Minimal intervention for controlling nosocomial transmission of methicillin-resistant staphylococcus aureus in resource limited setting with high endemicity

Epidemiology of multidrug-resistant organisms before and during COVID-19 in Hong Kong

Background

The coronavirus disease 2019 (COVID-19) has influenced antimicrobial consumption and incidence of multidrug-resistant organisms (MDROs). We aimed to study the epidemiology of MDROs before and during the COVID-19 pandemic in Hong Kong.

Methods

With the maintenance of infection control measures, we described the trend of MDRO infections, including methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter species (CRA), and extended-spectrum-beta-lactamase-(ESBL)-producing Enterobacterales, in a healthcare region with 3100-bed before (1 January 2016 to 31 December 2019, period 1) and during COVID-19 (1 January 2020 to 30 September 2022, period 2), together with the antimicrobial consumption using piecewise Poisson regression. The epidemiological characteristics of newly diagnosed COVID-19 patients with or without MDRO infections were analyzed.

Results

Between period 1 and 2, we observed a significant increase in the trend of CRA infections (P<0.001), while there was no significant increase in the trend of MRSA (P=0.742) and ESBL-producing Enterobacterales (P=0.061) infections. Meanwhile, a significant increase in the trend of carbapenems (P<0.001), extended-spectrum beta-lactam-beta-lactamase inhibitor combinations (BLBI) (P=0.045), and fluoroquinolones (P=0.009) consumption was observed. The observed opportunity (23,540 ± 3703 vs 26,145 ± 2838, p=0.359) and compliance (81.6% ± 0.5% vs 80.1% ± 0.8%, P=0.209) of hand hygiene per year was maintained. In a multivariable model, older age, male sex, referral from residential care home for the elderly, presence of indwelling device, presence of endotracheal tube, and use of carbapenems, use of BLBI, use of proton pump inhibitors and history of hospitalization in the past 3 months were associated with higher risks of infections by MDROs among COVID-19 patients.

Conclusion

Infection control measures may control the surge of MDROs despite an increasing trend of antimicrobial consumption.

Gastrointestinal colonization of methicillin-resistant Staphylococcus aureus: an unrecognized burden in the hospital infection control

The incidence, risk factors, outcomes, and genomic relatedness of patients with newly diagnosed gastrointestinal colonization of meticillin-resistant Staphylococcus aureus (MRSA) were analyzed epidemiologically and genetically by whole genome sequencing (WGS) in a hospital network in Hong Kong. Between 1 October 2015 and 31 December 2018, 919 (2.7%) of 34,667 patients had newly diagnosed gastrointestinal MRSA colonization by admission screening. The incidence was 0.67±0.32 per 1,000-patient-days-per-quarter. Including patients with gastrointestinal MRSA colonization, the overall burden of MRSA increased by 59.2% (from 1.13±0.13 to 1.80±0.36 case per 1,000-patient-days-per-quarter), with an addition of MRSA 4,727 patient-days during the study period. Patients referred from residential care home for the elderly [odds ratio (95% confidential interval): 4.18 (3.50-4.99), p<0.001], with history of hospitalization in the past 6 months [1.90 (1.56-2.30), p<0.001], and consumption of fluoroquinolones [1.76 (1.34-2.30), p<0.001], cephalosporins [1.61 (1.11-2.31), p=0.011], and proton pump inhibitors [1.31 (1.10-1.56), p=0.002] in the preceding 6 months were found to be independent risk factors by multivariable analysis in the case-control analysis. The median survival of case was significantly shorter than control (860 vs 1507 days, p<0.001). 127 (13.8%) of 919 patients developed symptomatic MRSA infection in 112 days (median, range: 2-712 days). Of 19 patients with paired MRSA faecal and blood culture isolates subjected to WGS, clonality was found in 16 (84.2%) pairs of MRSA isolates. MRSA ST45 constituted 44.7% (17/38) of MRSA isolates. Gastrointestinal MRSA colonization may contribute to adverse clinical outcomes and pose an unrecognized burden to the hospital infection control.

Reducing transmission of methicillin-resistant Staphylococcus aureus in a surgical ward of a resource-limited hospital in Indonesia: an intervention study

Background

Methicillin-resistant Staphylococcus aureus (MRSA) is endemic in healthcare settings in Indonesia.

Aim

To evaluate the effect of a bundle of preventive measures on the transmission and acquisition of MRSA in a surgical ward of a resource-limited hospital in Indonesia.

