Diversity changes of microbial communities into hospital surface environments

Trends in viable microbial bioburden on surfaces within a paediatric bone marrow transplant unit

BACKGROUND

Despite their role being historically overlooked, environmental surfaces have been shown to play a key role in the transmission of pathogens causative of healthcare-associated infection. To guide infection prevention and control (IPC) interventions and inform clinical risk assessments, more needs to be known about microbial surface bioburdens.

AIM

To identify the trends in culturable bacterial contamination across communal touch sites over time in a hospital setting.

METHODS

Swab samples were collected over nine weeks from 22 communal touch sites in a paediatric bone marrow transplant unit. Samples were cultured on Columbia blood agar and aerobic colony counts (ACC) per 100 cm2 were established for each site. Individual colony morphologies were grouped and identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry or 16s rDNA sequencing.

FINDINGS

Highest mean counts were observed for sites associated with ward management activity and computer devices (3.29 and 2.97 ACC/100 cm2 respectively). A nurses' station keyboard had high mean ACC/100 cm2 counts (10.67) and diversity, while laundry controls had high mean ACC/100 cm2 counts (4.70) and low diversity. Micrococcus luteus was identified in all sampling groups. Clinical staff usage sites were contaminated with similar proportions of skin and environmental flora (52.19-46.59% respectively), but sites associated with parental activities were predominantly contaminated by environmental microflora (86.53%).

CONCLUSION

The trends observed suggest patterns in microbial loading based on site activities, surface types and user groups. Improved understanding of environmental surface contamination could help support results interpretation and IPC interventions, improving patient safety.

Human pathogenic bacteria on high-touch dry surfaces can be controlled by warming to human-skin temperature under moderate humidity

Healthcare-associated infections have become a major health issue worldwide. One route of transmission of pathogenic bacteria is through contact with "high-touch" dry surfaces, such as handrails. Regular cleaning of surfaces with disinfectant chemicals is insufficient against pathogenic bacteria and alternative control methods are therefore required. We previously showed that warming to human-skin temperature affected the survival of pathogenic bacteria on dry surfaces, but humidity was not considered in that study. Here, we investigated environmental factors that affect the number of live bacteria on dry surfaces in hospitals by principal component analysis of previously-collected data (n = 576, for CFU counts), and experimentally verified the effect of warming to human-skin temperature on the survival of pathogenic bacteria on dry surfaces under humidity control. The results revealed that PCA divided hospital dry surfaces into four groups (Group 1~4) and hospital dry surfaces at low temperature and low humidity (Group 3) had much higher bacterial counts as compared to the others (Group 1 and 4) (p<0.05). Experimentally, warming to human-skin temperature (37°C with 90% humidity) for 18~72h significantly suppressed the survival of pathogenic bacteria on dry surfaces, such as plastic surfaces [p<0.05 vs. 15°C (Escherichia coli DH5α, Staphylococcus aureus, Pseudomonas aeruginosa, Acinetobacter baumannii, and blaNDM-5 E. coli)] or handrails [p<0.05 vs. 15~25°C (E. coli DH5α, S. aureus, P. aeruginosa, A. baumannii)], under moderate 55% humidity. Furthermore, intermittent heating to human-skin temperature reduced the survival of spore-forming bacteria (Bacillus subtilis) (p<0.01 vs. continuous heating to human-skin temperature). NhaA, an Na+/H+ antiporter, was found to regulate the survival of bacteria on dry surfaces, and the inhibitor 2-aminoperimidine enhanced the effect of warming at human-skin temperature on the survival of pathogenic bacteria (E. coli DH5α, S. aureus, A. baumannii) on dry surfaces. Thus, warming to human-skin temperature under moderate humidity is a useful method for impairing live pathogenic bacteria on high-touch surfaces, thereby helping to prevent the spread of healthcare-associated infections.

