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.

Control of Healthcare-Associated Carbapenem-Resistant Acinetobacter baumannii by Enhancement of Infection Control Measures

Antimicrobial stewardship and infection control measures are equally important in the control of antimicrobial-resistant organisms. We conducted a retrospective analysis of the incidence rate of hospital-onset carbapenem-resistant Acinetobacter baumannii (CRAB) infection (per 1000 patient days) in the Queen Mary Hospital, a 1700-bed, university-affiliated teaching hospital, from period 1 (1 January 2007 to 31 December 2013) to period 2 (1 January 2014 to 31 December 2019), where enhanced infection control measures, including directly observed hand hygiene before meal and medication rounds to conscious patients, and the priority use of single room isolation, were implemented during period 2. This study aimed to investigate the association between enhanced infection control measures and changes in the trend in the incidence rate of hospital-onset CRAB infection. Antimicrobial consumption (defined daily dose per 1000 patient days) was monitored. Interrupted time series, in particular segmented Poisson regression, was used. The hospital-onset CRAB infection increased by 21.3% per year [relative risk (RR): 1.213, 95% confidence interval (CI): 1.162−1.266, p < 0.001], whereas the consumption of the extended spectrum betalactam-betalactamase inhibitor (BLBI) combination and cephalosporins increased by 11.2% per year (RR: 1.112, 95% CI: 1.102−1.122, p < 0.001) and 4.2% per year (RR: 1.042, 95% CI: 1.028−1.056, p < 0.001), respectively, in period 1. With enhanced infection control measures, the hospital-onset CRAB infection decreased by 9.8% per year (RR: 0.902, 95% CI: 0.854−0.953, p < 0.001), whereas the consumption of the extended spectrum BLBI combination and cephalosporins increased by 3.8% per year (RR: 1.038, 95% CI: 1.033−1.044, p < 0.001) and 7.6% per year (RR: 1.076, 95% CI: 1.056−1.097, p < 0.001), respectively, in period 2. The consumption of carbapenems increased by 8.4% per year (RR: 1.84, 95% CI: 1.073−1.094, p < 0.001) in both period 1 and period 2. The control of healthcare-associated CRAB could be achieved by infection control measures with an emphasis on directly observed hand hygiene, despite an increasing trend of antimicrobial consumption.

Nonfermenting, Gram-Negative Bacilli Causing Neonatal Sepsis in Odisha, India: Four-Year Surveillance

Introduction

In India, blood culture-positive sepsis results in mortality in 33%-35% of affected neonates. Nonfermenting Gram-negative bacilli (NFGNB), particularly Acinetobacter baumannii and Burkholderia cepacia commonly cause hospital-acquired infection.

Materials and methods

We performed a subgroup analysis as part of a prospective study conducted in a neonatal intensive care unit in a tertiary care hospital in Odisha, India, between January 2017 and December 2020. Neonates with blood culture-positive sepsis caused by NFGNB were enrolled in this study. Demographic characteristics of the neonates, clinical features of sepsis, complications, need for supportive care, and blood culture sensitivity patterns were recorded and analyzed.

Results

A total of 168 organisms were isolated in blood cultures during our study period, of which 48 (29%) were NFGNB species. Among these 48 species, A. baumannii (37.5%) and B. cepacia (33.3%) were the most common NFGNB in our study. Neonates with sepsis commonly exhibited feeding intolerance (64.5%), circulatory insufficiency that necessitated vasopressor treatment (54.1%), disseminated intravascular coagulopathy (35.4%), seizures (33.3%), and the need for respiratory support (56.2%). NFGNB were multidrug-resistant (MDR) in 70.8% of cases, and 93.7% of B. cepacia and 55.5% of A. baumannii were MDR.

Conclusions

A. baumannii and B. cepacia are NFGNB commonly isolated in neonatal cases of blood culture-positive sepsis. The prevalence of MDR NFGNB sepsis is gradually increasing, which poses a threat to neonates. Strict aseptic precautions and antibiotic stewardship are thus mandatory in perinatal practice.

High Burden of Bloodstream Infections Associated With Antimicrobial Resistance and Mortality in the Neonatal Intensive Care Unit in Pune, India

BACKGROUND

Antimicrobial resistance (AMR) is a growing threat to newborns in low- and middle-income countries (LMIC).

METHODS

We performed a prospective cohort study in 3 tertiary neonatal intensive care units (NICUs) in Pune, India, to describe the epidemiology of neonatal bloodstream infections (BSIs). All neonates admitted to the NICU were enrolled. The primary outcome was BSI, defined as positive blood culture. Early-onset BSI was defined as BSI on day of life (DOL) 0-2 and late-onset BSI on DOL 3 or later.

