1
Re iew A icle
JPP 2297
JPP 2003 55 000±000
#2003 The Au ho s
Recei ed Sep embe 9, 2002
Accep ed Oc obe 21, 2002
DOI 10.1211/002235702469
ISSN 0022-3573
Medical Mycology Uni , Na ional
Ins i u e o Cellula
Bio echnology, Depa men o
Biology, Na ional Uni e si y o
I eland, Maynoo h, Co. Kilda e,
I eland
Pa ick Ge agh y, Ke in
Ka anagh
Co espondence: K. Ka anagh,
Medical Mycology Uni , NICB,
Depa men o Biology, NUI
Maynoo h, Co. Kilda e, I eland.
E-mail: [email p o ec ed]
Funding: This wo k was
suppo ed by unding o he
Na ional Ins i u e o Cellula
Bio echnology unde PRTLI 3.
Pa ick Ge agh y is a ecipien o
a ellowship om he I ish
Ame ican Pa ne ship.
E y h omycin, an inhibi o o mi o ibosomal p o ein
biosyn hesis, al e s he ampho e icin B suscep ibili y o
Candida albicans
Pa ick Ge agh y and Ke in Ka anagh
Abs ac
Exposu e o he yeas Candida albicans o he mac olide an ibio ic e y h omycin (C
37
H
67
NO
13
) esul s in
ele a ed ole ance o he polyene an i ungal ampho e icin B. E y h omycin displays no ungis a ic ac i i y
agains C. albicans bu inhibi s he syn hesis o cy och omes, pa icula ly cy och ome aa
3
. Consequen ly he e
is a educ ion in ae obic espi a ion by up o 90% when cells a e exposed o 10 mg mL
1
e y h omycin. Cellula
e gos e ol le els a e also se e ely educed. E y h omycin inhibi s p o ein biosyn hesis in ibosomes (mi o ibo-
somes) loca ed wi hin he mi ochond ion o he yeas cell, which esul s in a dis up ion o cy och ome
biosyn hesis wi h an ad e se e ec on espi a ion. The syn hesis o e gos e ol is oxygen dependen and
consequen ly e gos e ol le els a e deple ed in e y h omycin- ea ed C. albicans. E gos e ol is he a ge o
ampho e icin B and since he e is less o his s e ol in e y h omycin- ea ed cells, he e is an inc ease in
ole ance o he an i ungal agen . Ou wo k indica es ha co-adminis a ion o e y h omycin and ampho e icin B
o con ol bac e ial and ungal in ec ions, espec i ely, may inad e en ly lead o an ele a ion in he
ole ance o C. albicans o his an i ungal agen .
In oduc ion
The yeas Candida albicans is an oppo unis ic ungal pa hogen ha is capable o
inducing a ange o supe icial and sys emic in ec ions in he immunocomp omised
hos (Odds 1996). The incidence o in ec ions due o yeas o he genus Candida has
inc eased d ama ically in he las wo decades due, in pa , o he ad en o diseases
such as AIDS (Gil illan e al 1998), he use o immunosupp essi e he apy as a
p e equisi e o o gan ansplan a ion (Lunel e al 1999) and he inc easing numbe o
immunocomp omised pa ien s (P alle e al 1998).
Con en ional he apy o he con ol o in ec ion by C. albicans elies upon he use o
a ange o polyene and azole an i ungal agen s (Munoz e al 2000) ha bind he ungal
memb ane s e ol e gos e ol (Abu-Salah 1996) o dis up s e ol biosyn hesis, espec i ely.
In he case o polyene d ugs, he binding o e gos e ol leads o he o ma ion o po es in
he ungal cell memb ane, me aboli e leakage and subsequen cell dea h (Abu Salah
1996). Azoles dis up e gos e ol syn hesis and induce he o ma ion o oxic s e ol
in e media es, which p o e le hal o he cell (Whi e e al 1998). The polyene an i ungal
agen ampho e icin B is conside ed o be he gold s anda d o an i ungal chemo he apy
and is gene ally ese ed o li e- h ea ening sys emic in ec ions due o i s ex eme
neph o oxici y (Polak 1999). An i ungal he apy can be comp omised by he appea ance
o isola es ha may be inhe en ly esis an o speci ic an i ungals o de elop esis ance
a e p olonged exposu e. The main mechanisms con e ing esis ance o azole d ugs
include inc eased exp ession o e lux pumps, al e ed a ge si es and modi ica ions o
s eps leading o e gos e ol biosyn hesis (Whi e e al 1998). Resis ance o ole ance o
polyene d ugs is clinically a e bu can be media ed by educ ions in he s e ol con en o
he ungal cell memb ane (Kelly e al 1997).
