Non-multidrug-resistant, methicillin-resistant Staphylococcus aureus in a neonatal unit.

BACKGROUND: In the last decade, non-multiresistant methicillin-resistant Staphylococcus aureus (NM-MRSA) has been described as an important agent in bloodstream infections in our hospital. METHODS: This prospective cohort study, conducted from February 2009 through January 2010 in the neonatal unit, evaluated 403 newborns (NB), their 382 mothers and 148 health care workers (HCW). RESULTS: Approximately 217 NB (54%), 187 mothers (48%) and 87 HCW (59%) were colonized by S. aureus (SA). MRSA colonization was greater among NB (15%) than mothers (4.7%) and HCW (3.4%). Although mother-to-NB transmission occurred, in most cases mothers were not responsible for NB colonization. There were 2 predominant PFGE patterns among the NB and some mothers and HCW became colonized by them. Factors significantly associated with MRSA carriage by NB were lower level of maternal schooling (risk factor: odds ratio: 2.99; 95% confidence interval: 1.10-8.07) and maternal rhinosinusitis (protective factor: odds ratio: 0.33; 95% confidence interval:0.12-0.88). Among NB who remained hospitalized for more than 72 hours, breast feeding was protective (odds ratio: 0.22; 95% confidence interval: 0.05-0.98). All the isolates were NM-MRSA, carried few virulence factors and SCCmec types IVa and type IVd predominated. CONCLUSIONS: Although there were no cases of infection, nosocomial transmission of MRSA clearly occurred in the neonatal unit, and this highlights the need for infection control practices such as hand hygiene to prevent cross-dissemination. Other healthcare practices, which are very basic but also ample in scope, may play a role, such as general education of women and breast feeding.

Performance of surveillance cultures at different body sites to identify asymptomatic Staphylococcus aureus carriers.

The objective was to evaluate the performance of surveillance cultures at various body sites for Staphylococcus aureus colonization in pregnant women and newborns (NB) and the factors associated with nasal colonization. For NB, 4 sites were evaluated: nares, oropharynx, perineum, and umbilical stump (birth, third day, and weekly). For pregnant women, 4 sites during labor: anterior nares, anus, perineum, and oropharynx. Nasally colonized patients were compared with colonized only extranasally. Colonization was 53% of 392 pregnant women (methicillin-resistant S. aureus [MRSA]: 4%) and 47% of 382 NB (MRSA: 9%). For newborn patients, the best body site was the umbilical stump (methicillin-susceptible S. aureus [MSSA]: 64%; MRSA: 68%) and the combination of nares + umbilical (MSSA: 86%; MRSA: 91%). Among pregnant women, the best body site was the anterior nares (MSSA: 59%; MRSA: 67%) and the combination of nares + oropharynx (MSSA: 83%; MRSA: 80%). A smaller number of household members were associated with MRSA carriage in pregnant women (2.2 ± 0.6 versus 3.6 ± 1.8; P = 0.04). In conclusion, multiple culture sites are needed. Control programs based on surveillance cultures may be compromised.

Evaluation of interventions to reduce catheter-associated bloodstream infection: continuous tailored education versus one basic lecture.

BACKGROUND: This study evaluated the impact of 2 models of educational intervention on rates of central venous catheter-associated bloodstream infections (CVC-BSIs). METHODS: This was a prospective observational study conducted between January 2005 and June 2007 in 2 medical intensive care units (designated ICU A and ICU B) in a large teaching hospital. The study was divided into in 3 periods: baseline (only rates were evaluated), preintervention (questionnaire to evaluate knowledge of health care workers [HCWs] and observation of CVC care in both ICUs), and intervention (in ICU A, tailored, continuous intervention; in ICU B, a single lecture). The preintervention and intervention periods for each ICU were compared. RESULTS: During the preintervention period, 940 CVC-days were evaluated in ICU A and 843 CVC-days were evaluated in ICU B. During the intervention period, 2175 CVC-days were evaluated in ICU A and 1694 CVC-days were evaluated in ICU B. Questions regarding CVC insertion, disinfection during catheter manipulation, and use of an alcohol-based product during dressing application were answered correctly by 70%-100% HCWs. Nevertheless, HCWs' adherence to these practices in the preintervention period was low for CVC handling and dressing, hand hygiene (6%-35%), and catheter hub disinfection (45%-68%). During the intervention period, HCWs' adherence to hand hygiene was 48%-98%, and adherence to hub disinfection was 82%-97%. CVC-BSI rates declined in both units. In ICU A, this decrease was progressive and sustained, from 12 CVC-BSIs/1000 CVC-days at baseline to 0 after 9 months. In ICU B, the rate initially dropped from 16.2 to 0 CVC-BSIs/1000 CVC-days, but then increased to 13.7 CVC-BSIs/1000 CVC-days. CONCLUSION: Personal customized, continuous intervention seems to develop a "culture of prevention" and is more effective than single intervention, leading to a sustained reduction of infection rates.

