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Letters to the Editor

Possible Impact of Severe Acute Respiratory Syndrome Coronavirus-2 Control Measures in Reducing Colonization by Gram-negative Bacteria and Candida spp. in a Neonatal Intensive Care Unit

Pezzotta, Ramona BSc; De Francesco, Maria Antonia PhD; Caruso, Arnaldo MD, PhD

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The Pediatric Infectious Disease Journal: May 2021 - Volume 40 - Issue 5 - p e211-e213
doi: 10.1097/INF.0000000000003092
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To the Editors:

Neonates admitted to neonatal intensive care units (NICUs) are susceptible to acquire nosocomial infections because of the lack of an effective skin barrier and the immaturity of their immune system that allow the entry of different microorganisms from various colonization sites.

Then, host factors such as prematurity and low birth weight, use of broad-spectrum antimicrobials, invasive procedures, parenteral nutrition and contact with healthcare workers and parents increase the risk to develop infections.1

Bacterial and viral agents may be all responsible of infections, but in particular, NICU patients are more vulnerable to colonization and infection with microorganisms such as multidrug-resistant, Gram-negative bacteria, which are associated with increased infection- related morbidities and higher case-fatality rates.2

Furthermore, also fungi may be responsible of invasive infections in low-birth-weight neonates, associated with high rates of morbidity and mortality.3

Risk factors for invasive fungal infections are mucosal and skin colonization. Neonatal colonization with Candida spp. is subsequent to either maternal transmission or nosocomial acquisition by hands of healthcare workers in the nosocomial environment.4

The incidence of invasive fungal infections may fluctuate by geographical areas varying from 0.33 per 1000 live births of hospitalized neonates in Japan5 to an estimated 2.4 per 1000 neonatal unit admissions in England during a period ranging from 2004 to 2010.6

Prevention for high-risk patients (ie, extremely low-birth-weight neonates) is based on fluconazole prophylaxis. Other strategies to reduce infections include improving hand hygiene, appropriate use of antiseptics and avoiding unnecessary antibiotic therapy.

The coronavirus disease 2019 pandemic has induced a reinforcement of infection control measures in all the hospital setting.

During this exceptional situation, also our hospital (Spedali Civili) located in Brescia in the north of Italy, one of the more affected geographical area in Italy by the pandemic, introduced an extraordinary reinforcement of all infection control measures. These include the use of universal personal protective equipment, limited patient visits and movement and reinforcement of cleaning regimens that might have had an impact also on the bacterial and fungal colonization of neonates in NICU.

Our neonatal care unit is adopted from August 2018, following a Serratia spp. outbreak, a routine active surveillance by collecting rectal and nasopharyngeal swabs from NICU patients. This screening was performed at admission of the neonates and every week for their entire stay in the ward to rule out colonization with multiresistant organisms (MDROs) and fungi to prevent spread and, therefore, potential transmission between the colonized and noncolonized neonates.

We therefore compared the prevalence of MDROs and Candida colonization over the period ranging between March and August 2020 with the same period of the previous year (March–August 2019). We observed a high statistically significant reduction of prevalence of Gram-negative bacteria colonization from 38% (80/211) to 20% (47/239) and a statistically significant reduction of extended-beta-lactamase-positive bacteria colonization from 8% (17/211) to 2.5% (6/239) (Fig. 1). Furthermore, a drastic decrease in Candida spp. colonization from 8% (17/211) to 2% (5/239) (P = 0.001) was detected (Fig. 1). In Table 1, it is reported the trend of MDROs, methicillin-resistant Staphylococcus aureus and Candida colonization during all the months of the study period. A reduction in methicillin-resistant Staphylococcus aureus colonization was observed during the study period from 3.3% (7/211) to 0.8% (2/239), even if the p value achieved is not statistically significant. No decrease in colonization rates was observed in the previous 6 months (from September 2019 to February 2020) compared with the same period of the previous year (from September 2018 to February 2019) (data not shown) for any of the microorganisms analyzed.

TABLE 1. - Trend of Bacteria and Candida spp. Colonization During the Study Period
MDR Gram-negative Bacteria, Number of Positive/Total (%) ESBL-producing Bacteria, Number of positive/total (%) Candida spp, Number of Positive/Total (%) MRSA, Number of Positive/Total (%)
2019 2020 2019 2020 2019 2020 2019 2020
March 13/57 (23) 8/60 (13) 2/57 (3.5) 2/60 (3.3) 4/57 (7) 1/60 (1.6) 1/57 (1.7) 0/60
April 14/41 (34) 6/45 (13)* 2/41 (4.8) 1/45 (2.2) 4/41 (10) 0/45* 1/41 (2.4) 1/45 (2.2)
May 12/26 (46) 13/36 (36) 1/26 (3.8) 0/36 2/26 (7.6) 1/36 (2.7) 2/26 (7.6) 1/36 (2.7)
June 13/29 (45) 10/35 (28) 5/29 (17) 1/35 (3) 2/29 (6.8) 0/35 0/29 0/35
July 14/34 (41) 5/35 (14)* 5/34 (15) 1/35 (3) 3/34 (8.8) 1/35 (2.8) 2/34 (5.8) 0/35
August 14/24 (58) 5/28 (18) 2/24 (8.3) 1/28 (3.5) 2/24 (8.3) 1/28 (3.5) 1/24 (4.1) 0/28
Total 80/211 (38) 47/239 (20) 17/211 (8) 6/239 (2.5) 17/211 (8) 4/239 (2) 7/211 (3.3) 2/239 (0.8)
*P < 0.05 2020 vs. 2019.
P < 0.001 2020 vs. 2019
ESBL indicates extended-beta-lactamase; MDR, multidrug resistant; MRSA, methicillin-resistant Staphylococcus aureus.

Percentage of bacterial and fungal colonization over time study from control period March–August 2019 to COVID-19 period (March–August 2020). COVID-19 indicates coronavirus disease 2019; ESBL, extended-beta-lactamase.

The rate of infection during the study period decreased from 2.3% (5/211) to 1.6% (4/239) (P = 0.74).

This observation, the first to the best of our knowledge in Europe, needs to be confirmed by other larger studies. However, it underlines the importance to implement strategies aimed to reduce nosocomial transmission in NICUs that include not only a reinforcement of infection control measures but also a stringent compliance with those measures by healthcare workers and parents as obtained in the dramatic situation generated during the coronavirus disease 2019 “era.”


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2. Tsai MH, Chu SM, Hsu JF, et al. Risk factors and outcomes for multidrug-resistant Gram-negative bacteremia in the NICU. Pediatrics. 2014; 133:e322–e329.
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5. Ishiwada N, Kitajima H, Morioka I, et al. Nationwide survey of neonatal invasive fungal infection in Japan. Med Mycol. 2018; 56:679–686.
6. Oeser C, Vergnano S, Naidoo R, et al.; Neonatal Infection Surveillance Network (neonIN). Neonatal invasive fungal infection in England 2004-2010. Clin Microbiol Infect. 2014; 20:936–941.
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