Methods

The study consisted of a pre-intervention (7 months), intervention (2 months), and post-intervention phase (5 months) and included screening for MRSA among eligible patients, healthcare workers (HCWs), and the hospital environment. In the intervention phase, a bundle of preventive actions was introduced, comprising: a hand hygiene educational program, cohorting of MRSA-positive patients, decolonization therapy for all MRSA-positive patients and HCWs, and cleaning and disinfection of the ward's innate environment. Hand hygiene compliance was assessed throughout the study period. The primary outcome was the acquisition rate of MRSA among patients per 1,000 patient-days at risk. Clonality of MRSA isolates was determined by Raman spectroscopy and multilocus sequence typing.

Findings

In total, 1,120 patients were included. Hand hygiene compliance rate rose from 15% pre-intervention to 65% post-intervention (P<0.001). The MRSA acquisition decreased from 9/1,000 patient-days at risk pre-intervention to 3/1,000 patient-days at risk post-intervention, but this difference did not reach statistical significance (P=0.08). Raman type 9 which belonged to ST239 was the single dominant MRSA clone.

Conclusion

The introduction of a bundle of preventive measures may reduce MRSA transmission and acquisition among surgery patients in a resource-limited hospital in Indonesia, but additional efforts are needed.

Effects of the proportion of high-risk patients and control strategies on the prevalence of methicillin-resistant Staphylococcus aureus in an intensive care unit

Background

The presence of nosocomial pathogens in many intensive care units poses a threat to patients and public health worldwide. Methicillin-resistant Staphylococcus aureus (MRSA) is an important pathogen endemic in many hospital settings. Patients who are colonized with MRSA may develop an infection that can complicate their prior illness.

Methods

A mathematical model to describe transmission dynamics of MRSA among high-risk and low-risk patients in an intensive care unit (ICU) via hands of health care workers is developed. We aim to explore the effects of the proportion of high-risk patients, the admission proportions of colonized and infected patients, the probability of developing an MRSA infection, and control strategies on MRSA prevalence among patients.

Results

The increasing proportion of colonized and infected patients at admission, along with the higher proportion of high-risk patients in an ICU, may significantly increase MRSA prevalence. In addition, the prevalence becomes higher if patients in the high-risk group are more likely to develop an MRSA infection. Our results also suggest that additional infection prevention and control measures targeting high-risk patients may considerably help reduce MRSA prevalence as compared to those targeting low-risk patients.

Conclusions

The proportion of high-risk patients and the proportion of colonized and infected patients in the high-risk group at admission may play an important role on MRSA prevalence. Control strategies targeting high-risk patients may help reduce MRSA prevalence.

Tolerance of MRSA ST239-TW to chlorhexidine-based decolonization: Evidence for keratinocyte invasion as a mechanism of biocide evasion

OBJECTIVES

Information on genetic determinants of chlorhexidine tolerance (qacA carriage and MIC) in vitro is available, although evidence of the clinical impact and mechanisms remain poorly understood. We investigated why, following chlorhexidine intervention, prevalent epidemic MRSA ST22 and ST36 clones declined at an ICU, whilst an ST239-TW clone did not. The chlorhexidine tolerant ST239-TW phenotypes were assessed for their protein binding, cell adhesion and intracellular uptake potential.

METHODS

Six ST22, ST36 and ST239-TW bloodstream infection isolates with comparable chlorhexidine MICs were selected from a 2-year outbreak in an ICU at Guy's and St. Thomas' Hospital. Isolates were tested for fibrinogen and fibronectin binding, and adhesion/internalization into human keratinocytes with and without biocide.

RESULTS

Binding to fibrinogen and fibronectin, adhesion and intracellular uptake within keratinocytes (P < 0.001) and intracellular survival in keratinocytes under chlorhexidine pressure (ST22 3.18%, ST36 4.57% vs ST239-TW 12.79%; P < 0.0001) was consistently higher for ST239-TW.

CONCLUSIONS

We present evidence that MRSA clones with similarly low in vitro tolerance to chlorhexidine exhibit different in vivo susceptibilities. The phenomenon of S. aureus adhesion and intracellular uptake into keratinocytes could therefore be regarded as an additional mechanism of chlorhexidine tolerance, enabling MRSA to evade infection control measures.

The use of vancomycin in the treatment of adult patients with methicillin-resistant Staphylococcus aureus (MRSA) infection: a survey in a tertiary hospital in China

BACKGROUND

Vancomycin is frequently used in the treatment of methicillin-resistant Staphylococcus aureus (MRSA).

OBJECTIVES

To determine MRSA infection status and the use of vancomycin in its treatment at a teaching hospital in China.

