Wednesday, 7 May 2008

Alcohol hand rubs increase growth of Acinetobacter

Edwards, J., Patel, G. & Wareham, D.W. (2007). Low concentrations of commercial alcohol hand rubs facilitate growth of and secretion of extracellular proteins by multidrug-resistant strains of Acinetobacter baumannii. J Med Microbial 56, 1595–1599.

The medical profession continues to be haunted by serious bacterial infections acquired within hospitals. If the bacteria can survive antibiotics, as in the so-called multidrug-resistant strains, treatment can be very difficult. The classic measure of good hand hygiene can reduce infection rates by 10–50 %, so hospitals have introduced ways for staff to clean their hands frequently without suffering from chapped skin. These include using alcohol-based hand rubs (ABHRs) dispensed from a pump adjacent to patients’ beds. These are solutions of ethanol or isopropanol, often in combination with an antiseptic and moisturiser which are less irritating to skin than soap.

Although studies have shown that ABHRs reduce infection rates, they are not effective against all bacteria. One example is the spores of Clostridium difficile that can cause very serious gastrointestinal infections. Now, Justin Edwards, Greta Patel and David Wareham from Barts and The London NHS Trust and the MRC Clincal Sciences Centre of Imperial College London have found evidence that low concentrations of ABHRs enhance in vitro growth of Acinetobacter baumannii, an opportunistic pathogen of critically ill patients.

A. baumannii has emerged in recent years as an important cause of ventilatorassociated pneumonia and blood infections in patients with burns, immunosuppression and critical illness. Many strains also turn out to be resistant to many antibiotics so that treatment is extremely difficult. The bacteria have a remarkable ability to persist on surfaces in the hospital environment and are spread by the hands of hospital staff so that hand hygiene is the key factor in preventing these infections.

The researchers therefore tested whether low concentrations of commercially available ABHRs could affect the growth of multidrug-resistant A. baumannii. Depending on the growth medium, the presence of 0.01–1 % ABHR resulted in increased growth of A. baumannii. In contrast, a hand-cleaning product that was free of alcohol and relied on strong detergents to kill bacteria did not support the growth of A. baumannii at all.

The researchers then investigated the proteins secreted by A. baumannii as it grew because previous work has shown that low concentrations of ethanol increase the virulence as well as the numbers of A. baumannii. They discovered that oomph was a major secreted protein, along with another protein with an unknown role. OmpA is well known and may help the cells take up ethanol as a food source when other nutrients are in short supply. It may also help the bacterial cells sense each other and form films on surfaces.

The findings of this paper are certainly interesting, but their clinical significance remains unclear. However, if low concentrations of ABHRs do indeed exist in the clinical environment, this work may have implications for those hospitals currently experiencing outbreaks of A. baumannii.

Sunday, 27 April 2008

And so to bed ...

The contribution of beds to healthcare-associated infection: the importance of adequate decontamination
E. Creamer and H. Humphrey
Journal of Hospital Infection
Volume 69, Issue 1, May 2008, Pages 8-23
The hospital bed is comprised of different components, which pose a potential risk of infection for the patient if not adequately decontaminated. In the literature there are a number of descriptions of outbreaks or experimental investigations involving meticillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Acinetobacter spp., and other pathogens. Often only the bedrail has been sampled during investigation of outbreaks, rather than more important potential reservoirs of infection, such as mattresses and pillows, which are in direct contact with patients. It is essential that these items and other bed components are adequately decontaminated to minimise the risk of cross-infection, but detailed advice on this aspect is often lacking in reports and official documents. The ideal would be to decontaminate the bed by thermal disinfection between patients. Institutions, especially acute hospitals with endemic MRSA and VRE, should consider investing in this type of equipment or at least endeavour to ensure that the critical components, e.g. mattresses and pillows, are processed in a thermal disinfection unit. Other technology such as hydrogen peroxide should be studied further to determine its role for routine use as well as during outbreaks. Clear guidelines should be formulated for bed decontamination and systems established, such as labelling, to indicate when a bed has undergone decontamination. Pillows and mattresses should be made of materials that are easily washed, dried and decontaminated, and have the lowest potential to harbour organisms. The regular replacement of mattress and pillows should be included in hospital budgets. While all equipment and environmental aspects in contact with the patient can cause infection, and therefore require appropriate decontamination, priority should be given to mattresses and pillows, due to their greater degree of contact with the patient.

Monday, 11 February 2008

Microbe Facts - Be Scared !!

The average load of clean laundry contains 10 million CFUs of faecal matter!

The dirtiest place in the average home is the kitchen sink.

Faecal bacteria and viruses are ejected from toilets during flushing.

Tuesday, 8 January 2008

Computer Keyboards Spread Stomach Flu

Norovirus, the highly contagious agent that causes the so-called "stomach flu", is passed from person to person through contact with commonly shared items including computer keyboards and mice (United States health officials report). The virus is common in winter, is the most frequent cause of outbreaks of vomiting and diarrhea in the US, and is often contracted in schools, workplaces and on cruise ships. It is second only to the common cold in terms of numbers of infections.

Last Thursday, the U.S. Centers for Disease Control and Prevention reported on a norovirus outbreak last February at an elementary school in Washington, D.C. when some of the victims picked up the virus from contaminated computer equipment.

Sunday, 6 January 2008

Rise In UK Hepatitis B Cases

Recent data (Source: Hepatitis B Foundation) indicates that the number of UK cases of Hepatitis B has doubled within the 5 years. The number of people having chronic hepatitis B infection now stands at 325,000, but when considering under-reporting, the actual number could be considerably greater. Government estimates in 2002 reported 180 000 UK cases of chronic hepatitis B.

David Mutimer of Birmingham University, UK stated: “The report clearly shows that Britain is seeing a steady, ongoing, and dramatic increase in the number of chronically infected people”, and called on the UK government to develop a strategy and set in place an action plan to halt the upwards surge in cases.

Jane Zuckerman of University College London, UK has suggested that the rise is attributed to a substantial increase in recent migration. There has been available for 25 years an effective and safe vaccine but the UK and several other European countries only target vaccination at high risk groups. “The UK policy has been defended because of the presumed low endemicity of hepatitis B in the UK … these new data support arguments that it is now time to change UK policy on the prevention of hepatitis B”, added Zuckerman.