Fungal in ec ions in immunocomp omised pa ien s a e equen ly ound in associa-
ion wi h bac e aemia, which c ea es he possibili y ha d ugs used o con ol bac e ial
in ec ions can ha e an ad e se impac on he he apeu ic ou come o a ungal in ec ion.
E y h omycin (C
37
H
67
NO
13
) is a mac olide an ibio ic o iginally isola ed om
S ep omyces e y heus, wi h ac i i y agains G am-posi i e and G am-nega i e bac e ia.
I con ains a la ge (14-ca bon) lac one ing, which may be
subs i u ed wi h one o mo e suga esidues. E y h o-
mycin unc ions by binding he 50S ibosomal sub-uni
and inhibi ing ansloca ion o he elonga ed pep ide
om one binding si e o ano he on he ibosome hus inhi-
bi ing he addi ion o amino acids o he g owing pep ide
chain (Ib ahim & Bea ie 1973; Gale e al 1981). E y h o-
mycin he apy leads o a modes inc ease in he C. albicans
popula ion o he uppe gas o-in es inal ac o mice
(Samonis e al 2002).
The mi ochond ion is he si e o phospho yla ion o
ADP o ATP and is he si e o ae obic espi a ion wi hin
he ungal cell. Fungal mi ochond ia a e semi-au ono-
mous o ganelles wi hin he cell and con ain ibosomes
( e e ed o as mi o ibosomes), which a e p oka yo ic in
na u e and sensi i e o an ibio ics (eg. chlo amphenicol,
e y h omycin) unlike hei cy oplasmic coun e pa s
(Bo ge e al 2001). Mi o ibosomes a e dis inguishable
om cy oplasmic ibosomes based on sedimen a ion coe -
icien s, wi h he la e ibosomes being 80S and composed
o 60S and 40S sub-uni s while yeas mi o ibosomes a e
app oxima ely74Swi h50Sand37Ssub-uni s(Whi ake &
Danks 1978). An ibio ics ha a ec bac e ia also a ec
ungal mi o ibosmes, inhibi ing he ac i i y o he la ge
50S sub-uni s (Bo ge e al 2001). Recen wo k has
demons a ed ha e y h omycin e a ds he ageing p o-
cess in Saccha omyces ce e isiae by in e e ing wi h mi o -
ibosome unc ion (Holb ook & Menninge 2002);
consequen ly, he e is he possibili y ha e y h omycin
he apy o ea a bac e ial in ec ion could esul in an
al e a ion in he ac i i y o ungal mi o ibosomes wi h
a dele e ious e ec on he ou come o ungal he apy.
The aim o he wo k p esen ed he e was o es ablish he
na u e o he in e ac ion o e y h omycin wi h C. albicans
and o de e mine whe he his has any ole in mode a ing
he suscep ibili y o C. albicans o an i ungal he apy.
Ma e ials and Me hods
Yeas isola es and cul u e condi ions
Candida albicans MEN (se o ype B, o iginally isola ed om
an eye in ec ion and a gi om D D. Ke idge, Camb idge,
UK) was used h oughou his s udy as i is a clinical isola e
wi h a well cha ac e ised esponse o an i ungal agen s.
Cul u es we e g own in YEPD (yeas ex ac ±pep one±D-
glucose) b o h (2% w/ glucose (Sigma-Ald ich Chemical
Co. L d, Do se , UK), 2% w/ bac opep one (Di co
Labo a o ies, MI) and 1% w/ yeas ex ac (Oxoid,
Basings oke, UK)) o he s a iona y phase. S a iona y-
phase cul u es had a ypical cell iabili y o 77.4 6.2%.
Whe e app op ia e, media we e solidi ied by he addi ion o
2% w/ aga (Oxoid). Yeas cul u es we e main ained on
YEPD aga a 4 C and sub-cul u ed e e y 4±6 weeks.
E y h omycin oxici y assay
E y h omycin (Sigma Ald ich) was dissol ed a a concen-
a ion o 500 mg mL
1
in dime hyl sul oxide (DMSO).
