Adenosine triphosphate (ATP) sampling algorithm for monitoring the cleanliness of surgical instruments

BACKGROUND

Timely detection of cleaning failure is critical for quality assurance within Sterilising Service Units (SSUs). Rapid Adenosine Triphosphate (ATP) testing provides a real time and quantitative indication of cellular contaminants, when used to measure surface or device cleanliness. The aim of this study was to investigate the use of an ATP algorithm and to whether it could be used as a routine quality assurance step, to monitor surgical instruments cleanliness in SSUs prior to sterilisation.

METHODS

Cleanliness monitoring using rapid ATP testing was undertaken in the SSUs of four hospitals located in the western (Amazonia) region of Brazil. ATP testing was conducted (Clean Trace, 3M) on 163 surgical instruments, following manual cleaning. A sampling algorithm using a duplicate swab approach was applied to indicate surgical instruments as (i) very clean, (ii) clean, (iii) equivocal or (iv) fail, based around a 'clean' cut-off of 250 Relative Light Units (RLU) and a 'very clean' <100 RLU.

RESULTS

The four cleanliness categories were significantly differentiated (P≤0.001). The worst performing locations (hospitals A & C) had failure rates of 39.2% and 32.4%, respectively, and were distinctly different from hospitals B & D (P≤0.001). The best performing hospitals (B & D) had failure rates of 7.7% and 2.8%, respectively.

CONCLUSION

The ATP testing algorithm provides a simple to use method within SSUs. The measurements are in real time, quantitative and useful for risk-based quality assurance monitoring, and the tool can be used for staff training. The four-tiered approach to the grading of surgical instrument cleanliness provides a nuanced approach for continuous quality improvement within SSU than does a simple pass/fail methodology.

Using a simplified ATP algorithm to improve data reliability and improve cleanliness standards for surface and medical device hygiene

BACKGROUND

An algorithm has been improved to mitigate variability in cleanliness measurements of various surfaces using rapid Adenosine Triphosphate (ATP) testing. A cleaning intervention step (CIS) verifies the cleanability of those surfaces.

METHODS

ATP testing was performed on surfaces which were pre-approved as "clean" and ready for re-use. Adjacent (duplicate) ATP sampling was undertaken on 421 environmental surfaces, medical devices and other implements. The CIS was conducted on 270 surfaces using an aseptic technique and disposable cleaning wipes.

RESULTS

The two initial ATP results were plotted against each other with a 100 RLU threshold grading the results as clean (2x < 100RLU), dirty (2x > 100RLU) or equivocal (1x < 100RLU and 1x > 100RLU). Of the surfaces sampled, 68.5 % were clean (288/421), 13.5 % were dirty (57/421) and 18 % were equivocal (76/421). The duplicate testing demonstrated a false negative rate of 10 % (44/421) where the first swab was <100 RLU and the second swab >100 RLU. For the equivocal group, the gap between the two swabs was >100 RLU for 7.5 % of surfaces (33/421). The CIS was conducted on 270 of the surfaces tested and showed that cleaning could be improved (P=<0.001) on 88.5 % of surfaces (239/270).

CONCLUSION

The simplified ATP testing algorithm provides real-time discrimination between surface cleanliness levels and improved certainty over surface hygiene. The duplicate swab sampling approach mitigates uncontrolled variability in the results and the CIS provides a nuanced understanding of the measurable cleanliness of any surface.

Staphylococcus aureus dry-surface biofilms are more resistant to heat treatment than traditional hydrated biofilms

BACKGROUND

The importance of biofilms to clinical practice is being increasingly realized. Biofilm tolerance to antibiotics is well described but limited work has been conducted on the efficacy of heat disinfection and sterilization against biofilms.

AIM

To test the susceptibility of planktonic, hydrated biofilm and dry-surface biofilm forms of Staphylococcus aureus, to dry-heat and wet-heat treatments.

