Assessment of test methods for evaluating effectiveness of cleaning flexible endoscopes

Impact of water quality on reprocessing equipment: Assessment of neurosurgical instruments cleaning and biofilm formation in hospital pipes

Background

The presence of contamination and microorganisms at any stage of processing renders a method unsafe, leading to a high risk of cross-transmission and cross-infection.

Objective

The objective of this study was to assess the cleaning quality of aspirator instruments used in neurosurgical procedures.

Methods

The experimental study was conducted at the materials and sterilization center, as well as the microbiology laboratory, of a philanthropic hospital in Brazil. A study protocol was implemented, which involved the analysis of 10 samples of Yasargil aspirators with varying dimensions. The samples were subjected to protein tests to detect the presence of organic matter and microbiological analysis. Descriptive statistics were used to analyze the data.

Results

The results indicated that 40% of the instruments tested positive for protein after manual cleaning. Furthermore, after automated cleaning, samples showed an increased microbiological load, with Escherichia coli accounting for 20% and Klebsiella aerogenes for 10% of the identified microorganisms.

Conclusion

This study provides evidence of failures in the cleaning process of healthcare products and highlights the presence of biofilm in the pipes, thereby compromising the drinking water quality standard.

Cleaning of in-hospital flexible endoscopes: Limitations and challenges

OBJECTIVE

to analyze the cleaning process of gastroscopes, colonoscopes and duodenoscopes in eight in-hospital health services.

METHOD

a cross-sectional study conducted with 22 endoscopes (eight gastroscopes, eight colonoscopes and six duodenoscopes), and microbiological analysis of 60 samples of air/water channels (all endoscopes) and elevator (duodenoscopes), in addition to protein testing. Descriptive statistics with calculation of frequencies and central tendency measures was used in data analysis.

RESULTS

the processing of 22 endoscopes was monitored with microbiological analysis for 60 channels. In the pre-cleaning procedure, in 82.3% (14/17) of the devices, gauze was used in cleaning the insertion tube. Incomplete immersion of the endoscope in detergent solution occurred in 72.3% (17/22) of the cases, and in 63.6% (14/22) there was no standardization of filling-in of the channels. Friction of the biopsy channel was not performed in 13.6% (3/22) of the devices. In the microbiological analysis, 25% (7/32) of the samples from the stored endoscopes were positive for microbial growth (from 2x101 to 9.5x104 CFU/mL), while after processing, contamination was 32% (9/28). Protein residues in the elevator channel were detected in 33% of duodenoscopes.

CONCLUSION

the results indicate important gaps in the stages of pre-cleaning and cleaning of endoscopes that, associated with presence of protein residues and growth of microorganisms of epidemiological importance, indicate limitations in safety of the processing procedures, which can compromise the disinfection processes and, consequently, their safe use among patients subjected to such tests.

No relation between adenosine triphosphate after manual cleaning and presence of microorganisms on endoscopes after automated high-level disinfection

Background and study aims  Adenosine triphosphate (ATP) tests are increasingly used to detect biological material; however, their reliability to detect bacterial contamination in endoscopes is not proven. We investigated the predictive value of ATP tests after manual cleaning for presence or absence of microorganisms as shown by culture after automated high-level disinfection (HLD) in duodenoscopes and linear echoendoscopes (DLEs). Patients and methods  After manual cleaning, ATP tests were performed on swab samples taken from the detachable cap and forceps elevator, and on flush samples of the DLE working channels. These results were compared to the growth of any microorganisms in cultures acquired after automated HLD. ATP tests with > 200 relative light units (RLU) were considered positive. Receiver operator characteristic (ROC) curves were used to compare the RLU levels with microbial presence in cultures. Results  In total, 903 procedures were performed involving 26 distinct DLEs. Depending on sample site, 20.8 % (cap) to 63.8 % (channel brush) of the ATP negative samples were accompanied by positive post-HLD cultures. 54.4 % of the cap samples with a positive culture (growth of any kind of microorganism) and 91.8 % of the channel samples with a positive culture had a negative ATP test after manual cleaning. ROC curves per sample site, DLE type and microorganism type all had area under the curves below 0.6. Conclusions  In our study, ATP tests performed after manual cleaning could not predict presence or absence of microorganisms after automated HLD as shown by culture. More than half of the positive cultures were preceded by a negative ATP test.

Assessment of postmanual cleaning adenosine triphosphate tests to prevent the use of contaminated duodenoscopes and linear echoendoscopes: the DETECT study

BACKGROUND AND AIMS

We investigated whether the use of postmanual cleaning adenosine triphosphate (ATP) tests lowers the number of duodenoscopes and linear echoendoscopes (DLEs) contaminated with gut flora.

