Air dispersal of respiratory viruses other than severe acute respiratory coronavirus virus 2 (SARS-CoV-2) and the implication on hospital infection control

Antimicrobial Resistance Situation and Control Measures in Hong Kong: From a One Health Perspective

Multidrug-resistant organisms pose a critical public health challenge globally, particularly in densely populated Hong Kong with a rapidly aging population, where over 90% of food is imported. This review examines the targeted surveillance and control efforts implemented under the One Health framework to combat antimicrobial resistance (AMR). Between 2010 and 2023, surveillance revealed a prevalence of extended-spectrum-beta-lactamase-producing Escherichia coli (ESBL-E.coli) in tested pigs (51.5%) and chickens (86.3%). Alarmingly, carbapenemase-producing E. coli was increasingly detected in pigs (<5 to 19.2% from 2017 to 2023). For other food items, ESBL-producing Enterobacterales were found in sashimi (11.5%), sushi (4.8%) ready-to-eat (RTE) vegetables (26.9%), RTE cut fruits (5.6%), braised dishes (19.8%), and roast meat (2.4%). Mean antimicrobial consumption in food animals was 113.4mg/kg target animal biomass for pigs from 2019 to 2022. Antimicrobial consumption in hospitals and community, expressed as defined daily doses per 1,000 inhabitants per day, declined from 20.4 to 13.8 during the COVID-19 pandemic, and gradually rebounded to 17.1 in 2023. In residential care homes for the elderly (RCHE), MRSA prevalence rapidly escalated from 2.8 to 48.7% between 2005 and 2021, triggering a pilot MRSA decolonization program in 257 RCHEs, which led to a significant reduction in community-onset MRSA infections (from 3.526 to 2.632 per 1,000-resident-days,p<0.005) and MRSA bacteremia (from 0.322 to 0.197 per 1,000-resident-days,p=0.025). These findings highlight the challenges in the control of ESBL and carbapenemase-producing E. coli in animals, compliance with food hygiene measures, and infection control in overcrowded and understaffed RCHE or hospitals in perpetuating MRSA infections in healthcare settings.

Tracking SARS-CoV-2 RNA in the air: Lessons from a COVID-19 outbreak in an infirmary unit

BACKGROUND

The duration and magnitude of SARS-CoV-2 air dispersal during nosocomial outbreaks remain uncertain. This study evaluates the impact of mobile modular high-efficiency particulate air filter units (MMHUs) on SARS-CoV-2 air dispersal.

METHODS

We investigated a nosocomial COVID-19 outbreak in an infirmary unit. The viral load (VL) of SARS-CoV-2 in air samples was correlated with the VL in nasopharyngeal swabs with or without MMHU. These samples underwent whole-genome sequencing and phylogenetic analysis.

RESULTS

Upon outbreak declaration (August 2, 2024, day 0), 44 (69.8%) of 63 patients acquired COVID-19 in Ward 2B (19 male) and 2C (25 female) by day 4. The VL of SARS-CoV-2 remained detectable in air until day 11 (2B) and day 20 (2C). The VL of air samples was significantly correlated with the VL in nasopharyngeal swabs collected on days 5, 7, 10, and 13 in 2C (r = -0.975, P = .004). Using MMHU, the mean daily ratio of SARS-CoV-2 RNA (copies/1,000 L of air/patient) in 2B was 5 times lower than in 2C from days 5 to 10. Whole-genome sequencing revealed all 41 tested strains belonged to the Omicron variant, KP.3.1.1, phylogenetically related to the prevailing community strains.

CONCLUSIONS

Using MMHU mitigates the duration and magnitude of SARS-CoV-2 air dispersal during nosocomial outbreak.

Hospital-borne hazardous air pollutants and air cleaning strategies amid the surge of SARS-CoV-2 new variants

Indoor air pollutants and airborne contamination removal have been challenging in healthcare facilities. The airborne transmission control and HVAC system may collapse in hospitals due to the highly infectious respiratory disease-associated patient surge, like COVID-19. Common air filtration systems and HVAC systems enhance the patients' comfort and support indoor hygiene, hitherto insufficient to control highly infectious airborne pathogens and hospital-borne pollutants such as radon, PM2.5, patient droplets, VOC, high CO2, and anesthetic gases. This review summarized important air cleaning interventions to enhance HVAC efficiency and indoor safety. We discussed efficient air cleaning and ventilation strategies including air filtration, air ionization, passive removal materials (PRM), and UVGI to minimize cross-contamination in hospital wards.

The Emergence of Candida auris is Not Associated with Changes in Antifungal Prescription at Hospitals

Purpose

This study describes the emergence of Candida auris in Hong Kong, focusing on the incidence and trends of different Candida species over time. Additionally, the study analyzes the relationship between C. auris and antifungal prescription, as well as the impact of outbreaks caused by C. auris.