METHODS

We retrospectively reviewed 140 cases of MRSA infection that were treated from January 2013 to October 2014. We analyzed the etiology of MRSA infection and the use of vancomycin in these cases.

RESULTS

MRSA infection mainly occurred in elderly patients concomitant with a variety of diseases, which incidence was more in men than women. More cases of MRSA infection were encountered in the ICU than in other departments. The positive culture results for MRSA were obtained in the sputum (38.57%), pharyngeal swab (19.29%), blood (5.71%), and wound secretion (11.43%) samples. The MRSA patients were sensitive to vancomycin, with the minimum inhibitory concentration (MIC) being 1 μg/mL in 53.80% of the cases and 2 μg/mL in 44.10% of the cases, respectively. Among the 35 (25%) cases treated with vancomycin, 23 were cured, while 3 died and 7 (20%) were considered as an unreasonable application.

CONCLUSIONS

MRSA infection mainly appeared in patients admitted to the ICU. The MIC of vancomycin had a tendency to increase gradually.

Use of fluoroquinolones is the single most important risk factor for the high bacterial load in patients with nasal and gastrointestinal colonization by multidrug-resistant Acinetobacter baumannii

Gastrointestinal colonization by carbapenem-resistant Acinetobacter baumannii (CRAB) and multidrug-resistant Acinetobacter baumannii (MRAB) provides an important reservoir for clinical infections and hospital outbreaks. We conducted a 7-month study in a 3200-bed healthcare network to investigate the prevalence of gastrointestinal colonization of CRAB and MRAB in Hong Kong. Between 1 June and 31 December 2014, a total of 17,760 fecal specimens from 9469 patients were screened. Testing showed that 340 (1.9%) specimens from 224 (2.6%) patients were CRAB-positive, which included 70 (0.39%) MRAB-positive specimens from 54 (0.57%) patients. The presence of wound or ulcer, use of broad-spectrum antibiotics in the preceding 6 months, and residence in elderly homes are independent risk factors for gastrointestinal colonization of CRAB. Quantitative bacterial counts in various body sites (rectal, nasal, axilla, wound, catheterized urine, if available) were performed in 33 (61.1%) of 54 MRAB patients. Ten (30.3%) and 8 (24.2%) patients had high bacterial load (defined as over 3 log10) in rectal and nasal swabs, with a median of 5.04 log10 cfu/ml of rectal swab and 4.89 log10 cfu/ml of nasal swab in saline diluent, respectively. Nine (81.8%) of 11 patients with wounds had high bacterial load in wound swabs, with a median of 5.62 log10 cfu/ml. Use of fluoroquinolones 6 months before admission was the only significant factor associated with high bacterial load in nasal and rectal swabs. With the implementation of directly observed hand hygiene before meals and medications to all conscious hospitalized patients, no hospital outbreaks were observed during our study period.

Effect of proactive infection control measures on benchmarked rate of hospital outbreaks: An analysis of public hospitals in Hong Kong over 5 years

Background

Hospital outbreaks of epidemiologically important pathogens are usually caused by lapses in infection control measures and result in increased morbidity, mortality, and cost. However, there is no benchmark to compare the occurrence of hospital outbreaks across hospitals.

Methods

We implemented proactive infection control measures with an emphasis on timely education of health care workers and hospitalized patients at Queen Mary Hospital, a teaching hospital. Our benchmarked performance (outbreak episodes per 1 million patient discharges and 1 million patient-days) was compared with those of other regional public hospitals without these additional proactive measures in place between 2010 and 2014.

Results

During the study period, Queen Mary Hospital had 1 hospital outbreak resulting in 1.48 and 0.45 outbreak episodes per 1 million patient discharges and patient-days, respectively, values significantly lower than the corresponding overall rates in the 7 acute regional hospitals (24.26 and 6.70 outbreak episodes per 1 million patient discharges and patient-days, respectively; P < .001) and that of all 42 public hospitals in Hong Kong (41.62 and 8.65 outbreak episodes per 1 million patient discharges and patient-days, respectively; P < .001).

Conclusions

The results of this large study on benchmarked rate of hospital outbreaks per patient discharges or patient-days suggests that proactive infection control interventions may minimize the risk of hospital outbreaks.

Hand-touch contact assessment of high-touch and mutual-touch surfaces among healthcare workers, patients, and visitors

BACKGROUND

Unlike direct contact with patients' body, hand hygiene practice is often neglected by healthcare workers (HCWs) and visitors after contact with patients' environment. Contact with hospital environmental items may increase risk of pathogen transmission.

