Gastrointestinal endoscopy decontamination failure and the risk of transmission of blood-borne viruses: a review

Meta-analysis: risk of hepatitis C virus infection associated with hospital-based invasive procedures

BACKGROUND

Healthcare settings, where invasive procedures are frequently performed, may play an important role in the transmission dynamics of blood-borne pathogens when compliance with infection control precautions is suboptimal.

AIMS

To understand and quantify the role of hospital-based invasive procedures on hepatitis C virus (HCV) transmission.

METHODS

We conducted a systematic review and meta-analysis to identify recent studies reporting association measures of HCV infection risk that are linked to iatrogenic procedures. Based on expert opinion, invasive procedures were categorised into 10 groups for which pooled measures were calculated. Finally, the relationship between pooled measures and the country-level HCV prevalence or the Healthcare Access and Quality (HAQ) index was assessed by meta-regression.

RESULTS

We included 71 studies in the analysis. The most frequently evaluated procedures were blood transfusion (66 measures) and surgery (43 measures). The pooled odds ratio (OR) of HCV infection varied widely, ranging from 1.46 (95% confidence interval: 1.14-1.88) for dental procedures to 3.22 (1.7-6.11) for transplantation. The OR for blood transfusion was higher for transfusions performed before 1998 (3.77, 2.42-5.88) than for those without a specified/recent date (2.20, 1.77-2.75). In procedure-specific analyses, the HCV infection risk was significantly negatively associated with the HAQ for endoscopy and positively associated with HCV prevalence for endoscopy and surgery.

CONCLUSIONS

Various invasive procedures were significantly associated with HCV infection. Our results provide a ranking of procedures in terms of HCV risk that may be used for prioritisation of infection control interventions, especially in high HCV prevalence settings.

Risk Communication After Health Care Exposures: An Experimental Vignette Survey With Patients

Purpose. We investigated how health care systems should communicate with patients about possible exposures to blood-borne pathogens that may have occurred during their care. Our goal was to determine how best to communicate uncertain risk information in a way that would minimize harm to patients, maintain their trust, and encourage patients to seek follow-up treatment. Methods. Participants (N = 1103) were randomized to receive one of six vignette surveys; 997 (98.4%) responded. All vignettes described the same event, but differed by risk level and recommendations (lower risk v. higher risk) and by communication mode (telephone, letter, social media). We measured participants’ perceived risk of blood-borne infection, trust in the health care system, and shared decision making about next clinical steps. Open-ended questions were analyzed using grounded thematic analysis. Results. When the vignette requested patients to undergo testing and practice certain health behaviors (higher risk), participants’ likelihood of seeking follow-up testing for blood-borne pathogens and their understanding of health issues increased. Perceived trust was unaffected by risk level or communication processes. Qualitative data indicated a desire for telephone communication from providers known to the patient. Limitations. It is not clear whether higher risk language or objective risk levels in vignettes motivated patients’ behavioral intentions. Conclusion. Using higher risk language when disclosing large-scale adverse events increased participants’ willingness to seek follow-up care. Implications. Health care organizations’ disclosures should focus on the next steps to take after health care exposures. This communication should involve helping patients to understand their personal health issues better, make them feel that they know which steps to take following the receipt of this information, and encouraging them to seek follow-up infectious disease testing in order to better take care of themselves.

Reprocessing semicritical items: Outbreaks and current issues

Semicritical medical devices are defined as items that come into contact with mucous membranes or nonintact skin (eg, gastrointestinal endoscopes, endocavitary probes). Such medical devices require minimally high-level disinfection. As many of these items are temperature sensitive, low-temperature chemical methods must be used rather than steam sterilization. Strict adherence to current guidelines is required as more outbreaks have been linked to inadequately cleaned or disinfected endoscopes and other semicritical items than any other reusable medical devices.

