Journal of Hospital Infection (2005) 59, 159–162
High frequency of Candida parapsilosis on thehands of healthy hosts
L.A. Bonassolia, M. Bertolia, T.I.E. Svidzinskib,*
aUniversidade Estadual de Maringa´, Hospital Universita´rio Regional de Maringa´, Parana´, BrazilbUniversidade Estadual de Maringa´, Departamento de Ana´lises Clı´nicas, Laborato´rio de Micologia Clı´nica,Avenida Colombo, 5790, Bloco J90, sala 11, 87020-900 Maringa
Received 1 March 2004; accepted 14 June 2004Available online 13 October 2004
The presence of yeasts on the hands of 86 healthy hosts (62
hospital workers and 24 healthy members of the community with no hospital
exposure) was investigated. A high rate of colonization was found (59.3%).
Candida parapsilosis was the most frequently isolated species (51%),
independent of the origin of the samples. The potential virulence and
resistance to antifungals of the 26 C. parapsilosis isolates were determined.
All were proteinase producers and formed biofilms. The haemolytic activitywas variable, with a predominance of total haemolysis of sheep erythro-cytes. All isolates were susceptible to amphotericin B but two showedreduced susceptibility to fluconazole. Healthy people may be colonized by aspecies of yeast with a high capacity for adhesion to plastic surfaces,providing an infection risk to susceptible individuals.
Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rightsreserved.
The patients most susceptible to C. parapsilosis
infections are very-low-birthweight infants in neo-
Candida species are now considered to be the
natal intensive care units (NICUs) and immunocom-
fourth largest cause of systemic nosocomial infec-
tion.C. parapsilosis is probably the species that
antibiotics and central venous catheters (CVCs)
has had the largest increase in incidence since 1990,
for long periods and frequently receive total
becoming the predominant agent of candidaemia in
The main source of hospital infections by yeasts
is still the endogenous flora of the patient.
However, the hands of healthcare workers (HCWs)
* Corresponding author. Tel.: C55-44-261-4809; fax: C55-44-
are also considered to be important for colonization
and infection, especially with C. parapsilosis.
The virulence of C. parapsilosis is associated
0195-6701/$ - see front matter Q 2004 The Hospital Infection Society. Published by Elsevier Ltd. All rights reserved.
with its capacity for adhesion to plastic surfaces,
and consequently to the development of candidae-mia related to catheters.It is able to proliferate
Biofilm production was determined using the
in high-concentration glucose solutions, and pro-
spectrophotometric method described by Shin et al.
duces a large quantity of extracellular materials,forming extensive biofilms on the surface of a
catheter, enabling the multiplication and perma-nence of the yeast and, consequently, its
A blood agar medium containing 7% glucose and 7%
sheep blood was used to look for haemolysis,which
The aims of this study were to evaluate the rate
was classified as absent, partial or total.
of colonization by C. parapsilosis on the hands ofhealthy hosts, the potential virulence and the
antifungal susceptibility of the strains isolated.
The microdilution method in RPMI 1640 broth wasused to test fluconazole and amphotericin B by theNational Committee for Clinical Laboratory Stan-
dards’s method.The minimal inhibitory concen-trations (MIC) of the antifungals against each C.
parapsilosis isolate were determined. For flucona-zole, the MIC was the lowest concentration of
Samples were collected from the hands of 86
antifungal capable of inhibiting R50% of microbial
individuals. Of these, 62 were health professionals
growth compared with the positive control, and for
amphotericin B, the MIC was the lowest concen-
the NICU (NZ21), laboratories (NZ22) and the
tration that inhibited 100% of the growth.
blood bank (NZ19). The remainder were healthymembers of the community (NZ24) with no
The chi-squared test was used to compare the rate
of colonization by C. parapsilosis with other yeastson the hands of different healthy hosts.
Samples were collected during unannounced visitsto the workplaces. Hands were washed in 20 mL ofbrain heart infusion broth (Difco) in sterilized
plastic containers. After centrifugation, 20 mL ofsediment was spread on CHROMagar Candidaw
Of the people analysed, 59.3% carried yeasts on
(CHROMagar Company, Paris, France), and incu-
their hands. C. parapsilosis was the most common
bated at 25 8
C for 48 h. After incubation, a
semiquantitative evaluation of the colonies pro-
Qualitatively, there was no significant difference
in colonization between workplaces (PO0.05), butan important variation in the concentration of these
micro-organisms, evidenced by the number ofisolated colonies, was observed. Samples obtainedfrom the NICU staff contained few yeasts (one to
The yeasts were identified by two methods: the
three colonies per plate), and more growth was
classical biochemical method and the MicroScanw
observed in the other sectors (laboratories, blood
rapid yeast identification panel (Dade Behring Inc,
bank and community). This was sometimes difficult
All 26 C. parapsilosis isolates produced protein-
ase, with 84.6% showing high enzymatic activity andthe others showing intermediate activity. They also
Proteinase was detected by the formation of an
produced biofilm. Twenty-two isolates were mod-
opaque halo of degraded protein around the colony.