Novel Designed Surgical Drapes Reducing Fluid Permeability in the Surgical Critical Area of a Sterile Operation Interface: A Randomized Controlled Trial

Aim. To compare the impact and cost effects of medical long fiber polyester drapes and cotton fabric drapes on operative sterile operation interfaces. Background. The comparison of the properties of the commonly used surgical drapes materials in terms of leakage, device slip, and prevention of intraoperative adverse events is not clear. Method. A prospective randomized controlled study was conducted in the operating room of a tertiary hospital in Chengdu, China. A total of 400 patients who underwent urology surgery were enrolled and randomly divided into two groups by computer, the study group (200 cases) selected the new long-fiber polyester cloth, while the control group (200 cases) selected conventional cotton fabric surgical drapes during the operation to maintain a sterile operating interface. The impermeability and water absorption of surgical drapes, the rate of device slip and skin scald in surgical patients, and the cost effect of the two kinds of surgical drapes were compared. Results. The long fiber polyester surgical drapes were superior to conventional cotton cloth in water absorption (g/m2) (835 ± 15.8 VS 225 ± 21.0, t = 328.261, $P<0.001$ ), preventing surgical site infections (2.5% VS 8.0%, χ2 = 6.081, $P=0.014$ ), device slip (7.5% VS 17.0%, χ2 = 8.396, $P=0.004$ ), patients from burning (0 VS 1, Fisher $P=1.0$ ), and total cost per use ($) (0.83 VS 0.96–1.09). Conclusion. Long fiber polyester fabric has a stronger antipenetration ability of fluid and microorganisms thus forming an effective protective barrier. It also has strong hygroscopicity, and its special design can prevent the occurrence of sliding of surface instruments and skin scald in patients. In addition, its cost effect is superior. Implications for Nursing Management. Operating room nursing managers can introduce long fiber polyester drapes into the selection of medical textiles to construct aseptic surgical barriers and prevent surgical site infection.

How Does Hospital Microbiota Contribute to Healthcare-Associated Infections?

Healthcare-associated infections (HAIs) are still a global public health concern, associated with high mortality and increased by the phenomenon of antimicrobial resistance. Causative agents of HAIs are commonly found in the hospital environment and are monitored in epidemiological surveillance programs; however, the hospital environment is a potential reservoir for pathogenic microbial strains where microorganisms may persist on medical equipment surfaces, on the environment surrounding patients, and on corporal surfaces of patients and healthcare workers (HCWs). The characterization of hospital microbiota may provide knowledge regarding the relatedness between commensal and pathogenic microorganisms, their role in HAIs development, and the environmental conditions that favor its proliferation. This information may contribute to the effective control of the dissemination of pathogens and to improve infection control programs. In this review, we describe evidence of the contribution of hospital microbiota to HAI development and the role of environmental factors, antimicrobial resistance, and virulence factors of the microbial community in persistence on hospital surfaces.

Antibiotic-resistant organisms establish reservoirs in new hospital built environments and are related to patient blood infection isolates

Background

Healthcare-associated infections due to antibiotic-resistant organisms pose an acute and rising threat to critically ill and immunocompromised patients. To evaluate reservoirs of antibiotic-resistant organisms as a source of transmission to patients, we interrogated isolates from environmental surfaces, patient feces, and patient blood infections from an established and a newly built intensive care unit.

Methods

We used selective culture to recover 829 antibiotic-resistant organisms from 1594 environmental and 72 patient fecal samples, in addition to 81 isolates from blood cultures. We conducted antibiotic susceptibility testing and short- and long-read whole genome sequencing on recovered isolates.

Results

Antibiotic-resistant organism burden is highest in sink drains compared to other surfaces. Pseudomonas aeruginosa is the most frequently cultured organism from surfaces in both intensive care units. From whole genome sequencing, different lineages of P. aeruginosa dominate in each unit; one P. aeruginosa lineage of ST1894 is found in multiple sink drains in the new intensive care unit and 3.7% of blood isolates analyzed, suggesting movement of this clone between the environment and patients.

Conclusions

These results highlight antibiotic-resistant organism reservoirs in hospital built environments as an important target for infection prevention in hospitalized patients.