Is an endoscopic examination associated with transfusion-transmissible infections? A systematic review and meta-analysis

BACKGROUND

The purpose of a donor medical questionnaire is to identify the blood donor's history relative to the current known blood-safety risks. A temporary deferral from blood donation after an endoscopic examination is enforced because of the reusable nature of the endoscope and close contact with the inner body. The objective of this systematic review was to find the best available evidence on the association between an endoscopic examination and the risk of transfusion-transmissible infections.

METHODS

Studies from five databases investigating the link between an endoscopic examination and transfusion-transmissible infections (hepatitis B virus, hepatitis C virus, human immunodeficiency virus infection, Treponema pallidum) were retained and assessed independently by two reviewers. The association between endoscopy and transfusion-transmissible infections was identified by conducting meta-analyses and calculating pooled effect measures (odds ratios and 95% confidence intervals). The Grading of Recommendations, Assessment, Development, and Evaluation methodology was used to assess the quality of evidence.

RESULTS

We identified 7571 references and finally included 29 observational studies. A significant association between an endoscopic examination and hepatitis B virus infection (pooled odds ratio [OR], 2.21; 95% confidence interval [CI], 1.26-3.86; p = 0.005) or hepatitis C virus infection (pooled OR 1.76, 95% CI, 1.45-2.14; p < 0.00001) was found. The level of evidence was considered as "very low" due to the type of study design (i.e., observational) and indirect study populations (i.e., no blood donor populations).

CONCLUSION

An endoscopic examination is associated with an increased hepatitis B virus or hepatitis C virus infection risk. Further high-quality trials are required to formulate stronger evidence-based recommendations on endoscopic examination as a blood donor deferral criterion.

Infectious diseases linked to cross-contamination of flexible endoscopes

Flexible endoscopes are widely used to examine, diagnose, and treat medical disorders. While the risk of endoscopy-related transmission of infection is estimated to be very low, more health care-associated infections are related to contaminated endoscopes than to any other medical device. Flexible endoscopes can get highly contaminated with microorganisms, secretions and blood during use. The narrow lumens and multiple internal channels make the cleaning of flexible endoscopes a complex and difficult task. Despite the availability of international, national and local endoscope reprocessing guidelines, contamination and transmission of microorganisms continue to occur. These transmissions are mostly related to the use of defective equipment, endoscope reprocessing failures, and noncompliance with recommended guidelines. This article presents an overview of publications about case reports and outbreaks related to contamination of flexible endoscopes.

[Disinfection and recontamination of rigid endoscopes: improved safety using an immersion quiver system]

BACKGROUND

In Otorhinolaryngology, rigid endoscopes are used daily at a high frequency. There is no consensus for reprocessing these medical instruments. Often immersion disinfection procedures are used. The present study examined the possible risk of recontamination by this disinfection method and investigated the possibility of avoiding this risk by using a new immersion quiver system.

METHODS

Using coloured markers, a possible contact of the endoscope with the top edges of quivers of different diameters during endoscope removal was tested for. In addition, it was evaluated whether Staphylococcus aureus transfer is possible via this route. The same methodology was applied to a new immersion quiver system.

RESULTS

Whenever removing the rigid endoscopes from the conventional quiver, these touched the top of the quiver, regardless of its diameter. A transfer of Staphylococcus aureus from the quiver to the endoscope via this route could be detected in five out of eight attempts. During endoscope removal from the new immersion quiver system, no contact of the endoscope with the outer quiver occurred in 20 passes. In none of eight trials was a transfer of Staphylococcus aureus from previously contaminated immersion quivers to the endoscope shown; all immersion quivers were sterile after disinfection.

DISCUSSION

After conventional immersion disinfection, recontamination of rigid endoscopes by a contaminated quiver edge is possible. An immersion quiver system can resolve this risk of recontamination easily, by decontaminating not only the endoscope, but also the immersion quiver (inner quiver) itself in the disinfectant solution.

