legionella act as most common pathogens responsible for nosocomial infections.

Several studies have been conducted in Sri Lankan hospitals to study the prevalence rates of nosocomial infections. A research conducted at Teaching hospital, Karapitiya,Galle reveals that ventilator associated pneumonia(26.4%) and urinary tract infection (10.9%) are the two main nosocomial infections seen among the ICU patients of the hospital. [8] Another one- year prospective study carried out at the Intensive care units of National Hospital Sri Lanka shows Lower respiratory tract infections (28.4%), Urinary tract infections (20%) and infection of intravenous cannula site(19.2%) are the major nosocomial infections of patients admitted to ICU. [9]

Identification of nosocomial bacterial pathogens is significantly vital as some pathogens can be potentially life threatening. Altered host defense mechanisms, underlying complex etiologies, coexisting systemic dysfunctions intricate the infections and demands highly sensitive fast and descriptive identification measurements. Although ICU patients, indoor environments, healthcare workers’, medical equipment are screened and continuously monitored, bacterial populations are often underestimated by conventional microbiological methods due to the lack of test sensitivity. Golden standard techniques of conventional microbial analysis methods such as plating of bacteria contain a restricted spectrum and only a very small proportion of the total bacteria [10] thus restraining identification limits. Similar applies to alternative methodologies such as membrane filtration, biochemical testing, molecular techniques as well as serological assays. Additionally, conventional plating technique requires a minimum turnaround time of 7-10 days, and includes chances of culture failures due to fastidious growth requirements, unculturable bacteria and complex biochemical reactions. Investigations of ICU contaminations require faster, accurate and sensitive measurements in order to establish better identification approaches. Many scientist hypothesize that the ICU microbiome is characterized by a much higher bacterial diversity and abundance than is currently thought. [10]

Recently, the application of next generation sequencing techniques has allowed new insight into ICU microbial communities. 16s rRNA gene sequencing of bacteria is one such extremely successful approach that enables the identification of the whole spectrum of known bacteria within a run time of 48 hours. Test speed of the technique along with its accuracy and high sensitivity is clearly a life saving approach to ICU patients infected with nosocomial infection as the test enables result generation about eight times faster than conventional methods, facilitating immediate provision of medical care. It also distinguishes between the intragenic variations between closely related species while identifying relative abundances allowing further analysis of microbes at species level. Therefore, this broad spectrum technology delivers relief at alarming situations helping the healthcare workers’ to save lives that are at stake.

Profile clustering cytoscape network visualizing 40 most abundant microorganisms across the floor(green) medical devices (red) and workplaces (blue) [10]

Bacterial communities of the floor environment (A) medical devices (B) and workplaces (C) [10]

REFERENCE-

1. Khodavaisy, S., et al. “Evaluation of bacterial and fungal contamination in the health care workers’ hands and rings in the intensive care unit.” J Prev Med Hyg4 (2011): 215-8.
2. Rowin, Mark E., Vipul V. Patel, and John C. Christenson. “Pediatric intensive care unit nosocomial infections.” Critical care clinics3 (2003): 473-487.
3. Whittington, A. M., et al. “Bacterial contamination of stethoscopes on the intensive care unit.” Anaesthesia6 (2009): 620-624.
4. Levin, Phillip D., et al. “Contamination of portable radiograph equipment with resistant bacteria in the ICU.” CHEST Journal2 (2009): 426-432.
5. Ochie, K., and C. C. Ohagwu. “Contamination of X-ray equipment and accessories with nosocomial bacteria and the effectivenss of common disinfecting agents.” African Journal of basic and applied sciences1-2 (2009): 31-35.
6. Pittet, Didier, et al. “Considerations for a WHO European strategy on health-care-associated infection, surveillance, and control.” The Lancet infectious diseases4 (2005): 242-250.
7. Snydman, David R. “Shifting patterns in the epidemiology of nosocomial Candida infections.” CHEST Journal5_suppl (2003): 500S-503S.
8. Gunaratne, A., et al. “Nosocomial infection in the Intensive Care Unit at Teaching Hospital Karapitiya, Galle; an audit.” Galle Medical Journal2 (2011): 13-16.
9. WANIGASURIYA, JKP. Nosocomial infections in the intensive care units at the National Hospital of Sri Lanka. Diss. University of Colombo: UC (MED), USJ (MED)., 1999.
10. Oberauner, Lisa, et al. “The ignored diversity: complex bacterial communities in intensive care units revealed by 16S pyrosequencing.” Scientific reports3 (2013).