Super Heated Steam in the fight against Hospital Acquired Infections

Report to Osprey Ltd from Hygenica UK Ltd
By Dr. Peter Kite – Lead Clinical Microbiologist

The Problem

The rise and recognition of Hospital acquired infections (HAI) has become a key issue in the National Health Service (NHS) today and in other first world countries. The concerns have been building globally due to the emergence of resistant strains such as antibiotic resistant Staphylococci (MRSA) and the antibiotic resistant Enterococci (VRE), which have become endemic in our health institutions. This situation has also been compounded by the increasing population in our hospitals of vulnerable patient groups such as immuno–suppressed malignancy patients, renal disease, premature infants and geriatric patients.

The Causes

Three main factors have been fuelled the development of “Superbugs”: – firstly the overuse of antimicrobials and the lowering of hygiene standards due to overconfidence in antimicrobials plus economic workload pressure which have led to poorer standards of cleaning/hygiene that are inevitably linked. A third factor, which we are only just recognising, is the community activity of microbes, which interact in the “biofilm” situation to resist potent antiseptic agents, which appear susceptible on cultured strains.

UK Government Awareness and Initiatives

Three major reports were commissioned to evaluate the current problems: –

The public Health Service report entitled “The Socio–Economic Burden of Acquired Infection.”

A report commissioned by the UK Parliament from the National Audit Office entitled “The Management and Control of Hospital Acquired Infection in the Acute NHS Trusts in England”.

A report issued by the NHS Estates Executive entitled: – “Standards for Environmental Cleanliness in Hospitals”.

Report Conclusions

A consensus of some of the conclusions indicates that: –

There is insufficient surveillance and infection control teams.

The HAI rate averages at 9% during the inpatient stay and goes up to 30% following discharge from hospital.

The cost of HAI in the UK is estimated to be 1 Billion Pounds.

Mortality in hospital in–patients without HAI was 2% and rose to 13% in patients with HAI’s.

Hospital cleaning and staff hygiene standards were consistently poor and surveillance inadequate.

Proposed Solutions

Increase cross infection teams and surveillance resources.

Better hygiene protocols for nurses and medics.

More efficient cleaning and instrument sterilisation.

Research into better techniques in specified “model” hospitals.

Government Expectations

The government expects a realistic target reduction in HAI’s of 15% if possible, which would save an estimated 150 million pounds. (The savings to pay for increase expenditure on the new initiatives).

Evaluation of Super Heated Steam Disinfection/Cleaning

Principle

Sterilisation by steam is a true verified practice used on instruments for surgical operations and to kill organisms in infected materials and cultures.

The use of autoclaves to raise steam temperatures above 100°C by increasing chamber pressure in the absence of air is the most efficient way to achieve this objective.

Solution

The use of mobile high pressure Steam Generators as a cleaning tool facilitates a means to decontaminates floors, sanitary units, walls, beds, curtains, radiators, lockers and other features of ward furnishings in order to reduce the bioload of organisms which cause nosocomial (HAI) infections.

Research

Laboratory tests performed by Dr Peter Kite a clinical scientist using super heated steam, demonstrated the efficiency to kill the organisms causing the majority of Hospital Acquired Infections (HAI’s). These include Staphylococci (including MRSA), Enterococci (including VREs), Coliforms (including Salmonella, Campylobacter and other enteric infective agents), and also fungi, including Aspergillus and yeasts. Furthermore the most thermal resistant pathogens causing HAI’s are Clostridium Difficile (C–Diff) spores and these can be reduced substantially (50–90%) using this Super Heated Steam process. Results were compared by standard quantitative bacteriological cultures.
(Ref: – Reports 1, 2a and 2b)

Domestic Environment Evaluation

This work was necessary to determine the effective killing of microbes in their own environment in which they embed themselves into adhesive self–generated slime (biofilm), in moist conditions. These specific conditions are found in bathrooms, kitchens, toilets, and showers. The protective biofilm can resist powerful chemical agents for prolonged periods. The condensing Super Heated Steam transfers it’s latent heat energy totally into the biofilm, which is composed of 97% water, and kills the organisms underneath. The results indicate a 90–100% kill rate was achieved. (Ref:– Domestic report.)

Clinical Training Ward Study

A clinical training ward was used to simulate ward furniture and bed layout to develop a steam clean and vacuum protocol and assess timing and disinfection efficiency.