Emergence of resistance in Pseudomonas aeruginosa and Acinetobacter species after the use of antimicrobials for burned patients.

OBJECTIVES: To evaluate the emergence of resistance of Pseudomonas aeruginosa and Acinetobacter species to imipenem, ciprofloxacin, or both after the use of these drugs and to compare resistant with susceptible isolates by molecular typing. DESIGN: Cohort study. SETTING: Burn intensive care unit (ICU) with 4 beds in a tertiary-care university hospital. METHODS: During 16 months, surveillance cultures were performed for all patients admitted to the ICU. Demographic information was obtained for each patient. Molecular typing was done by pulsed-field gel electrophoresis using restriction enzymes for 71 isolates of P. aeruginosa and Acinetobacter species. RESULTS: Thirty-four patients were admitted and 22 were colonized by susceptible P. aeruginosa or Acinetobacter species before they used the antimicrobials. Nine (41%) of these patients had a resistant isolate after antimicrobial use: 5 had used imipenem alone, 1 had used ciprofloxacin, and 3 had used both drugs. The interval between isolation of the susceptible and resistant isolates ranged from 4 to 25 days, but was 10 or more days for 6 patients. Molecular typing revealed that susceptible and resistant isolates from each patient were different and that although there were no predominant clones among susceptible isolates, there was a predominant clone among resistant isolates of P. aeruginosa and of Acinetobacter. CONCLUSIONS: Resistance was not due to the acquisition of resistance mechanisms by a previously susceptible strain, but rather to cross-transmission. Although various measures involving antimicrobial use have received great attention, it would seem that practices to prevent cross-transmission are more important in controlling resistance.

Central venous catheter-related infections in intensive care units

Objective: To determine the rates of colonization and infection related to central venous catheter (CVC), the causative microorganisms, and the influence of various factors. Methods: From June to August 1993, all CVC in 4 Intensive Care Units were evaluated from their insertion to removal. Data were collected, by 3 nurses. Blood and catheter tips were cultured. Results: Of 84 catheters, 29.8 percent were colonized, 9.5 percent of patients showed evidence of local infection, and 4.8 percent had primary bloodstream infections. The internal jugular vein was the most commun site for catheter insertion (81 percent). Causes of removal were: end of need (48.3 percent), suspected infection (23.3 percent), malfunction (20 percent), routine change (8.3 percent). Among removals because of suspected infection 50 percent presented evidence of local infection, 43 percent were colonized (>15cfu), but there were no bloodstream infections. The average time of catheter use for those which became colonized was longer than for catheters that did not become colonized (p=0.008). The average time of catheter use associated with removal for infection (local and bloodstream) was longer than for removal for other reasons (p=0.042). Among colonized catheters, 16 percents developed bloodstream infection and 20 percent local infection. Immunosupressive drugs, cancer, diabets mellitus, HIV-infection, and neutropenia were not associated with infection or colonization. The most common microorganisms were gram-negative rods and S.aureus. Conclusions: The duration of venous catheter use increased the risk of colonization and infection. The observation suggests that physicians must strive for the shortest time of use of venous catheters, but it does not indicate a need for routine central venous catheter removal.