Public health response to a large-scale endoscopy infection control lapse in a nonhospital clinic

In 2011, a nonhospital endoscopy clinic in Ottawa, Ontario, was found to have numerous lapses in infection control procedures during an inspection by the College of Physicians and Surgeons of Ontario. The public was notified and patients who had undergone procedures at the clinic were offered testing for blood-borne pathogens. This article describes the procedure that was followed in response to the lapse, and reports the results of the tests for blood-borne pathogens as well as analyses conducted to determine whether any infections occurred as a result of the infection control lapse.

OBJECTIVE:

To determine whether transmission of blood-borne pathogens (BBPs) (hepatitis B virus [HBV], hepatitis C virus [HCV] and HIV) occurred as a result of endoscopy reprocessing failures identified during an inspection of a nonhospital endoscopy clinic in 2011.

METHODS:

The present analysis was a retrospective cohort study. Registered notification letters were mailed to 6992 patients who underwent endoscopy from 2002 to 2011 at one Canadian nonhospital endoscopy clinic, informing them of the infection control lapse and offering BBP testing. Multimedia communications and a telephone line supplemented notification. A retrospective study of patients with BBPs was performed with viral genetic testing and risk factor assessment for eligible patients. Risk for infection among patients whose procedure was within seven days of a known positive patient was compared with those whose procedure was performed more than seven days after a known postive patient. The seven-day period was selected as the period most likely to present a risk for transmission based on the documented cleaning procedures at the clinic and the available literature on virus survival.

RESULTS:

Ninety-five percent (6628 of 6992) of patients/estates were contacted and 5042 of 6728 (75%) living patients completed BBP testing. Three were newly diagnosed with HBV and 14 with HCV. Twenty-three and 48 tested positive for previously known HBV or HCV, respectively, 367 were immune to HBV due to natural infection and one was immune to HBV due to immunization. None tested positive for HIV. Sequencing did not reveal any relationships among the 46 unique case patients with viral genetic test results available. Ninety-three percent of patients reported alternative risk factors for BBP. An increased risk for infection among those who underwent a procedure within seven days of a known HBV or HCV case was not demonstrated.

CONCLUSIONS:

Endoscopy reprocessing failures were not associated with an increased risk for BBP among individuals tested.

Results from a Large-Scale Epidemiologic Look-Back Investigation of Improperly Reprocessed Endoscopy Equipment

Objective.

To determine whether improper high-level disinfection practices during endoscopy procedures resulted in bloodborne viral infection transmission.

Design.

Retrospective cohort study.

Setting.

Four Veterans Affairs medical centers (VAMCs).

Patients.

Veterans who underwent colonoscopy and laryngoscopy (ear, nose, and throat [ENT]) procedures from 2003 to 2009.

Methods.

Patients were identified through electronic health record searches and serotested for human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV). Newly discovered case patients were linked to a potential source with known identical infection, whose procedure occurred no more than 1 day prior to the case patient's procedure. Viral genetic testing was performed for case/proximate pairs to determine relatedness.

Results.

Of 10,737 veterans who underwent endoscopy at 4 VAMCs, 9,879 patients agreed to viral testing. Of these, 90 patients were newly diagnosed with 1 or more viral bloodborne pathogens (BBPs). There were no case/proximate pairings found for patients with either HIV or HBV; 24 HCV case/proximate pairings were found, of which 7 case patients and 8 proximate patients had sufficient viral load for further genetic testing. Only 2 of these cases, both of whom underwent laryngoscopy, and their 4 proximates agreed to further testing. None of the 4 remaining proximate patients who underwent colonoscopy agreed to further testing. Mean genetic distance between the 2 case patients and 4 proximate patients ranged from 13.5% to 19.1%.

Conclusions.

Our investigation revealed that exposure to improperly reprocessed ENT endoscopes did not result in viral transmission in those patients who had viral genetic analysis performed. Any potential transmission of BBPs from colonoscopy remains unknown.

Results from a Large-Scale Epidemiologic Look-Back Investigation of Improperly Reprocessed Endoscopy Equipment

Objective.