This was dilu ed wi h g ow h medium o gi e he app o-
p ia e wo king dilu ions. Yeas cul u es we e g own o he
s a iona y phase (app oxima ely 1.5 10
8
mL
1
)in
YEPD o e nigh a 30 C (200 o a ions pe minu e on
an o bi al shake ). The cells we e coun ed and 5 10
6
cells
we e added o 10 mL o YEPD b o h con aining e y h o-
mycin (Sigma-Ald ich) a 2.5, 5 o 10 mg mL
1
. A DMSO
con ol was included. The cell suspensions we e incuba ed
a 30 C o 24 h, a e which ime he inal cell densi y was
es ablished mic oscopically.
An i ungal suscep ibili y es ing
Yeas cul u es we e g own o he s a iona y phase in an i-
bio ic medium 3 (AB 3) (Oxoid) o e nigh a 30 C and
200 o a ions pe minu e, ha es ed by cen i uga ion
(2220 g o 5 min in a Beckmann GS-6 cen i uge) and
dilu ed o 1 10
6
cells/mL in AB3. Cells (1 10
5
in
100 L) we e added o each well o a 96-well pla e con ain-
ing ampho e icin B (Sigma-Ald ich) dissol ed in AB3 in
se ial dilu ions om 1.25 o 0.0025 gmL
1
. The pla es
we e incuba ed a 30 C o 24 h and he op ical densi y
was ead a 540 nm using a mic opla e eade (Labs
Sys ems iEMS). The MIC80 was de e mined o be he
lowes concen a ion o ampho e icin B equi ed o educe
g ow h by 80% ela i e o he con ol (Mo an e al 1997).
Measu emen o oxygen up ake
S a iona y-phase cells (app oxima ely 1.5 10
8
cells/mL)
g own in YEPD b o h a 30 C o e nigh we e ha es ed,
washed wi h phospha e-bu e ed saline (PBS) and esus-
pended in 0.025 Mphospha e bu e (pH 7.2) a a densi y
o 5 10
8
mL
1
. Oxygen up ake measu emen s we e made
a 30 C, using a Cla k- ype oxygen elec ode. Oxygen
up ake a es we e calcula ed as mol o oxygen consumed
in 30 s pe 10
8
cells.
Cy och ome analysis
S a iona y-phase cells (4 10
9
in o al) we e ha es ed by
cen i uga ion and washed wice in PBS (pH 7.2). Hal o
he sample was oxidised by suspending in 20 mL o 0.3%
w/ sodium hypochlo i e (Sigma-Ald ich). The cells we e
ha es ed and esuspended in 50% / glyce ol. The
emaining 2 10
9
cells we e esuspended in 50% /
glyce ol o which a ew c ys als o sodium di hioni e
(Me ck, Da ms ad , Ge many) we e added o educe he
cy och omes. Reduced-oxidised di e en ial spec a we e
measu ed on a dual beam Ca y IE UV - VISIBLE spec o-
pho ome e o e 500±650 nm.
S e ol ex ac ion and analysis
S e ols we e ex ac ed using he me hod o A hing on-
Skaggs e al (1999) wi h sligh modi ica ions. S a iona y-
phase cells (1 g we weigh ) we e ha es ed and washed
wi h PBS. Cells we e esuspended in 20% w/ KOH and
60% / e hanol and placed in a shaking wa e ba h (80±
90 C) o 90 min. N-hep ane was added o he solu ion,
2Pa ick Ge agh y and Ke in Ka anagh
which was igo ously agi a ed o 10 s and he aqueous
(uppe ) laye was emo ed. The s e ol con en o he hexane
laye was quan i ied using a dual beam spec opho ome e
o e he ange 240±320 nm. An e gos e ol s anda d cu e
was calcula ed o e he ange 100±0.25 gmL
1
and he
ange o linea i y was 0.25±6.25 gmL
1
. The lowes le el
o de ec ion o e gos e ol was 0.1 gmL
1
.
S a is ical analysis
The K uskal±Wallis es was pe o med on he esul s
eco ded om he ampho e icin B suscep ibili y es s,
cell espi a ion and s e ol de e mina ions wi h a s a is ical
package (SigmaS a S a is ical Analysis Sys em, Ve sion
1.00). All se s o esul s displayed a signi ican di e ence
wi h espec o he con ols. In he case o espi a ion
he e is a s a ically signi ican di e ence (P0.03), while
in he ampho e icin B suscep ibili y de e mina ions he e
is a s a ically signi ican di e ence (P50.04). In he s e ol
de e mina ions he di e ence be ween he con ol and he
ea men s is signi ican a P50.001.