METHODS

S. aureus was grown as both hydrated biofilm and dry-surface biofilm in the CDC biofilm generator. Biofilm was subjected to a range of temperatures in a hot-air oven (dry heat), water bath or autoclave (wet heat).

FINDINGS

Dry-surface biofilms remained culture positive even when treated with the harshest dry-heat condition of 100°C for 60min. Following autoclaving samples were culture negative but 62-74% of bacteria in dry-surface biofilms remained alive as demonstrated by live/dead staining and confocal microscopy. Dry-surface biofilms subjected to autoclaving at 121°C for up to 30min recovered and released planktonic cells. Recovery did not occur following autoclaving for longer or at 134°C, at least during the time-period tested. Hydrated biofilm recovered following dry-heat treatment up to 100°C for 10min but failed to recover following autoclaving despite the presence of 43-60% live cells as demonstrated by live/dead staining.

CONCLUSION

S. aureus dry-surface biofilms are less susceptible to killing by dry heat and steam autoclaving than hydrated biofilms, which are less susceptible to heat treatment than planktonic suspensions.

A pilot study into locating the bad bugs in a busy intensive care unit

BACKGROUND

The persistence of multidrug-resistant organisms (MDROs) within an intensive care unit (ICU) possibly contained within dry surface biofilms, remains a perplexing confounder and is a threat to patient safety. Identification of residential locations of MDRO within the ICU is an intervention for which new scientific approaches may assist in finding potential MDRO reservoirs.

METHOD

This study investigated a new approach to sampling using a more aggressive environmental swabbing technique of high-touch objects (HTOs) and surfaces, aided by 2 commercially available adenosine triphosphate (ATP) bioluminometers.

RESULTS

A total of 13 individual MDRO locations identified in this pilot study. The use of ATP bioluminometers was significantly associated with the identification of 12 of the 13 individual MDRO locations. The MDRO recovery and readings from the 2 ATP bioluminometers were not significantly correlated with distinct cutoffs for each ATP device, and there was no correlation between the 2 ATP devices.

CONCLUSION

The specific MDRO locations were not limited to the immediate patient surroundings or to any specific HTO or type of surface. The use of ATP testing helped rapidly identify the soiled locations for MDRO sampling. The greatest density of positive MDRO locations was around and within the clinical staff work station.

Intensive care unit environmental surfaces are contaminated by multidrug-resistant bacteria in biofilms: combined results of conventional culture, pyrosequencing, scanning electron microscopy, and confocal laser microscopy

BACKGROUND

Hospital-associated infections cause considerable morbidity and mortality, and are expensive to treat. Organisms causing these infections can be sourced from the inanimate environment around a patient. Could the difficulty in eradicating these organisms from the environment be because they reside in dry surface biofilms?

AIM

The intensive care unit (ICU) of a tertiary referral hospital was decommissioned and the opportunity to destructively sample clinical surfaces was taken in order to investigate whether multidrug-resistant organisms (MDROs) had survived the decommissioning process and whether they were present in biofilms.

METHODS

The ICU had two 'terminal cleans' with 500 ppm free chlorine solution; items from bedding, surrounds, and furnishings were then sampled with cutting implements. Sections were sonicated in tryptone soya broth and inoculated on to chromogenic plates to demonstrate MDROs, which were confirmed with the Vitek2 system. Genomic DNA was extracted directly from ICU samples, and subjected to polymerase chain reaction (PCR) for femA to detect Staphylococcus aureus and the microbiome by bacterial tag-encoded FLX amplicon pyrosequencing. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) were performed on environmental samples.

FINDINGS

Multidrug-resistant bacteria were cultured from 52% (23/44) of samples cultured. S. aureus PCR was positive in 50%. Biofilm was demonstrated in 93% (41/44) of samples by CLSM and/or SEM. Pyrosequencing demonstrated that the biofilms were polymicrobial and contained species that had multidrug-resistant strains.

CONCLUSION

Dry surface biofilms containing MDROs are found on ICU surfaces despite terminal cleaning with chlorine solution. How these arise and how they might be removed requires further study.