To determine whether improper high-level disinfection practices during endoscopy procedures resulted in bloodborne viral infection transmission.

Design.

Retrospective cohort study.

Setting.

Four Veterans Affairs medical centers (VAMCs).

Patients.

Veterans who underwent colonoscopy and laryngoscopy (ear, nose, and throat [ENT]) procedures from 2003 to 2009.

Methods.

Patients were identified through electronic health record searches and serotested for human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV). Newly discovered case patients were linked to a potential source with known identical infection, whose procedure occurred no more than 1 day prior to the case patient's procedure. Viral genetic testing was performed for case/proximate pairs to determine relatedness.

Results.

Of 10,737 veterans who underwent endoscopy at 4 VAMCs, 9,879 patients agreed to viral testing. Of these, 90 patients were newly diagnosed with 1 or more viral bloodborne pathogens (BBPs). There were no case/proximate pairings found for patients with either HIV or HBV; 24 HCV case/proximate pairings were found, of which 7 case patients and 8 proximate patients had sufficient viral load for further genetic testing. Only 2 of these cases, both of whom underwent laryngoscopy, and their 4 proximates agreed to further testing. None of the 4 remaining proximate patients who underwent colonoscopy agreed to further testing. Mean genetic distance between the 2 case patients and 4 proximate patients ranged from 13.5% to 19.1%.

Conclusions.

Our investigation revealed that exposure to improperly reprocessed ENT endoscopes did not result in viral transmission in those patients who had viral genetic analysis performed. Any potential transmission of BBPs from colonoscopy remains unknown.

Risk of Infections Associated with Improperly Reprocessed Transrectal Ultrasound–Guided Prostate Biopsy Equipment

Objective.

A hospital discovered a lapse in the reprocessing procedures for transrectal ultrasound-guided prostate biopsy equipment. An investigation was initiated to assess the risks of transmission of hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and bacteria during prostate biopsies.

Methods.

We offered testing for HBV, HCV, and HIV infection to patients who had undergone prostate biopsies from January 30, 2003, through January 27, 2006. We reviewed their medical records and obtained information on the reprocessing procedures that were in use at the time for the prostate biopsy equipment.

Setting.

A healthcare facility in Maine.

Results.

Of the 528 patients exposed to improperly reprocessed prostate biopsy equipment, none tested positive for HIV or HCV. Sixteen patients (3%) tested positive for past HBV infection but had no prebiopsy HBV serologic test results available (ie, transmission from improperly reprocessed biopsy equipment was possible), and 11 (2%) had evidence of postbiopsy bacterial infections. The number of cases of HBV and bacterial infections were within reported ranges for this population and were not clustered in time. Review of the reprocessing procedures in use at the time revealed that the manufacturer-recommended brushes for cleaning the reusable biopsy needle guide were never used. Brushes did not come with the equipment and had to be ordered separately.

Conclusions.

Despite the lack of evidence of pathogen transmission in this investigation, it is critical to review the manufacturer's reprocessing recommendations and to establish appropriate procedures to avert potential pathogen transmission and subsequent patient concerns. This investigation provides a better understanding of the risks associated with improperly reprocessed transrectal ultrasound prostate biopsy equipment and serves as a methodologic tool for future investigations.

Environmental survey to assess viral contamination of air and surfaces in hospital settings

The presence of pathogenic viruses in healthcare settings represents a serious risk for both staff and patients. Direct viral detection in the environment poses significant technical problems and the indirect indicators currently in use suffer from serious limitations. The aim of this study was to monitor surfaces and air in hospital settings to reveal the presence of hepatitis C virus, human adenovirus, norovirus, human rotavirus and torque teno virus by nucleic acid assays, in parallel with measurements of total bacterial count and haemoglobin presence. In total, 114 surface and 62 air samples were collected. Bacterial contamination was very low (<1 cfu/cm²) on surfaces, whereas the ‘medium’ detected value in air was 282 cfu/m³. Overall, 19 (16.7%) surface samples tested positive for viral nucleic acids: one for norovirus, one for human adenovirus and 17 (14.9%) for torque teno virus (TTV). Only this latter virus was directly detected in 10 air samples (16.1%). Haemoglobin was found on two surfaces. No relationship was found between viral, biochemical or bacterial indicators. The data obtained confirm the difficulty of assessing viral contamination using bacterial indicators. The frequent detection of TTV suggests its possible use as an indicator for general viral contamination of the environment.