Resul s
E ec o e y h omycin on he g ow h
o C. albicans
E y h omycin displays ac i i y agains G am-posi i e
and G am-nega i e bac e ia by in e e ing wi h he unc-
ioning o bac e ial ibosomes which a e s uc u ally
simila o euka yo ic mi o ibosomes (Bo ge e al 2001).
As a consequence, i is possible ha e y h omycin may
display ungis a ic ac i i y agains C. albicans. YEPD
b o h supplemen ed wi h 2.5, 5 o 10 mg mL
1
e y h o-
mycin was inocula ed wi h C. albicans MEN a an ini ial
cell densi y o 5 10
5
mL
1
. Cul u es we e incuba ed
o 24 h a 30 C and he inal cell densi y was de e -
mined by haemocy ome e coun . The esul s indica ed
ha a concen a ions o 2.5±10 mg mL
1
e y h omycin
displayed no subs an ial ungis a ic e ec on C. albicans
(da a no p esen ed).
E ec o e y h omycin on suscep ibili y
o C. albicans o ampho e icin B
The simul aneous occu ence o bac e ial and ungal in ec-
ions in immunocomp omised pa ien s c ea es he possibi-
li y o an ibac e ial and an i ungal d ugs in e ac ing wi h
each o he , o he a ge o ganism o he o he agen , hus
comp omising he apy. Ampho e icin B is a polyene an i-
ungal o iginally isola ed om S ep omyces nodosus and
used in he ea men o li e- h ea ening sys emic mycoses
(Polak 1999). I unc ions by binding e gos e ol in he un-
gal cell memb ane and c ea ing a po e, which leads o loss o
me aboli es and acidi ica ion o he cy oplasm (Abu-Salah
1996). Toxici y assays we e pe o med o es ablish whe he
cells p e- ea ed wi h e y h omycin had al e ed suscep ibil-
i y o ampho e icin B. Cells p e-exposed o e y h omycin
displayed ampho e icin B MIC80 alues inc eased by
app oxima ely 80±110% (Figu e 1). In he case o con ol
cells he MIC80 alue was 0.018 gmL
1
whe eas in cells
p e-g own in he p esence o 2.5, 5 o 10 mg mL
1
e y h o-
mycin he MIC80 anged om 0.033 o 0.038 gmL
1
.
Compa able oxici y assays we e pe o med using he
azole d ugs clo imazole, ke oconazole and miconazole
and no al e a ion in an i ungal suscep ibili y was de ec ed
ollowing p e-g ow h o C. albicans in e y h omycin.
E ec o e y h omycin on cellula espi a ion
o C. albicans
E y h omycin inhibi s he ac ion o mi o ibosomes by
p e en ing p o ein elonga ion a he anspep ida ion
s ep (Gale e al 1981) Ð a p ocess ha could dis up
mi ochond ial espi a ion since a numbe o he sub-
uni s o he cy och omes in ol ed in he elec on ans e
pa hway o espi a ion a e syn hesised on mi o ibosomes
(Whi ake & Danks 1978). The cy och ome p o iles o
cells ea ed wi h e y h omycin we e ob ained o es ablish
he e ec o his d ug on cy och ome biosyn hesis. The
cy och ome p o ile (Figu e 2) o con ol cells indica ed he
p esence o cy och omes aa
3
(602 nm), b (564 nm) and
c (550±554 nm), bu hese we e al e ed in hose cells exposed
o e y h omycin. In pa icula , he cy och ome aa
3
peak
0.05
0.045
0.04
0.035
0.03
0.025
0.02
0.015
0.01
0.005
0
No
e y h omycin
+2.5 mg mL
e y h omycin
–1 +5 mg mL
e y h omycin
–1 +10 mg mL
e y h omycin
–1
Ampho e icin B ( gmL )
µ
–1
**
*
Figu e 1 Suscep ibili y o Candida albicans o ampho e icin B ollowing g ow h in e y h omycin, exp essed as MIC80. Da a a e
means s.e.m. o 5 independen de e mina ions; *P50.04 s no e y h omycin.
E y h omycin al e s he ampho e icin B suscep ibili y o Candida albicans 3
was se e ely dis up ed in he cul u es ea ed wi h 5 and
10 mg mL
1
e y h omycin.
