Researchers employ four local plants to treat drug resistant Staphylococcus aureus

Nigerian researchers have found four local plants used traditionally
to cure skin and upper respiratory tract infections such as pneumonia,
carbuncle, purple, impetigo and tonsillitis to be effective in
treating drug resistant microbial infections. CHUKWUMA MUANYA reports.

IT has been blamed for skin, respiratory and genital tract infections
with symptoms of persistent itching of the affected areas. It is no
respecter of person- it affects both the young and old. Available
conventional drugs have failed in containing this dreaded infection.

Drug resistant Staphylococcus aureus is indeed on rampage. However, a
recent discovery by Nigerian scientists suggests that the bug could be
beaten after all.

Researchers at the Lagos State University (LASU), Ojo, have
investigated six Nigerian medicinal plants used by traditional medical
practitioners in Western Nigeria for the treatment of several ailments
of microbial and non-microbial origins for in vitro anti-Methicillin
Resistant Staphylococcus aureus (MRSA) activity. Methicillin is a
conventional antibiotic.

The six plants include: Terminalia avicennioides, Phylantus
discoideus, Bridella ferruginea, Ageratum conyzoides, Ocimum
gratissimum and Acalypha wilkesiana.

The results of the study published in the journal, BMC Complementary
and Alternative Medicine, indicated that four out of six medicinal
plants commonly used by traditional medical practitioners to cure skin
and upper respiratory tract infections such as pneumonia, carbuncle,
purple, impetigo and tonsillitis were active against hospital strains
of MRSA. The four plants include: Terminalia avicennioides, Phylantus
discoideus, Ocimum gratissimum and Acalypha wilkesiana.

The study is titled "Screening of crude extracts of six medicinal
plants used in Southwest Nigerian unorthodox medicine for
anti-methicillin resistant Staphylococcus aureus activity". The
researchers include Kabir O. Akinyemi, Olukayode Oladapo, Chidi E.
Okwara , Christopher C. Ibe and Kehinde A. Fasure of the Department of
Microbiology, LASU.

Staphylococcus aureus (literally the "golden cluster seed" or "the
seed gold" and also known as golden staph) is the most common cause of
staph infections. It is a spherical bacterium, frequently found in the
nose and skin of a person.

About 20 per cent of the population are long-term carriers of S.
aureus. S. aureus can cause a range of illnesses from minor skin
infections, such as pimples, impetigo (may also be caused by
Streptococcus pyogenes), boils, cellulitis folliculitis, furuncles,
carbuncles, scalded skin syndrome and abscesses, to life-threatening
diseases such as pneumonia, meningitis, osteomyelitis endocarditis,
Toxic shock syndrome (TSS), and septicemia. Its incidence is from
skin, soft tissue, respiratory, bone, joint, endovascular to wound
infections. It is still one of the four most common causes of
nosocomial infections, often causing postsurgical wound infections.

MRSA is a bacterium responsible for difficult-to-treat infections in
humans. It may also be referred to as multiple-resistant
Staphylococcus aureus or oxacillin-resistant Staphylococcus aureus
(ORSA). MRSA is by definition a strain of Staphylococcus aureus that
is resistant to a large group of antibiotics called the beta-lactams,
which include the penicillins and the cephalosporins.

Over the last three decades, MRSA had caused major problems in
hospitals throughout the world. The first outbreak caused by MRSA
occurred in European hospitals in the early 1960's. During the late
1970's, strains of S. aureus resistant to multiple antibiotics
including methicillin and gentamycin were increasingly responsible for
many outbreaks in the United States and United Kingdom, and by 1980's
MRSA was considered a major clinical and epidemiological pathogen in
human hospitals. Since then strains of MRSA and coagulase-negative
Staphylococci had spread worldwide. Recent reports indicated that MRSA
strains account for 10 to 40 per cent of S. aureus isolated from some
European hospitals.

In many parts of the globe, particularly the developed countries,
fluoroquinolones (pefloxacin, ciprofloxacin and ofloxacin) are
recommended for serious infections associated with Staphylococci,
although, occasional resistance among MRSA has been documented.

Furthermore, in spite of recent reports of vancomycin resistant
strains MRSA in some parts of the globe, vancomycin still remains the
drug of choice for most MRSA-associated diseases.

The use of medicinal plants all over the world predates the
introduction of antibiotics and other modern drugs into Africa
continent. Herbal medicine has been widely used and formed an integral
part of primary health care in China, Ethiopia, Argentina and Papau
New Guinea. Traditional medical practitioners in Southwest, Nigeria,
use a variety of herbal preparations to treat different kinds of
microbial diseases including MRSA-associated diseases.