Evaluation of a new selective medium, BD BBL CHROMagar MRSA II, for detection of methicillin-resistant Staphylococcus aureus in different specimens

The sensitivity of screening for methicillin-resistant Staphylococcus aureus (MRSA) can be improved by adding other specimen sites to nares. We describe an evaluation of a new selective medium, BBL CHROMagar MRSA II (CMRSAII), for its ability to detect MRSA from different specimen types. CMRSAII is a chromogenic medium which incorporates cefoxitin for the detection of MRSA. A study was performed at four clinical laboratories with the following specimens: 1,446 respiratory, 694 stool, 1,275 skin, and 948 wound specimens and 688 blood culture bottles containing Gram-positive cocci. The recovery of MRSA on traditional culture media was compared to results with CMRSAII. S. aureus was tested by cefoxitin disk diffusion. CMRSAII was interpreted as positive for MRSA at 24 h (range, 18 to 28 h) based solely on the visualization of mauve-colored colonies and at 48 h (range, 36 to 52 h) based on detection of mauve colonies with subsequent confirmation as S. aureus (by coagulase or latex agglutination testing). MRSA was recovered more frequently on CMRSAII (89.8% at 24 h and 95.6% at 48 h) than on traditional culture plates (83.1% at 24 h and 79.8% at 48 h) for all specimen types combined (P < 0.001). The percent sensitivities of CMRSAII at 24- and 48-h reads, respectively, were 85.5 and 92.4% for respiratory specimens, 87.9% and 98.3% for stool specimens, 88.4% and 96.1% for skin specimens, 92.1% and 94.6% for wound specimens, and 100% and 100% for positive blood cultures. The specificity was 99.8% for respiratory specimens and 100% for all others. In conclusion, CMRSAII is a reliable screening medium for multiple specimen types.

Clinical application of real-time PCR to screening critically ill and emergency-care surgical patients for methicillin-resistant Staphylococcus aureus: a quantitative analytical study

The clinical utility of real-time PCR screening assays for methicillin (methicillin)-resistant Staphylococcus aureus (MRSA) colonization is constrained by the predictive values of their results: as MRSA prevalence falls, the assay's positive predictive value (PPV) drops, and a rising proportion of positive PCR assays will not be confirmed by culture. We provide a quantitative analysis of universal PCR screening of critical care and emergency surgical patients using the BD GeneOhm MRSA PCR system, involving 3,294 assays over six months. A total of 248 PCR assays (7.7%) were positive; however, 88 failed to be confirmed by culture, giving a PPV of 65%. Multivariate analysis was performed to compare PCR-positive culture-positive (P+C+) and PCR-positive culture-negative (P+C-) assays. P+C- results were positively associated with a history of methicillin-sensitive Staphylococcus aureus infection or colonization (odds ratio [OR], 3.15; 95% confidence interval [CI], 1.32 to 7.54) and high PCR thresholds of signal intensity, indicative of a low concentration of target DNA (OR, 1.19 per cycle; 95% CI, 1.11 to 1.26). P+C- results were negatively associated with a history of MRSA infection or colonization (OR, 0.19; 95% CI, 0.09 to 0.42) and male sex (OR, 0.40; 95% CI, 0.20 to 0.81). P+C+ patients were significantly more likely to have subsequent positive MRSA culture assays and microbiological evidence of clinical MRSA infection. The risk of subsequent MRSA infection in P+C- patients was not significantly different from that in case-matched PCR-negative controls. We conclude that, given the low PPV and poor correlation between a PCR-positive assay and the clinical outcome, it would be prudent to await culture confirmation before altering infection control measures on the basis of a positive PCR result.

