Note: Descriptions are shown in the official language in which they were submitted.
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CLOTRIMAZOL FOR TREATING STAPHYLOCOCCAL INFECTIONS
FIELD OF THE INVENTION
The present invention provides medicaments and methods for the treatment of
infections caused or contributed to by multi-drug resistant bacterial species.
BACKGROUND
Drug resistant microorganisms, especially bacteria, are becoming increasingly
problematic as infection rates continue to rise and effective methods of
control
become more and more limited. Prolific use of antibiotics over the last 50 or
so years
together with the indiscriminate prescribing of antibiotics and patient non-
compliance
with treatment regimes, has selected for microorganisms that have developed or
acquired ways of overcoming the effects of antibiotics. The transmission and
control
of drug-resistant organisms is becoming one of the most significant problems
within
healthcare.
Of particular note are strains of Staphylococcus that have developed or
obtained
varying levels of resistance to antibiotics such as methicillin (meticillin).
These
strains are commonly known as methicillin resistant Staphylococcus aureus
(MRSA).
In addition, coagulase-negative Staphylococci, such as Staphylococcus
epidermidis,
have also emerged as important nosocomial pathogens. Approximately 80% of S.
epidermidis isolates from device-associated infections are methicillin
resistant
(MRSE) as well as being multi-resistant. Resistance to multiple antibiotics
and the
ability of S. epidef=rnidis to form biofilms on inert surfaces exacerbate the
challenges
of treating infections caused by these organisms. The acquisition of
methicillin
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resistance among Staphylococcal species not only precludes the use of all
currently
available (3-lactam antibiotics, but also is commonly associated with
resistance to
multiple drug classes.
Young, elderly and immunocompromised people/patients tend to be at most risk
of
contracting infections from methicillin resistant Staphylococcal strains.
Consequently, persistent infections caused or contributed to by drug resistant
microorganisms, such as methicillin Staphylococci, are often contracted in
hospitals
and/or nursing homes where the frequent use of antibiotics has created an
envirorunent particularly suitable for the survival of drug resistant
microorganisms.
In addition, community-acquired MRSA (cMRSA) is also now being recognised as
an
increasing problem, with transmission occurring in public and social areas
such as
public gyms and sports centres.
MRSA and MRSE are genotypically and phenotypically distinct from other
Staphylococci; tending to form discrete clonal lineages. The acquisition of
large
mobile genetic elements carrying virulence and resistance determinants by
these
strains results in staphylococci that are often resistant to a number of
drugs.
Resistance can be specific, i.e. particular to a certain drug or class of
drugs or non-
specific in that the resistance applies to a range of drugs, not necessarily
related.
Methicillin resistant Staphylococci may be defined as Staphylococci that
harbour the
mecA gene. Expression of this gene yields PBP2a which confers resistance to
all
currently available (3-lactam antibiotics. The presence of the gene or protein
product
may be detected by polymerase chain reaction (PCR) or latex agglutination
assay
respectively. The mecA gene and its regulators are present on a large DNA
elements
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(SCCmec) which often carry other resistance and virulence genes. The
management
of infections caused by methicillin resistant Staphylococcal species, reflect
these
genotypic and phenotypic differences, and requires greater investment in
hospital
infrastructure, facilities for patient isolation, and infection control
measures than for
other strains of Staphylococci.
Conventionally, vancomycin, a glycopeptide antibiotic, is used to treat MRSA
infections. However, it is disadvantageous in that, inter alia, it has low
oral
absorption. Furthermore, vancomycin is also found to be inferior in terms of
its
efficacy compared to antistaphylococcal penicillins. Therefore, the treatment
options
for infections contributed to or caused by methicillin resistant bacteria such
as MRSA
and MRSE, are now limited and there is an urgent need to discover new
compounds
which inhibit or kill such organisms.
Lee, et al, in J. Microbiol. Biotechnol. 9 (1999) 572-575, reported that
miconazole
was estimated to have a minimum inhibitory concentration of 0.78 g/ml against
MRSA. However, the anti-MRSA activity of miconazole was completely suppressed
by lipophilic a-tocopherol (vitamin E).
