Successful control of an Acinetobacter baumannii outbreak in a neonatal intensive care unit

Infection control measures against multidrug-resistant Gram-negative bacteria in children and neonates

The increase in infections caused by multidrug-resistant (MDR) Gram-negative bacteria in neonatal and pediatric intensive care units over recent years is alarming. MDR Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter baumannii have constituted the main causes of the MDR Gram-negative bacteria problem. The implementation of infection control measures such as hand hygiene, cohorting of patients, contact precautions, active surveillance and environmental cleaning could diminish their spread. Recently, water safety has been identified as a major component of infection control policies. The aim of the current review is to highlight the effectiveness of these infection control measures in managing outbreaks caused by MDR Gram-negative bacteria in neonatal and pediatric intensive care units and highlight future perspectives on the topic.

Relationship Between COVID-19 Lockdown and Epidemiology of Neonatal Sepsis

BACKGROUND

We compared the hospital-based epidemiology of neonatal sepsis after the coronavirus disease 2019 lockdown (LD) versus historical epochs and the LD period versus phases of unlocking.

METHODS

This retrospective cohort study was conducted in a level 3 neonatal unit. We compared neonates born in three 24-week periods-Group LD: 22 March 2020 to 5 September 2020-the reference group, Group pre-LD: 29 September 2019 to 14 March 2020 and Group temporally corresponding to LD in 2019 (corres-LD): 24 March 2019 to 7 September 2019. We also studied linear trends from LD phase 1.0 until Unlock 4.0. The key outcome was culture-positive sepsis.

RESULTS

There were 1622, 2744 and 2700 subjects in groups LD, pre-LD and corres-LD, respectively. The incidence of any culture-positive sepsis in pre-LD was higher than LD [odds ratio (95% CI) = 1.61 (1.02-2.56)]. This was mainly due to a statistically significant reduction in Acinetobacter baumannii sepsis, with incidence rate differences of pre-LD versus LD [0.67 (95% CI: 0.37-0.97), P = 0.0001] and corres-LD versus LD [0.40 (95% CI: 0.16-0.64), P = 0.0024]. Groups pre-LD and corres-LD had higher proportion of multi-drug resistant (MDR)/extreme drug resistance/pan drug resistance sepsis than LD [77%, 77% and 44%, respectively (P values of both groups vs. LD = 0.01)]. From LD 1.0 to unlock 4.0, there were fewer episodes of MDR sepsis (Plinear trends = 0.047). On multivariable analysis, group pre-LD (vs. reference group LD), male sex, birth weight and Apgar score independently predicted culture-positive sepsis.

CONCLUSIONS

LD favorably impacted the epidemiology of neonatal sepsis in a hospital setting, with less A. baumannii and MDR sepsis, which persisted during unlocking.

Neonatal multidrug-resistant gram-negative infection: epidemiology, mechanisms of resistance, and management

Infants admitted to the neonatal intensive care unit, particularly those born preterm, are at high risk for infection due to the combination of an immature immune system, prolonged hospitalization, and frequent use of invasive devices. Emerging evidence suggests that multidrug-resistant gram-negative (MDR-GN) infections are increasing in neonatal settings, which directly threatens recent and ongoing advances in contemporary neonatal care. A rising prevalence of antibiotic resistance among common neonatal pathogens compounds the challenge of optimal management of suspected and confirmed neonatal infection. We review the epidemiology of MDR-GN infections in neonates in the United States and internationally, with a focus on extended-spectrum β-lactamase (ESBL)-producing Enterobacterales and carbapenem-resistant Enterobacterales (CRE). We include published single-center studies, neonatal collaborative reports, and national surveillance data. Risk factors for and mechanisms of resistance are discussed. In addition, we discuss current recommendations for empiric antibiotic therapy for suspected infections, as well as definitive treatment options for key MDR organisms. Finally, we review best practices for prevention and identify current knowledge gaps and areas for future research. IMPACT: Surveillance and prevention of MDR-GN infections is a pediatric research priority. A rising prevalence of MDR-GN neonatal infections, specifically ESBL-producing Enterobacterales and CRE, compounds the challenge of optimal management of suspected and confirmed neonatal infection. Future studies are needed to understand the impacts of MDR-GN infection on neonatal morbidity and mortality, and studies of current and novel antibiotic therapies should include a focus on the pharmacokinetics of such agents among neonates.

Assessment of surface cleaning and disinfection in neonatal intensive care unit

Background

Surveillance for healthcare-associated infections (HAI) is a priority in the neonatal intensive care unit (NICU), given the critical immune status of patients. The aim of this study was to assess surface bacterial contamination before and after improving cleaning and disinfection practices.

Materials and methods

This was a cross-sectional study conducted in March 2018. Surface samples were taken from the same areas in three steps: after cleaning, after "improved" cleaning, and after terminal disinfection using hydrogen peroxide vapor (VHP). Sampling and culture was carried out according to standard ISO14698-1: 2004. Results interpretation was based on the thresholds defined by good hospital pharmacy practice. Statistical analysis was performed by SPSS 21.0 and a P-value < 0.05 was considered to be significant.

Results

In total, 290 samples were taken from different zones: fixed equipment (69%), aseptic washbasins (12%), pneumatic system (9%), computer equipment (6%) and mobile equipment (4%). Prevalence of non-compliances after cleaning and disinfection was 75%, 10% after “improved” cleaning, and 0% after automated VHP (P < 0.0001). Median of CFU was 24[EI (0–625)] after standard cleaning, 2[EI (0–35)] after “improved” cleaning and 0 [EI (0–3)] after VHP (P < 0.0001). Isolated germs werecoagulase-negative Staphylococcus (31.2%), Acinetobacter baumannii (26%), Staphylococcus aureus (19.5%), Pseudomonas aeruginosa (9%), Klebsiella pneumoniae (9%), E. coli (4%) and Enterobacter sp (1.3%).

Conclusion

Improved cleaning and disinfection practices associated to VHP give microbiological satisfactory results. It is important to educate cleaning staff for effective surface cleaning and disinfection operations to control HAI.

