Considerations in control and treatment of nosocomial infections due to multidrug-resistant Acinetobacter baumannii

Acinetobacter baumannii infection in intensive care unit: analysis of distribution and drug resistance

BACKGROUND

The isolation rate and drug resistance rate of Acinetobacter baumannii (A.baumannii) have increased over the years, which has become one of the main causes of infection and death in intensive care unit (ICU) patients. Analysis of the distribution characteristics, drug resistance and influencing factors of A.baumannii in ICU could provide basis and reference for the infection prevention and clinical treatment.

METHODS AND RESULTS

In this study, patients diagnosed with A.baumannii infection in ICU from January 2020 to December 2021 were selected. Samples of patients were collected for bacterial culture, drug sensitivity test analysis and drug resistant gene detection of A.baumannii. A total of 197 strains of A.baumannii were cultured in 2021, which was 18 strains more than in 2020. The specimens were mainly from lower respiratory tract secretions, and the isolated strains were multi-drug resistant. The resistance of isolates to tobramycin, gentamicin, and trimethoprim-sulfamethoxazole in 2021 showed a significant increase compared to 2020, while there were no significant differences observed in other resistance changes. The prevalence of multi-drug resistant A.baumannii in ICU remains high. Among them, all imipenem-resistant A.baumannii strains carried OXA-23 gene.

CONCLUSION

Clinical treatment should use antibiotics reasonably based on the characteristics of bacterial resistance, and strengthen the prevention and control of hospital infection, pay more attention to the disinfection and isolation to reduce the risk of cross infection.

Challenging the Hypothesis of in Utero Microbiota Acquisition in Healthy Canine and Feline Pregnancies at Term: Preliminary Data

At present, there are no data on the presence of bacteria in healthy canine and feline pregnancies at term. Here, we investigated the uterine microbiome in bitches (n = 5) and queens (n = 3) undergoing elective cesarean section in two facilities. Samples included swabs from the endometrium, amniotic fluid, and meconium, and environmental swabs of the surgical tray as controls. Culture and 16S rRNA gene sequencing were used to investigate the presence of bacteria. Culture was positive for 34.3% of samples (uterus n = 3, amniotic fluid n = 2, meconium n = 4, controls n = 0), mostly with low growth of common contaminant bacteria. With sequencing techniques, the bacterial abundance was significantly lower than in environmental controls (p < 0.05). Sequencing results showed a species-specific pattern, and significant differences between canine and feline bacterial populations were found at order, family, and genus level. No differences were found in alpha and beta diversities between feto-maternal tissues and controls (p > 0.05). Dominant phyla were Bacteroidetes, Firmicutes, and Proteobacteria in different proportions based on tissue and species. Culture and sequencing results suggest that the bacterial biomass is very low in healthy canine and feline pregnancies at term, that bacteria likely originate from contamination from the dam's skin, and that the presence of viable bacteria could not be confirmed most of the time.

Lice and lice-borne diseases in humans in Africa: a narrative review

Lice are host-specific insects. Human lice include Pediculus humanus humanus (body lice) which are known to be vectors of serious human bacterial infectious diseases including epidemic typhus, relapsing fever, trench fever and plague; Pediculus humanus capitis (head lice) that frequently affect children; and Pthirus pubis, commonly known as crab lice. In Africa, human infections transmitted by lice remained poorly known and therefore, underestimated, perhaps due to the lack of diagnostic tools and professional knowledge. In this paper we review current knowledge of the microorganisms identified in human lice in the continent of Africa, in order to alert health professionals to the importance of recognising the risk of lice-related diseases.

A Randomized Controlled Trial of Colistin Combined with Sulbactam: 9 g per Day versus 12 g per Day in the Treatment of Extensively Drug-Resistant Acinetobacter baumannii Pneumonia: An Interim Analysis