An objective of the present invention is to provide a new and effective
treatment for
infections caused or contributed to by methicillin resistant Staphylococci.
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SUMMARY OF THE INVENTION
In a first aspect, the present invention provides clotrimazole or a derivative
thereof,
for treatment of an infection caused or contributed to by a methicillin
resistant
Staphylococcus species.
The present invention encompasses clotrimazole for treating infections caused
or
contributed to by methicillin resistant strains of Staphylococcus such as, for
example,
Staphylococcus aureus and/or Staphylococcus epidermidis. Such strains may
commonly be known as methicillin resistant Staphylococcus aureus (MRSA) or
methicillin resistant Staphylococcus epidermidis (MRSE). While MRSA and MRSE
may be defmed as being resistant to methicillin, they may also be resistant to
other
types of antibiotic particularly those belonging to the (3-lactam family such
as
flucloxacillin and oxacillin. It should be noted that the Staphylococcal
strains
encompassed by this invention may also be resistant to other antibiotics not
mentioned here.
It is a surprising aspect of the present invention that of the large number of
therapeutically effective imidazoles that are commercially available, only
clotrimazole
has been found to be efficacious in the treatment of an infection caused or
contributed
to by a methicillin resistant Staphylococcus species. We have found that other
imidazoles structurally more closely related to miconazole, such as
ketoconazole, did
not inhibit the growth of Staphylococcus species as is illustrated in Table 2.
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In addition, the present invention also encompasses uses of various salts and
therapeutically active addition salts of clotrimazole and derivatives of
clotrimazole; in
particular, clotrimazole nitrate (Ca2H17CIN2 = HN03).
It may be convenient or desirable to prepare, purify, and/or handle a
corresponding
solvate of the compounds described herein, which may be used in any one of the
uses/methods described. The tenn solvate is used herein to refer to a complex
of
solute, such as a compound or salt of the compound, and a solvent. If the
solvent is
water, the solvate may be termed a hydrate, for example a mono-hydrate, di-
hydrate,
tri-hydrate etc, depending on the number of water molecules present per
molecule of
substrate.
Furthermore, and in a second aspect, the present invention provides a method
of
treating a subject suffering from an infection caused or contributed to by a
methicillin
resistant Staphylococcus species, said method comprising the step of
administering an
effective amount of a compound comprising clotrimazole, or a derivative
thereof.
Furthermore, the present invention encompasses a method of treating an
infection
caused or contributed to by a methicillin resistant Staphylococcus species,
said
method comprising the step of administering an effective amount of
clotrimazole or
clotrimazole nitrate.
Advantageously, compounds comprising clotrimazole and/or a derivative thereof
may
be administered orally, topically to the site of an infection, or
intravenously.
Z5 Accordingly, compounds comprising clotrimazole and/or a derivative thereof
may be
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formulated as polymeric nanoparticles such as alginate or polylactide-co-
glycolide
nanoparticles, or as sterile pharmaceutical compositions comprising a
pharmaceutically acceptable carrier or excipient. Such carriers or excipients
are well
known to one of skill in the art and may include, for example, water, saline,
phosphate
buffered saline, dextrose, glycerol, ethanol, ion exchangers, alumina,
aluminium
stearate, lecithin, serum proteins, such as serum albumin, buffer substances
such as
phosphates, glycine, sorbic acid, potassium sorbate, partial glyceride
mixtures of
saturated vegetable fatty acids, lactic acid, water salts or electrolytes,
such as
protamine sulphate, disodium hydrogen phosphate, potassium hydrogen phosphate,
sodium chloride, zinc salts, colloidal silica, magnesium trisilicate,
polyvinyl
pyrrolidone, cyclodextrins, such as a-cyclodextrin, 0-cyclodextrin,
sulfobutylether7-
(3cyclodextrin and hydroxypropyl-(3-cyclodextrin, cellulose-based substances,
polyethylene glycol, sodium carboxymethylcellulose, polyacrylates, waxes,
polyethylene-polypropylene-block polyiners, polyethylene glycol and wool fat
and the
like, or combinations thereof.