Control of Acinetobacter baumannii outbreak in the neonatal intensive care unit in Latvia: whole-genome sequencing powered investigation and closure of the ward

Background

Acinetobacter baumannii is an emerging pathogen capable of causing hospital-acquired infections (HAIs). It has the ability to survive on environmental surfaces for months, making transmission difficult to control. Our report describes the investigation and restriction of an outbreak of A.baumannii in the Neonatal Intensive Care Unit (NICU) using whole-genome sequencing (WGS) and multi-modal infection control measures.

Methods

A prospective surveillance of HAIs was initiated in the NICU at the Pauls Stradins Clinical University Hospital (PSCUH) in Latvia on 1/9/2012 and identified an outbreak of A.baumannii. Case definitions for A.baumannii bloodstream infection (BSI) and colonization were implemented; surveillance cultures were obtained from all admitted patients to monitor the rate of colonization; an infection prevention and control team was formed and infection control interventions implemented. Environmental sampling of the NICU and Labour ward was performed. We employed WGS to differentiate phenotypically identical multidrug-resistant A.baumannii (MDRAB) strains from simultaneous intrahospital outbreaks in the adult Intensive Care Unit and NICU.

Results

Between 1/9/2012 and 31/12/2017 the surveillance included 2157 neonates. A total of 17 neonates had A.baumannii BSI, with the highest rate of 30.0 cases per 1000 bed-days in November 2012. Rectal screening samples were positive for A.baumannii-complex in 182 neonates reaching 119.6 per 1000 bed-days in July 2015. All 298 environmental cultures were negative. Two phenotypically identical MDRAB isolates from the simultaneous intrahospital outbreaks were differentiated using WGS, ruling out an inter-ward transmission. Adherence to stringent infection control measures decreased BSI cases but colonization remained persistent. With several relapses, the outbreak was ongoing for four years. No new A.baumannii BSI cases were registered after total environmental decontamination in the NICU in July 2015. Colonization reappeared and persisted until in November 2016 when the ward was temporarily closed, relocated and renovated. No A.baumannii cases were registered after the renovation.

Conclusion

The HAI surveillance system successfully detected and facilitated the control of the A.baumannii outbreak. Whole-genome sequencing was found to be a useful method for differentiation of phenotypically identical A.baumannii strains from the intrahospital outbreak. Only multi-modal infection control program, including closure, temporary relocation, and renovation of the ward, restricted the outbreak.

An outbreak of bloodstream infection due to extensively resistant Acinetobacter baumannii among neonates

BACKGROUND

Extensively resistant Acinetobacter baumannii has emerged and spread worldwide as a significant cause of health care-associated infections and outbreaks. It also causes life-threatening infections among neonates, including bacteremia. The aim of this study was to investigate an outbreak of A baumannii bacteremia (ABB) among neonates.

MATERIALS AND METHODS

A retrospective, case-control study was conducted from July 2014 to July 2015 in a neonatal intensive care unit (NICU). Risk factors associated with ABB in univariate and multivariate analysis with logistic regression was performed. Molecular typing by pulsed field gel electrophoresis was used to confirm relatedness of bacteremic A baumannii strains.

RESULTS

During the 5-year period (2011-2016), 68 patients in our NICU were diagnosed with BSI due to A baumannii. The case-control study included 41 case patients within the outbreak caused by a major epidemic clone and 108 control patients. Risk factors (by univariate analysis) associated with ABB were intubation, 14-day mortality, and use of peritoneal dialysis and an umbilical catheter. Multivariate analysis identified 14-day mortality (odds ratio, 5.75; 95% confidence interval, 2.58-12.79) and umbilical catheter use (odds ratio, 2.44; 95% confidence interval, 1.1-5.4) as independent risk factors for ABB.

CONCLUSIONS

This outbreak of bacteremia due to resistant A baumannii affected 41 infants and was associated with 58% mortality. Control of the outbreak was achieved by implementing long-term sustained infection control measures within the unit.

The role of vancomycin in addition with colistin and meropenem against colistin-sensitive multidrug resistant Acinetobacter baumannii causing severe infections in a Paediatric Intensive Care Unit

Background

Acinetobacter baumannii has been associated with high morbidity and mortality rates, even in pediatric patients. Therapeutic options are limited, especially when the strain is multidrug resistant.

Methods

Clinical and microbiological analyses of 4 cases of systemic infections caused by multi drug resistant A. baumannii treated with colistin/vancomycin combination at a Pediatric Intensive Care Unit were performed in order to explore the potential synergistic activity of colistin plus vancomycin. All the patients were treated with colistin, meropenem and vancomycin.

Results

Four severe infections due to MDR A. baumannii were observed. All patients treated with colistin/vancomycin combination had a positive outcome with no infection relapses. Most importantly, no significant adverse events related to the simultaneous administration of COL plus VAN were observed. In our in-vitro experiments, the synergistic effect of the combination COL plus VAN showed an early bactericidal activity even at VAN concentration of 16 mg/L, which reflects the serum trough concentrations obtained in patients.

Discussion

An antimicrobial strategy based on the activity of colistin plus vancomycin was in-vitro and in-vivo effective in life-threatening infections caused by multidrug-resistant A. baumannii in a Pediatric Intensive Care Unit, in the absence of adverse effects. Colistin plus vancomycin were highly synergic and bactericidal against carbapenem-resistant, colistin sensitive A. baumannii whereas the addition of meropenem did not enhance the in-vitro activity of colistin plus vancomycin.

Conclusions

Our results confirm existing data on the potential synergistic activity of a therapeutic strategy including colistin plus vancomycin and provide important new clinical information for its potential use as a therapeutic option against MDR A. baumannii infections, especially in the pediatric population.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1133-3) contains supplementary material, which is available to authorized users.

