Papel del ambiente hospitalario y los equipamientos en la transmisión de las infecciones nosocomiales

Nosocomial outbreak caused by Serratia marcescens in a neonatology intensive care unit in a regional hospital. Analysis and improvement proposals

OBJECTIVES

Serratia marcescens (SM) may cause nosocomial outbreaks in Neonatal Intensive Care Units (NICU). We describe an outbreak of SM in a NICU and propose additional prevention and control recommendations.

METHODS

Between March 2019 and January 2020, samples were taken from patients in the NICU (rectal, pharyngeal, axillary and other locations) and from 15 taps and their sinks. Control measures were implemented including thorough cleaning of incubators, health education to staff and neonates'relatives, and use of single-dose containers. PFGE was performed in 19 isolates from patients and in 5 environmental samples.

RESULTS

From the first case in March 2019 to the detection of the outbreak, a month elapsed. Finally, 20 patients were infected and 5 colonized. 80% of infected neonates had conjunctivitis, 25% bacteremia, 15% pneumonia, 5% wound infection, and 5% urinary tract infection. Six neonates had two foci of infection. Among the 19 isolates studied, 18 presented the same pulsotype and only one of the isolates from the sinkhole showed a clonal relationship with those of the outbreak. Initial measures established were ineffective to control de outbreak and were implemented with exhaustive cleaning, use of individual eye drops, environmental sampling and changing sinks.

CONCLUSION

This outbreak presented a high number of neonates affected due to its late detection and torpid evolution. The microorganisms isolated from the neonates were related to an environmental isolate. Additional prevention and control measures are proposed, including routine weekly microbiological sampling.

Understanding the influence of the bioaerosol source on the distribution of airborne bacteria in hospital indoor air

The composition and concentration of airborne microorganisms in hospital indoor air has been reported to contain airborne bacteria and fungi concentrations ranged 10¹-10³ CFU/m³ in inpatients facilities which mostly exceed recommendations from the World Health Organization (WHO). In this work, a deeper knowledge of the performance of airborne microorganisms would allow improving the designs of the air-conditioning installations to restrict hospital-acquired infections (HAIs). A solution containing Escherichia coli (E. coli) as a model of airborne bacteria was nebulized using the Collison nebulizer to simulate bioaerosols in various hospital areas such as patients' rooms or bathrooms. Results showed that the bioaerosol source had a significant influence on the airborne bacteria concentrations since 4.00 10², 6.84 10³ and 1.39 10⁴ CFU mL^-1 were monitored during the aerosolization for 10 min of urine, saliva and urban wastewater, respectively. These results may be explained considering the quite narrow distribution profile of drop sizes around 1.10-1.29 μm obtained for urban wastewater, with much vaster distribution profiles during the aerosolization of urine or saliva. The airborne bacteria concentration may increase up to 10⁷ CFU mL^-1 for longer sampling times and higher aerosolization pressures, causing several cell damages. The cell membrane damage index (I_D) can vary from 0 to 1, depending on the genomic DNA releases from bacteria. In fact, the I_D of E. coli was more than two times higher (0.33 vs. 0.72) when increasing the pressure of air flow was applied from 1 to 2 bar. Finally, the ventilation air flow also affected the distribution of bioaerosols due to its direct relationship with the relative humidity of indoor air. Specifically, the airborne bacteria concentration diminished almost below 3-logs by applying more than 10 L min^-1 during the aerosolization of urine due to their inactivation by an increase in their osmotic pressure.

Impact of sink removal from intensive care unit rooms on the consumption of antibiotics and on results of Zero Resistance Project

INTRODUCTION

Due to the favourable impact of removing the sinks on isolations in bronchoaspirate samples of patients with mechanical ventilation, we now evaluate the impact on the consumption of antibiotics as well as on the results of the Zero Resistance Project (ZRP).

PATIENTS AND METHODS

All the patients admitted to the unit in a quasi-experimental before-after study with a pre-intervention period between 2014 and 2016 and a post-intervention period from 2016 to 2017, to evaluate antibiotic consumption in defined daily doses, and until 2018, to evaluate the ZRP indicators. The intervention was the removal of the sinks from the rooms of the ICU. We evaluated antibiotic consumption densities and their ratios, grouped as Enterobacteriaceae and non-fermenting gram-negative bacilli (NFGNB) according to their antibiograms; the absolute number of 'antibiotic days', 'hospitalised days', 'isolation days', and 'multi-resistant bacteria (MRB) days'; as well as their incidence densities per 1000 hospitalised days and the ratio between the two years prior to and the two years after the intervention.

RESULTS

Post-intervention antibiotic use was 1.61-fold (1.60-1.62) and 2.24-fold (2.10-2.37) lower for antibiotics used against Enterobacteriaceae and NFGNB, respectively. There were also reductions in the number of days of antibiotic use by 1.29-fold (1.22-1.36), number of MRB days by 1.84-fold (1.63-2.08), and number of patient isolation days by 1.51-fold (1.38-1.66).

DISCUSSION

The results suggest that the intervention had a favourable impact on the consumption of antibiotics, as well as on the number of days on antibiotics, MRB, and isolation.

Does using outpatient room air for bleomycin foam preparation increase the risk of infection?

OBJECTIVE

To evaluate whether the risk of infections is increased with the use of air from outpatient rooms to prepare bleomycin foam.

METHODS

Settling plates were adopted to collect bacteria from outpatient room air, operating theatre air, human serum albumin, bleomycin solution and bleomycin foam prepared with both outpatient room and operating theatre air. The plates were placed in an incubator at 37°C for 48 h, and the number of bacterial colonies was recorded using colony-forming units. The results were analysed by the t-test. A retrospective study was then performed to evaluate the outpatient safety of bleomycin foam.

RESULTS

The number of colony-forming units in the bleomycin foam produced using both operating and outpatient room air was very low, with no statistic difference. No infection cases were reported in clinical evaluation.

CONCLUSION

Using the air from outpatient treatment rooms for bleomycin foam preparation does not increase the risk of infections.

Characteristics of airborne micro-organisms in a neurological intensive care unit: Results from China

OBJECTIVE

To describe the characteristics of airborne micro-organisms in the environment in a Chinese neurological intensive care unit (NICU).

METHODS

This prospective study monitored the air environment in two wards (large and small) of an NICU in a tertiary hospital in China for 12 months, using an LWC-1 centrifugal air sampler. Airborne micro-organisms were identified using standard microbiology techniques.

RESULTS

The mean ± SD number of airborne bacteria was significantly higher in the large ward than in the small ward (200 ± 51 colony-forming units [CFU]/m(3) versus 110 ± 40 CFU/m(3), respectively). In the large ward only, the mean number of airborne bacteria in the autumn was significantly higher than in any of the other three seasons. A total of 279 airborne micro-organisms were identified (large ward: 195; small ward: 84). There was no significant difference in the type and distribution of airborne micro-organisms between the large and small wards. The majority of airborne micro-organisms were Gram-positive cocci in both wards.

CONCLUSION

These findings suggest that the number of airborne micro-organisms was related to the number of patients on the NICU ward.