Hi, in my previous post I briefly discussed the bacterial pathogens that can contribute to HAI and that are found in the inanimate environment surroundings of the patients. In addition to bacterial pathogens, fungi also pose a significant risk to the patients. For example, among the pathogens reported to the National Healthcare Safety Network (NHSN) during 2009–2010 as the causative agents of HAI, 90% were bacteria and 10% were fungi.(1)

Candida albicans
Candida albicans

Candida albicans contributed 5.3% of the reported HAI and other Candida spp. contributed 4.2% of the reported HAI. (1)

C. albicans has been show to be able to survive for up to 4 months on surfaces. Persistence of other yeasts on inanimate surfaces is similar (Torulopsis glabrata: 5 months) or shorter (Candida parapsilosis: 14 days).(2)

 

 

Aspergillus
Aspergillus

Other fungi, in particular invasive molds such as  Aspergillus spp.,can also contaminate the hospital environment and cause HAI. Indeed, one of the most common fungal infections of immunocompromised hematopoietic stem cell transplant  (HSTC) individuals is aspergillosis. (3) The incidence rates of invasive aspergillosis have increased dramatically during the last two decades, and, despite all diagnostic and therapeutic efforts, outcome is often fatal. Aspergillus can remain viable for more than 30 days on inanimate surfaces, (2) during which spores are released into the air where they remain airborne for prolonged periods contaminating all immediate and non-immediate patient surrounding surfaces.(4)

 

Of increasing concern is the rise in resistance of fungi to the frontline antifungal agents-polyenes, pyrimidine analogs, echinocandins, and triazoles.  Briefly these anti fungal agents work via a variety of mechanisms including binding ergosterol and blocking sterol destabilising the membrane (polyenes), blocking DNA replication and inhibiting growth (pyrimidine blockers), blocking glucan synthase and thus inhibit cell wall biosynthesis (echinocandins), and targetting a step in the biosynthesis of ergosterol that catalyzes lanosterol 14α-demethylation (triazoles).

Approximately 7% of Candida spp bloodstream isolates tested by the CDC (especially C. glabrata) (5,6) are resistant to fluconazole, and global prevalence of azole resistance in Aspergillus is estimated to be approximately 3 to 6 percent. (7)

In addition Echinocandin resistance,appears to be on the rise according to the CDC’s surveillance data.  Resistance rates of up to 8% of Candida glabrata isolates were found in 2014 may not be susceptible to echinocandins; which has doubled from 4% in 2008. (7)

Not only can anti fungal resistant Candida not be readily treated, data is available that indicates a nti fungal resistant Candida infected patients have worse outcomes. (8, 9)

Recently the CDC has reported that an emerging Candida strain-Candida auris has caused severe illness in hospitalized patients worldwide, including  the USA. This strain has some characteristics that make it concerning including some strains of Candida auris are resistant to all three major classes of antifungal drugs, and that there is evidence that Candida auris can persist in the environment and additional environmental cleaning is required. (10)

 

Candida auris grown in a petri dish-Photo Credit: Shawn Lockhart, CDC
Candida auris grown in a petri dish-Photo Credit: Shawn Lockhart, CDC

 

 

In conclusion, it is clear that pathogenic microorganisms, including both gram positive, and gram negative bacteria as well as fungi  can be disseminated on environmental surfaces, remain viable on these surfaces for prolonged periods of time on inanimate surfaces, and be a source or reservoir of potential nosocomial pathogens.

We would like to hear your feedback or thoughts on bacterial and fungal environmental contamination!

 

References quoted

1) Sievert DM et al., Antimicrobial-Resistant Pathogens Associated with HealthcareAssociated Infections: Summary of Data Reported to the National Healthcare Safety Network at the Centers for Disease Control and Prevention, 2009–2010. Infection Control and Hospital Epidemiology, Vol. 34, No. 1 (January 2013), pp. 1-14.

2) Neely AN, Orloff MM. Survival of Some Medically Important Fungi on Hospital Fabrics and Plastics. Clin Microbiol 2001;39:3360-1

3) Kontoyiannis DP, Marr KA, Park BJ, Alexander BD, Anaissie EJ, Walsh TJ, Ito J, Andes DR, Baddley JW, Brown JM, Brumble LM, Freifeld AG, Hadley S, Herwaldt LA, Kauffman CA, Knapp K, Lyon GM, Morrison VA, Papanicolaou G, Patterson TF, Perl TM, Schuster MG, Walker R, Wannemuehler KA, Wingard JR, Chiller TM, Pappas PG. Prospective surveillance for invasive fungal infections in hematopoietic stem cell transplant recipients, 2001–2006: overview of the Transplant-Associated Infection Surveillance Network (TRANSNET) Database. Clin Infect Dis. 2010;50:1091–100

4) VandenBergh MF, Verweij PE, Voss A. Epidemiology of nosocomial fungal infections: invasive aspergillosis and the environment. Diagn Microbiol Infect Dis 1999;34:221-227.

5) Vallabhaneni S, Cleveland A, Farley M, et al. Epidemiology and Risk Factors for Echinocandin Nonsusceptible Candida glabrata Bloodstream Infections: Data From a Large Multisite Population-Based Candidemia Surveillance Program, 2008–2014. Open Forum Infect Diseases 2015;2(4)

6) Lockhart SR, Iqbal N, Cleveland AA, et al. Species identification and antifungal susceptibility testing of Candida bloodstream isolates from population-based surveillance studies in two U.S. cities from 2008 to 2011. Journal of clinical microbiology 2012;50:3435-42.

7) Arendrup MC. Update on antifungal resistance in Aspergillus and Candida. Clinical microbiology and infection 2013.

8) van Hal SJ, Chen SC, Sorrell TC, Ellis DH, Slavin M, Marriott DM. Support for the EUCAST and revised CLSI fluconazole clinical breakpoints by Sensititre® YeastOne® for Candida albicans: a prospective observational cohort study. J Antimicrob Chemother. 2014;69:2210-2214.

9) Slavin MA, Sorrell TC, Marriott D, et al; Australian Candidemia Study, Australasian Society for Infectious Diseases. Candidaemia in adult cancer patients: risks for fluconazole-resistant isolates and death. J Antimicrob Chemother. 2010;65:1042-1051

10) Candida auris CDC overview

Images taken from MicrobeWiki-(this is an excellent resource and I would urge anyone interested in microbes to check it out!), and the CDC.