Infection Control Programs and Antibiotic Control Programs to Limit Transmission of Multi-Drug Resistant Acinetobacter baumannii Infections: Evolution of Old Problems and New Challenges for Institutes

Background: Acinetobacter baumannii complex (A. baumannii) has been isolated worldwide. The rapid spread of multidrug-resistant A. baumannii complex (MDRAB) in clinical settings has made choosing an appropriate antibiotic to treat these infections and executing contact precautions difficult for clinicians. Although controlling the transmission of MDRAB is a high priority for institutions, there is little information about MDRAB control. Therefore, this study evaluated infection control measures for A. baumannii infections, clusters and outbreaks in the literature. Methods: We performed a review of OVID Medline (from 1980 to 2015), and analyzed the literature. Results: We propose that both infection control programs and antibiotic control programs are essential for control of MDRAB. The first, effective control of MDRAB infections, requires compliance with a series of infection control methods including strict environmental cleaning, effective sterilization of reusable medical equipment, concentration on proper hand hygiene practices, and use of contact precautions, together with appropriate administrative guidance. The second strategy, effective antibiotic control programs to decrease A. baumannii, is also of paramount importance. Conclusion: We believe that both infection control programs and antibiotics stewardship programs are essential for control of MDRAB infections.

An Outbreak of Carbapenem-Resistant Acinetobacter baumannii Infection in a Neonatal Intensive Care Unit: Investigation and Control

Objective.

To investigate the mode of transmission of and assess control measures for an outbreak of carbapenem-resistant (multidrug-resistant) Acinetobacter baumannii infection involving 6 premature infants.

Design.

An outbreak investigation based on medical record review was performed for each neonate during the outbreak (from November 2008 through January 2009) in conjunction with an infection control investigation.

Setting.

A 36-bed, level 3 neonatal intensive care unit in a university-affiliated teaching hospital in Detroit, Michigan.

Interventions.

Specimens were obtained for surveillance cultures from all infants in the unit. In addition, geographic cohorting of affected infants and their nursing staff, contact isolation, re-emphasis of adherence to infection control practices, environmental cleaning, and use of educational modules were implemented to control the outbreak.

Results.

Six infants (age, 10-197 days) with multidrug-resistant A. baumannii infection were identified. All 6 infants were premature (gestational age, 23-30 weeks) and had extremely low birth weights (birth weight, 1000 g or less). Conditions included conjunctivitis (2 infants), pneumonia (4 infants), and bacteremia (1 infant). One infant died of causes not attributed to infection with the organism; the remaining 5 infants were discharged home. All surveillance cultures of unaffected infants yielded negative results.

Conclusions.

The spread of multidrug-resistant A. baumannii infection was suspected to be due to staff members who spread the pathogen through close contact with infants. Clinical staff recognition of the importance of multidrug-resistant A. baumannii recovery from neonatal intensive care unit patients, geographic cohorting of infected patients, enhanced infection control practices, and staff education resulted in control of the spread of the organism.

Clinical Features and Epidemiology ofAcinetobacter baumanniiColonization and Infection in Spanish Hospitals

Objective:

To investigate the clinical features and the epidemiology ofAcinetobacter baumanniiin Spanish hospitals.

Design:

Prospective multicenter cohort study.

Setting:

Twenty-seven general hospitals and one paraplegic center in Spain.

Methods:

All cases ofA. baumanniicolonization or infection detected by clinical samples during November 2000 were included. Isolates were identified using phenotypic and genotypic methods. The molecular relatedness of the isolates was assessed by pulsed-field gel electrophoresis.

Results:

Twenty-five (89%) of the hospitals had 221 cases (pooled rate in general hospitals, 0.39 case per 1,000 patient-days; range, 0 to 1.17). The rate was highest in intensive care units (ICUs). Only 3 cases were pediatric. The mean age of the patients in the general hospitals was 63 years; 69% had a chronic underlying disease and 80% had previously received antimicrobial treatment. Fifty-three percent of the patients had an infection (respiratory tract, 51%; surgical site, 16%; and urinary tract, 11%). Crude mortality was higher in infected than in colonized patients (27% vs 10%; relative risk, 1.56; 95% confidence interval, 1.2 to 2.0;P= .003). Molecular analysis disclosed 79 different clones. In most hospitals, a predominant epidemic clone coexisted with other sporadic clones. Imipenem resistance was present in 39% of the hospitals.

Conclusions:

A. baumanniiwas present in most participating Spanish hospitals (particularly in ICUs) with different rates among them. The organisms mainly affected predisposed patients; half of them were only colonized. Epidemic and sporadic clones coexisted in many centers.

Successful management of an outbreak due to carbapenem-resistant Acinetobacter baumannii in a neonatal intensive care unit

The investigation and successful management of a monoclonal Acinetobacter baumannii outbreak in a neonatal intensive care unit are described. Upon the first clustered carbapenem-resistant A. baumannii (CRAB) infections, a bundle of actions were taken, including enhanced infection control, active surveillance (weekly stool samples), case-control study, staff education, daily audits and discontinuation of new admissions. Between September and December 2011, eight neonates developed 10 CRAB infections (five blood, four respiratory and one eye). A total of 216 active surveillance cultures were obtained from 96 neonates (43 % had ≥2 samples). During weeks 12, 16 and 17, active surveillance detected 3, 1 and 2 new CRAB acquisitions, respectively. Prevalence of infections/colonizations decreased, and no event occurred after 20th week. A colonized neonate developed CRAB sepsis and died. All CRAB isolates harboured bla OXA-58 and the intrinsic chromosomal bla OXA-51 carbapenemase genes.

CONCLUSION

Active surveillance and enhanced infection control measures effectively contained spread of CRAB clone in the neonatal intensive care unit.

Draft Genome Sequence of Multidrug-Resistant Acinetobacter baumannii Strain MMC4, Isolated from a Patient in Tennessee

Acinetobacter baumannii multidrug-resistant strain MMC4 was isolated from a bronchoalveolar lavage fluid sample from a patient in Nashville, TN, USA. Here, we report a draft genome sequence with a size of 3,985,367 bp, an average G+C content of 39.8%, and 3,863 predicted protein-coding sequences.

Case-control analysis of endemic Acinetobacter baumannii bacteremia in the neonatal intensive care unit

BACKGROUND

We aimed to characterize the clinical manifestations and outcomes of patients with Acinetobacter baumannii bacteremia in the neonatal intensive care unit (NICU).