The dis up ion o cy och ome biosyn hesis ollowing
g ow h in e y h omycin has he po en ial o ad e sely a ec
cellula espi a ion, since an incomple e elec on ans e
pa hway would esul in he cells. The espi a ion a es o
cul u es g own in e y h omycin was de e mined using a
Cla k- ype oxygen elec ode. The esul s indica e ha expos-
u e o 2.5, 5 o 10 mg mL
1
e y h omycin dep esses oxygen
consump ion (Figu e 3) Ð in he case o cells ea ed wi h
10 mg mL
1
e y h omycin by up o 90%.
E ec o e y h omycin on e gos e ol con en
o C. albicans
E gos e ol is a key componen o he ungal cell mem-
b ane and he a ge o ampho e icin B (Abu Salah 1996).
The con en ional belie is ha ampho e icin B unc ions
by binding e gos e ol and o ming a po e in he cell mem-
b ane, which leads o leakage o me aboli es and acidi ica-
ion o he cy oplasm. Resis ance o ampho e icin B is a e
bu whe e i has been eco ded he e has been a educed
le el o e gos e ol in he cell memb ane, p o iding ewe
binding si es o he polyene an i ungal (Kelly e al 1997).
The e gos e ol con en o cells ea ed wi h e y h omycin
was de e mined o es ablish whe he a educ ion in e gos-
e ol con en could be a mechanism o he inc eased
ole ance o ampho e icin B. E gos e ol was ex ac ed
om con ol cells and cells g own in he p esence o 2.5,
5 and 10 mg mL
1
e y h omycin, and quan i ied by scan-
ning o e he ange 240±330 nm in a dual beam spec o-
pho ome e . E gos e ol p oduces a cha ac e is ic 4-peak
p o ile in he ange 240±300 nm and his echnique can
be used o quan i y le els wi hin ungal cells (A hing-
on-Skaggs e al 1999). The esul s (Figu e 4) indica e a
educ ion in e gos e ol con en o he h ee e y h omycin-
ea ed cul u es, wi h he g ea es educ ion being e iden
in cul u es ea ed wi h 10 mg mL
1
e y h omycin. Cells
g own in he p esence o 2.5 mg mL
1
e y h omycin had
an e gos e ol le el app oxima ely 66% o he con ol
while hose cells g own in 10 mg mL
1
had an e gos e ol
le el hal he con ol le el.
Discussion
The esul s p esen ed in his pape indica e ha e y h o-
mycin has no signi ican e ec on he g ow h o C. albi-
cans bu ha p e-g ow h o cells in he p esence o
e y h omycin al e s he suscep ibili y o cells o ampho e -
icin B (Figu e 1). E y h omycin ac s on mi ochond ial
p o ein biosyn hesis, which leads o a educ ion in he
No
e y h omycin
+2.5 mg mL
e y h omycin
–1
+5 mg mL
e y h omycin
–1
+10 mg mL
e y h omycin
–1
Wa eleng h (nm)
550 600
Abs 0.1 uni
Figu e 2 Di e en ial spec a o mi ochond ial cy och omes o
Candida albicans ollowing g ow h in e y h omycin. Cy och ome
aa
3
(602 nm), cy och ome b (564 nm) and cy och ome c (550±
554 nm).
No
e y h omycin
+2.5 mg mL
e y h omycin
–1+5 mg mL
e y h omycin
–1+10 mg mL
e y h omycin
–1
120
100
80
40
60
20
0
µmol oxygen consumed
pe 10 cells in 30 s
8
*
*
*
Figu e 3 E ec o e y h omycin on espi a ion o Candida albicans.
Da a a e means s.e.m. o 5 independen de e mina ions; *P0.03
s no e y h omycin.
80
70
60
50
40
30
20
10
0
No
e y h omycin
+2.5 mg mL
e y h omycin
–1+5 mg mL
e y h omycin
–1+10 mg mL
e y h omycin
–1
E gos e ol ( gmL )
µ
–1
*
*
*
Figu e 4 E ec o e y h omycin on e gos e ol con en o Candida
albicans. Da a a e means s.e.m. o 5 independen de e mina ions;
*P50.0001 s no e y h omycin.
4Pa ick Ge agh y and Ke in Ka anagh
amoun o cy och ome aa
3
(Figu e 2). In addi ion, he e is
some dis up ion o cy och omes b and c1. Th ee o he
se en sub-uni s o cy och ome aa
3
a e mi ochond ially
encoded, being syn hesised on mi o ibosomes (Whi ake
& Danks 1978). Cy och ome aa
3
is an in eg al pa o he
elec on ans e pa hway and i s supp ession could
explain he educ ion in oxygen consump ion e iden in
e y h omycin- ea ed cells.