RESULTS

From 1 May 2017 until 30 April 2018, 4073 neonates were enrolled. Among at-risk neonates, 55 (1.6%) developed early-onset BSI and 176 (5.5%) developed late-onset BSI. The majority of BSIs were caused by gram-negative bacteria (GNB; 58%); among GNB, 61 (45%) were resistant to carbapenems. Klebsiella spp. (n = 53, 23%) were the most common cause of BSI. Compared with neonates without BSI, all-cause mortality was higher among neonates with early-onset BSI (31% vs 10%, P < .001) and late-onset BSI (24% vs 7%, P < .001). Non-low-birth-weight neonates with late-onset BSI had the greatest excess in mortality (22% vs 3%, P < .001).

CONCLUSIONS

In our cohort, neonatal BSIs were most commonly caused by GNB, with a high prevalence of AMR, and were associated with high mortality, even in term neonates. Effective interventions are urgently needed to reduce the burden of BSI and death due to AMR GNB in hospitalized neonates in LMIC.

Molecular investigation of an outbreak associated with total parenteral nutrition contaminated with NDM-producing Leclercia adecarboxylata

Background

This study aimed to determine the epidemiological, microbiological, and molecular characteristics of an outbreak of carbapenem-resistant Leclercia adecarboxylata in three hospitals associated with the unintended use of contaminated total parental nutrition (TPN).

Methods

For 10 days, 25 patients who received intravenous TPN from the same batch of a formula developed sepsis and had blood cultures positive for L. adecarboxylata. Antimicrobial susceptibility and carbapenemase production were performed in 31 isolates, including one from an unopened bottle of TPN. Carbapenemase-encoding genes, extended-spectrum β-lactamase–encoding genes were screened by PCR, and plasmid profiles were determined. Horizontal transfer of carbapenem resistance was performed by solid mating. Clonal diversity was performed by pulsed-field gel electrophoresis. The resistome was explored by whole-genome sequencing on two selected strains, and comparative genomics was performed using Roary.

Results

All 31 isolates were resistant to aztreonam, cephalosporins, carbapenems, trimethoprim/sulfamethoxazole, and susceptible to gentamicin, tetracycline, and colistin. Lower susceptibility to levofloxacin (51.6%) and ciprofloxacin (22.6%) was observed. All the isolates were carbapenemase producers and positive for bla_NDM-1, bla_TEM-1B, and bla_SHV-12 genes. One main lineage was detected (clone A, 83.9%; A1, 12.9%; A2, 3.2%). The bla_NDM-1 gene is embedded in a Tn125-like element.

Genome analysis showed genes encoding resistance for aminoglycosides, quinolones, trimethoprim, colistin, phenicols, and sulphonamides and the presence of IncFII (Yp), IncHI2, and IncHI2A incompatibility groups. Comparative genomics showed a major phylogenetic relationship among L. adecarboxylata I1 and USDA-ARS-USMARC-60222 genomes, followed by our two selected strains.

Conclusion

We present epidemiological, microbiological, and molecular evidence of an outbreak of carbapenem-resistant L. adecarboxylata in three hospitals in western Mexico associated with the use of contaminated TPN.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-05923-0.

Genome Sequences of Four Strains of Acinetobacter bereziniae Isolated from Human Milk Pumped with a Personal Breast Pump and Hand-Washed Milk Collection Supplies

Acinetobacter bereziniae, formerly Acinetobacter genomospecies 10, is an opportunistic pathogen possessing resistance to multiple antibiotics, and it has been reported to be responsible for hospital-associated infections in immunocompromised individuals. We report the draft genome sequences of four Acinetobacter bereziniae strains that were isolated from a single human milk sample collected with a personal breast pump and a hand-washed milk collection kit.

Acinetobacter bereziniae, formerly Acinetobacter genomospecies 10, is an opportunistic pathogen possessing resistance to multiple antibiotics, and it has been reported to be responsible for hospital-associated infections in immunocompromised individuals. We report the draft genome sequences of four Acinetobacter bereziniae strains that were isolated from a single human milk sample collected with a personal breast pump and a hand-washed milk collection kit.

Cohorting to prevent acquisition of multidrug-resistant bacteria: An interrupted time series study

BACKGROUND

Grouping patients who acquired resistant microorganisms within a single area (cohorting) has been used to prevent cross-transmission. We aimed to assess cohorting effectiveness in the absence of an outbreak.

METHODS

An interrupted time series study was performed in a general hospital considering patients admitted to wards. In the first year, patients who acquired multidrug-resistant (MDR) bacteria were isolated without physical transfer. In the second year, cohorting was implemented, and patients with mixed MDR bacteria were transferred to individual rooms in a specific isolation unit. Cultures were requested upon clinician orders, and surveillance or routine cultures were not performed. The effect of cohorting on the incidence density of MDR bacteria acquisition was assessed using segmented regression analysis.