Molecular surveillance and population structure analysis of methicillin-susceptible and methicillin-resistant Staphylococcus aureus in high-risk wards

In this study we report the results of analysis of 253 isolates of Staphylococcus aureus (132 methicillin [meticillin]-resistant S. aureus [MRSA] isolates and 121 methicillin-susceptible S. aureus [MSSA] isolates) from 209 patients admitted to 18 high-risk wards of six hospitals located in Florence, Italy, over an 8-month period during which a program of epidemiological surveillance of hospital-acquired infections was conducted. The majority (69%) of the 87 reported S. aureus infections were caused by MRSA. No outbreak events have been reported. All the isolates were typed by amplified fragment length polymorphism (AFLP), and AFLP profiles were analyzed in order to define similarity groups. The discriminatory power of AFLP is very high with MSSA (Simpson index of diversity [D], 95.9%), whereas its resolution capability with MRSA (D, 44.7%) is hampered by the well-known high clonality of these populations (the main MRSA group accounted for 74% of the MRSA isolates). Combining AFLP, improved by visual inspection of polymorphisms, with multiplex PCR greatly increases MRSA resolution (D, 85.5%), resolving the MRSA population to a level that is one of the highest reported in the literature. Widespread and sporadic clones of MSSA and MRSA were identified, and their diffusion in the different hospitals and wards over the surveillance period was studied. The understanding of MSSA and MRSA population structures should be the starting point for the design of a more rational surveillance program for S. aureus species, maximizing benefits and reducing the cost of infection control strategies.

No evidence for patient-to-patient transmission of hepatitis C virus during upper gastrointestinal endoscopy: molecular studies on three acute hepatitis C patients

BACKGROUND

The risk of patient-to-patient transmission of hepatitis C virus (HCV) during endoscopy remains controversial. Using molecular approaches, we examined the possibility of patient-to-patient transmission of HCV in three patients who developed acute hepatitis C 1-6 months after examination by upper gastrointestinal endoscopy (UGIE) in a hospital endoscopy unit in Japan.

METHODS

For the source of HCV infection, we used frozen sera obtained from potential candidates who underwent UGIE earlier than three index patients on the same days in the same unit. HCV genotype was determined by multiplex polymerase chain reaction (PCR) with genotype-specific primers. The 1087-nucleotide (nt) sequence of the NS5B region of the HCV genome was compared between index patients and their HCV-viremic candidates.

RESULTS

The three index patients were exclusively infected with HCV of genotype 1b. Among a total of 60 candidate patients who underwent UGIE earlier than the index patients, 14 were positive for anti-HCV, of whom 12 had detectable HCV-RNA (1b, n = 9; 2a, n = 1; 2b, n = 2) on sera collected during each UGIE. Shared identity within the 1087-nt NS5B sequence was less than 95.0% between index patients and HCV/1b-infected candidates (n = 3, 1 and 5, respectively). None of the remaining 46 candidates who were negative for anti-HCV at UGIE examination tested positive for HCV-RNA, nor seroconverted to anti-HCV on their sera, which most likely excludes the possibility of HCV viremia despite the anti-HCV-negative serology at UGIE examination.

CONCLUSION

The present study suggests that patient-to-patient transmission of HCV during UGIE is infrequent.

