On the difficulties of isolating Clostridium difficile from hospital environments

How to carry out microbiological sampling of healthcare environment surfaces? A review of current evidence

There is increasing evidence that the hospital surface environment contributes to the spread of pathogens. However, evidence on how best to sample these surfaces is inconsistent and there is no guidance or legislation in place on how to do this. The aim of this review was to assess current literature on surface sampling methodologies, including the devices used, processing methods, and the environmental and biological factors that might influence results. Studies published prior to March 2019 were selected using relevant keywords from ScienceDirect, Web of Science, and PubMed. Abstracts were reviewed and all data-based studies in peer-reviewed journals in the English language were included. Microbiological air and water sampling in the hospital environment were not included. Although the numbers of cells or virions recovered from hospital surface environments were generally low, the majority of surfaces sampled were microbiologically contaminated. Of the organisms detected, multidrug-resistant organisms and clinically significant pathogens were frequently isolated and could, therefore, present a risk to vulnerable patients. Great variation was found between methods and the available data were incomplete and incomparable. Available literature on sampling methods demonstrated deficits with potential improvements for future research. Many of the studies included in the review were laboratory-based and not undertaken in the real hospital environment where sampling recoveries could be affected by the many variables present in a clinical environment. It was therefore difficult to draw overall conclusions; however, some recommendations for the design of routine protocols for surface sampling of healthcare environments can be made.

Establishment of an environmental microbiological monitoring program in a mice barrier facility

Rodents used in biomedical research are maintained behind barriers to exclude microbial contaminants. Several check points have to be monitored to eliminate the potential of introducing adventitious agents into the facility. Microbiological monitoring of a mouse facility environment enables to evaluate the efficiency of sanitization and cleaning procedures, air quality, and technician good practices. At our SPF mouse facility, we implemented an environmental microbiological monitoring program based in sedimentation and swabbing, inexpensive and easy to use methods. The aim of this work was to evaluate the results and the efficiency of the monitoring program after seven years. The median for bacteria and fungi counts in the SPF sampled areas was ≤2 CFU/2 h for settle plates and <1 CFU per swabbing plate, satisfying the requirements for grade C of the EU-GMP, with some modifications. The environmental monitoring program was useful to detect early warning of problems and enabled us to define a safe range of microbiological counts. In addition, SPF status defined for our mice was maintained throughout this study, confirmed by our HM program. This work could encourage directors and technicians of other mouse facilities in Latin America and rest of the world to implement this kind of program.

Clostridium difficile infection in pregnant and postpartum women in 2 hospitals and a review of literature

BACKGROUND

Healthcare-associated Clostridium difficile infection (CDI) in pregnant/postpartum women is underreported, especially outside of North America. We report a cluster of cases in 2 neighboring secondary care hospitals in South-East England. The objective of this study was to identify the epidemiology and risk factors for infection.

METHODS

An investigation into a cluster of cases of confirmed CDI in pregnant/postpartum women was performed over a 12-month period, from June 2016 to June 2017.

RESULTS

Eleven cases, in 10 patients, were identified, including 1 patient who had a relapse. Eight of 10 patients developed symptoms after hospital discharge. All patients had received broad-spectrum antibiotics prior to CDI onset. Environmental vectors, such as labor room mattresses, that were found difficult to effectively decontaminate after heavy contamination with blood, feces, and other body fluids may have been possible reservoirs. An infection control care bundle was successful in preventing further cases.

CONCLUSIONS

Antibiotic use and exposure to the organism in a contaminated labor room environment are likely risk factors for healthcare-associated CDI in postpartum women. Active surveillance is necessary to prevent these infections, as these cases often present after hospital discharge.

Use of RODAC plates to measure containment of Mycobacterium tuberculosis in a Class IIB biosafety cabinet during routine operations

OBJECTIVE/BACKGROUND

Guidelines for the manipulation of Mycobacterium tuberculosis (MTB) cultures require a Biosafety Level 3 (BSL-3) infrastructure and accompanying code of conduct. In this study, we aimed to validate and apply detection methods for viable mycobacteria from surfaces in a BSL-3 MTB laboratory.

METHODS

We evaluated phenotypic (Replicate Organism Detection and Counting [RODAC] plates) and molecular (propidium monoazide [PMA]-based polymerase chain reaction [PCR]) approaches for the detection of viable mycobacteria, as well as the effect of 70% ethanol applied for 5min for disinfection against mycobacteria. For validation of the method, recovery of serial dilutions of Mycobacterium bovis bacillus Calmette-Guérin from glass slides was measured. Subsequently, we stamped surfaces in and around the biosafety cabinet (BSC) after different technicians had manipulated high bacterial load suspensions for routine drug-susceptibility testing in a Class II BSC.

