Guardian

Scientists have warned that antibiotics are becoming increasingly “useless.” Virtually every pathogenic microorganism has defied available conventional antibiotics. But traditional remedies such as herbal teas and honey are being deployed in the fight against drug-resistant microbes. CHUKWUMA MUANYA writes.

PATHOGENIC microorganisms from Mycobacterium tuberculosis (causes tuberculosis), Neisseria gonorrheae (causes gonorrhea) to Staphylococcus aureus (implicated in most skin and urino-genital infections) are increasingly becoming resistant to available conventional drugs.

In fact recent reports suggests that if nothing was done urgently all the infectious diseases including syphilis and tuberculosis might become untreatable.  But scientists are looking into whether old-fashioned cures such as herbal teas and honey, could be the next way to take on superbugs.

Nigerian researchers have identified common local plants like bitter kola, alligator pepper and West African black pepper (Uda in Igbo) to have strong antibiotic activities and can even be used to treat Ebola virus.

Maurice M. Iwu, Angela R. Duncan, and Chris O. Okunji wrote in a study titled: “New antimicrobials of plant origin” published in the Perspectives on new crops and new uses examined local Nigerian plants for antibiotic (antimicrobial) activities.

The Nigerian researchers found that bitter kola (Garcinia kola), alligator pepper (Aframomum melegueta), West African black pepper (Xylopia aethiopica), Cryptolepis sanguinolenta, Chasmanthera dependens, Nauclea latifolia and Araliopsis tabouensis to be very effective against major disease-causing micro-organisms such as Escherichia coli, Candida albicans, Staphylococcus aureus, Pseudomonas aeruginosa, Vibrio cholera, Salmonella spp, Streptococcus sp., Neisseria gonorrhoea.

Earlier studies by Professor Iwu had found bitter kola to halt the deadly Ebola virus in its tracks in laboratory tests. Compounds from the plant have also proved effective against some strains of flu.

According to the team of researchers led by Iwu, Garcinia kola, which belongs to the plant family Guttiferae is found in moist forest and grows as a medium size tree, up to 12 m high. “It is cultivated and distributed throughout West and Central Africa. Medicinal uses include, purgative, anti-parasitic, antimicrobial. The seeds are used in the treatment of bronchitis and throat infections. They are also used to prevent and relieve colic, cure head or chest colds and relieve cough. Also the plant is used for the treatment of liver disorders and as a chewing stick.”

The constituents they say include-biflavonoids, xanthones and benzophenones. The researchers attribute the antimicrobial properties of bitter kola to the benzophenone, flavanones. “This plant has shown both anti-inflammatory, antimicrobial and antiviral properties. Studies show very good antimicrobial and antiviral properties. In addition, the plant possesses anti-diabetic, and anti-hepatotoxic activities.”

If the anti-Ebola compound proves successful in animal and human trials, it will be the first medicine to successfully treat the virus that causes Ebola haemorrhagic fever - an often-fatal condition.

Researchers have also confirmed that garlic could be used to treat multi-drug resistant (MDR) and extremely drug resistant (XDR) tuberculosis and other antibiotic resistant diseases like cystic fibrosis (a disease passed down through families that causes thick, sticky mucus to build up in the lungs, digestive tract, and other areas of the body).

Saudi and Pakistani researchers in a study titled: “Anti-mycobacterial activity of garlic (Allium sativum) against multi-drug resistant and non-multi-drug resistant Mycobacterium tuberculosis (MTB)” concluded, “this study demonstrated that the garlic extract has showed its effectiveness against clinical isolates of MDR M. tuberculosis. It is worthwhile to utilise garlic as natural supplement with other standard anti tuberculosis treatment (ATT). It is corresponding that substitute medicines practices with plant extracts including garlic as a means of decreasing the burden of drug resistance and reducing the cost of management of diseases would be of public health importance.”

The researchers in the study Pakistan Journal of Pharmaceutical Science investigated a total of 20 clinical isolates of MTB including 15 MDR and five non-MDR strains. Ethanolic extract of garlic was prepared by maceration method. Minimum inhibitory concentration (MIC) was performed by using 7H9 middle brook broth dilution technique. MIC of garlic extract was ranged from one to three mg/ml, showing inhibitory effects of garlic against both non-MDR and MDR M tuberculosis isolates.