ATP Bioluminescence Testing

Also a new rapid test was also used for biological dirt assessment using the principle of ATP Detection, which is only found in living cells (human and bacterial). The reaction between the ATP in living bacteria and a chemical from firefly tails causes a proportional emission of light which is recorded in a sensitive light meter as relative light units (RLU’s). (Ref:– Biotrace Ltd.)
Results are expressed in the Clinical Study Ward ATP Report and indicate that 80 to 90% killing efficacy was achieved in a 15–minute period in a typical ward bay (including bed curtains), except on fabric chairs, which require a more thorough process.

Functional Ward Study

Two busy geriatric wards were used in a comparative study of 12 weeks duration, testing 70 sampling sites in patient bays, toilets and sluice rooms. The results of this study will be sent to a cross–infection journal, therefore cannot be revealed in advance.
However the overall results 30 mins post steaming were mainly as predicted by the preliminary workups. The integration of a more intrusive disinfection/cleaning technique is not easy in a busy clinical area and great sensitivity and flexibility is required. The disinfection of vacated wards or areas is the preferred option and operating theatres.

Report 1
Evaluation of Super Heated Steam for Microbial Killing

Objective

To determine the exposure times required for killing isolated human bacterial pathogens.

Methods

Eighteen–hour broth cultures of Enterococci, E Coli, CNS and Staph aureus, were diluted to 106 organisms per ml and six 1 cm diameter blotting paper discs 1mm thick were saturated with the culture from each organism. Each disc of the 6 series was placed in a sterile plastic petrie dish and exposed consecutively to 1, 2, 3, 4 and 5 seconds of vertically applied S/H Steam, whilst the control disc was unexposed. Each disc was transferred to blood culture plates (six per plate) and removed after a few seconds to give an impression inoculum, following which the plates were cultured for 48h at 37°C and colony counts performed.

Results

Colony Count per ml

Organism Control 1 Sec 2 Secs 3 Secs 4 Secs 5 Secs
Entercoccus >1000 0 0 0 0 0
E Coli >1000 2 0 0 0 0
CNS >1000 3 0 0 0 0
Staph aureus >100<1000 2 0 0 0 0

Conclusions

S/H Steam kills organisms of the above species at concentrations up to 106 orgs/ml within two seconds exposure.

Report 2a
Evaluation of Super Heated Steam for Microbial Killing

Objective

To determine the exposure times required for killing commonly isolated fungal pathogens.

Methods

Eighteen–hour broth cultures of Candida glabrata, Candida albicans and Saccharomyces sp, were diluted to 106 organisms per ml and six 1cm diameter blotting paper discs 1mm thick were saturated with the culture from each organism. Each disc of the 6 series was placed in a sterile plastic petrie dish and exposed consecutively to 1, 2, 3, 4 and 5, seconds of vertically applied S/H steam, whilst the control disc was unexposed. Each disc was transferred to blood culture plates (six per plate) and removed after a few seconds to give an impression inoculum, following which the plates were cultured for 48h at 37°C and colony counts performed.

Results

Colony Count per ml

Organism Control 1 Sec 2 Secs 3 Secs 4 Secs 5 Secs
C glabrata >1000 0 0 0 0 0
C albicans >1000 3 2 0 0 0
Saccaromyces >1000 5 0 0 0 0

Conclusions

S/H Steam kills the fungal species above at concentrations of up to 106 orgs/ml within 3 seconds exposure.

Report 2b
Super Heated Steam Experiments on Clostridium difficile

Background

C.difficile is an organism associated with nosocomial diarrhea (45%), a relatively common problem within hospitals, particularly amongst the elderly. Most sporadic and outbreak cases of C.difficile appear to be caused by exposure to contaminated surfaces rather than by contact with an infected index case.

Methods

C.difficile was grown in Schadlers Medium using strain 1.
Strain 1 in Schadlers medium produces relatively few spores and was mainly in the vegetative phase.
Strain 1 were grown for 30 h mixed and diluted 1:10000 prior to the test.

Swab Test

Standard microbiology swabs were dipped into the diluted culture and exposed to the 120°C steam jet from the SHS machine for timed exposures of 0, 3, 5, 10 and 20 seconds in triplicate. The swabs were then inoculated onto C/diff plates and also rinsed in BHI broth tubes representing each time exposure.
The plates and broths were incubated anaerobically for 48 hours at 37°C, examined and counted before further incubation for 24 hours.

Results

Plates 0 Control 3 secs 5 secs 10 secs 20 secs
Vegetative strain 30 0 0 0 0 Colony Count
Broth 0 Control 3 secs 5 secs 10 secs 20 secs
Vegetative Strain Positive Neg. Neg. Neg. Neg.