Extensively drug-resistant A. baumannii (XDRAB) pneumonia has a high mortality rate in hospitalized patients. One of the recommended treatments is colistin combined with sulbactam; however, the optimal dosage of sulbactam is unclear. In an open-label, superiority, randomized controlled trial, patients diagnosed with XDRAB pneumonia were randomly assigned (1:1) to receive colistin in combination with sulbactam at either 9 g/day or 12 g/day. The primary outcome was the 28-day mortality rate in the intention-to-treat population. A total of 88 patients received colistin in combination with sulbactam at a dosage of either 12 g/day (n = 45) or 9 g/day (n = 43). Trends toward a lower mortality rate were observed in the 12 g/day group at 7 days (11.1% vs. 23.3%), 14 days (33.3% vs. 41.9%), and 28 days (46.7% vs. 58.1%). The microbiological cure rate at day 7 was significantly higher in the 12 g/day group (90.5% vs. 58.1%; p = 0.02). Factors associated with mortality at 28 days were asthma, cirrhosis, APACHEII score ≥ 28, and a dosage of sulbactam of 9 g/day for mortality at any timepoint. Treatment with colistin combined with sulbactam at 12 g/day was not superior to the combination treatment with sulbactam at 9 g/day. However, due to being an interim analysis, this trial was underpowered to detect mortality differences.

Rhizospheric Actinomycetes Revealed Antifungal and Plant-Growth-Promoting Activities under Controlled Environment

Actinomycetes has large habitats and can be isolated from terrestrial soil, rhizospheres of plant roots, and marine sediments. Actinomycetes produce several bioactive secondary metabolites with antibacterial, antifungal, and antiviral properties. In this study, some Actinomycetes strains were isolated from the rhizosphere zone of four different plant species: rosemary, acacia, strawberry, and olive. The antagonistic activity of all isolates was screened in vitro against Escherichia coli and Bacillus megaterium. Isolates with the strongest bioactivity potential were selected and molecularly identified as Streptomyces sp., Streptomyces atratus, and Arthrobacter humicola. The growth-promoting activity of the selected Actinomycetes isolates was in vivo evaluated on tomato plants and for disease control against Sclerotinia sclerotiorum. The results demonstrated that all bacterized plants with the studied Actinomycetes isolates were able to promote the tomato seedlings’ growth, showing high values of ecophysiological parameters. In particular, the bacterized seedlings with Streptomyces sp. and A. humicola showed low disease incidence of S. sclerotiorum infection (0.3% and 0.2%, respectively), whereas those bacterized with S. atratus showed a moderate disease incidence (7.6%) compared with the positive control (36.8%). In addition, the ability of the studied Actinomycetes to produce extracellular hydrolytic enzymes was verified. The results showed that A. humicola was able to produce chitinase, glucanase, and protease, whereas Streptomyces sp. and S. atratus produced amylase and pectinase at high and moderate levels, respectively. This study highlights the value of the studied isolates in providing bioactive metabolites and extracellular hydrolytic enzymes, indicating their potential application as fungal-biocontrol agents.

The Impact of Natural Transformation on the Acquisition of Antibiotic Resistance Determinants

Carbapenem and multidrug-resistant (MDR) Acinetobacter baumannii leads the World Health Organization's list of priority pathogens and represents an unmet medical need. Understanding the mechanisms underpinning the acquisition of antibiotic resistance in this pathogen is fundamental to the development of novel therapeutics as well as to infection prevention and antibiotic stewardship strategies designed to limit its spread. In their investigation, "Interbacterial Transfer of Carbapenem Resistance and Large Antibiotic Resistance Islands by Natural Transformation in Pathogenic Acinetobacter," Anne-Sophie Godeux and colleagues (mBio 13:e0263121, 2022, https://doi.org/10.1128/mBio.02631-21) delineate the unsuspected extent and circumstances under which natural transformation as a mechanism of intraspecies and interspecies exchange of genetic material occurs in Acinetobacter spp. This study offers key insights into how this notorious pathogen may have accelerated the development of its MDR phenotype via an unexpectedly robust and unnervingly casual approach to the acquisition of antibiotic resistance determinants through natural transformation.

Ten-Year Changes in Bloodstream Infection With Acinetobacter Baumannii Complex in Intensive Care Units in Eastern China: A Retrospective Cohort Study