Failure analysis in the identification of synergies between cleaning monitoring methods

BACKGROUND

The 4 monitoring methods used to manage the quality assurance of cleaning outcomes within health care settings are visual inspection, microbial recovery, fluorescent marker assessment, and rapid ATP bioluminometry. These methods each generate different types of information, presenting a challenge to the successful integration of monitoring results. A systematic approach to safety and quality control can be used to interrogate the known qualities of cleaning monitoring methods and provide a prospective management tool for infection control professionals. We investigated the use of failure mode and effects analysis (FMEA) for measuring failure risk arising through each cleaning monitoring method.

METHODS

FMEA uses existing data in a structured risk assessment tool that identifies weaknesses in products or processes. Our FMEA approach used the literature and a small experienced team to construct a series of analyses to investigate the cleaning monitoring methods in a way that minimized identified failure risks.

RESULTS

FMEA applied to each of the cleaning monitoring methods revealed failure modes for each. The combined use of cleaning monitoring methods in sequence is preferable to their use in isolation.

CONCLUSIONS

When these 4 cleaning monitoring methods are used in combination in a logical sequence, the failure modes noted for any 1 can be complemented by the strengths of the alternatives, thereby circumventing the risk of failure of any individual cleaning monitoring method.

Reliability testing for portable adenosine triphosphate bioluminometers

Measurement of adenosine triphosphate (ATP) using portable bioluminometers has been adapted from the food manufacturing sector, and it has been suggested that it could be used as an indicator of surface soiling or cleanliness in hospital settings. Some healthcare authorities are considering the use of portable ATP bioluminometers as a tool for standard setting for surface cleanliness to improve cleaning standards. Central to this approach is the use of a commonly accepted level of detected ATP—expressed as relative light units (RLUs)—that may be used as a surrogate for underlying soiling, including the presence of pathogenic microorganisms.

It has been demonstrated that improvements can be made to cleaning processes with fluorescent markers through a simpler approach that provides a qualitative efficiency measurement of the cleaning process. Measurement of surface hygiene using ATP bioluminometers is thought to provide a more quantitative surrogate of surface cleanliness.

Relaparotomy: a five-year review of indications and outcome

Complications from abdominal surgery may necessitate reoperation and can be associated with significant morbidity and mortality. This review aims to analyse the incidence and outcome of relaparotomy for various indications. In a retrospective review of case notes of patients who had undergone one or more relaparotomies during the same hospitalisation between 1996 and 2000, 55 patients required relaparotomy. Indications included bleeding, infection, anastomotic leakage, wound dehiscence, necrotising pancreatitis, bowel necrosis, bowel obstruction and miscellaneous indications. Relaparotomy for dehiscence and obstruction carried minimal risk; for bleeding and infection entailed moderate risks; and for anastomotic leak had the highest mortality rate. The mortality rate increased in older age groups, multiple system and organ failure and multiple relaparotomies. The overall mortality rate was 38%. Twenty-nine per cent of patients had MRSA infection contributing to sepsis and multiple system and organ failure. Reintervention had brought to evidence technical errors, which could be corrected, and resulted in patient salvage in some cases. The mortality rate of relaparotomy has remained unchanged compared with data published previously, despite improvements in surgical techniques and critical care. Timely relaparotomy is valuable in the identification and treatment of complications following abdominal surgery.

'Catastrophic' antiphospholipid syndrome

When 'catastrophic' is applied as an adjective to the antiphospholipid syndrome, it implies a characteristic presentation due to predominantly small blood vessel thrombosis leading to rapidly progressive failure of multiple organs and a frequently fatal outcome. We present the case of a 48-year-old woman who presented with the 'catastrophic' antiphospholipid syndrome without previous history of coagulation disorder or connective tissue disease that illustrates the difficulties in diagnosing and managing this disorder. We also review the factors that have been reported to have a role in the development of this condition and show how this case throws light on its pathogenesis.