RESULTS

In the first and second years, 2.0 and 2.8 cases per 1,000 patient-days acquired MDR bacteria. The length of hospitalization and mortality rate were similar between phases. There was a linear increase of the monthly incidence densities of MDR bacteria acquisition in the first year (β_1: 0.11; 95% confidence interval [CI]: -0.02 to 0.24), though without an immediate impact of cohorting (β_2: -1.32; 95% CI: -3.81 to 1.16) or a change in the temporal trend (β₃: 0.04; 95% CI: -0.14 to 0.23) from the first to second phase.

CONCLUSION

Cohorting may not reduce the incidence density of MDR bacteria acquisition in the absence of an outbreak.

Acinetobacter Infections in Neonates

PURPOSE OF REVIEW

MDR-Gram-negative bacteria are a great concern in the neonatal population, with a worldwide rise in the reported incidence and with very limited therapeutic options. Acinetobacter baumannii is responsible for many infections in neonates and outbreaks in neonatal intensive care unit (NICU); also, outbreaks caused by other Acinetobacter species have been reported. The aim of this review is to document the epidemiology of Acinetobacter spp. infections in neonates and risk factors for acquisition of Acinetobacter spp. in the NICU using data from published studies.

RECENT FINDINGS

Acinetobacter spp. infections are increasing in neonates in NICU. Outbreak caused by multidrug resistant (MDR) or extensively drug resistant (XDR) A. baumannii but also outbreak caused by susceptible A. soli and A. septicus sp. nov., were reported in neonates. Acinetobacter spp. were responsible for bloodstream infections and respiratory tract infections in neonates. Risk factors for A. baumannii acquisition in neonates were low birthweight, length of NICU stay, umbilical catheterization, central-venous catheterization, assisted ventilation, and prior antibiotic use. This review highlights the importance of surveillance of risk factors for healthcare-associated infections in NICU to control MDR and XDR A. baumannii infections in neonates.

Molecular investigation of isolates from a multistate polymicrobial outbreak associated with contaminated total parenteral nutrition in Brazil

Background

Between November 2013 and June 2014, 56 cases of bacteremia (15 deaths) associated with the use of Total Parenteral Nutrition (TPN) and/or calcium gluconate (CG) were reported in four Brazilian states.

Methods

We analyzed 73 bacterial isolates from four states: 45 from blood, 25 from TPN and three from CG, originally identified as Acinetobacter baumannii, Rhizobium radiobacter, Pantoea sp. or Enterobacteriaceae using molecular methods.

Results

The first two bacterial species were confirmed while the third group of species could not be identified using standard identification protocols. These isolates were subsequently identified by Multi-Locus Sequence Analysis as Phytobacter diazotrophicus, a species related to strains from similar outbreaks in the United States in the 1970’s. Within each species, TPN and blood isolates proved to be clonal, whereas the R. radiobacter isolates retrieved from CG were found to be unrelated.

Conclusion

This is the first report of a three-species outbreak caused by TPN contaminated with A. baumannii, R. radiobacter and P. diazotrophicus. The concomitant presence of clonal A. baumannii and P. diazotrophicus isolates in several TPN and blood samples, as well as the case of one patient, where all three different species were isolated simultaneously, suggest that the outbreak may be ascribed to a discrete contamination of TPN. In addition, this study highlights the clinical relevance of P. diazotrophicus, which has been involved in outbreaks in the past, but was often misidentified as P. agglomerans.

Electronic supplementary material

The online version of this article (10.1186/s12879-018-3287-2) contains supplementary material, which is available to authorized users.

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.

Carbapenem-Resistant Enterobacteriaceae: A Strategic Roadmap for Infection Control

The incidence of carbapenem-resistant Enterobacteriaceae (CRE) has increased worldwide with great regional variability. Infections caused by these organisms are associated with crude mortality rates of up to 70%. The spread of CRE in healthcare settings is both an important medical problem and a major global public health threat. All countries are at risk of falling victim to the emergence of CRE; therefore, a preparedness plan is required to avoid the catastrophic natural course of this epidemic. Proactive and adequate preventive measures locally, regionally, and nationally are required to contain the spread of these bacteria. The keys to success in preventing the establishment of CRE endemicity in a region are early detection through targeted laboratory protocols and containment of spread through comprehensive infection control measures. This guideline provides a strategic roadmap for infection control measures based on the best available evidence and expert opinion, to enable preparation of a multifaceted preparedness plan to abort epidemics of CRE. Infect Control Hosp Epidemiol 2017;38:580-594.