Background: There is little evidence on the changing prevalence, microbiological profile, and outcome of nosocomial Acinetobacter baumannii complex (ABC)-caused bloodstream infection (ABCBSI) specified in intensive care units (ICUs) in long-term studies, especially in China. Objective: We aimed to investigate changes in incidence, antibiotic resistance, therapy, and prognosis of ABCBSI in ICUs in eastern China during 2009-2018. Methods: A multicenter retrospective cohort study was conducted, and microbiological and clinical data for patients with ABCBSI acquired in nine adult ICUs in eastern China from 2009 to 2018. Results: A total of 202 cases were enrolled. For the years 2009-2010, 2011-2012, 2013-2014, 2015-2016, and 2017-2018, the incidence of ABCBSI increased significantly, as did the percentage of pan-drug-resistant isolates and resistant rates to most of antimicrobial agents; the percentage of drug-sensitive isolates decreased (all P < 0.05). The frequency of treatment with carbapenems and tigecycline increased, and that of cephalosporins decreased. Compared with those in the first years (2009-2012), ABCBSI patients in the lattermost years (2017-2018) were less often treated with appropriate empirical therapy, more often underwent pneumonia-related ABCBSI and mechanical ventilation support, and had higher 28-day mortality rates. Multivariate Cox regression indicated that increase in the degree of ABC antibiotics resistance, pneumonia-related ABCBSI, and septic shock were risk factors of 28-day mortality and associated with significant lower survival days. Conclusions: The past decade has witnessed a marked increase in the incidence of ABCBSI and in antibiotic resistance, with increasing pneumonia-related infections and worrisome mortality in ICUs in China. Controlling increasing resistance and preventing nosocomial pneumonia may play important roles in combatting these infections.

High Frequency of AdeA, AdeB and AdeC Genes among Acinetobacter baumannii Isolates

Background:

Efflux pumps are involved in resistance of Acinetobacter baumannii isolates to antimicrobial agents. AdeABC efflux pump is one of the RND superfamily efflux pump and consists of adeA (membrane fusion), adeB (multidrug transporter) and adeC (outer membrane) genes. In this study, the frequency of adeA, adeB and adeC genes among A. baumannii isolates with resistance to erythromycin, trimethoprim, meropenem and imipenem was investigated.

Methods:

Overall, 79 strains of A. baumannii were isolated from patients admitted to two major hospitals in Tehran during 2016. Antibiotic susceptibility testing was determined by disc diffusion and microdilution methods according to Clinical and Laboratory Standards Institute (CLSI) guideline. The presence of adeA, adeB and adeC genes was also determined using Multiplex PCR assay.

Results:

The highest and the lowest resistance among A. baumannii isolates were to trimethoprim (93%) and erythromycin (53%), respectively. The frequency of adeA, adeB and adeC genes was 96.2%, 96.2% and 91.1 % respectively. There was a significant relationship between imipenem resistance and presence of efflux pump genes (P<0.05).

Conclusion:

According to the high prevalence of the AdeABC efflux system genes, it may involve in resistance of clinical isolates of A. baumannii to imipenem, especially.

Genetic relatedness in carbapenem-resistant isolates from clinical specimens in Ghana using ERIC-PCR technique

AIM

Enterobacterial repetitive intergenic consensus (ERIC) sequence analysis is a powerful tool for epidemiological analysis of bacterial species. This study aimed to determine the genetic relatedness or variability in carbapenem-resistant isolates by species using this technique.

METHODS

A total of 111 non-duplicated carbapenem-resistant (CR) Gram-negative bacilli isolates from a three-year collection period (2012-2014) were investigated by enterobacterial repetitive intergenic consensus-polymerase chain reaction (ERIC-PCR) in four selected hospital laboratories in Ghana. The isolates were also screened for carbapenemase and extended spectrum β-lactamase genes by PCR.

RESULTS

A proportion of 23.4% (26/111) of the genomic DNA extracts were carriers of PCR-positive carbapenemase genes, including 14.4% blaNDM-1, 7.2% blaVIM-1 and 1.8% blaOXA-48. The highest prevalence of carbapenemase genes was from non-fermenters, Acinetobacter baumannii and Pseudomonas aeruginosa. For the ESBL genes tested, 96.4% (107/111) of the CR isolates co-harboured both TEM-1 and SHV-1 genes. The ERIC-PCR gel analysis exhibited 1 to 8 bands ranging from 50 to 800 bp. Band patterns of 93 complex dissimilarities were visually distinguished from the 111 CR isolates studied, while the remaining 18 showed band similarities in pairs.

CONCLUSION

Overall, ERIC-PCR fingerprints have shown a high level of diversity among the species of Gram-negative bacterial pathogens and specimen collection sites in this study. ERIC-PCR optimisation assays may serve as a suitable genotyping tool for the assessment of genetic diversity or close relatedness of isolates that are found in clinical settings.