METHODS

All patients with A baumannii bacteremia in our NICU from 2004 to 2010 were reviewed. A matched case-control study was performed by comparing each case of A baumannii to 2 uninfected controls and all cases of Escherichia coli and Klebsiella bacteremia, respectively.

RESULTS

Thirty-seven cases with A baumannii bacteremia were identified. Multidrug-resistant isolate was noted in only 2 cases (5.4%), and the overall mortality rate was 8.1%. Compared with matched, uninfected controls, infants with A baumannii were more likely to have had a central vascular catheter (CVC) (P = .009), use of total parenteral nutrition (TPN) (P = .021), longer duration of ventilator use (P = .002), and hospitalization (P = .010). Compared with E coli or Klebsiella bacteremia, infants with A baumannii bacteremia had lower birth weight (median of 1,090 g vs 1,300 g, P = .044) and a higher rate of CVC and TPN use (both P < .001) at the time of infection.

CONCLUSION

A baumannii bacteremia occurs endemically or sporadically in the NICU, primarily in low-birth-weight infants on TPN use and with CVC in situ. Although A baumannii does not often cause mortality, and multidrug-resistant A baumannii is uncommon, it contributes significantly to longer hospitalization.

Acinetobacter septicemia in neonates admitted to intensive care units

Background:

Acinetobacter species are gaining importance as potential pathogens in neonatal septicemia because of their frequent isolation and multidrug resistance.

Aims and Objectives:

The aim of the present study was to evaluate the role of Acinetobacter spp. as important pathogens in neonatal blood stream infection, to identify the associated risk factors, and to evaluate the drug sensitivity pattern.

Materials and Methods:

Blood samples of infected neonates were studied bacteriologically. Cases of Acinetobacter septicemia were identified. Speciation of Acinetobacter species was done. Various risk factors were identified. The drug-sensitivity test was done.

Results:

A total of 26 Acinetobacter septicemia cases were identified by blood culture. Acb complex strains predominated. Institutional birth and preterm birth were identified as the most frequent significant risk factors. 11.3% mortality rate was recorded. Acb complex strains exhibited a multi-drug resistant pattern. No carbapenem resistance was observed.

Conclusion:

Acinetobacter should be added to the list of organisms causing severe nosocomial infection in neonatal intensive care units. Continuous bacteriological surveillance, implementation of infection control policies, careful disinfection of intensive care equipment, and rational antibiotic use are required for control of such infections.

Surface microbes in the neonatal intensive care unit: changes with routine cleaning and over time

Premature infants in neonatal intensive care units (NICUs) are highly susceptible to infection due to the immaturity of their immune systems, and nosocomial infections are a significant risk factor for death and poor neurodevelopmental outcome in this population. To investigate the impact of cleaning within a NICU, a high-throughput short-amplicon-sequencing approach was used to profile bacterial and fungal surface communities before and after cleaning. Intensive cleaning of surfaces in contact with neonates decreased the total bacterial load and the percentage of Streptococcus species with similar trends for total fungal load and Staphylococcus species; this may have clinical relevance since staphylococci and streptococci are the most common causes of nosocomial NICU infections. Surfaces generally had low levels of other taxa containing species that commonly cause nosocomial infections (e.g., Enterobacteriaceae) that were not significantly altered with cleaning. Several opportunistic yeasts were detected in the NICU environment, demonstrating that these NICU surfaces represent a potential vector for spreading fungal pathogens. These results underline the importance of routine cleaning as a means of managing the microbial ecosystem of NICUs and of future opportunities to minimize exposures of vulnerable neonates to potential pathogens and to use amplicon-sequencing tools for microbial surveillance and hygienic testing in hospital environments.

Clonal spread and patient risk factors for acquisition of extensively drug-resistant Acinetobacter baumannii in a neonatal intensive care unit in Italy

AIM

To report an outbreak of extensively drug-resistant (XDR) Acinetobacter baumannii in the neonatal intensive care unit (NICU) of an Italian university hospital. Patient risk profiles for acquisition of A. baumannii and measures used to control the outbreak are described.

METHODS

Antibiotic susceptibility of strains was evaluated by microdilution. Genotyping was performed by pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing. Carbapenemase genes were analysed by polymerase chain reaction and DNA sequencing. A case-control study was designed to identify risk factors for acquisition of A. baumannii.

FINDINGS

A. baumannii was isolated from 22 neonates, six of whom were infected. One major PFGE type was identified, assigned to sequence type (ST) 2, corresponding to International Clone II; this was indistinguishable from isolates from the adult ICU in the same hospital. A. baumannii isolates were resistant to aminoglycosides, quinolones and classes of β-lactam antibiotics, but were susceptible to tigecycline and colistin. Carbapenem resistance was associated with the presence of transposon Tn2006 carrying the bla(OxA-23) gene. Length of NICU stay, length of exposure to A. baumannii, gestational age, use of invasive devices and length of exposure to invasive devices were significantly associated with acquisition of A. baumannii on univariate analysis, while length of exposure to central venous catheters and assisted ventilation were the only independent risk factors after multi-variate analysis.

CONCLUSIONS

This XDR A. baumannii outbreak in an NICU was probably caused by intrahospital transfer of bacteria via a colonized neonate whose mother was admitted to the adult ICU. Strengthened infection control measures were necessary to control the outbreak.

Control of an Acinetobacter [corrected] baumannii outbreak in a neonatal ICU without suspension of service: a devastating outbreak in Diyarbakir, Turkey

BACKGROUND

A nosocomial outbreak of Acinetobacter baumannii bloodstream infections (Ab-BSI) was identified in Diyarbakir Children's Hospital's (Diyarbakir, Turkey) 60-bed Neonatal Intensive Care Unit (NICU) in 2006 and 2007.

METHODS

The investigation and control of the outbreak were based on case-control and epidemiological studies as well as multifaceted interventions. Sixty-four neonates (case patients) with Ab-BSI and 128 neonates (control patients) free of Ab-BSI, who had been hospitalized at the unit during the outbreak period, were included in the study. Case and control patients were compared for possible predisposing factors (e.g., gender, length of NICU stay, antibiotic use, intubation, etc.). An intervention program (cohorting, education, reinforcing hand hygiene, antibiotic restriction, improving processes of patient care, environmental cleaning, and barrier isolation) was implemented to control the outbreak. Surveillance cultures were collected from all possible sources, and the epidemiological investigation was supplemented by a pulsed field gel electrophoresis (PFGE) study.