Clotrimazole is well absorbed in humans following oral administration and is
eliminated mainly as inactive metabolites. Oral administration of 1.5-3-g
doses of
clotrimazole gave a half-life of around 3 hours; single or twice daily oral
administration may be suitable for the treatment of multiresistant
staphylococcal
infections with clotrimazole. Less than 1% of the adininistered dose was
detected in
urine as active drug after 6 hours.
A clotrimazole topical solution containing, for example, 10 mg/ml (1%)
clotrimazole
would be suitable for the treatment of multi-resistant staphylococci. Six
hours after
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the application of clotrimazole 1% cream and 1% solution onto intact and
acutely
inflamed skin, the concentration of Clotrimazole varied from 100 jig/cm 3 in
the
stratum corneum to 0.5 to 1 jig/cm3 in the stratum reticulare, and 0.1 g/cm3
in the
subcutis. Gentle massage of sufficient clotrimazole topical solution into the
affected
and surrounding skin areas twice a day, in the morning and evening, is
suggested for
the treatment of multidrug resistant staphylococcal infections.
Compounds comprising clotrimazole or a derivative thereof may be administered
in
combination with another treatment. For example, compounds comprising
clotrimazole and/or a derivative thereof may be administered in combination
with
another antibiotic, for example vancomycin, to reduce the likelihood of
emergence of
antibiotic resistance, or antifungal or antiviral, agents or compounds.
Additionally or
alternatively, clotrimazole and/or a derivatives thereof may be administered
in
combination with a chemotherapeutic agent, an immunostimulatory compound or
drug, an oligonucleotide, a cytokine, hormone or the like.
It may be possible to administer a compound comprising clotrimazole and/or a
derivative thereof or any combined regime as described above, transdennally
via, for
example, some form of transdermal delivery device. Such devices are
advantageous,
particularly for the administration of antibiotic compounds, as they may allow
a
prolonged period of treatment relative to for example, an oral or intravenous
medicament.
Examples of transdermal delivery devices may include, for example, a patch,
dressing, bandage or plaster adapted to release a compound or substance
through the
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skin of a patient. A person of skill in the art would be familiar with the
materials and
techniques which may be used to tran.sdermally deliver a compound or substance
and
exemplary transdermal delivery devices are provided by GB2185187, US3249109,
US3598122, US4144317, US4262003 and US4307717.
By way of example, clotrimazole and/or a derivative thereof may be combined
with
some form of matrix or substrate, such as a non-aqueous polymeric carrier, to
render
it suitable for use in a transdermal delivery system. The clotrimazole (and/or
derivative)/matrix or substrate mixture may be further strengthened by the use
of a
woven or knit, non-woven, relatively open mesh fabric, to produce a patch,
bandage,
plaster or the like which may be temporarily attached to a particular region
of a
patient's body. In this way, while in contact with a patient's skin, the
transdermal
delivery device releases the compound or substance directly to the site of
infection or
through the skin as required.
Advantageously, the medicaments and/or methods described herein may have
particular application in institutions housing, sheltering, caring or
otherwise holding
people or patients vulnerable to or "at risk" of developing or contracting a
methicillin
resistant Staphylococcus species, especially for example MRSA or MRSE. The
medicaments and methods may be particularly useful in hospitals, nursing
homes,
nurseries and/or schools. More generally, an elderly, young or
immunocompromised
person or patient may particularly benefit from the medicaments and methods
described herein. Moreover, the methods and medicaments of the present
invention
may be particularly useful to those undergoing a prolonged stay in hospital,
for
example in an intensive care facility.
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Additionally, or alternatively, the medicaments and methods described herein
may be
useful in community centres, sports facilities, shops, restaurants, cafes or
other places
where transmission of bacteria, particularly methicillin resistant
Staphylococcus
species, is likely.