In recent times, the number of traditional healers claiming the
efficacies of six medicinal plants; namely, Terminalia avicennioides,
Bridella ferruginea, Ageratum conyzoides, Ocimum gratissimum, Acalypha
wilkesiana and Phylantus discoideus for the cure of patients with
Staphylococcus aureus-associated diseases such as, eczema, carbuncles
and osteomyelitis is on the increase.

Terminalia avicennioides belongs to the plant family Combretaceae. It
is called kpaca in Nupe, kpayi in Gwari, baushe in Hausa, igiodan in
Yoruba and edo in Igbo. Terminalia avicennioides is a yellowish brown,
hard and durable wood. The roots, which are used as chewing sticks
have been claimed to cure dental caries and skin infections. Previous
studies showed that the bark extract of Terminalia avicennioides
exhibited both vibrocidal and typhoidal activities.

Like other Ocimum species of Lamiaceae family, Ocimum gratissimum,
traditionally called efirin-aja in Yoruba and nchuanwu or arigbe in
Igbo has been reported to have medicinal properties. The leaf extracts
are popularly used for the treatment of diarrhoea while the cold leaf
infusions are used for the relief of stomach upset and haemorrhoids.
The thymol-riched leaf has been reported to have antimicrobial
properties.

Commonly called Red acalypha and Popose pupa locally, Acalypha
wilkesiana, belongs to the plant family Euphorbiaceae. It is called
aworoso in Yoruba (Ijebu). It is popularly used for the treatment of
malaria, dermatological and gastrointestinal disorders. The leaf
decoction is used for the treatment of gastrointestinal disorders and
fungal infection particularly impetigo contagiosa and Tinea
versicolour which affect the back, chest and axillae of many babies in
Nigeria.

Phyllathus discoideus, of plant family Euphorbiaceae, is a small tree
widely used in tropical West Africa. In Southwest part of Nigeria, the
bark extract is used locally to cure stomachache and lumbago. It is
also useful in the treatment of helminthes infections. The bark
extract of Phyllanthus discoideus is used locally to cure stomachache
and lumbago.

Ageratum conyzoides is of plant family Compositae. It is called
�b�gh�-d�r� in Edo, �k� �fu �y�n (leaf of the excreta of a child) in
Efik, �g�d-�s�-awa (old person with grey hair) or �g�d-�s�-�w-�och�
(old person with white hair) in Igbo (Asaba), oso angweri ngwa in Igbo
(Onitsha), �h h �-nw�-�sh� n'�k� (grass that smells in the hand) in
Igbo (Owerri), f r �t�k� (smelling herb) in Ijaw; h�h� in Tiv; �k�
y�ny�n in Yoruba. It is an annual herb abundant in preclusive forests
and farmland in southern part of Nigeria. Previous study showed that
methanolic leaf extracts corrected fibrinogaemia in poultry chicks.
Also both methanol and water extracts of the leaves exhibited
anti-bacterial effect.

According to The Useful Plants of West Tropical Africa by H. M.
Burkill, the leaves are considered to be antiseptic. Preparations are
commonly applied to craw-craw in the West Africa, and to itch in
Southeast Asia.

In Congo the sap is put onto prurient affections of the skin. The
leaves are cicitrisant. They are applied to chronic ulcers, to
bruises, cuts and sores, and circumcision wounds in Nigeria, to cuts
and sores in Gabon, Tanzania (formerly Tanganyika) and in Ethiopia, as
a haemostatic topically on wounds and haemorrhoids and intravaginally
for uterine bleeding in Ivory Coast. The sap or the plant, dried and
powdered, is a wound dressing in Tanganyika, and is valued especially
for burns, similar uses are recorded in South East Asia.

Bridellia ferruginea, which belongs to the plant family Euphorbiaceae
is used for treatment of insomnia. The bark in combination with other
herbs is used to cure pile in western part of Nigeria.

The reputed efficacies of these plants have been experienced and
passed on from one generation to the other. Apparently, lack of
scientific proof of efficacies claimed by traditional medical
practitioners in Nigeria called for the LASU study.

The results of the LASU study offer a scientific basis for the
traditional use of water and ethanol extracts of A. wilkesiana, O.
gratissimum, T. avicennioides and P. discoideus against
MRSA-associated diseases. However, B. ferruginea and A. conyzoides
were ineffective in vitro in this study. The researchers, therefore,
suggest the immediate stoppage of their traditional use against
MRSA-associated diseases.