RESULTS

Fifty-three neonates (82.8%) died in the case group and 51 (39.8%) in the control group (P < 0.001). The duration of stay at the NICU [odds ratio (OR) 1.15; 95% confidence interval (CI) 1.07-1.23; P < 0.001] and re-intubation (OR 38.62; CI 12.66-117.87; P < 0.001) were found to be significant risk factors for Ab-BSI. Surveillance cultures showed a heavy contamination in the NICU, and the outbreak ended after a series multifaceted interventions. All A. baumannii isolates, both from the cases and environmental samples, had an identical PFGE fingerprint pattern.

CONCLUSION

The control of Ab-BSI requires a multifaceted intervention program and complex efforts and implementations, especially if the ICU does not implement any suspension of care provision.

Clinical and molecular microbiological characteristics of carbapenem-resistant Acinetobacter baumannii strains in an NICU

BACKGROUND

Seventeen cases of Acinetobacter baumannii infection in a neonatal intensive care unit (NICU) were evaluated. The strains were characterized as resistant to carbapenems. The aim of the present study was therefore to investigate the clinical and molecular epidemiological characteristics of the 17 carbapenem-resistant A. baumannii strains.

METHODS

Samples were isolated from blood or sputum from the patients in the NICU, cultured using conventional techniques and an automated system. Multiplex polymerase chain reaction (PCR) was used to detect blaOXA-51-like, blaOXA-23-like, OXA-24, OXA-58 and Ambler class B carbapenemases. The genotype of the strains was identified on pulsed-field gel electrophoresis (PFGE).

RESULTS

BlaOXA-23 was detected in all of the isolates. PFGE genotype analysis suggested three clones among the 17 strains. Two clones were isolated from other wards of the hospital including the adult ICU and Department of Pulmonology. The other clone was proved to be the first appearance in the hospital as genotype analysis.

CONCLUSION

BlaOXA-23 was the drug-resistant gene that made A. baumannii resistant to carbepenem. The source of blaOXA-23 in the 17 isolates was different.

Comparison of culture media for detection of Acinetobacter baumannii in surveillance cultures of critically-ill patients

The objective of this study was to evaluate the performance of CHROMagar Acinetobacter when compared to sheep blood agar, MacConkey agar and MacConkey agar with 6 μg/ml of imipenem for the detection of A. baumannii in surveillance cultures of hospitalized patients. We utilized peri-anal swabs and sputum samples from patients admitted to the University of Maryland Medical Center ICUs from December 7 through December 21, 2009. Samples were plated onto four media in the following order: (1) 5% sheep blood agar (SBA), (2) MacConkey agar, (3) MacConkey agar with 6 μg/ml of imipenem, and (4) CHROMagar Acinetobacter (CHROMagar). SBA was the gold standard to which all media was compared. There were 165 samples collected during the study period. SBA and CHROMagar detected 18 of 18 (100%) Acinetobacter and 11 of 11 (100%) MDR-A. baumannii. MacConkey agar detected 16 of 18 (89%) Acinetobacter and 10 of 11 (91%) MDR- A. baumannii while MacConkey agar with 6 μg/ml imipenem detected 9 of 11 (82%) MDR-A. baumannii. CHROMagar did not differentiate MDR- A. baumannii from non-MDR-A. baumannii. CHROMagar may be useful for rapid detection of patients with MDR-A. baumannii if improved upon to better select for MDR-A. baumannii.

Systematic review of invasive Acinetobacter infections in children

INTRODUCTION

Clinicians are generally familiar with Acinetobacter as an etiological agent for serious nosocomial infections in intensive care units. However, there are no previous reviews of the full spectrum of invasive infections in children.

METHODS

A systematic review of the literature was completed up to December 2008 for reports of invasive Acinetobacter infections in children.

RESULTS

There were 101 studies that met the inclusion criteria including 18 possible outbreaks, 33 case series and 49 case reports. Suspected outbreaks were concentrated in neonatal intensive care units (16 of 18 outbreaks) and involved bacteremia or meningitis. Proof of isolate clonality or identification of the source of the outbreak was seldom established. Case series were primarily of children younger than five years of age presenting with bacteremia (sometimes multiresistant), meningitis, endocarditis or endophthalmitis, with many community-acquired infections being reported from India. Case reports consisted of unique presentations of disease or the use of novel therapies. Attributable mortality in the outbreaks and case series combined was 68 of 469 (14.5%).

DISCUSSION

Invasive Acinetobacter infections in children usually manifest as bacteremia, meningitis or both, but can result in a wide variety of clinical presentations. Outbreaks are primarily a problem in newborns with underlying medical conditions. Most reports of community-acquired infections are from tropical countries. The study of the mechanism of colonization and infection of children in intensive care units and of neonates in tropical countries may provide some insight into prevention of invasive infections.

Outbreak of Acinetobacter infection in extremely low birth weight neonates

OBJECTIVE

We describe the first outbreak of multiple drug-resistant Acinetobacter baumannii (MDR-Ab) in a neonatal intensive care unit in the United States.

DESIGN/METHODS

MDR-Ab was identified in the blood of a 24-week gestation, 7-day-old extremely low birth weight neonate. Multiple samplings of surveillance surface cultures were performed on exposed and nonexposed neonates. Enhanced infection control measures were implemented. Pulsed-field gel electrophoresis was performed to determine the genetic relatedness of the MDR-Ab isolates. Medical records were reviewed for all exposed patients.

RESULTS

MDR-Ab was recovered from 6 additional neonates. Of these 7 MDR-Ab (index + 6) neonates, 4 died, 3 of whom had positive blood cultures. All affected neonates were born between 23 to 26 weeks gestational age, and were <7 days postnatal age and <750 g (430-720) at the time of exposure. All were housed within the same room as the index case. None of the other 5 exposed neonates older than postnatal day 7 or weighing >750 g at birth were affected. No additional cases occurred outside the original room. Pulsed-field gel electrophoresis was consistent with a clonal origin, identical to MDR-Ab recovered from the referring hospital.