Next-Generation Sequencing and Comparative Analysis of Sequential Outbreaks Caused by Multidrug-Resistant Acinetobacter baumannii at a Large Academic Burn Center

Next-generation sequencing (NGS) analysis has emerged as a promising molecular epidemiological method for investigating health care-associated outbreaks. Here, we used NGS to investigate a 3-year outbreak of multidrug-resistant Acinetobacter baumannii (MDRAB) at a large academic burn center. A reference genome from the index case was generated using de novo assembly of PacBio reads. Forty-six MDRAB isolates were analyzed by pulsed-field gel electrophoresis (PFGE) and sequenced using an Illumina platform. After mapping to the index case reference genome, four samples were excluded due to low coverage, leaving 42 samples for further analysis. Multilocus sequence types (MLST) and the presence of acquired resistance genes were also determined from the sequencing data. A transmission network was inferred from genomic and epidemiological data using a Bayesian framework. Based on single-nucleotide variant (SNV) differences, this MDRAB outbreak represented three sequential outbreaks caused by distinct clones. The first and second outbreaks were caused by sequence type 2 (ST2), while the third outbreak was caused by ST79. For the second outbreak, the MLST and PFGE results were discordant. However, NGS-based SNV typing detected a recombination event and consequently enabled a more accurate phylogenetic analysis. The distribution of resistance genes varied among the three outbreaks. The first- and second-outbreak strains possessed a blaOXA-23-like group, while the third-outbreak strains harbored a blaOXA-40-like group. NGS-based analysis demonstrated the superior resolution of outbreak transmission networks for MDRAB and provided insight into the mechanisms of strain diversification between sequential outbreaks through recombination.

The Complex Epidemiology of Carbapenem-Resistant Enterobacter Infections: A Multicenter Descriptive Analysis

BACKGROUND

The pandemic of carbapenem-resistant Enterobacteriaceae (CRE) was primarily due to clonal spread of bla KPC producing Klebsiella pneumoniae. Thus, thoroughly studied CRE cohorts have consisted mostly of K. pneumoniae.

OBJECTIVE

To conduct an extensive epidemiologic analysis of carbapenem-resistant Enterobacter spp. (CREn) from 2 endemic and geographically distinct centers.

METHODS

CREn were investigated at an Israeli center (Assaf Harofeh Medical Center, January 2007 to July 2012) and at a US center (Detroit Medical Center, September 2008 to September 2009). bla KPC genes were queried by polymerase chain reaction. Repetitive extragenic palindromic polymerase chain reaction and pulsed-field gel electrophoresis were used to determine genetic relatedness.

RESULTS

In this analysis, 68 unique patients with CREn were enrolled. Sixteen isolates (24%) were from wounds, and 33 (48%) represented colonization only. All isolates exhibited a positive Modified Hodge Test, but only 93% (27 of 29) contained bla KPC. Forty-three isolates (63%) were from elderly adults, and 5 (7.4%) were from neonates. Twenty-seven patients died in hospital (40.3% of infected patients). Enterobacter strains consisted of 4 separate clones from Assaf Harofeh Medical Center and of 4 distinct clones from Detroit Medical Center.

CONCLUSIONS

In this study conducted at 2 distinct CRE endemic regions, there were unique epidemiologic features to CREn: (i) polyclonality, (ii) neonates accounting for more than 7% of cohort, and (iii) high rate of colonization (almost one-half of all cases represented colonization). Since false-positive Modified Hodge Tests in Enterobacter spp. are common, close monitoring of carbapenem resistance mechanisms (particularly carbapenemase production) among Enterobacter spp. is important.

In vitro activity of colistin in antimicrobial combination against carbapenem-resistant Acinetobacter baumannii isolated from patients with ventilator-associated pneumonia in Vietnam

Acinetobacter baumannii has become one of the major infection threats in intensive care units (ICUs) globally. Since 2008, A. baumannii has been the leading cause of ventilator-associated pneumonia (VAP) in our ICU at an infectious disease hospital in southern Vietnam. The emergence of this pathogen in our setting is consistent with the persistence of a specific clone exhibiting resistance to carbapenems. Antimicrobial combinations may be a strategy to treat infections caused by these carbapenem-resistant A. baumannii. Therefore, we assessed potential antimicrobial combinations against local carbapenem-resistant A. baumannii by measuring in vitro interactions of colistin with four antimicrobials that are locally certified for treating VAP. We first performed antimicrobial susceptibility testing and multilocus variable number tandem repeat analysis (MLVA) genotyping on 74 A. baumannii isolated from quantitative tracheal aspirates from patients with VAP over an 18-month period. These 74 isolates could be subdivided into 21 main clusters by MLVA and >80 % were resistant to carbapenems. We selected 56 representative isolates for in vitro combination synergy testing. Synergy was observed in four (7 %), seven (13 %), 20 (36 %) and 38 (68 %) isolates with combinations of colistin with ceftazidime, ceftriaxone, imipenem and meropenem, respectively. Notably, more carbapenem-resistant A. baumannii isolates (36/43; 84 %) exhibited synergistic activity with a combination of colistin and meropenem than carbapenem-susceptible A. baumannii isolates (2/13; 15 %) (P = 0.023; Fisher's exact test). Our findings suggest that combinations of colistin and meropenem should be considered when treating carbapenem-resistant A. baumannii infections in Vietnam, and we advocate clinical trials investigating combination therapy for VAP.