Patients in hospitals often have a suppressed immune system, putting them at increased risk of infection by bacteria that are resistant to antibiotics, some of which may come from sources in the hospital environment. We sampled multiple different surfaces in an established and a newly built intensive care unit and collected patient infection samples. We tested bacteria in these samples for their resistance to antibiotics and sequenced the genetic code of the bacteria to identify relationships between environmental and patient infections. We found the most antibiotic resistant organisms in hospital sink drains. Our sequencing data revealed strains of a certain kind of bacteria could form reservoirs and survive in sink drains and also cause patient infections. These results highlight the importance of removing these antibiotic resistant organism reservoirs to prevent infections.

Sukhum, Newcomer et al. evaluate reservoirs of antibiotic-resistant organisms within the built environment and patient samples from an established and a newly-built intensive care unit. The authors demonstrate colonization of sink drains and other sites and show relatedness between environmental reservoirs and patient infections.

Temporal variation in bacterial community profile on patients' bedsheets in a primary healthcare unit

Fabrics serve as fomites in spreading nosocomial infections. As a patient is in close contact with bedsheets, it is important to assess the seasonal variation in bacterial diversity on these in healthcare units. The study was conducted to characterise the bacterial diversity on patients' bedsheets across 7 months in a primary healthcare unit. Polyester-cotton blend fabric was stitched on bedsheets, and temporal dynamics of bacterial communities was assessed from May to November 2019. qPCR and amplicon sequencing of 16S rRNA gene was performed for profiling of bacterial community. Results revealed the dominance of Bacillota followed by Pseudomonadota, and Actinomycetota. A seasonal variation was observed in the bacterial load, with maximum values in June. This indicates the impact of environmental conditions on bacterial abundance and composition on fabrics in healthcare unit. The presence of priority pathogens on the patient bedsheets is a human health concern reiterating the need for season-specific laundering protocol.

Mobilizable antibiotic resistance genes are present in dust microbial communities

The decades-long global trend of urbanization has led to a population that spends increasing amounts of time indoors. Exposure to microbes in buildings, and specifically in dust, is thus also increasing, and has been linked to various health outcomes and to antibiotic resistance genes (ARGs). These are most efficiently screened using DNA sequencing, but this method does not determine which microbes are viable, nor does it reveal whether their ARGs can actually disseminate to other microbes. We have thus performed the first study to: 1) examine the potential for ARG dissemination in indoor dust microbial communities, and 2) validate the presence of detected mobile ARGs in viable dust bacteria. Specifically, we integrated 166 dust metagenomes from 43 different buildings. Sequences were assembled, annotated, and screened for potential integrons, transposons, plasmids, and associated ARGs. The same dust samples were further investigated using cultivation and isolate genome and plasmid sequencing. Potential ARGs were detected in dust isolate genomes, and we confirmed their placement on mobile genetic elements using long-read sequencing. We found 183 ARGs, of which 52 were potentially mobile (associated with a putative plasmid, transposon or integron). One dust isolate related to Staphylococcus equorum proved to contain a plasmid carrying an ARG that was detected metagenomically and confirmed through whole genome and plasmid sequencing. This study thus highlights the power of combining cultivation with metagenomics to assess the risk of potentially mobile ARGs for public health.

Effect of thermal control of dry fomites on regulating the survival of human pathogenic bacteria responsible for nosocomial infections