According to the researchers, “alternate medicine practices with plant extracts including garlic should be considered to decrease the burden of drug resistance and cost in the management of diseases. The use of garlic against MDR-TB may be of great importance regarding public health.”

Meanwhile, researchers have found that Manuka honey could help clear chronic wound infections and even prevent them from developing in the first place, according to a new study published in Microbiology. The findings provide further evidence for the clinical use of Manuka honey to treat bacterial infections in the face of growing antibiotic resistance.

Streptococcus pyogenes is a normal skin bacterium that is frequently associated with chronic (non-healing) wounds. Bacteria that infect wounds can clump together forming ‘biofilms’, which form a barrier to drugs and promotes chronic infection.

Researchers at Cardiff Metropolitan University have shown that manuka honey can not only destroy fully formed S. pyogenes biofilms in vitro but also prevent the bacteria initially binding to components of wound tissue.

Honey has long been acknowledged for its antimicrobial properties. Traditional remedies containing honey were used in the topical treatment of wounds by diverse ancient civilisations. Manuka honey is derived from nectar collected by honey-bees foraging on the manuka tree found growing in New Zealand and parts of Australia. It is included in modern licensed wound-care products around the world. Manuka honey has been reported to inhibit more than 80 species of bacteria, yet the antimicrobial properties of honey have not yet been fully exploited by modern medicine as its mechanisms of action are not fully understood.

Wounds that are infected with S. pyogenes often fail to respond to treatment. This is largely due to the development of biofilms, which may be difficult for antibiotics to penetrate -in addition to problems of antibiotic resistance. The results of the study showed that very small concentrations of honey prevented the start of biofilm development and that treating established biofilms grown in Petri dishes with honey for two hours killed up to 85 per cent of bacteria within them.

The Cardiff team are working towards providing molecular explanations for the antibacterial action of honey. The latest study reveals that honey can disrupt the interaction between S. pyogenes and the human protein fibronectin, which is displayed on the surface of damaged cells. 

“Molecules on the surface of the bacteria latch onto human fibronectin, anchoring the bacteria to the cell. This allows infection to proceed and biofilms to develop,” explained Dr Sarah Maddocks, who led the study. “We found that honey reduced the expression of these bacterial surface proteins, inhibiting binding to human fibronectin, therefore making biofilm formation less likely. This is a feasible mechanism by which manuka honey minimizes the initiation of acute wound infections and also the establishment of chronic infections.

Ongoing work in Maddocks’ lab is investigating other wound-associated bacteria including Pseudomonas aeruginosa and meticillin-resistant Staphylococcus aureus (MRSA). Manuka honey has also been shown to be effective at killing these bacteria.

“There is an urgent need to find innovative and effective ways of controlling wound infections that are unlikely to contribute to increased antimicrobial resistance. No instances of honey-resistant bacteria have been reported to date, or seem likely,” said Maddocks.

“Applying antibacterial agents directly to the skin to clear bacteria from wounds is cheaper than systemic antibiotics and may well complement antibiotic therapy in the future. This is significant as chronic wounds account for up to four per cent of health care expenses in the developed world.”

A research published in the July 2010 print edition of the FASEB Journal had explained for the first time how honey kills bacteria. Specifically, the research shows that bees make a protein that they add to the honey, called defensin-1, which could one day be used to treat burns and skin infections and to develop new drugs that could combat antibiotic-resistant infections.

“We have completely elucidated the molecular basis of the antibacterial activity of a single medical-grade honey, which contributes to the applicability of honey in medicine,” said Dr. Sebastian A.J. Zaat, a researcher involved in the work from the Department of Medical Microbiology at the Academic Medical Center in Amsterdam. “Honey or isolated honey-derived components might be of great value for prevention and treatment of infections caused by antibiotic-resistant bacteria.”

To make the discovery, Zaat and colleagues investigated the antibacterial activity of medical-grade honey in test tubes against a panel of antibiotic-resistant, disease-causing bacteria. They developed a method to selectively neutralise the known antibacterial factors in honey and determine their individual antibacterial contributions.

Ultimately, researchers isolated the defensin-1 protein, which is part of the honeybee immune system and is added by bees to honey. After analysis, the scientists concluded that the vast majority of honey’s antibacterial properties come from that protein. This information also sheds light on the inner workings of honey- bee immune systems, which may one day help breeders create healthier and heartier honeybees.