METHODS

In this single-center before-and-after study, DLEs were ATP tested after cleaning. During the control period, participants were blinded to ATP results: ATP-positive DLEs were not recleaned. During the intervention period, ATP-positive DLEs were recleaned. DLEs underwent microbiologic sampling after high-level disinfection (HLD) with participants blinded to culture results.

RESULTS

Using 15 endoscopes of 5 different DLE types, we included 909 procedures (52% duodenoscopes, 48% linear echoendoscopes). During the intervention period, the absolute rate of contamination with gut flora was higher (16% vs 21%). The main analysis showed that contamination was less likely to occur in the intervention period (odds ratio, .32; 95% credible interval [CI], .12-.85). A secondary analysis showed that this effect was based on 1 particular duodenoscope type (estimated probability, 39% [95% CI, 18%-64%] vs 9% [95% CI, 2%-21%]), whereas no effect was seen in the other 4 DLE types. In detail, of the 4 duodenoscopes of this type, 2 had lower contamination rates (69% vs 39% and 36% vs 10%). During the control period, both these duodenoscopes had multiple episodes with ongoing contamination with the same microorganism that ended weeks before the start of the intervention period (ie, they were not terminated by ATP testing).

CONCLUSIONS

Postmanual cleaning ATP tests do not reduce post-HLD gut flora contamination rates of DLEs. Hence, postcleaning ATP tests are not suited as a means for quality control of endoscope reprocessing.

Limpieza de endoscopios flexibles intrahospitalarios: limitaciones y desafíos

Resumen Objetivo: analizar el proceso de limpieza de gastroscopios, colonoscopios y duodenoscopios en ocho servicios de salud intrahospitalarios. Método: estudio transversal con 22 endoscopios, de los cuales ocho eran gastroscopios, ocho colonoscopios y seis duodenoscopios, y análisis microbiológico de 60 muestras de los canales de aire/agua (todos los endoscopios) y elevador (duodenoscopios), además de prueba de proteínas. En el análisis de los datos se utilizó estadística descriptiva, con cálculo de frecuencias y medidas de tendencia central. Resultados: el procesamiento de los 22 endoscopios fue monitoreado con el análisis microbiológico de 60 canales. En la prelimpieza, en el 82,3% (14/17) de los equipos se utilizó gasa para limpiar el tubo de inserción. En el 72,3% (17/22) de los casos la inmersión del endoscopio en solución detergente fue incompleta y en el 63,6% (14/22) no hubo estandarización del llenado de los canales. La fricción del canal de biopsia no se realizó en el 13,6% (3/22) de los equipos. En el análisis microbiológico, el 25% (7/32) de las muestras endoscópicas almacenadas dio positivo para crecimiento microbiano (2x101 a 9,5x104 UFC/ml), mientras que después del procesamiento, la contaminación fue del 32% (9/28). Se detectaron residuos de proteína en el canal elevador en el 33% de los duodenoscopios. Conclusión: los resultados indican que hay importantes lagunas en las etapas de prelimpieza y limpieza de los endoscopios que, junto con la presencia de residuos de proteínas y del crecimiento de microorganismos de importancia epidemiológica, indican limitaciones en la seguridad del procesamiento, que pueden comprometer los procesos de desinfección y, por ende, el uso seguro en los pacientes que se someten a esos procedimientos.

Limpeza de endoscópios flexíveis intra-hospitalares: limitações e desafios

Resumo Objetivo: analisar o processo de limpeza de gastroscópios, colonoscópios e duodenoscópios em oito serviços de saúde intra-hospitalar. Método: estudo transversal com 22 endoscópios, sendo oito gastroscópios, oito colonoscópios e seis duodenoscópios, e análise microbiológica de 60 amostras dos canais de ar/água (todos os endoscópios) e elevador (duodenoscópios), além de teste de proteína. Na análise dos dados, utilizou-se estatística descritiva, com cálculo de frequências e medidas de tendência central. Resultados: o processamento de 22 endoscópios foi acompanhado com análise microbiológica de 60 canais. Na pré-limpeza, em 82,3% (14/17) dos equipamentos, foi utilizada gaze na limpeza do tubo de inserção. A imersão incompleta do endoscópio em solução detergente ocorreu em 72,3% (17/22) dos casos, e em 63,6% (14/22) não havia padronização do preenchimento dos canais. A fricção do canal de biópsia não foi realizada em 13,6% (3/22) dos equipamentos. Na análise microbiológica, 25% (7/32) das amostras dos endoscópios armazenados foram positivas para crescimento microbiano (2x101 a 9,5x104 UFC/mL), enquanto após o processamento, a contaminação foi de 32% (9/28). Resíduos de proteína no canal do elevador foram detectados em 33% dos duodenoscópios. Conclusão: os resultados apontam lacunas importantes nas etapas de pré-limpeza e limpeza dos endoscópios que, associadas à presença de resíduos de proteína e ao crescimento de microrganismo de importância epidemiológica, sinalizam limitações na segurança do processamento, que podem comprometer os processos de desinfecção e consequentemente seu uso seguro entre pacientes submetidos a tais exames.