Antibacterial Activity of the Essential Oil of Lippia oreganoides against Multiresistant Bacterial Strains of Nosocomial Origin

Antibacterial activity of the essential oil of Lippia oreganoides was evaluated against thirty-nine multiresistant bacterial strains of nosocomial origin and five reference bacterial strains using the disk diffusion agar method. The results obtained have revealed strong antibacterial activity against methicillin resistant Staphylococcus aureus, extended spectrum β-lactamase producing Klebsiella pneumoniae, and multiresistant Acinetobacter baumannii with MIC values ranging from 20 to 40 μg/mL. The low dose antibacterial activity observed in this investigation suggested that the essential oil of L. oreganoides could be used in pharmaceutical preparations for the treatment of infections caused by multiresistant bacteria. According to the literature consulted, this is the first time that antibacterial activity of this species against multiresistant bacterial strains of nosocomial origin has been reported.

Ionic silver functionalized ovine forestomach matrix - a non-cytotoxic antimicrobial biomaterial for tissue regeneration applications

BACKGROUND

Antimicrobial technologies, including silver-containing medical devices, are increasingly utilized in clinical regimens to mitigate risks of microbial colonization. Silver-functionalized resorbable biomaterials for use in wound management and tissue regeneration applications have a narrow therapeutic index where antimicrobial effectiveness may be outweighed by adverse cytotoxicity. We examined the effects of ionic silver functionalization of an extracellular matrix (ECM) biomaterial derived from ovine forestomach (OFM-Ag) in terms of material properties, antimicrobial effectiveness and cytotoxicity profile.

METHODS

Material properties of OFM-Ag were assessed by via biochemical analysis, microscopy, atomic absorption spectroscopy (AAS) and differential scanning calorimetry. The silver release profile of OFM-Ag was profiled by AAS and antimicrobial effectiveness testing utilized to determine the minimum effective concentration of silver in OFM-Ag in addition to the antimicrobial spectrum and wear time. Biofilm prevention properties of OFM-Ag in comparison to silver containing collagen dressing materials was quantified via in vitro crystal violet assay using a polymicrobial model. Toxicity of ionic silver, OFM-Ag and silver containing collagen dressing materials was assessed toward mammalian fibroblasts using elution cytoxicity testing.

RESULTS

OFM-Ag retained the native ECM compositional and structural characteristic of non-silver functionalized ECM material while imparting broad spectrum antimicrobial effectiveness toward 11 clinically relevant microbial species including fungi and drug resistant strains, maintaining effectiveness over a wear time duration of 7-days. OFM-Ag demonstrated significant prevention of polymicrobial biofilm formation compared to non-antimicrobial and silver-containing collagen dressing materials. Where silver-containing collagen dressing materials exhibited cytotoxic effects toward mammalian fibroblasts, OFM-Ag was determined to be non-cytotoxic, silver elution studies indicated sustained retention of silver in OFM-Ag as a possible mechanism for the attenuated cytotoxicity.

CONCLUSIONS

This work demonstrates ECM biomaterials may be functionalized with silver to favourably shift the balance between detrimental cytotoxic potential and beneficial antimicrobial effects, while preserving the ECM structure and function of utility in tissue regeneration applications.

Intensive Care Unit Relocation and Its Effect on Multidrug-Resistant Respiratory Microorganisms

Background

Infection by multidrug-resistant (MDR) pathogens leads to poor patient outcomes in intensive care units (ICUs). Contact precautions are necessary to reduce the transmission of MDR pathogens. However, the importance of the surrounding environment is not well known. We studied the effects of ICU relocation on MDR respiratory pathogen detection rates and patient outcomes.

Methods

Patients admitted to the ICU before and after the relocation were retrospectively analyzed. Baseline patient characteristics, types of respiratory pathogens detected, antibiotics used, and patient outcomes were measured.

Results

A total of 463 adult patients admitted to the ICU, 4 months before and after the relocation, were included. Of them, 234 were admitted to the ICU before the relocation and 229 afterward. Baseline characteristics, including age, sex, and underlying comorbidities, did not differ between the two groups. After the relocation, the incidence rate of MDR respiratory pathogen detection decreased from 90.0 to 68.8 cases per 1,000 patient-days, but that difference was statistically insignificant. The use of colistin was significantly reduced from 53.5 days (95% confidence interval [CI], 20.3 to 86.7 days) to 18.7 days (95% CI, 5.6 to 31.7 days). Furthermore, the duration of hospital stay was significantly reduced from a median of 29 days (interquartile range [IQR], 14 to 50 days) to 21 days (IQR, 11 to 39 days).