Conclusion

S/H steam was able to kill vegetative cells of c/diff in less than 3 seconds exposure at 2cm distance.

S/H Steam Domestic Sampling Evaluations16.05.00

Objective:
To determine the capacity of S/H steam to diminish or sterilise areas of domestic microbial bioload within a standard timeframe (30 sec) and area (1 sq ft) except where impractical i.e. taps/ showerhead.

Method:
Sterile dry, single packet cotton wool swabs are labelled prior to use for pre and post Steaming. Immediately prior to use each swab is dipped in sterile saline and an area equivalent to 1 sq. inch is swabbed and returned to its sleeve. Post steaming an equivalent area is swabbed adjacent to the pre swab. The swabs are placed at 4°C until Plating. The swabs are aseptically cut into 1ml sterile saline in sterile bijou bottles and vortexed for 10 sec. Ten 100 ul aliquots from each sample are placed on CLED medium plates and spread with disposable sterile spreaders. The plates are incubated at 37°C for 48h and colonies counted (mean).

Results:


Site: Bathroom/WC Pre cc/ml Post cc/ml % Survival
WC seat 150 0 0
WC rim 500000 3000 10
Washbasin bowl 500000 10000 2
Washbasin taps 60000 20 0.03
Bath interior 50000 300 0.6
Shower Tile/grout 500000 15000 3
Shower Head 2000 0 0

Conclusions:
Exposure to S/H Steam for 30 seconds kills 90–100% of Micro–organisms in a bathroom environment. The kill rate is dependent on the bioload and exposure time, and probably also on the number of sporing organisms and the presence of Biofilm. The highest microbial survival rate from the toilet rim contained all the above adverse factors. As this experiment only concerned the effect of S/H Steam and no removal element by the fabric head or brush the actual overall effect would be greater.

Hygenica UK Clinical Training Ward Study

Objective – To measure the effectiveness of the SHS disinfection process on a patient bed area, inclusive of the furniture.

Location – Clinical Study Suite, Leeds General Infirmary

Machine – Osprey, Vega Steam ‘n’ Vac

Date – 16.04.01

Operator – JSK

Method of Measurement – Biotrace, ATP Bio–luminometer

Procedure – Machine was water primed and brought to operation mode. Two 10cm2 areas were chosen and a Total ATP swab count was taken on each of the following: – locker, adjustable bed table and chair, Bed rail curtains, bed frame and vinyl flooring. The operator proceeded to disinfect the hospital bed area ensuring to cover total surfaces and dimensions. This process took in total 15 mins. Post steaming total ATP swab counts were then carried out and the results recorded.

Results

Effectiveness of disinfection on a hospital bed area

Pre Steam (RLU) Post Steam (RLU) Efficiency
1 2 1 2 1 2
Locker 957 657 81 68 92% 90%
Adjustable Table 1623 523 48 132 97% 75%
Chair – fabric 1151 3205 562 1262 51% 61%
Floor – Bay area 1044 621 86 128 92% 79%
Bed Rail – Curtains 1206 682 166 108 87% 84%
Bed Frame 1741 2744 472 35 73% 99%

Conclusions

The overall time was satisfactory as it included the bed curtains, which would only be done infrequently, in normal practice.
The efficiency of most of the procedure was good apart from the fabric chair.
The pot steam RLU values from the fabric chair suggest that other ATP contamination is occurring from sub fabric material.
A routine of 10 mins per patient area (excluding curtains) would be maximal to be able to complete a 4–bed ward bay in 45 mins.

Hygenica UKHospital Disinfection Trial

Objective – To measure the effectiveness of the SH/Steam disinfection process on a Ward Bathroom.

Location – Ward 93, Leeds General Infirmary

Machine – Osprey Vega Steam ‘N’ Vac

Date – 27.04.01

Operator – JSK

Method of Measurement – Biotrace, ATP Bio–luminometer

Procedure – Machine was water primed and brought to operation mode. Four 10cm2 swabbing area’s were chosen and Total ATP was measured pre–steam. The bathroom consisted of 2 sinks and 1 toilet with a curtain separating the sink units. The bathroom was steam cleaned for duration of 15 mins, with the operator using a systematic approach, ensuring no area was missed. ATP was measured post steam and recorded in RLU.

Results

Effectiveness of the disinfection process in a ward bathroom environment.

Pre Steam RLU Post Steam RLU Effectiveness
Toilet floor 8017 417 95%
Curtain Rail 2498 299 88%
Sink Basin 279 110 61%
Toilet Handle 767 58 93%

Conclusions

1) The overall results are acceptable apart from the washbasin, which would require more regular attention.