The researchers wrote: "The crude extracts of B. ferruginea and A.
conyzoides were weakly active against MRSA strains with ethanol
extract of both plants exerting stronger antibacterial activity than
water extracts. Previous studies indicated that the crude extracts of
these plants were effective against S. aureus. The present study was
slightly conformed to their findings but the only area of concern is
that while their studies only dealt with the effect of crude extracts
on S. aureus, the study focused on the effect of crude extract on the
MRSA, and determination of both MIC & MBC values of the extracts.

"For example, the MIC values of 30.6 and 43.0 mcg/ml obtained for
ethanol extracts of B. ferruginea and A. conyzoides in this study were
lower than their corresponding water extracts of 55.4 and 71.0 mcg/ml.
Similarly, MBC values of 63.6 and 84.2 mcg/ml were recorded for
ethanol extract of B. ferruginea and A. conyzoides respectively. These
values were too high to be considered active against the pathogen. It
is worthy of note that traditional medical practitioners used these
plant extracts solely without combining with other plant extracts for
the treatment of MRSA-associated skin and respiratory diseases. This
finding may disagree with the traditional therapeutic indications
claimed on these plants we, therefore, suggest the immediate stoppage
of their traditional use against MRSA-associated diseases in Lagos,
Nigeria.

" However, the in-vitro inactivity of these plants on MRSA may not
necessarily translate to their in-vivo inactivity but the extracts may
probably be playing immuno-modulatory roles in the body system. Bever
had documented immunodulation of chemical compounds from medicinal
plants many of which have been proved to be inactive or weakly active
in-vitro against pathogens. In this study, we are unable to determine
immuno-modulating action of these plants due to lack of facilities.

"Our investigation further showed that both water and ethanol extracts
of T. avicennioides, P. discoideus, O. gratissimum and A. wilkessiana
were active against S. aureus and MRSA. The MIC value of the four
active plant extracts obtained in this study were lower than the MBC
values suggesting that the plant extracts were bacteriostatic at lower
concentration and bactericidal at higher concentration. The ethanol
extract of the four plants exerted greater antibacterial activity than
corresponding water extract at the same concentrations. These
observations may be attributed to two reasons; firstly, the nature of
biological active components (saponins, tannins, alkaloids and
anthraquinone) which could be enhanced in the presence of ethanol. It
has been documented that tannins, saponins and alkaloids are plants
metabolites well known for antimicrobial activity. Secondly, the
stronger extraction capacity of ethanol could have produced greater
number of active constituents responsible for antibacterial activity.

"Traditionally, leaves of O. gratissimum and A. wilkesiana and barks
of T. avicenniodes and P. discoideus are soaked in ethanol or water
(in case of patients forbidding alcoholic intake due to religious
belief) for days, large quantities of these extracts, which lack
specific concentration are usually administered to patients. Our
results therefore tend to support the traditional claim that these
four medicinal plants are preferably extracted in ethanol. Strong
vibriocidal activity of water and ethanol extracts of T. avicennioides
and typhoidal activity of aqueous extracts of O. gratissimum had been
reported in Lagos, Nigeria.

"The result of phytochemical screening of six plants indicated the
presence of tannins, alkaloids and saponins. Interestingly, only the
four plant extracts that were active against MRSA in this study
contained at least trace amount of anthraquinone. It is, therefore,
most probable that the presence of anthraquinone contributed to
anti-MRSA activity observed. We were unable to carry out bioautography
of the extracts due to lack of facilities."

The researchers said that the results offer a scientific basis for the
traditional use of both water and ethanol extracts of A. wilkesiana,
O. gratissimum, T. avicennioides and P. discoideus separately against
MRSA-associated skin and respiratory diseases. But said in vivo
studies on these medicinal plants are necessary and should seek to
determine toxicity of the active constituents, their side effects,
serum-attainable levels, pharmacokinetic properties and diffusion in
different body sites.

They said that the antimicrobial activities could be enhanced if the
active components were purified and adequate dosage determined for
proper administration. "This may go a long way in curbing
administration of inappropriate concentration, a common practice among
many traditional medical practitioners in Nigeria. This study
represents the first preliminary report on anti-methicillin resistant
Staphylococcus aureus activity of the crude extracts of these
medicinal plants in Lagos, Nigeria," they concluded.