AIM

To enumerate the number of hand-touch contacts by patients, HCWs and visitors with any hospital environmental items.

METHODS

All contact-episodes between person and item were recorded by direct observation in a six-bed cubicle of acute wards for 33 working days. High-touch and mutual-touch items with high contact frequencies by HCWs, patients, and visitors were analysed.

FINDINGS

In total, 1107 person-episodes with 6144 contact-episodes were observed in 66 observation hours (average: 16.8 person-episodes and 93.1 contact-episodes per hour). Eight of the top 10 high-touch items, including bedside rails, bedside tables, patients' bodies, patients' files, linen, bed curtains, bed frames, and lockers were mutually touched by HCWs, patients, and visitors. Bedside rails topped the list with 13.6 contact-episodes per hour (mean), followed by bedside tables (12.3 contact-episodes per hour). Using patients' body contacts as a reference, it was found that medical staff and nursing staff contacted bedside tables [rate ratio (RR): 1.741, 1.427, respectively] and patients' files (RR: 1.358, 1.324, respectively) more than patients' bodies, and nursing staff also contacted bedside rails (RR: 1.490) more than patients' bodies.

CONCLUSION

Patients' surroundings may be links in the transmission of nosocomial infections because many are frequently touched and mutually contacted by HCWs, patients, and visitors. Therefore, the focus of hand hygiene education, environmental disinfection, and other system changes should be enhanced with respect to high-touch and mutual-touch items.

Strategic measures for the control of surging antimicrobial resistance in Hong Kong and mainland of China

Antimicrobial-resistant bacteria are either highly prevalent or increasing rapidly in Hong Kong and China. Treatment options for these bacteria are generally limited, less effective and more expensive. The emergence and dynamics of antimicrobial resistance genes in bacteria circulating between animals, the environment and humans are not entirely known. Nonetheless, selective pressure by antibiotics on the microbiomes of animal and human, and their associated environments (especially farms and healthcare institutions), sewage systems and soil are likely to confer survival advantages upon bacteria with antimicrobial-resistance genes, which may be further disseminated through plasmids or transposons with integrons. Therefore, antibiotic use must be tightly regulated to eliminate such selective pressure, including the illegalization of antibiotics as growth promoters in animal feed and regulation of antibiotic use in veterinary practice and human medicine. Heightened awareness of infection control measures to reduce the risk of acquiring resistant bacteria is essential, especially during antimicrobial use or institutionalization in healthcare facilities. The transmission cycle must be interrupted by proper hand hygiene, environmental cleaning, avoidance of undercooked or raw food and compliance with infection control measures by healthcare workers, visitors and patients, especially during treatment with antibiotics. In addition to these routine measures, proactive microbiological screening of hospitalized patients with risk factors for carrying resistant bacteria, including history of travel to endemic countries, transfer from other hospitals, and prolonged hospitalization; directly observed hand hygiene before oral intake of drugs, food and drinks; and targeted disinfection of high-touch or mutual-touch items, such as bed rails and bed curtains, are important. Transparency of surveillance data from each institute for public scrutiny provides an incentive for controlling antimicrobial resistance in healthcare settings at an administrative level.

Control of hospital endemicity of multiple-drug-resistant Acinetobacter baumannii ST457 with directly observed hand hygiene

An increasing endemicity of multiple-drug-resistant Acinetobacter baumannii (MRAB) ST457 was noted in Hong Kong. The epidemiology, risk factors, and infection control measures to prevent nosocomial transmission of this epidemic clone were analyzed. A total of 5,058 patients cultured positive with A. baumannii between 1 January 2004 and 30 June 2014 were included, of which 297 (5.9 %) had bacteremia. The first case of MRAB bacteremia emerged in 2009, with an incidence that increased from 0.27 (one case) in 2009 to 1.86 (14 cases) per 100,000 patient-days in 2013 (p < 0.001). With the implementation of strict contact precautions and directly observed hand hygiene in conscious patients immediately before receiving meals and medications in July 2013, the incidence of MRAB bacteremia reduced from its peak to 0.77 (one case) per 100,000 patient-days in the first 6 months of 2014 (p < 0.001). Patients from long-term care facilities for the elderly [odds ratio (OR) 18.6, confidence interval (CI) 2.1-162.4, p = 0.008] and history of carbapenem (OR 7.0, CI 1.7-28.0, p = 0.006) and beta-lactam/beta-lactamase use (OR 5.6, CI 1.1-28.7, p = 0.038) 90 days prior to admission were independent risk factors for MRAB bacteremia by logistic regression when compared with carbapenem-susceptible A. baumannii bacteremia.