Transmission of hepatitis C virus in an orthopedic hospital ward

Healthcare-associated infections with hepatitis C virus (HCV) hitherto have been observed mainly in hemodialysis settings as well as in hematology and oncology wards. In this communication, molecular and epidemiologic investigations to elucidate an HCV outbreak in an orthopedic ward are reported. One hundred and thirty-five patients hospitalized in the ward and 104 staff members were tested. In addition to extensive epidemiologic reviews and hygienic inspections, direct sequencing of HCV PCR fragments and phylogenetic analysis of more than 300 partial HCV sequences obtained by end-point limiting-dilution real-time PCR assay were carried out. Six patients were infected with very closely related HCV variants. Patient-to-patient spread of the virus was inferred to have started from one patient with previous HCV infection to the other five patients during their hospital stay. Inspections did not reveal substantial breaches in basic infection control practices and did not identify a specific activity that might have led to nosocomial transmission. As a result of the investigations, the hospital corrected the documentation of all medical and nursing activities undertaken in the ward, abandoned the use of all multidose saline and other medication vials, and included explicitly recommendations for the safe preparation and administration of injectable drugs into internal infection control guidelines. Thereafter, no further nosocomial transmissions of HCV have been recorded in the orthopedic ward. The events observed suggest that nosocomial transmission of HCV is not limited to hemodialysis, hematology or oncology settings, and they also reinforce the mandatory adherence to basic infection control practices.

Endoscopy-related infection: relic of the past?

PURPOSE OF REVIEW

Recent outbreaks of nosocomial infection and pseudoinfection have been linked to contaminated endoscopes. This review summarizes the recent literature, analyzes the latest published information related to the epidemiology, examines potential causes for the outbreaks, and discusses current alternatives for preventing infection.

RECENT FINDINGS

A systematic follow-up of patients revealed that the risk of infection attributed to inadequate endoscope reprocessing was very low. Nevertheless, inadequate reprocessing practices are still considered the main culprit underlying contamination from endoscopy procedures. Moreover, standards of care are difficult to maintain given the numerous inconsistencies that exist among reprocessing guidelines and manufacturer's recommended practices. Exposure to contaminated equipment could be prevented through better reprocessing practices and adherence to decontamination guidelines. Recent literature reinforces the need for endoscopy drying after each reprocessing cycle, endoscope reprocessing after short periods of disuse, surveillance, and for a coordinated approach to handle postcontamination responses. Additional analyses such as health technology assessment and cost analysis are needed to identify control alternatives that are most effective.

SUMMARY

Although the risk of endoscopy-related infection is very low, continued efforts are needed to ensure that quality is maintained during endoscope reprocessing to reduce the incidence of endoscopy-related infections.

Sensitivities of nasal and rectal swabs for detection of methicillin-resistant Staphylococcus aureus colonization in an active surveillance program

All medical and high-risk surgical patients were screened for methicillin-resistant Staphylococcus aureus colonization over 3.5 years. The sensitivities of nasal and rectal swabs were 68% and 62%, respectively. Naris and open-skin-site swabs detected 467 (74%) of 627 adult carriers identified. Rectal swabs detected an additional 160 (26%) carriers.

Antimicrobial and barrier effects of silver against methicillin-resistant Staphylococcus aureus

OBJECTIVE

Two strains of methicillin-resistant Staphylococcus aureus (MRSA), termed epidemic strains (EMRSA-15 and EMRSA-16), were used to evaluate the antimicrobial and barrier effect of four silver dressings (two silver donating and two non-silver-donating) available in the UK at the time of the study.

METHOD

The moist surface of a blood agar plate was covered with 10(6) colony-forming units of the respective strain of MRSA, and dressings were applied to the surface and incubated at 37 degrees C for different time periods and the upper and lower surfaces subcultured for residual growth.

RESULTS

The nanocrystalline dressings (silver donating) were effective as a barrier from one hour until the study end (72 hours): no penetration of EMRSA-15 and EMRSA-16 through the dressing occurred. Moreover, the nanocrystalline dressings showed some antimicrobial activity at one hour in the areas underneath and surrounding the dressing until the study end. The remaining two dressings had no barrier effect and only demonstrated limited antimicrobial activity after 24 hours.

CONCLUSION

This in vitro study suggests that the nanocrystalline dressings are more effective than other silver dressings in terms of providing a barrier function and antimicrobial activity against EMRSA-15 and EMRSA-16.