Conclusions

Incidence rates of MDR respiratory pathogen detection were not significantly different before and after ICU relocation. However, ICU relocation could be helpful in reducing the use of antibiotics against MDR pathogens and improving patient outcomes.

Acinetobacter spp. as nosocomial pathogens: Epidemiology and resistance features

The genus Acinetobacter is a major cause of nosocomial infections; it is increasingly being associated with various epidemics and has become a widespread concern in a variety of hospitals worldwide. Multi-antibiotic resistant Acinetobacter baumannii, is now recognized to be of great clinical significance. Numerous reports relay to the spread of A. baumannii in the hospital settings which leads to enhanced nosocomial outbreaks associated with high death rates. However, many other Acinetobacter spp. also can cause nosocomial infections. This review focused on the role of Acinetobacter spp. as nosocomial pathogens in addition to their persistence, antimicrobial resistance patterns and epidemiology.

Molecular characterization of β-lactamase genes in clinical isolates of carbapenem-resistant Acinetobacter baumannii

Background

Acinetobacter baumannii is a nosocomial pathogen which is establishing as a major cause of morbidity and mortality within the healthcare community. The success of this pathogen is largely due to its ability to rapidly gain resistance to antimicrobial therapies and its capability to persist in an abiotic environment through the production of a biofilm. Our tertiary-care hospital has showed high incidence of carbapenem-resistant Acinetobacter baumannii (CRAB) isolates.

Methods

In this study we explore both genotypic and phenotypic properties of 26 CRAB isolates: 16 isolates were collected from January 2010 to March 2011, and 10 were collected between February and May 2015.

Results

We determined that all 26 CRAB isolates possessed multiple β-lactamase genes, including genes from Groups A, C, and D. Specifically, 42% of the isolates possesses the potentially plasmid-borne genes of OXA-23-like or OXA-40-like β-lactamase. The presence of mobile gene element integron cassettes and/or integrases in 88% of the isolates suggests a possible mechanism of dissemination of antibiotic resistance genes. Additionally, the location of insertion sequence (IS) ISAba1 in promotor region of of the OXA-51-like, ADC-7, and ampC genes was confirmed. Multilocus sequence typing (MLST) demonstrated that all 26 CRAB isolates were either sequence type (ST)-229 or ST-2. Interestingly, ST-2 went from being the minority CRAB strain in the 2010–2011 isolates to the predominant strain in the 2015 isolates (from 32 to 90%). We show that the ST-2 strains have an enhanced ability to produce biofilms in comparison to the ST-229 strains, and this fact has potentially led to more successful colonization of the clinical environment over time.

Conclusions

This study provides a longitudinal genetic and phenotypic survey of two CRAB sequence types, and suggests how their differing phenotypes may interact with the selective pressures of a hospital setting effecting strain dominance over a 5-year period.

Electronic supplementary material

The online version of this article (10.1186/s12941-017-0248-3) contains supplementary material, which is available to authorized users.

The effect of immune modulation of Streptococcus constellatus SC10 strain upon Acinetobactor baumannii infection

Acinetobacter baumannii is a tiny, plump and rod-shaped Gram-negative coccobacillus, notorious as an opportunistic pathogen, which is now being considered by CDC as a serious public health threat. Preventing colonization may be a better therapeutic choice using microbiota to protect against A. baumannii transmission. Human microbiota not only regulates immune homeostasis as well provides essential health benefits therefore discovering the interface due microbiota in host immune system will allow to recognise novel immuno- or microbe-based therapies. Streptococcus constellatus frequently isolated from oral cavity was selected for this study to check if its guards against A. baumannii by improving the immune response and the immune signalling pathway. In a mouse model we explored various parameters which include mouse body weight, internal organ weight, level of sIgA and different cytokine changes to evaluate its prophylactic effect against A. baumannii. Administration of S. constellatus SC10 was able to control the weight lose induced by A. bumannii infection in both the protected and treated groups. Particularly resistant against infection was more in treated group where the different cytokine following administration of SC10 strain remarkably controlled the infection and induced more sIgA production. The level of different interleukins IL-4, IL-10, IL-12 and IFN-γ was suppressed in treatment and protected group after exposure of S. constellatus. The excretion of sIgA following infection was many folds high in both group treated and protected groups Study suggests that SC10 L16 have potential immunomodulating effect which is able to regulate cytokines and sIgA response at the early phase of infection and modulate the further progress of clinical symptoms during infection.