RESULTS

RODAC stamping could detect as few as three bacteria on slides stamped either 5min or 60min after inoculation. PMA-based PCR, tested in parallel, did not pass validation. Mycobacteria were still detected after 5-min disinfection with ethanol 70%. In the BSL-3, from 201 RODAC-stamped surfaces, MTB was detected in four: three inside a BSC-on a tube cap and on an operator's gloves-and one outside, on an operator's gown.

CONCLUSION

RODAC plates detect mycobacteria at low numbers of microorganisms. In addition, this method allowed us to show that 70% ethanol does not reliably kill mycobacteria when applied for 5min to a dried surface, and that MTB bacilli may arrive outside a Class II BSC during routine practice, although the route could not be documented.

A Novel Quantitative Sampling Technique for Detection and Monitoring of Clostridium difficile Contamination in the Clinical Environment

The horizontal transmission of Clostridium difficile in the hospital environment is difficult to establish. Current methods to detect C. difficile spores on surfaces are not quantitative, lack sensitivity, and are protracted. We propose a novel rapid method to detect and quantify C. difficile contamination on surfaces. Sponge swabbing was compared to contact plate sampling to assess the in vitro recovery of C. difficile ribotype 027 contamination (∼10(0), 10(1), or 10(2) CFU of spores) from test surfaces (a bed rail, a stainless steel sheet, or a polypropylene work surface). Sponge swab contents were concentrated by vacuum filtration, and the filter membrane was plated onto selective agar. The efficacy of each technique for the recovery of C. difficile from sites in the clinical environment that are touched at a high frequency was evaluated. Contact plates recovered 19 to 32% of the total contamination on test surfaces, whereas sponge swabs recovered 76 to 94% of the total contamination, and contact plates failed to detect C. difficile contamination below a detection limit of 10 CFU/25 cm(2) (0.4 CFU/cm(2)). In use, contact plates failed to detect C. difficile contamination (0/96 contact plates; 4 case wards), while sponge swabs recovered C. difficile from 29% (87/301) of the surfaces tested in the clinical environment. Approximately 74% (36/49) of the area in the vicinity of the patient was contaminated (∼1.34 ± 6.88 CFU/cm(2) C. difficile spores). Reservoirs of C. difficile extended to beyond the areas near the patient: a dirty utility room sink (2.26 ± 5.90 CFU/cm(2)), toilet floor (1.87 ± 2.40 CFU/cm(2)), and chair arm (1.33 ± 4.69 CFU/cm(2)). C. difficile was present on floors in ∼90% of case wards. This study highlights that sampling with a contact plate may fail to detect C. difficile contamination and result in false-negative reporting. Our sponge sampling technique permitted the rapid and quantitative measurement of C. difficile contamination on surfaces with a sensitivity (limit, 0 CFU) greater than that which is otherwise possible. This technique could be implemented for routine surface hygiene monitoring for targeted cleaning interventions and as a tool to investigate routes of patient-patient transmission in the clinical environment.

Evaluation of three enzyme immunoassays and a nucleic acid amplification test for the diagnosis of Clostridium difficile-associated diarrhea at a university hospital in Brazil

INTRODUCTION

Despite the known importance of Clostridium difficile as a nosocomial pathogen, few studies regarding Clostridium difficile infection (CDI) in Brazil have been conducted. To date, the diagnostic tests that are available on the Brazilian market for the diagnosis of CDI have not been evaluated. The aim of this study was to compare the performances of four commercial methods for the diagnosis of CDI in patients from a university hospital in Brazil.

METHODS

Three enzyme immunoassays (EIAs) and one nucleic acid amplification test (NAAT) were evaluated against a cytotoxicity assay (CTA) and toxigenic culture (TC). Stool samples from 92 patients with suspected CDI were used in this study.

RESULTS

Twenty-five (27.2%) of 92 samples were positive according to the CTA, and 23 (25%) were positive according to the TC. All EIAs and the NAAT test demonstrated sensitivities between 59 and 68% and specificities greater than 91%.

CONCLUSIONS

All four methods exhibited low sensitivities for the diagnosis of CDI, which could lead to a large number of false-negative results, an increased risk of cross-infection to other patients, and overtreatment with empirical antibiotics.

Detecting Clostridium difficile spores from inanimate surfaces of the hospital environment: which method is best?

The recovery of Clostridium difficile spores from hospital surfaces was assessed using rayon swabs, flocked swabs, and contact plates. The contact plate method was less laborious, achieved higher recovery percentages, and detected spores at lower inocula than swabs. Rayon swabs were the least efficient method. However, further studies are required in health care settings.