CONCLUSIONS

This MDR-Ab outbreak was rapidly controlled with enhanced infection control measures and was novel in that it affected only <750 g neonates, at < or =26 weeks gestational age, and < or =7 days postnatal age at the time of exposure, suggesting that invasive Ab has a special affinity for damaged or nonkeratinized immature skin in developmentally immature immunologic hosts.

Nosocomial multidrug-resistant Acinetobacter baumannii in the neonatal intensive care unit in Gaza City, Palestine

OBJECTIVES

We performed a prospective case-control study of bloodstream infections in order to determine the infection rate of Acinetobacter baumannii and to determine the risk factors associated with infection and mortality.

METHODS

Between February 2004 and January 2005, 579 consecutive blood specimens were collected from the two neonatal intensive care units (NICUs) of Al-Nasser and Al-Shifa hospitals in Gaza City.

RESULTS

Forty (6.9%) isolates of A. baumannii were obtained from neonates aged under 28 days. Of the patients, 62.5% were male and 37.5% were female. Compared to matched, uninfected controls, statistically significant risk factors were weight<1500 g (odds ratio (OR) 3.89, p<0.001), age <7 days (OR 2.33, p=0.027), median hospitalization of =20 days (OR 3.1, p=0.003), mechanical ventilation (OR 3.5, p=0.001), use of a central venous catheter (CVC; OR 10.5, p<0.001), and prior antibiotic use (OR 4.85, p=0.003). The overall mortality was also significantly different (overall mortality 37.5% in cases vs. 12% in uninfected controls; OR 4.4, p=0.001). Compared to infected controls, statistically significant risk factors were mechanical ventilation (OR 2.68, p=0.008), use of a CVC (OR 6.68, p<0.001), and prior antibiotic use (OR 5.68, p=0.001). The multidrug-resistant type was significantly associated with death in the neonates (p=0.023). The isolates of A. baumannii were resistant to commonly used antibiotics, while susceptible to meropenem (92.5%), imipenem (90%), ciprofloxacin (75%), gentamicin (57.5%), and ceftriaxone (50%).

CONCLUSIONS

The infection rate with multidrug-resistant A. baumannii is considerable and alarming in NICU infants, and is associated with significant mortality.

Epidemiology of and risk factors for Acinetobacter species bloodstream infection in children

BACKGROUND

Acinetobacter species has emerged as an important cause of healthcare-associated bloodstream infections (BSI) in adults. Little is known about development of Acinetobacter spp. BSI in children.

METHODS

A retrospective case-control study was conducted at a tertiary care children's hospital between January 1, 2000 and July 31, 2005. All patients with Acinetobacter spp. BSI (N = 92) were compared with a random sample of patients with non-Acinetobacter spp. Gram-negative rod BSI (N = 156).

RESULTS

Acinetobacter spp. were isolated from blood cultures in 7% of the 1269 patients with Gram-negative rod BSI during the study period. The median age of patients with Acinetobacter spp. BSI was 5.4 years (interquartile range 1.8-13.2 years) and 57% were male. Antibiotic susceptibility patterns of Acinetobacter spp. isolates varied by class: 47% were nonsusceptible to cefotaxime; 3% were nonsusceptible to imipenem; 3% were nonsusceptible to ciprofloxacin. On multivariable analysis, patients with Acinetobacter spp. BSI were significantly more likely to develop their infection in the home setting [adjusted odds ratio (OR) = 3.58; 95% confidence interval (CI): 1.89-6.79], to be male (adjusted OR = 2.25; 95% CI: 1.24-4.08), to have a solid malignancy (adjusted OR = 4.23; 95% CI: 2.00-8.95), and to have renal failure (adjusted OR = 5.16; 95% CI: 1.07-24.96).

CONCLUSIONS

Acinetobacter spp. are an underreported cause of endemic BSI in children. Patients with Acinetobacter spp. BSI are more likely to develop their infection in the home setting compared with patients with BSI caused by other Gram-negative rods.

The molecular epidemiological study of colistin-only-sensitive strains in multi-drug resistant Acinetobacter baumannii

This paper reported the epidemiology of the colistin-only-sensitive Acinetobacter baumannii (COS-AB) in a tertiary teaching hospital in China. We analyzed the clinical data of 136 COS-AB isolates from June 2004 to May 2005 and collected 66 A. baumannii isolates in which 33 strains were COS-AB, and the rest were non-COS-AB. Random amplified polymorphic DNA (RAPD) analysis (primer ERIC2 and 272) showed that all COS-AB were identical, while pulsed-field gel electrophotesis (PFGE) analysis showed two separate genotypes of these COS-AB which were distinctly different from that of non-COS-AB. The COS-AB from burn wards showed the identical PFGE pattern which was distinguished from the genotype of COS-AB in other departments, mainly surgical systems. The cross-infection was severe and strict methods of disinfection and sterilization should be implemented. Meanwhile, the epidemiology of COS-AB in environment and patients should be closely monitored. The PFGE analysis is a reliable method of A. baumannii typing.

Prevention of catheter-related bloodstream infections in the neonatal intensive care setting

Nosocomial infection causes substantial morbidity and mortality among neonates treated in the neonatal intensive care setting. Colonization and subsequent infection of central venous catheters leading to catheter-related bloodstream infection is among the most common causes of nosocomial sepsis in this patient population. Prevention of catheter-related bloodstream infection is a major challenge and numerous strategies have been attempted in this context with varying success. Given the dynamic epidemiology of nosocomial infection among neonates and the emergence of antimicrobial resistance, novel prevention strategies are urgently required.