Trimethoprim/sulfamethoxazole for Acinetobacter spp.: A review of current microbiological and clinical evidence

Clinicians nowadays are confronted with an epidemic of multidrug-resistant (MDR) Acinetobacter infections and are forced to consider every treatment alternative, including older antibiotic agents, not conventionally used. This review aimed to evaluate the published evidence on the antimicrobial activity and clinical effectiveness of trimethoprim/sulfamethoxazole (TMP-SMX) against Acinetobacter spp. Selected in vitro studies included antimicrobial surveillance reports, microbiological studies regarding the activity of TMP-SMX against MDR Acinetobacter isolates, and clinical studies published after the year 2000. Non-susceptibility rates for Acinetobacter spp. in surveillance studies ranged from 4% to 98.2%; in 23 of 28 studies, non-susceptibility to TMP-SMX was >50% and in a subset of 15 studies non-susceptibility was >70%. In studies regarding MDR Acinetobacter spp., non-susceptibility rates ranged from 5.9% to 100%; however, 19 of 21 studies reported >70% non-susceptibility. Extensively drug-resistant Acinetobacter baumannii complex had total (100%) resistance in five of six studies. Carbapenem-resistant Acinetobacter spp. had non-susceptibility rates to TMP-SMX of >80% in 22 of 26 studies. One study on polymyxin-resistant A. baumannii showed a susceptibility rate of 54.2% (13/24). Only seven case reports evaluated TMP-SMX for Acinetobacter spp. infections, mainly in combination with other agents; all cases were deemed therapeutic successes. Although TMP-SMX is not usually active against Acinetobacter spp., it might be considered in cases where there are no other options.

[Update on outbreaks reported from neonatal intensive care units: Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa]

In terms of the unique risk profile, the clinical course of nosocomial infections, and the most prevalent bacterial pathogens, literature on outbreaks of potentially pathogenic bacteria on neonatal intensive care units (NICUs) needs to be analyzed separately from reports derived from other intensive care units. With the purpose of updating important information for those involved in outbreak management and fostering preventive efforts, this article summarizes the results of a systematic literature analysis, referring to an earlier publication by Gastmeier et al. This review focuses on NICU outbreaks caused by Serratia marcescens, Klebsiella pneumoniae, Acinetobacter baumannii, and Pseudomonas aeruginosa.

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.

Treatment option for sepsis in children in the era of antibiotic resistance

Sepsis caused by multidrug-resistant microorganisms is one of the most serious infectious diseases of childhood and poses significant challenges for pediatricians involved in management of critically ill children. This review discusses the use of pharmacokinetic/dynamic principles (i.e., prolonged infusion of β-lactams and vancomycin, once-daily administration of aminoglycosides and rationale of therapeutic drug monitoring) when prescribing antibiotics to critically ill patients. The potential of 'old' agents (i.e., colistin, fosfomycin) and newly approved antibiotics is critically reviewed. The pros and cons of combination antibacterial therapy are discussed and finally suggestions for the treatment of sepsis caused by multidrug-resistant organisms are provided.

Control of a two-decade endemic situation with carbapenem-resistant Acinetobacter baumannii: electronic dissemination of a bundle of interventions

BACKGROUND

Our institution continued to experience a hyperendemic situation with carbapenem-resistant Acinetobacter baumannii despite a bundle of interventions. We aim to describe the effect of the subsequent implementation of electronic dissemination of the weekly findings of a bundle of interventions.

METHODS

This was a quasiexperimental study performed at a 1,500-bed, public, teaching hospital. From January 2011 to March 2012, weekly electronic communications were sent to the hospital leadership and intensive care units (ICUs). These communications aimed to describe, interpret, and package the findings of the previous week's active surveillance cultures, environmental cultures, environmental disinfection, and hand cultures. Additionally, action plans based on these findings were shared with recipients.

RESULTS

During 42 months and 1,103,900 patient-days, we detected 438 new acquisitions of carbapenem-resistant A baumannii. Hospital wide, the rate of acquisition decreased from 5.13 ± 0.39 to 1.93 ± 0.23 per 10,000 patient-days, during the baseline and postintervention periods, respectively (P < .0001). This effect was also observed in the medical and trauma ICUs, with decreased rates from 67.15 ± 10.56 to 17.4 ± 4.6 (P < .0001) and from 55.9 ± 8.95 to 14.71 ± 4.45 (P = .0004), respectively.

CONCLUSION

Weekly and systematic dissemination of the findings of a bundle of interventions was successful in decreasing the rates of carbapenem-resistant A baumannii across a large public hospital.

Spatial and temporal analyses to investigate infectious disease transmission within healthcare settings

Background

Healthcare-associated infections (HCAIs) cause significant morbidity and mortality worldwide, and outbreaks are often only identified after they reach high levels. A wide range of data is collected within healthcare settings; however, the extent to which this information is used to understand HCAI dynamics has not been quantified.