Turbulent fluid flow is a novel closed-system sample extraction method for flexible endoscope channels of various inner diameters

OVERVIEW

Effective sample extraction from endoscope channels is crucial for monitoring manual cleaning adequacy as well as for ensuring optimal sensitivity for culture after disinfection. The objective of this study was to compare the efficacy of Turbulent Fluid Flow (TFF) to Flush (F) or Flush-Brush-Flush (FBF) methods.

MATERIALS & METHODS

Pseudomonas aeruginosa and Enterococcus faecalis in artificial test soil-2015 (ATS2015) were used as bacterial markers while protein and carbohydrate were the organic markers for biofilm formed inside 3.2-mm and 1.37-mm polytetrafluoroethylene (PTFE) channels. TFF was generated using compressed air and sterile water to provide friction for sample extraction. Extraction for biofilm coated PTFE channels as well as for colonoscope channels perfused with ATS2015 containing 108 CFU/mL P. aeruginosa, E. faecalis and Candida albicans was determined using TFF compared to FBF and F.

RESULTS

The extraction ratio for P. aeruginosa and E. faecalis from biofilm extracted by TFF compared to the positive control was significantly better than F for 1.37-mm channels (≥0.94 for both bacteria by TFF versus 0.69 to 0.72 by F for P. aeruginosa and E. faecalis, respectively) but not significantly different between TFF and FBF for 3.2-mm channels. F was also ineffective for extraction of protein and carbohydrate from 1.37-mm channels. Extraction efficacy by TFF from inoculated colonoscope channels was >98% for all test markers.

CONCLUSIONS

The novel TFF method for extraction of samples from colonoscope channels is a more effective method than the existing FBF and F methods.

What's new in reprocessing endoscopes: Are we going to ensure "the needs of the patient come first" by shifting from disinfection to sterilization?

Millions of gastrointestinal endoscopes are performed each year in the United States. Gastrointestinal endoscopes become highly contaminated during use (ie, internal channels contain 7-10-log₁₀ enteric microorganisms). Currently, endoscopes (eg, bronchoscopes and gastrointestinal endoscopes) are classified as semicritical items because they contact intact mucous membranes and most commonly undergo cleaning followed by high-level disinfection, which may result in as little as a 6-log₁₀ reduction of microorganisms. Therefore, and not surprisingly, in recent years there have been multiple reports that have documented that endoscopes, especially duodenoscopes, frequently remain contaminated with bacterial pathogens after proper cleaning and disinfection. Multiple outbreaks of multidrug-resistant organisms from contaminated duodenoscopes have resulted in substantial death and morbidity. Because duodenoscopes commonly contact nonintact mucous membranes and sterile tissue, such endoscopes should be considered critical items. We propose that to ensure patient safety, we follow the Spaulding scheme and move from high-level disinfection to sterilization of reusable endoscopes or use an alternative diagnostic/therapeutic method (eg, disposable sterile endoscopes).

Evaluation of an overnight non-culture test for detection of viable Gram-negative bacteria in endoscope channels

Background and study aims  Prevention of infection transmission from contaminated endoscopes would benefit from a rapid test that could detect low levels of viable bacteria after high level disinfection. The aim of this study was to evaluate the rapid NOW! (RN) test's ability to detect endoscope contamination. Materials and methods  The RN test kit and the accompanying fluorometer were evaluated. The manufacturer states that a fluorometer signal > 300 units is indicative of viable Gram-negative bacteria. Suspension testing of varying concentrations of Escherichia coli, Pseudomonas aeruginosa and Enterococcus faecalis were used to determine the RN test limit of detection. Simulated-use testing was done using a duodenoscope inoculated with 10 % blood containing approximately 35 CFU E. coli per channel. Samples were extracted from the duodenoscope instrument channel and tested using the manufacturer's instructions. Results  The RN test could consistently detect 10 CFU of E. coli and P. aeruginosa (fluorescent signal of 9,000 to 11,000 units) but not E. faecalis. Sensitivity and specificity for Gram-negative bacteria were 93 % and 90 %, respectively, using all of the suspensions in the study. Extraction of E. coli from an inoculated duodenoscope instrument channel repeatedly provided a positive signal (i. e. > 2,000 units). Conclusions  The RN test can reliably detect low levels of Gram-negative bacteria in suspension as well as from samples extracted from endoscope channels. These preliminary findings are encouraging but further assessment of extraction efficacy, impact of organic residuals and clinical workflow are still needed.