In a furtlier embodiment, the methods and medicaments described herein may be
used
prophylactically as a means to prevent the development of an infection caused
or
contributed to by a methicillin resistant Staphylococcus species. Medicaments
and/or
methods for prophylactic use may be administered or applied to any person at
risk of
developing an infection caused or contributed to by a methicillin resistant
Staphylococcus species. For example, people working in care homes, nursing
homes,
sports centres, community centres, shops, restaurants, cafes, nurseries and/or
schools
may require prophylactic treatments.
The compounds provided herein may also be used as sterilising or cleaning aids
for
use, for example, on surfaces to reduce and/or eliminate contamination by
methicillin
resistant Staphylococcus species such as MRSA or MRSE. By way of example,
clotrimazole or derivatives thereof such as, for example clotrimazole, may be
prepared for application to any surface suspected of being contaminated by
methicillin
resistant Staphylococcus species. For example, compounds of the present
invention
may be added to or diluted in an appropriate excipient or solution prior to
use as a
sterilising or cleaning agent. Exemplary excipients are described above. Such
sterilising or cleaning solutions may be used to decontaminate, for example,
furniture,
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floors, equipment including for example specialised hospital equipment and/or
surgical equipment.
In particular, the . present invention concerns the use of clotrimazole, or a
derivative
thereof, in the manufacture of an antibacterial agent against methicillin
resistant
Staphylococcus species.
In a further embodiment, the compounds described herein may be used to
eliminate
and/or reduce contamination by methicillin resistant Staphylococcus species on
parts
of the body, particularly for example, the hands. Clotrimazole and/or a-
derivative
thereof, may be diluted as an aqueous or non-aqueous solution (dissolved in
aqueous,
non aqueous or organic solvent) and which may be applied to a body part, for
example the hands. Such a solution may find particular application in, for
example
hospitals, care homes and or nurseries where the prevalence and transmission
rates of
methicillin resistant Staphylococcus species are often high.
DETAILED DESCRIPTION
METHODS
In example experiments, clotrimazole was dissolved in methanol. Other solvents
that
may be used include caster oil, pyridine, DMSO and 0.9% saline. For IV
administration agents may be solubilised in polyethoxylated caster oil, or
cyclodextrins such as sulfobutylether7-ocyclodextrin or hydroxypropyl-(3-
cyclodextrin
and lactic acid. Minimum inhibitory concentrations (MICs) of a range of
clinical and
control bacterial organisms were measured according to BSAC (British Society
for
Antimicrobial Chemotherapy) guidelines, described briefly as follows;
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PREPARATION OF AGAR PLATES AND BROTHS.
Stock solutions of each agent were prepared using the formula:
1000xVxC=W
P
Where P jig of active compound per mg ( g/mg)
V = volume required (mL)
C final concentration of solution (mg/L)
W= weight of agent (mg) to be dissolved in volume V (mL)
Stock solutions were prepared at concentrations of 1000mg/L and 100mg/L. The
appropriate amounts of each stock solution were added to separate Petri dishes
to give
the following final concentrations (after the addition of 20mL molten agar):
128, 64,
32, 16, 8, 4, 2, 1, 0.5, 0.25, 0.12, 0.06, 0.03, 0.015mg/L.
Volumes (2OmL) of cooled molten IST agar (oxoid) was added to each Petri dish
and
mixed by swirling.
After drying, the plates were stored at 4 C and protected from light. Plates
were used
on the day of preparation.
PREPARATION OF INOCULUM
The test organisms were grown overnight in 5mL IST broth. Using a dilution in
0.9%
saline of 1:500 for Gram-negative organisms and 1:100 for Gram-positive
organisms,
the appropriate agar plates were inoculated using a multipoint inoculator.
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INCUBATION
Plates were incubated at 37 C in air for 18-20 hours.
INTERPRETATION OF RESULTS
The MIC is the minimum amount of an antibiotic at which there is no visible
growth
of bacteria. Tiny single colonies or faint hazes were not counted as growth.
RESULTS
Clotrimazole demonstrated good activity against S. epidernais and a range of
clinical
MRSA strains (Table 1), but had no significant activity against Gram-negative
organisms. Other related imidazoles did not inhibit the growth of any strain
tested
(Table 2).
20
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