Epidemiology of multiple Acinetobacter outbreaks in The Netherlands during the period 1999–2001

An increase in the number of outbreaks of Acinetobacter infection was notified in The Netherlands during 1999-2001. The present study compared the outbreaks at the species and strain levels, and analysed the epidemiology and control measures at the different locations. For each institute, three representative isolates from three patients were identified to the species and strain levels by genotyping methods. A questionnaire investigated the impact of the outbreak, the control measures that were taken, and the possible effects of the measures. Seven outbreaks were associated with Acinetobacter baumannii (three outbreaks with a strain designated strain A, two outbreaks with a strain designated strain B, and one outbreak each with strains designated C and D). An additional outbreak was caused by genomic species 13TU, which is related closely to A. baumannii. Strains B and D were identified as European clones III and II, respectively. Except for two hospitals with outbreaks caused by strain A, there was no known epidemiological link between the participating hospitals. In all hospitals the outbreak occurred on one or several intensive care units, and spread to other departments was noted in two hospitals. The number of patients affected ranged from six to 66 over a period of 2-22 months. In most outbreaks, patients were the likely reservoir from which spread occurred. In all hospitals, a large panel of measures was required to bring the outbreak to an end. Extensive environmental sampling yielded numerous positive samples in most but not all hospitals.

Risk factors for the isolation of multi-drug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa: a systematic review of the literature

An understanding of the epidemiology of multi-drug-resistant (MDR) Acinetobacter baumannii and Pseudomonas aeruginosa infections is necessary in order to develop strategies to curtail their spread. For this purpose, the evidence linking the isolation of MDR A. baumannii and P. aeruginosa with specific risk factors was evaluated. PubMed was searched for the 20-year period from September 1985 to September 2005, and eligible studies were considered to be those that: (1) linked the isolation of A. baumannii and P. aeruginosa with specific risk factors; (2) described the characteristics of the affected patients in detail; and (3) provided data on the antibiotic resistance profile of the isolated micro-organisms. Fifty-five studies were found referring to A. baumannii (28 with case-control methodology and 27 outbreak investigations without case-control methodology), and 42 studies were found referring to P. aeruginosa (25 with case-control methodology and 17 outbreak investigations without case-control methodology). Although heterogeneous study designs and investigated risk factors limited this analysis, it was concluded that acquisition and spread of these micro-organisms appear to be related to a large number of variables. Among the most important were deficiencies in the implementation of infection control guidelines and the use of broad-spectrum antibiotics. Use of carbapenems and third-generation cephalosporins appear to be related to the development of an MDR phenotype by A. baumannii, while carbapenems and fluoroquinolones are implicated in MDR P. aeruginosa. The diversity of risk factors associated with the development of MDR A. baumannii and P. aeruginosa suggests that a separate outbreak investigation should be performed in each hospital setting. The development of innovative control strategies is needed in order to limit the spread of these pathogens.

An outbreak of Pantoea spp. in a neonatal intensive care unit secondary to contaminated parenteral nutrition

Contaminated parenteral nutrition (PN) is an important source of infection in neonates. Many organisms have been reported to cause contamination that results in outbreaks in intensive care units. The objective of this study was to investigate an outbreak caused by Pantoea spp., which contaminates PN, in a neonatal intensive care unit (NICU). This was a descriptive study of an outbreak of sepsis in an NICU of a tertiary teaching hospital in Malaysia. Pantoea spp. infection was detected in eight patients over a three-day period from 24 to 27 January 2004 following the administration of PN. Seven of the eight patients died due to the infection. Extensive environmental samplings for culture were performed. PN solution from the NICU and the pharmacy were also cultured during the outbreak period. Pantoea spp. was isolated from blood cultures of all infected patients, and the unused PN from the pharmacy and the NICU. All the strains of Pantoea spp. had a similar antibiotic susceptibility pattern and biochemical reaction. From the results, we concluded that PN was the source of the outbreak and the contamination may have occurred during its preparation in the pharmacy. A thorough investigation has been carried out and, where possible, corrective measures have been taken to avoid similar outbreaks in the future.

Acinetobacter baumannii: emergence and spread in Israeli hospitals 1997-2002

The incidence of multi-drug-resistant Acinetobacter baumannii bloodstream infections (BSIs) increased two- to four-fold in three Israeli hospitals between 1997 and 2002, accounting for 3.5-18% of all hospital-acquired BSIs. This was associated with increasing carbapenem resistance reaching 35-54%, and by a dramatic increase in carbapenem consumption. In-hospital fatality rates ranged between 47% and 58% and were significantly higher than those seen with other nosocomial Gram-negative pathogens. A. baumannii was not restricted to intensive care units, but had spread to all hospital wards. Multi-drug-resistant A. baumannii has the potential to reach endemicity in hospitals and warrants more vigorous and innovative efforts to limit its spread.

Outbreak of extended spectrum beta-lactamase-producing Klebsiella pneumoniae infection in a neonatal intensive care unit related to onychomycosis in a health care worker

Four cases of infection by extended spectrum beta-lactamase-producing Klebsiella pneumoniae occurred in the neonatal intensive care unit. Isolation, empiric therapy change and education produced no effect. Newborn weekly colonization rates were 0-18.7%. One health care worker with onychomycosis was positive for extended spectrum beta-lactamase-producing K. pneumoniae. Isolates were identical by molecular typing. Outbreak was controlled when the health care worker was excluded from the neonatal intensive care unit.

Multidrug-resistant Acinetobacter baumannii

A case-control, epidemiologic, and molecular study of nosocomial MDR A. baumannii showed the existence of multiple clones and a complex epidemiologic pattern.

To understand the epidemiology of multidrug-resistant (MDR) Acinetobacter baumannii and define individual risk factors for MDR, we used epidemiologic methods, performed organism typing by pulsed-field gel electrophoresis (PFGE), and conducted a matched case-control retrospective study. We investigated 118 patients, on 27 wards, in whom MDR A. baumannii was isolated from clinical cultures. Each case-patient had a control without MDR A. baumannii and was matched for hospital length of stay, ward, and calendar time. The epidemiologic investigation found small clusters of up to 6 patients each with no common identified source. Ten different PFGE clones were found, of which 2 dominated. The PFGE pattern differed within temporospatial clusters, and antimicrobial drug susceptibility patterns varied within and between clones. Multivariate analysis identified the following significant risk factors: male sex, cardiovascular disease, having undergone mechanical ventilation, and having been treated with antimicrobial drugs (particularly metronidazole). Penicillins were protective. The complex epidemiology may explain why the emergence of MDR A. baumannii is difficult to control.

