The Discovery Of Penicillin

Alexander Fleming fortuitously discovered the antibacterial properties of a Penicillium mould in 1928. During the Second World War much use was made of penicillin in the treatment of battle wounds. Between the years of 1943 and 1955, when he died, Fleming received around 172 honours from all over the world.

Penicillin transformed the treatment of many infections. One such infection was Staphylococcus aureus.

Fleming, in his acceptance speech for The Nobel Prize in Physiology or Medicine, gave the portentous warning that using penicillin inappropriately might lead to the development of resistance. Sure enough, resistance to penicillin of strains of Staphylococcus aureus became a major problem in hospitals in the 1950s. This resistance was caused by the selection of strains of staphylococcus that could produce the enzyme penicillinase (a drug destroying enzyme). These penicillin resistant Staphylococcus stimulated interest in developing semi synthetic penicillins able to withstand the enzyme. The first of these, produced in 1959, was methicillin.

Resistance to methicillin of Staphylococcus aureus was detected within a year of the antibiotic appearing on the market.

Vancomycin

Vancomycin, for many of the people who have fallen victim to Methicillin-resistant Staphylococcus aureus (MRSA), it is a final solution. Vancomycin is a glycopeptide antibiotic. It is the solution of last resort but highly effective.

Vancomycin is used to treat bacterial infections by stopping or killing the bacteria responsible. When treatment using other antibiotics has failed, Vancomycin is the strongest option available. The antibiotic is available in capsule and injection form, although oral Vancomycin is not effective against MRSA.

The advantage of capsules is that generally they are not absorbed into the blood stream. It is argued that because of this Vancomycin in capsule form is unlikely to cause any severe side effects. However, this is precisely where the problem lies. Should the side-effects occur, they have the potential to become quite severe.

Problems Associated With Vancomycin

Nausea, dizziness, feeling cold, flushing, pain, muscle spasms, bruising, the development of a rash, ringing in the ears, hearing difficulties, or breathing problems are all potential risks.

The severity of these side-effects can be variable and immediate medical attention should be sought if any one of the above become apparent whilst taking Vancomycin.

In addition to the above side-effects, Vancomycin is also criticised for being practically and economically troublesome.

The Practical Problem Of Vancomycin

Non-serious MRSA infections, which may include urinary-tract infections (UTI’s), wounds and skin problems, are difficult to treat with Vancomycin. Slow cure rates and even failure cloud the Vanconycin success story.

The Financial Problem Of Vancomycin

Financially, Vancomycin and its course of treatment are somewhat expensive. Particularly in recent years, increasing incidence of MRSA is adding to the National Health Services budgetary commitments. Contributing to the argument against Vancomycin is the toxic issue.

Vancomycin – The Toxic Problem

A particularly significant issue for patients receiving Vancomycin treatment is that the therapy is more toxic than other methicillin-type drugs. Consequently, a patient’s blood levels must be continually monitored.

The Replacement Case – Vancomycin and Linezolid

Rarely does a credible article draw upon the successes and failings of Vancomycin without making some kind of reference to the drug Linezolid. This is because with the emergence of Vancomycin-resistant organisms, increasingly Linezolid has displaced Vancomycin as the drug of last resort. It has always been a concern amongst healthcare leaders and professionals that increasing use of Vancomycin would result in the energence of resistant organisms and this danger has become a reality.

The Case for Linezolid Explained

Linezolid is part of the Oxazolidone antibiotics. It is highly active in vitro against MRSA and additionally it can be taken orally. It is this oral dosing that may permit an earlier discharge of hospitalised patients and what is more Linezolid and Vancomycin have similar clinical efficacy for MRSA infections. So what are the issues surrounding Linezolid?

Problems Associated With Linezolid

With the use of Linezolid comes the risk of haematological abnormalities, including Myelosuppression and Thrombocytopenia. To compound the problem Linezolid is extremely expensive, sometimes more so the Vancomycin.

The prevailing argument appears to be that Linezolid should not be used routinely. That is, to avoid the emergence of Linezolid-resistant Vancomycin-resistant enterococcus (VRE).

The Way Forward for Vancomycin

Vancomycin is a successful drug but with side-effects and associated problems. The spreading of MRSA and the increasing usage of Vancomycin make the drug more susceptible to failure from Vancomycin-resistant organisms. Furthermore, we cannot rely on Linezolid to completely fill the role of Vancomycin. Ultimately, a return to the idea that prevention is better than cure must be encouraged. MRSA prevention programmes are rolling out across the country with the expectation that this will, in time, reduce our dependence on Vancomycin. It is the drug of last resort and should remain so if its effectiveness is to be maintained.

US researchers in South Carolina have made a startling discovery in their fight against superbugs like MRSA. Their research has found that a compound from a sea sponge was able to reverse antibiotic resistance in several strains of bacteria. Erstwhile resistant strains became once again sensitive to readily available antibiotics

Resensitising Resistant Bacteria To Antibiotics

Peter Moeller of the National Oceanic and Atmospheric Administration’s Hollings Marine Laboratory in Charleston, South Carolina, reported that

We can resensitise these pathogenic bacteria to standard, current-generation antibiotics

Moeller works with researchers at the Medical University of South Carolina and North Carolina State University. His team noticed a sponge thriving in an otherwise dead coral reef and they started asking themselves how the sponge could survive when everything else was dying. The team then endeavoured to isolate the properties that helped the sponge thrive in hostile marine conditions.

The researchers found that pieces of sponge were able to repel bacterial biofilms – a slimy substance bacteria form to help stick to surfaces.

Moeller went on to say

What we found is these (sponge) derivatives actually dispersed existing bacterial biofilms as well as inhibited production of subsequent bacterial biofilms

As 65 to 80% of all human pathogenic infections are based on biofilms, this is a significant discovery.

Moeller’s team tested the substance on some of the toughest pathogens, including MRSA.

Mixing Sea Sponge With Antibiotics

The researchers found that several once-resistant bacteria were sensitive to antibiotics that were mixed with the sponge material. Moeller and his team are now working with a number of medical device companies to incorporate their discovery into the plastic materials used to make devices like stents (used to prop open diseased arteries or in intravenous lines used in critically ill patients).

Moeller envisages a new class of “helper drugs” that restore the potency of antibiotics that had previously lost the war to superbugs.

Overuse And Misuse Of Antibiotics

Overuse and misuse of antibiotics has led to drug resistance in some strains of bacteria, and this has become a serious problem in hospitals worldwide. This problem is highligted by the prevalence of  the superbug MRSA in our hospitals. In the US, infections such as MRSA kill a staggering 19,000 people every year.