Aim

To examine the use of spatiotemporal analyses to identify and prevent HCAI transmission in healthcare settings, and to provide recommendations for expanding the use of these techniques.

Methods

A systematic review of the literature was undertaken, focusing on spatiotemporal examination of infectious diseases in healthcare settings. Abstracts and full-text articles were reviewed independently by two authors to determine inclusion.

Findings

In total, 146 studies met the inclusion criteria. There was considerable variation in the use of data, with surprisingly few studies (N = 22) using spatiotemporal-specific analyses to extend knowledge of HCAI transmission dynamics. The remaining 124 studies were descriptive. A modest increase in the application of statistical analyses has occurred in recent years.

Conclusion

The incorporation of spatiotemporal analysis has been limited in healthcare settings, with only 15% of studies including any such analysis. Analytical studies provided greater data on transmission dynamics and effective control interventions than studies without spatiotemporal analyses. This indicates the need for greater integration of spatiotemporal techniques into HCAI investigations, as even simple analyses provide significant improvements in the understanding of prevention over simple descriptive summaries.

Antimicrobial treatment of serious gram-negative infections in newborns

The choice of antibiotics for serious Gram-negative bacterial infections in the newborn must balance delivery of effective antibiotics to the site(s) of infection with the need to minimize selection of antibiotic resistance. To reduce the risk of selective pressure from large-scale cephalosporin usage, a penicillin-aminoglycoside combination is recommended as empiric therapy for neonatal sepsis. Where Gram-negative sepsis is strongly suspected or proven, a third-generation cephalosporin should ordinarily replace penicillin. Piperacillin-tazobactam can provide better Gram-negative cover than penicillin-aminoglycoside combinations, without the risk of selecting antibiotic resistance seen with cephalosporins, but further clinical studies are required before this approach to empiric therapy can be recommended. For antibiotic-resistant infections, a carbapenem remains the mainstay of treatment. However, rapid emergence and spread of resistance to these antibiotics means that in the future, neonatologists may have to rely on antibiotics such as colistin, whose pharmacokinetics, safety, and clinical efficacy in neonates are not well-defined.

Eighteen years of experience with Acinetobacter baumannii in a tertiary care hospital

OBJECTIVE

To characterize the descriptive and molecular epidemiology of Acinetobacter baumannii in our hospital.

DESIGN

Longitudinal analysis of electronic microbiology laboratory records and isolates.

SETTING

A 1,500 bed public teaching hospital in the Miami area.

PATIENTS

Consecutive patients with A. baumannii from January 1994 to December 2011.

INTERVENTIONS

None

MEASUREMENTS AND MAIN RESULTS

: Data on all A. baumannii isolates were clustered at the patient level, and the first isolate per single patient was determined. Yearly trends were analyzed based on carbapenem susceptibilities and originating units for all first isolates and first blood isolates per unique patient. Additionally, carbapenem nonsusceptible isolates frozen in the microbiology laboratory since 1998 were retrieved and evaluated using polymerase chain reaction and randomly amplified polymorphic DNA techniques. A total of 9,334 A. baumannii isolates were detected, of which 4,484 isolates (48%) were identified as first positive isolates per unique patient. Most of the burden of disease was located in the ICUs (odds ratio, 2.64 [95% CI, 2.17-3.22]; p < 0.0001) and in the adult wards (odds ratio, 3.867 [95% CI, 2.71-5.52]; p < 0.0001). Respiratory specimens constituted the most frequent source (49%; odds ratio, 1.619 [95% CI, 1.391-1.884]; p < 0.0001). Of the 4,484 first isolates, 846 isolates (18.9%) were carbapenem nonsusceptible and 3,638 isolates (81.1%) were carbapenem susceptible. Over the years, the number of carbapenem nonsusceptible isolates increased, whereas the number of carbapenem susceptible decreased (p < 0.0001). The trauma ICU had the highest burden of carbapenem nonsusceptible first isolates (205 of 846; 24.2%). Seven clones were discovered among 144 carbapenem nonsusceptible isolates; one of these clones was found from 1999 to 2005. OXA-23 and OXA-40 were identified in 96 and 13 isolates, respectively. One isolate harbored a novel CTX-M-115 enzyme.

CONCLUSIONS

This constitutes the largest experience with A. baumannii reported to date from a single center. Half of all isolates were respiratory specimens and were from adult ICUs, especially trauma. Even though this was a polyclonal process, a single clone was identified in the hospital through a 6-year span.

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.

[New clone of ST-187 Acinetobacter baumannii responsible for an outbreak in an intensive care unit]

INTRODUCTION

An ICU-outbreak caused by a novel Acinetobacter baumannii clone is described.