Deterioration of cold-stored tissue specimens due to lipid peroxidation: modulation by antioxidants at high subzero temperatures

It is often necessary to store tissue specimens in subzero conditions for assay in batches. During storage at -20 degrees C we found that sufficient lipid peroxidation occurred in rat liver homogenates in phosphate-buffered saline to affect subsequent malondialdehyde assays. This peroxidation did not occur at -196 degrees C. The ratio of oxidized to reduced glutathione increased with storage at -20 degrees C and the level of conjugated dienes increased progressively. The addition of a specific free radical scavenger, superoxide dismutase (200 u/ml) reduced the level of malondialdehyde (P < 0.001) during -20 degrees C storage for periods of 28 days but failed to prevent the changes in the glutathione ratio or dienes. Storage in a less specific free radical scavenger, 0.25 molar sucrose/EDTA, instead of phosphate-buffered saline totally prevented the malondialdehyde production over similar storage periods.

Complications of percutaneous endoscopic enterostomy tubes

Percutaneous endoscopic gastrostomy and jejunostomy tubes have been used clinically for approximately 10 years. They have been used predominantly in patients who cannot sustain their weight by oral intake, such as individuals with abnormalities of swallowing or intestinal peristalsis. The percutaneous endoscopic method of placement confers some advantages over classical surgical placement, especially in poor risk cases. Although several types of tube are commercially available, a substantial complication rate is still directly attributable to the tubes. In some series, complications are reported in 70% of cases. This report describes two complications of endoscopically introduced jejunostomy tubes used in patients with Roux-en-Y reconstructions after previous multiple gastric surgical procedures.

Use of the de Pezzer catheter to facilitate endoanal pull-through during ileal pouch-anal anastomosis

Ileal pouch-anal anastomosis is now the treatment of choice for selected patients requiring proctocolectomy for benign mucosal disease of the large intestine. Pelvic sepsis continues to be a major postoperative complication. This is often subsequent to the technical complexity of the intestinal pull-through and ileal pouch-anal anastomosis. We report the use of the de Pezzer catheter to facilitate this often difficult reservoir pull-through during restorative proctocolectomy. This is an inexpensive and simple aid which has consistently helped to decrease operative difficulty, especially where pelvic access is restricted. By enabling the avoidance of clamps and tissue forceps, it has reduced the incidence of contamination and tissue trauma. It has enabled pull-through without undue tension on the reservoir and has facilitated postoperative drainage of the reservoir.

Small intestinal perforation following minor trauma

Small intestinal perforation occurred in two patients aged 70 years and 88 years who had experienced minor trauma by tripping or falling on the pavement. They both developed signs of generalized peritonitis and at laparotomy were found to have perforated the mid ileum. There was no sign of direct abdominal trauma but they had suffered minor facial trauma as a result of the fall.

Neonatal and adult copper-64 metabolism in the pig and the possible relationship between the ontogeny of copper metabolism and Wilson's disease

The copper profiles of neonatal mammals differ from those of the adult; in man they are similar to those found in people with Wilson's disease (WD). WD patients handle an intravenous bolus of radioactive copper in a characteristic manner which aids diagnosis. In view of the similarity between neonatal mammals and WD patients, we have studied the fate of an intravenous bolus of 64Cu injected into neonatal and adult pigs. In adult pigs, plasma 64Cu activity fell for 10 h and then slowly increased over the next 14 h as newly synthesised caeruloplasmin was secreted. In the neonate a secondary rise in 64Cu activity was not observed. Gel filtration of the soluble supernatant revealed significant differences in the association of 64Cu with hepatic copper proteins. In adults 64Cu associated predominantly with superoxide dismutase whilst in the neonate the 64Cu associated with metallothionein and a protein of high molecular weight. This study indicates that 64Cu export from the neonatal pig liver is in many ways similar to that found in WD. Additionally, there are similarities in the profile of hepatic 64Cu-binding proteins.