Patients and Methods

Data were collected from 43 public hospitals across seven healthcare networks (A to G) in Hong Kong, including Candida species culture and antifungal prescription information. Among 150,267 patients with 206,405 hospitalization episodes, 371,653 specimens tested positive for Candida species. Trends in Candida species and antifungal prescription were analyzed before (period 1: 2015 1Q to 2019 1Q) and after (period 2: 2019 2Q to 2023 2Q) the emergence of C. auris in Hong Kong.

Results

Candida albicans was the most prevalent species, accounting for 57.1% (212,163/371,653) of isolations, followed by Candida glabrata (13.1%, 48,666), Candida tropicalis (9.2%, 34,261), and Candida parapsilosis (5.3%, 19,688). C. auris represented 2.0% of all Candida species isolations. Comparing period 2 to period 1, the trend of C. albicans remained stable, while C. glabrata, C. tropicalis, and C. parapsilosis demonstrated a slower increasing trend in period 2 than in period 1. Other species, including C. auris, exhibited a 1.1% faster increase in trend during period 2 compared to period 1. Network A, with the highest antifungal prescription, did not experience any outbreaks, while networks F and G had 40 hospital outbreaks due to C. auris in period 2. Throughout the study period, healthcare networks B to G had significantly lower antifungal prescription compared to network A, ranging from 54% to 78% less than that of network A.

Conclusion

There is no evidence showing correlation between the emergence of C. auris and antifungal prescription in Hong Kong. Proactive infection control measures should be implemented to prevent nosocomial transmission and outbreak of C. auris.

Investigation of air dispersal during a rhinovirus outbreak in a pediatric intensive care unit

BACKGROUND

While airborne transmission of rhinovirus is recognized in indoor settings, its role in hospital transmission remains unclear.

METHODS

We investigated an outbreak of rhinovirus in a pediatric intensive care unit (PICU) to assess air dispersal. We collected clinical, environmental, and air samples, and staff's surgical masks for viral load and phylogenetic analysis. Hand hygiene compliance and the number of air changes per hour in the PICU were measured. A case-control analysis was performed to identify nosocomial rhinovirus risk factors.

RESULTS

Between March 31, 2023, and April 2, 2023, three patients acquired rhinovirus in a cubicle (air changes per hour: 14) of 12-bed PICU. A portable air-cleaning unit was placed promptly. Air samples (72,000 L in 6 hours) from the cohort area, and outer surfaces of staff's masks (n = 8), were rhinovirus RNA-negative. Hand hygiene compliance showed no significant differences (31/34, 91.2% vs 33/37, 89.2%, P = 1) before and during outbreak. Only 1 environmental sample (3.8%) was positive (1.86 × 103 copies/mL). Case-control and next-generation sequencing analysis implicated an infected staff member as the source.

CONCLUSIONS

Our findings suggest that air dispersal of rhinovirus was not documented in the well-ventilated PICU during the outbreak. Further research is needed to better understand the dynamics of rhinovirus transmission in health care settings.

Air dispersal of severe acute respiratory coronavirus virus 2 (SARS-CoV-2): Implications for hospital infection control during the fifth wave of coronavirus disease 2019 (COVID-19) due to the SARS-CoV-2 omicron variant in Hong Kong

We obtained 24 air samples in 8 general wards temporarily converted into negative-pressure wards admitting coronavirus disease 2019 (COVID-19) patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) omicron variant BA.2.2 in Hong Kong. SARS-CoV-2 RNA was detected in 19 (79.2%) of 24 samples despite enhanced indoor air dilution. It is difficult to prevent airborne transmission of SARS-CoV-2 in hospitals.

Evolution and Control of COVID-19 Epidemic in Hong Kong

Hong Kong SAR has adopted universal masking, social distancing, testing of all symptomatic and high-risk groups for isolation of confirmed cases in healthcare facilities, and quarantine of contacts as epidemiological control measures without city lockdown or border closure. These measures successfully suppressed the community transmission of pre-Omicron SARS-CoV-2 variants or lineages during the first to the fourth wave. No nosocomial SARS-CoV-2 infection was documented among healthcare workers in the first 300 days. The strategy of COVID-19 containment was adopted to provide additional time to achieve population immunity by vaccination. The near-zero COVID-19 situation for about 8 months in 2021 did not enable adequate immunization of the eligible population. A combination of factors was identified, especially population complacency associated with the low local COVID-19 activity, together with vaccine hesitancy. The importation of the highly transmissible Omicron variant kickstarted the fifth wave of COVID-19, which could no longer be controlled by our initial measures. The explosive fifth wave, which was partially contributed by vertical airborne transmission in high-rise residential buildings, resulted in over one million cases of infection. In this review, we summarize the epidemiology of COVID-19 and the infection control and public health measures against the importation and dissemination of SARS-CoV-2 until day 1000.