METHODS

An active search of carriers and environmental reservoirs was carried out. Carbapenemases genes were studied using multiplex-PCR and genotypic analysis by rep-PCR, PFGE and MLST.

RESULTS

A total 26 infected patients and 10 carriers were identified. A.baumannii was recovered from infusion pumps, walls, floor and washbasins. Phenotypic/genotypic analysis showed clonal expansion of a unique clone ST-187 producer of type OXA-24 and OXA-51 carbapenemases.

DISCUSSION

This is the first outbreak caused by ST-187 (ECI/GCI) multiresistant A.baumannii.

Nosocomial infection by sequence type 357 multidrug-resistant Acinetobacter baumannii isolates in a neonatal intensive care unit in Daejeon, Korea

Acinetobacter baumannii is an important microorganism responsible for a number of nosocomial outbreaks, in particular, in intensive care units (ICUs). We investigated a nosocomial infection caused by multidrug-resistant (MDR) A. baumannii in a neonatal intensive care unit (NICU) in Korea. A. baumannii isolates were characterized using Etest (AB Biodisk, Sweden), two multiplex PCR assays, and multilocus sequence typing (MLST) scheme. PCR and PCR mapping experiments were performed for detecting and characterizing the determinants of antimicrobial resistance. Eight strains isolated from an NICU belonged to European (EU) clone II and revealed only one sequence type (ST), namely, ST357. All the isolates were susceptible to imipenem but were resistant to amikacin, gentamicin, ceftazidime, cefepime, and ciprofloxacin. To the best of our knowledge, this is the first report of a nosocomial infection in an NICU in Korea caused by ST357 MDR/carbapenem-susceptible A. baumannii strains. This result demonstrates that nosocomial outbreaks of MDR/carbapenem-susceptible strains as well as MDR/carbapenem-resistant isolates may occur in NICUs.

Pregnancy and Perinatal Outcomes Associated with Acinetobacter baumannii Infection

Objective To determine perinatal and pregnancy outcomes of Acinetobacter baumannii infection using clinicopathologic material from pregnant women, neonates, and perinatal postmortem examinations with positive cultures. Study Design This is a retrospective record review with placental and postmortem examination. Results During a 5-year period, 40 positive cultures were found. Three pregnancies with positive cultures close in the peripartum period were all associated with adverse outcomes including spontaneous abortion, preterm labor, and one full-term birth with histological chorioamnionitis. Two positive cultures were found in preterm neonates in the neonatal intensive care unit. Two of three cases of perinatal death grew pure cultures from blood and/or fetal tissue with placental or fetal examination demonstrating evidence of infection/inflammation with fetal inflammatory response. Conclusion This is the first case series report of A. baumannii-positive cultures in maternal, fetal, and neonatal specimen, with histopathologic evidence of infection. The results suggest a significant role of A. baumannii infection in adverse pregnancy and perinatal outcomes.

Risk factors and outcomes of carbapenem-resistant Acinetobacter baumannii bacteremia in neonatal intensive care unit: a case-case-control study

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii (CRAB) has emerged as a serious threat among critically ill neonates.

METHODS

We performed a case-case-control study in a Thai neonatal intensive care unit to identify risk factors and outcomes for CRAB bacteremia. Case group (CG) I was defined as cases with CRAB (n = 14), and CG II was defined as cases with carbapenem-susceptible A. baumannii (n = 38) bacteremia. The control group (n = 44) was selected from all patients admitted before and after 3 days that CG I was identified, but had no infection.

RESULTS

The mean gestational age and birth weight of CG I, II and control were 33.5, 35.2 and 35.2 weeks and 1856.5, 2273.9 and 2309.5 g, respectively. By multivariate analysis, CG I was more likely to have had an umbilical artery catheter (adjusted odds ratio = 29.30; P = 0.019) whereas CG II was more likely exposed to ceftazidime (adjusted odds ratio = 5.19; P = 0.046) and aminoglycosides (adjusted odds ratio = 35.59; P = 0.002). There was a significant difference in history of cefoperazone/sulbactam (21.4% versus 0%; P = 0.01) and imipenem use (35.7% versus 0%; P < 0.001) among CG I compared with control. Crude mortality in CG I was higher than CG II (42.9% versus 13.2%; odds ratio = 5.0; P = 0.02).

CONCLUSION

Our cohort of neonatal CRAB bacteremia is characterized by a very high mortality. Infection-control interventions inclusive of strict adherence to infection-control process for central vascular line placement and maintenance as well as antimicrobial stewardship program are essential to help reduce CRAB bacteremia.

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.