We monitored the survival of human pathogenic bacteria [Escherichia coli (ATCC), extended-spectrum β-lactamase-producing E. coli (Clinical isolate), New Delhi metallo-β-lactamase-producing E. coli (clinical isolate), Staphylococcus aureus (ATCC)] on dry materials (vinyl chloride, aluminum, plastic, stainless steel) at distinct temperatures (room temperature or 15°C–37°C). These bacteria favored a lower temperature for their prolonged survival on the dry fomites, regardless of the material type. Interestingly, when mixed with S. aureus, E. coli survived for a longer time at a lower temperature. Cardiolipin, which can promote the survival of S. aureus in harsh environments, had no effect on maintaining the survival of E. coli. Although the trends remained unchanged, adjusting the humidity from 40% to 60% affected the survival of bacteria on dry surfaces. Scanning electron microscopic analysis revealed no morphological differences in these bacteria immediately before or after one day of dry conditions. In addition, ATP assessment, a method used to visualize high-touch surfaces in hospitals, was not effective at monitoring bacterial dynamics. A specialized handrail device fitted with a heater, which was maintained at normal human body core temperature, successfully prohibited the prolonged survival of bacteria [Enterococcus faecalis (ATCC), E. coli (ATCC), Pseudomonas aeruginosa (ATCC), S. aureus (ATCC), Acinetobacter baumannii (clinical isolate), and Serratia marcescens (clinical isolate)], with the exception of spore-forming Bacillus subtilis (from our laboratory collection) and the yeast-like fungus Candida albicans (from our laboratory collection)] on dry surfaces. Taken together, we concluded that the tested bacteria favor lower temperatures for their survival in dry environments. Therefore, the thermal control of dry fomites has the potential to control bacterial survival on high-touch surfaces in hospitals.

Diversity of nasal microbiota and its interaction with surface microbiota among residents in healthcare institutes

Nasal microbial communities may have crucial implications for human health, including for residents of healthcare institutes (HCIs). Factors that determine the diversity of nasal microbiota in HCIs remain unclear. Herein, we used 16S rRNA amplicon sequencing to investigate the relationship between nasal and surface microbiota in three HCIs. Participants were classified into a hospitalised or nonhospitalised group based on their most recent date of hospitalisation. A total of 88 nasal samples and 83 surface samples were analysed. Dysgonomonas and Corynebacterium were the most abundant taxa in the surface and nasal samples, respectively. Significant differences were discovered in microbiota diversity among HCIs when comparing the surface and nasal samples. Fifteen taxa were identified as present in all the surface and nasal samples. SourceTracker analysis revealed that the ventilation conditions of environment might be associated with the proportion of shared microbial communities between nasal and surface. Additionally, as compared with the nonhospitalised group, the hospitalised group had a higher proportion of surface microbiota in their nasal samples, which might lead to a higher risk of human-related microorganisms or pathogens colonising the nasal cavity. The data suggest that nasal bacterial diversity could be influenced by both health status and living environment. Our results therefore highlight the importance of the indoor environment for HCI residents.

Impact of bacterial traces belonging to the Enterobacteriaceae on the prevalence of Chlamydia trachomatis in women visiting a community hospital in Japan

We explored the bacteria present in the vaginal microbiota facilitating the prevalence of Chlamydia trachomatis in women visiting a community hospital in Sapporo, Japan, by amplicon sequencing. A total of 273 cervical swab samples were collected, and bacterial vaginosis was evaluated in all specimens by assessment of the Nugent score. In 16 of the samples, bacterial 16S rDNA could not be detected and they were therefore omitted from subsequent experiments (n = 257). A significant negative correlation was observed between the Nugent scores and the amount of Lactobacillus 16S rDNA. Among the 257 samples, chlamydial plasmid was detected in 20 samples and was used for amplicon sequencing. No significant association between the Nugent score and the prevalence of C. trachomatis was detected. Based on the results of chlamydial plasmid detection and the Nugent score, chlamydia-negative samples (n = 27) were randomly selected. Finally, the number of operational taxonomic units (OTUs) obtained from amplicon sequencing was compared between chlamydia-positive (n = 20) and -negative samples (n = 27), revealing that a significant difference was only detected for the OTU numbers of Enterobacteriaceae between the C. trachomatis-positive and -negative groups. However, almost all of the samples utilized for amplicon sequencing failed to grow on MacConkey agar plates and produce indole. Taken together, we concluded that traces of bacteria, not live bacteria, belonging to the Enterobacteriaceae indicated the flow of bacteria through the anogenital route along with gut indole, and the resulting impact on the prevalence of C. trachomatis in the cervicogenital tract of women in Japan.