A prevalent, multiresistant clone of Acinetobacter baumannii in Southeast England

A multiresistant clone of Acinetobacter baumannii was identified in 24 hospitals in the UK, predominantly in the London area, over a period of three years. Isolates were characterized by distinctive ApaI macrorestriction profiles, as resolved by pulsed-field gel electrophoresis (PFGE), which all clustered within 80% similarity using a 1% band position tolerance setting. The first isolates identified were received by the reference laboratories in April 2000, and by June 2003, a total of 375 isolates with similar PFGE profiles from 310 patients from 24 hospitals had been received. The isolates originated mainly from sputum and wound specimens, with the majority from patients in intensive care units. Amplified fragment length polymorphism analysis of a subset of isolates showed that they clustered closely, supporting the PFGE results. All the isolates tested were highly resistant to ampicillin, piperacillin, piperacillin/tazobactam, ceftazidime, cefotaxime, gentamicin and ciprofloxacin, and most isolates were carbapenem resistant. Amikacin sensitivity varied from susceptible [minimum inhibitory concentration (MIC) <or= 4 mg/L] to highly resistant (MIC >256 mg/L).

Evidence-based practice: examining the risk of toys in the microenvironment of infants in the neonatal intensive care unit

Toys placed in the bed or microenvironment of infants in the neonatal intensive care unit (NICU) demonstrate high rates of colonization (92%). As with other fomites, toys may be one potential source of nosocomial infection (NI). This project critically evaluated the practice of placing toys in the microenvironment of critically ill infants by using the Iowa Model of Evidence-Based Practice to Promote Quality Care. With the model as a guide for decision making, the existing evidence was explored using a systematic review of the literature, case studies, scientific principles, theory, and expert opinion. A comprehensive review of the literature did not clearly identify a causal relationship between toys in the NICU microenvironment and NI. Levels of evidence suggesting an association between toys and NI were determined to be moderately strong and consistent. A plausible relationship between the practice of placing toys in the beds of NICU patients and risk for infection was found. These findings prompted a pilot practice change, eliminating toys in the NICU, to test the potential impact of this intervention. Pre- and postintervention infection rates were compared. NI rates decreased from 4.6 to 1.99 per 1,000 patient days over a 6-month evaluation period. Although this decrease was not statistically significant, it was the lowest rate recorded in 5 years. Ongoing evaluation of NI rates is in progress. Individual NICUs must determine if the evidence warrants a practice change in their setting.

Outbreak of nosocomial meningitis caused by Acinetobacter baumannii in neurosurgical patients

An outbreak of nosocomial meningitis caused by Acinetobacter baumannii, which developed postoperatively in seven neurosurgical patients is described. The clinical isolates of A. baumannii were typed by biochemical profiles and antibiogram patterns, and by random amplified polymorphic DNA polymerase chain reaction (RAPD-PCR) and amplified fragment length polymorphism (AFLP) fingerprinting. The implicated strain was multi-drug resistant, however, susceptibility to imipenem and netilmicin was detected. An extensive search for the environmental source of the epidemic strain was carried out. Two of several isolates from hospital environment, corresponded to the A. baumannii outbreak strain, one being cultured from the suctioning equipment used in the care of these patients. The introduction of multiresistant epidemic A. baumannii into a neurosurgical unit is a severe risk factor for patients undergoing neurosurgical procedures. Genotypic typing methods are important for definitive identification of these strains in patients and their environment.

Epidemiology and control of antibiotic resistance in the intensive care unit

PURPOSE OF REVIEW

Resistance to antibiotics is very high in the intensive care units of many countries, although there are several exceptions. Some infections are becoming extremely difficult to treat. The risk of cross-transmission of those strains is very high. This review focuses on recent data (2003 to the present) that may help understanding and dealing with this serious public health problem.

RECENT FINDINGS

Intensive care units can be considered as 'factories' for creating, disseminating and amplifying resistance to antibiotics, for many reasons: importation of resistant microorganisms at admission, selection of resistant strains with an extensive use of broad-spectrum antibiotics, cross-transmission of resistant strains via the hands or the environment. Some national programs can be considered as failures, as in the UK and the USA. Other countries have been able to maintain a low level of resistance (Scandinavian countries, Netherlands, Switzerland, Germany, Canada). There is clearly an 'inoculum effect' above which preventive measures become poorly efficient. Several preventive measures have been proposed including preventive isolation, systematic screening at admission, local, national or international antibiotic guidelines, antibiotic prescriptions advice by infectious-disease teams, antibiotic prevention with selective digestive decontamination, antibiotic strategies such as 'cycling', or rather, for some authors, the use of an 'à la carte' antibiotic strategy which could be considered as a 'patient-to-patient antibiotic rotation'.

SUMMARY

There is obviously an international concern regarding the level of resistance to antibiotics in the intensive-care-unit setting. A strong program including prevention of cross-transmission and better usage of antibiotics seems to be needed in order to be successful. We do not know if this kind of program will enable countries with a very high endemic level of resistance to decrease the level in future years.

Clinical challenges of nosocomial infections caused by antibiotic-resistant pathogens in pediatrics

Antibiotic resistance in nosocomial infections is an ever-increasing problem as health care institutions provide care for children with more complicated medical and surgical problems. Several mechanisms of antibiotic resistance are reviewed for both gram-negative and gram-positive nosocomial pathogens. These adaptive resistance mechanisms allow organisms to survive in an environment of extensive antibiotic use and result in clinically significant infections. Mobile genetic elements have facilitated the rapid spread of antibiotic resistance within and among species. The clinical challenge faced by many practitioners is to understand these mechanisms of antibiotic resistance and to develop strategies for successfully treating infection caused by resistant pathogens. Nosocomial outbreaks caused by resistant organisms are described, and an approach to empiric therapy based on presumed pathogens, site of infection, and local resistance patterns is discussed.