T ea men o C. albicans wi h e y h omycin gi es a
subs an ial educ ion in espi a ion, wi h oxygen up ake
being educed by up o 90% when cells we e g own in
10 mg mL
1
e y h omycin (Figu e 3). Cells exposed o
e y h omycin also show a educ ion in he con en o
e gos e ol (Figu e 4), which is he a ge o ampho e icin B.
Fungal cells equi e oxygen o syn hesise e gos e ol and a
educ ion in espi a o y e iciency o an inabili y o espi e
leads o educed le els o his impo an memb ane s e ol.
Reduc ion in s e ol le els in C. albicans has been iden i ied
p e iously as a mechanism o inc eased g ow h in he
p esence o ampho e icin B (Kelly e al 1997; Whi e e al
1998). Dis up ion o he genes in he e gos e ol biosyn h-
esis pa hway gi es dec eased e gos e ol in Candida glab-
a a and an inc ease in d ug ole ance, pa icula ly o
ampho e icin B (Gebe e al 1995; Vazquez e al 1996).
The equi emen o a unc ional mi ochond ion in e gos-
e ol biosyn hesis is well cha ac e ised and a ises om he
p o ision o NADPH o squalene dime isa ion (Pa ks &
Casey 1995). In addi ion, E g1 encodes squalene epoxi-
dase which con e s squalene o 2,3-oxidosqualene, which
is an oxygen-dependen s ep and in a cell wi h educed
espi a ion he e would be li le syn hesis o e gos e ol
(Daum e al 1998) hus leading o he educed e gos e ol
con en e iden in e y h omycin- ea ed cells.
The wo k p esen ed he e, demons a es ha g ow h o
C. albicans in he p esence o e y h omycin supp esses he
syn hesis o mi ochond ial cy och omes, pa icula ly cy o-
ch ome aa
3
, which in u n leads o a educ ion in cellula
espi a ion. Reduced oxygen up ake leads o a educ ion
in he amoun o e gos e ol in he ungal cell memb ane
due o he equi emen o oxygen in s e ol biosyn hesis.
Reduced e gos e ol le els ha e p e iously been shown o
gi e an ele a ed ole ance o ampho e icin B in C. albicans
(Kelly e al 1997).
The da a p esen ed he e sugges ha co-adminis a ion
o e y h omycin and ampho e icin B o ea bac e ial and
ungal in ec ions, espec i ely, may lead o an ele a ion in
he ole ance o C. albicans o he polyene an i ungal,
wi h po en ially dele e ious consequences o pa ien
eco e y. The use o ampho e icin B is ese ed o se e e
sys emic ungal in ec ions and, as such, ep esen s he las
line o de ence in se e ely immunocomp omised pa ien s
(Polak 1999). Clinical esis ance o his polyene is a e
(Whi e e al 1998). Howe e , ou wo k indica es ha a
d ug ha educes he e gos e ol con en o he ungal
cell memb ane will esul in an ele a ion in he ole ance
o ampho e icin B. This may be su icien o educe he
e icacy o an i ungal he apy and lead o inc eased
pa ien mo ali y. E y h omycin ea men had no e ec
on he ole ance o C. albicans o azole d ugs, which is
no unexpec ed since azoles a ge s eps in he biosyn hesis
o e gos e ol a he han he molecule i sel and conse-
quen ly hei ac ion is no dependen upon he p esence o
e gos e ol in he ungal cell memb ane.
In e ms o pa ien ca e, cau ion should be exe cised in
he adminis a ion o d ugs o he con ol o bac e ial
in ec ions ha may inhibi ungal espi a ion since his
leads o a educ ion in e gos e ol and a concomi an ele a-
ion in ole ance o ampho e icin B. This phenomenon may
be clinically impo an whe e he e is p olonged he apy
wi h e y h omycin (o o he an ibio ics ha in e e e wi h
ungal espi a ion) and ampho e icin B since such condi-
ions may inc ease he p opo ion o he ungal popula ion
exhibi ing ele a ed ole ance o he la e agen .
In conclusion, his wo k demons a es ha e y h omy-
cin inhibi s espi a ion and mi ochond ially encoded cy o-
ch ome biosyn hesis in C. albicans, which leads o a
educ ion in e gos e ol le els in he ungal cell memb ane
and an inc eased ole ance o he an i ungal agen ampho-
e icin B.
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6Pa ick Ge agh y and Ke in Ka anagh