Surveillance of multidrug-resistant gram-negative bacilli in a neonatal intensive care unit: prominent role of cross transmission

doi:10.1016/j.ajic.2006.04.210

American Journal of Infection Control

Volume 35, Issue 4, May 2007, Pages 222-230

https://doi.org/10.1016/j.ajic.2006.04.210 Get rights and content

Background

Multidrug-resistant gram-negative bacilli (MDRGN) are an important cause of nosocomial infections in neonatal intensive care units (NICUs). We conducted a 1-year prospective surveillance study in an NICU to assess the epidemiology of MDRGN among newborns and the relative importance of acquisition routes.

Methods

Neonates admitted at the NICU of the Dipartimento Materno-Infantile, University Hospital, Palermo, Italy, from January 7, 2003, to January 6, 2004, were included in the study. Colonization of patients with MDRGN was assessed by cultures of rectal swabs sampled twice a week. Pulsed-field gel electrophoresis was used to determine relatedness among MDRGN isolates. Extended-spectrum β-lactamases (ESBL) and metallo-β-lactamases (MBL) production was investigated. The association between risk factors at admission and during the NICU stay was analyzed by multivariate logistic regression analysis.

Results

During the 12-month period January 7, 2003, through January 6, 2004, 1021 rectal swabs were cultured from 210 infants. One hundred sixteen infants (55.2%) were colonized by MDRGN. The monthly incidence of acquisition of MDRGN ranged between 12 and 53 cases per 1000 patient-days. Eighty-four (72.4%) of the 116 patients were cross colonized. Exclusive feeding by formula was significantly associated with cross transmission (RR = 1.8, P = .02). Fifty-seven (49.1%) of the 116 infants were colonized by ESBL-producing Enterobacteriaceae. Feeding by formula was significantly associated with colonization by ESBL-producing Enterobacteriaceae (RR = 1.6, P = .007), whereas breastfeeding proved to be protective (RR = 0.5, P = .001). Ninety-two (43.8%) of the 210 infants received antibiotics during the NICU stay, but exposure to those most frequently administered, ampicillin-sulbactam and gentamicin, was not significantly associated with MDRGN colonization.

Conclusion

The emerging picture of this study is that spread of MDRGN in an NICU may be the result of diffuse cross transmission and, consequently, of poor infection control procedures.

Section snippets

Setting

We conducted a 1-year prospective surveillance study in the NICU of the University Hospital of Palermo, Italy. The unit is part of the Dipartmento Materno-Infantile, which is a reference center for congenital malformation in Sicily. The department includes also units of infertility and assisted reproduction and materno-fetal medicine. In the NICU under study, approximately 200 patients are usually admitted annually, including approximately 15% of VLBW newborns (birthweight <1500 g). The NICU is

General

During the 12-month period January 7, 2003, through January 6, 2004, a total of 221 neonates were admitted to the NICU for at least 48 hours. Among these, only 11 missed rectal swab cultures and were excluded from further analysis.

A total of 1021 rectal swab cultures were sequentially obtained from 210 infants. The characteristics of the study population are summarized in Table 1. The average length of stay was 22.3 days (median, 13 days; range, 3-140). Ninety-two (43.8%) infants received

Discussion

MDRGN organisms are becoming the prevalent causal agents of infection in NICUs.²⁰ Epidemiologic features of circulation of these organisms have been described by several authors, who have identified risk factors for colonization and infection and applied molecular tracing as a tool for assessing transmission pathways and cross-transmission burden and addressing drug-resistance control strategies.4, 6, 8, 9, 10

Our study showed a colonization rate higher than that reported by some previous studies

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Citation Excerpt :
Apart from one study [23], all papers assessed colonization through rectal swab or stool culture (Table S2). Twenty-four (88.9%) out of 27 studies provided information about timing and frequency of microbiological screening [4,6,8,9,17–36]. In nearly half of the studies, rectal/skin swabs were performed weekly through the baby's NICU stay [4,6,17,19,20,24–30,32,33], whereas in six studies neonates were screened twice a week [8,21,22,31,35,36].
Neonates admitted to neonatal intensive care units (NICU) are at significant risk of developing bloodstream infections (BSIs). Gram-negative bacteria (GNB) both colonize and infect, but the association between these entities is unclear. By conducting a systematic literature review, we aimed to explore the impact of factors on the association between GN colonization and GN-BSI at both baby-level and unit-level.
We searched Medline, Embase, and Cochrane Library. Observational cohort studies published after 2000 up to June 2016 reporting data on the total number of neonates (0-28 days) colonized with GNB assessed by rectal/skin swab culture and the total number of neonates with GN-BSI (same bacteria) were included. Studies were excluded if data on skin/rectal colonization, neonates, and GNB could not be identified separately. Meta-analyses along with multivariate meta-regression with a random-effect model were performed to investigate factors associated with the GN colonization and GN-BSI at baby-level and unit-level.
Twenty-seven studies fulfilled our inclusion criteria, 15 for the baby-level and 12 for the unit-level analysis. Study heterogeneity was high, with suboptimal overall quality of reporting assessed by the STROBE-NI statement (44.8% of items adequately reported). In 1984 colonized neonates, 157 (7.9%) developed GN-BSI compared with 85 of 3583 (2.4%) non-colonized neonates. Considerable heterogeneity was observed across studies. Four factors were included in the meta-regression model: gross domestic product (GDP), pathogen, outbreak, and frequency of screening. There was no statistically significant impact of these factors on GN colonization and GN-BSI in baby-level. We were unable to perform the multivariate meta-regression because of insufficient reported data for unit-level.
Study limitations include the small number and the high heterogeneity of the included studies. While this report shows a correlation between colonization and BSI risk, these data currently do not support routine screening for GNB. Analysis of large cohorts of colonized neonates with clinical outcomes is still needed to define the major determinants leading from colonization to infection.

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Major ArticleSurveillance of multidrug-resistant gram-negative bacilli in a neonatal intensive care unit: prominent role of cross transmission

Background

Methods

Results

Conclusion

Section snippets

Setting

General

Discussion

J Hosp Infect

Am J Infect Control

J Hosp Infect

Clin Microbiol Infect

Clin Microbiol Infect

Lancet

Nosocomial infections among neonates in high-risk nurseries in the United States

Pediatrics

Late-onset sepsis in very low birth weight neonates: the experience of the NICHD Neonatal Research Network

Pediatrics

Neonatal sepsis: epidemiology and management

Paediatr Drugs

Molecular typing demonstrating transmission of gram-negative rods in a neonatal intensive care unit in the absence of a recognized epidemic

Clin Infect Dis

Extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella species: risk factors for colonization and impact of antimicrobial formulary interventions on colonization prevalence

Infect Control Hosp Epidemiol

Molecular epidemiology of ceftazidime-resistant gram-negative bacilli on inanimate surfaces and their role in cross-transmission during nonoutbreak periods

J Clin Microbiol

Outbreak of Enterobacter cloacae related to understaffing, overcrowding, and poor hygiene practices

Infect Control Hosp Epidemiol

Molecular epidemiology of antibiotic resistant gram-negative bacilli in a neonatal intensive care unit during a nonoutbreak period

Pediatrics

Molecular epidemiology of gram-negative bacilli from infected neonates and health care workers' hands in neonatal intensive care units

Clin Infect Dis

Major Article
Surveillance of multidrug-resistant gram-negative bacilli in a neonatal intensive care unit: prominent role of cross transmission