erately positive (C3) and four (15.4%) were
The enzymatic activity was measured by the ratio
between the colony diameter and the colony
Haemolytic activity was variable. Total and
diameter plus the precipitation zone.
partial haemolysis were observed with 16 (61.5%)
and nine (34.6%) isolates, respectively. Only one
biofilms in vitro may reflect their potential to cause
strain did not exhibit any haemolytic activity.
fungaemia related to CVCs in patients receiving
Amphotericin B had good activity, inhibiting
100% of the strains with MIC %1 mg/mL. Most
become more resistant to treatment than those in
isolates were susceptible to fluconazole, with an
average MIC of 5.42 mg/mL (MIC50Z4 mg/mL and
Research with invasive isolates of C. para-
MIC90Z8 mg/mL). However, two isolates from hos-
psilosis (blood and catheter) has confirmed the
pital environments (laboratory and NICU) showed
association between pathogenicity and the
reduced susceptibility with MICs of 16 and
extensive production of biofilm.Shin et al.
compared biofilm production between species ofCandida isolated from systemic infections andfrom other sources. They observed that C.
parapsilosis strains isolated from blood producedsignificantly more biofilm than those from else-
A high rate of yeast colonization on the hands of
healthy hosts has been reported previously, and C.
species of Candida produced one or more types
parapsilosis was the most commonly isolated
of haemolysin in vitro, but C. parapsilosis had
no haemolytic activity. In contrast, our study
The lower concentration of yeasts in NICU staff
showed variable haemolytic activity, with a
can be attributed to the strict application of
predominance of total haemolysis in sheep
hygienic hand disinfection. This is not common
erythrocytes. The function of haemolysin in
practice in the other sections of the hospital.
relation to virulence in yeasts is not clear.
C. parapsilosis is an important pathogen as it
Further studies are needed to investigate
implies the possibility of nosocomial transmission of
whether these haemolytic factors facilitate the
fungaemia by the hands of HCIn a Brazilian
dissemination of the micro-organisms.
multi-centre study, Colombo et aldemonstrated
The C. parapsilosis isolates were inhibited by low
that nosocomial candidaemias are caused predomi-
concentrations of amphotericin B (MIC90Z1 mg/mL),
nantly by non-albicans Candida species, and C.
which is in agreement with previous studies. Two
parapsilosis was the most frequently isolated
isolates had reduced susceptibility to fluconazole,
species. This was also found by Matsumoto et al.,
signalling a possible need for a higher dose of this
who isolated yeasts from the blood and catheters of
agent. In contrast, Colombo et al.reported low
resistance of C. parapsilosis to fluconazole.
We studied 26 skin isolates of C. parapsilosis and
Our results confirmed that C. parapsilosis is the
found that all of them were proteinase producers.
most frequently isolated yeast on the hands of
Bernardis et al.also reported production of high
healthy people, including NICU workers who fre-
concentrations of proteinase by skin isolates of C.
quently work with sick infants, increasing the risk of
Biofilms were produced by all the isolates when
Healthy people working in places unrelated to
grown in a glucose-containing solution. Most isolates
hospitals also carry yeasts on their hands with
were moderately positive as were those described by
the same potential virulence, and which there-
Bernardis et alIn contrast, Pfaller et alfound
fore offer the same risk of infection. This
that most skin isolates were weakly positive.
information should be considered when preven-
The capacity of the Candida species to produce
tive measures are established. Attention to the
Rate of yeast colonization on the hands of healthy hosts
colonization of hands should not be restricted to
high-risk units such as NICUs, but should also
Biotyping and virulence properties of skin isolates of Candidaparapsilosis. J Clin Microbiol 1999;37:3481—3486.
include other sections of hospitals and even
6. Douglas LJ. Candida biofilms and their role in infection.
families, babysitters and people that work with
7. Shin JH, Kee SJ, Shin MG, et al. Biofilm production by isolates
of Candida species recovered from non-neutropenicpatients: comparison of bloodstream isolates with isolatesfrom other sources. J Clin Microbiol 2002;40:1244—1248.
8. Luo G, Samaranayake LP, Yau JYY. Candida species exhibit
differential in vitro hemolytic activities. J Clin Microbiol
The authors wish to thank Peter Grimshaw for
9. National Committee for Clinical Laboratory Standards.
Reference method for broth dilution antifungal suscepti-bility testing for yeasts. Approved standard M27-A. Wayne,PA: NCCLS; 1997.
10. Huang YC, Lin TY, Leu HS, et al. Yeast carriage on hands of
hospital personnel working in intensive care units. J HospInfect 1998;39:47—51.
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