Molecular epidemiology of Acinetobacter baumannii and Acinetobacter nosocomialis in Germany over a 5-year period (2005-2009)

To investigate the species distribution within the Acinetobacter calcoaceticus-Acinetobacter baumannii complex and the molecular epidemiology of A. baumannii and Acinetobacter nosocomialis, 376 Acinetobacter isolates were collected prospectively from hospitalized patients at 15 medical centres in Germany during three surveillance studies conducted over a 5-year period. Species identification was performed by molecular methods. Imipenem minimum inhibitory concentrations (MIC) were determined by broth microdilution. The prevalence of the most common carbapenemase-encoding genes was investigated by oxacillinase (OXA) -multiplex polymerase chain reaction (PCR). The molecular epidemiology was investigated by repetitive sequence-based PCR (rep-PCR; DiversiLab™). Acinetobacter pittii was the most prevalent Acinetobacter species (n = 193), followed by A. baumannii (n = 140), A. calcoaceticus (n = 10) and A. nosocomialis (n = 8). The majority of A. baumannii was represented by sporadic isolates (n = 70, 50%) that showed unique rep-PCR patterns, 25 isolates (18%) clustered with one or two other isolates, and only 45 isolates (32%) belonged to one of the previously described international clonal lineages. The most prevalent clonal lineage was international clone (IC) 2 (n = 34) and IC 1 (n = 6). According to CLSI, 25 A. baumannii isolates were non-susceptible to imipenem (MIC ≥ 8 mg/L), all of which produced an OXA-58-like or OXA-23-like carbapenemase. The rate of imipenem susceptibility among A. baumannii isolates decreased from 96% in 2005 to 76% in 2009. All other Acinetobacter isolates were susceptible to imipenem. The population structure of carbapenem-susceptible A. baumannii in Germany is highly diverse. Imipenem non-susceptibility was strongly associated with the clonal lineages IC 2 and IC 1. These data underscore the high clonality of carbapenem-resistant A. baumannii isolates.

Investigation and control of an outbreak of imipenem-resistant Acinetobacter baumannii Infection in a Pediatric Intensive Care Unit

BACKGROUND

This study investigated the clinical details and epidemiology of the imipenem-resistant Acinetobacter baumannii (IRAB) outbreak that occurred at a pediatric intensive care unit (PICU), and describes successful outcome of the implemented infection control measures.

METHODS

With the recognition of 3 clustered cases with IRAB bacteremia at the PICU of Seoul National University Children's Hospital, Korea, from August to September 2010, the following outbreak control strategies were implemented: reinforcement of hand hygiene and contact precautions, investigation of environmental contamination, disinfection of the contaminated environment and medical equipment, active surveillance culture upon PICU admission and isolation of IRAB-positive patients. The clinical and microbiological data were reviewed for A. baumannii positive cases in the PICU from April 2001 to June 2011. Multilocus sequence typing was also performed.

RESULTS

Twenty IRAB-positive cases (bacteremia in 10, pneumonia in 3 and colonizers in 7) were detected from January 2010 to February 2011. Thirteen IRAB-infected patients were all placed on a mechanical ventilator, had central venous catheters, received broad-spectrum antimicrobial treatment and had underlying diseases. Eleven (85%) IRAB-infected patients died probably due to IRAB infection. IRAB grew in 4 samples obtained from sinks and water taps from 38 environmental samples. Multilocus sequence typing analysis revealed 2 sequence types: ST138 (n=16) and its single-locus variant ST92 (n=4). Eleven weeks after the initiation of active surveillance, no further IRAB isolates were identified.

CONCLUSIONS

This study identifies the environmental source of an IRAB outbreak in a PICU and describes successful control of the outbreak with a multicomponent intervention program.

Quarantine, isolation, and cohorting: from cholera to Klebsiella

BACKGROUND

Isolation is defined as the separation of persons with communicable diseases from those who are healthy. This public health practice, along with quarantine, is used to limit the transmission of infectious diseases and provides the foundation of current-day cohorting.

METHODS

Review of the pertinent English-language literature.

RESULTS

Mass isolation developed during the medieval Black Death outbreaks in order to protect ports from the transmission of epidemics. In the mid-1800s, infectious disease hospitals were opened. It now is clear that isolation and cohorting of patients and staff interrupts the transmission of disease. Over the next century, with the discovery of penicillin and vaccines against many infectious agents, the contagious disease hospitals began to close. Today, we find smaller outbreaks of microorganisms that have acquired substantial resistance to antimicrobial agents. In the resource-limited hospital, a dedicated area or region of a unit may suffice to separate affected from unaffected patients.

CONCLUSION

Quarantine, or cohorting when patients are infected with the same pathogen, interrupts the spread of infections, just as the contagious disease hospitals did during the epidemics of the 18th and 19th centuries.

Acinetobacter soli as a cause of bloodstream infection in a neonatal intensive care unit

Acinetobacter soli is a new bacterial species described from forest soil. Five cases of bloodstream infection caused by A. soli clonal isolates are reported here for the first time. The patients were neonates admitted to an intensive care unit. This is a new neonatal pathogen with the potential to cause outbreaks.