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.
doi:10.1016/j.jhin.2004.06.033 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 8C 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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3. Matsumoto FE, Gandra RF, Ruiz LS, et al. Yeasts isolated albicans candidemia in Brazilian tertiary care hospitals.
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13. Pfaller MA, Messer AS, Hollis RJ. Variations in DNA subtype, 4. Saiman L, Ludington E, Dawson J, et al. Risk factors for antifungal susceptibility, and slime production among Candida species colonization of neonatal intensive care unit clinical isolates of Candida parapsilosis. Diagn Microbiol patients. Pediatr Infect Dis J 2001;20:1119—1124.


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