Molecular Epidemiology and Drug Resistance of Acinetobacter baumannii Isolated from Hospitals in Southern Poland: ICU as a Risk Factor for XDR Strains

The objectives of the present study were to investigate the carbapenemase and metallo-beta-lactamase genes of Acinetobacter baumannii clinical isolates by polymerase chain reaction (PCR) and real time PCR and to determine the molecular epidemiology of the strains using the DiversiLab tool. From these data, correlations between drug resistance, resistance genes, and epidemiological clones may be revealed. The study was conducted on 125 A. baumannii collected over the 2013 year. The majority of the isolates from both intensive care unit (ICU) and non-ICU cases originated from pneumonia infections (79.2%), isolates from blood infections accounted for 17.6% and 3.2% were from meningitis infections. In the ICU cases compared with the non-ICU cases, bloodstream infections were more frequently diagnosed (19.2% vs. 11.5%). Sixty percent of A. baumannii strains were resistant to all the antimicrobials tested with the exception of colistin. All strains were susceptible to colistin and polymyxin B. Extensively drug-resistant (XDR) strains accounted for 80.8% of the isolates tested and these XDR strains were more frequently isolated from ICU cases than from non-ICU cases (93.9% vs. 30.8%). Among the 101 isolates of A. baumannii exhibiting the XDR pattern of resistance, 80 possessed the blaOXA-24 gene and 29 had the blaOXA-23 gene. Only two isolates possessed the blaVIM gene. The presence of the ISAba1element was confirmed among 10 strains from patients hospitalized in the ICU. Using repetitive extragenic palindromic sequence PCR (DiversiLab typing), six clones and 12 unique strains were identified, of which two clones dominated. Most isolates belonging to clone 1 (66.7%) and clone 2 (85.5%) were susceptible only to colistin. In summary, it is clear from our findings and those of other studies that carbapenem resistance among A. baumannii strains presents a serious clinical problem worldwide. Furthermore, the presence of XDR international clone II in ICUs poses a potential risk for future outbreaks of A. baumannii infection and controlling A. baumannii infections in hospitals presents a serious challenge.

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.

Prevalence of and risk factors for multidrug-resistant Acinetobacter baumannii colonization among high-risk nursing home residents

OBJECTIVE

To characterize the epidemiology of multidrug-resistant (MDR) Acinetobacter baumannii colonization in high-risk nursing home (NH) residents.

DESIGN

Nested case-control study within a multicenter prospective intervention trial.

SETTING

Four NHs in Southeast Michigan. PARTICIPANTS Case patients and control subjects were NH residents with an indwelling device (urinary catheter and/or feeding tube) selected from the control arm of the Targeted Infection Prevention study. Cases were residents colonized with MDR (resistant to ≥3 classes of antibiotics) A. baumannii; controls were never colonized with MDR A. baumannii.

METHODS

For active surveillance cultures, specimens from the nares, oropharynx, groin, perianal area, wounds, and device insertion site(s) were collected upon study enrollment, day 14, and monthly thereafter. A. baumannii strains and their susceptibilities were identified using standard microbiologic methods.

RESULTS

Of 168 NH residents, 25 (15%) were colonized with MDR A. baumannii. Compared with the 143 controls, cases were more functionally disabled (Physical Self-Maintenance Score >24; odds ratio, 5.1 [95% CI, 1.8-14.9]; P<.004), colonized with Proteus mirabilis (5.8 [1.9-17.9]; P<.003), and diabetic (3.4 [1.2-9.9]; P<.03). Most cases (22 [88%]) were colonized with multiple antibiotic-resistant organisms and 16 (64%) exhibited co-colonization with at least one other resistant gram-negative bacteria.

CONCLUSION

Functional disability, P. mirabilis colonization, and diabetes mellitus are important risk factors for colonization with MDR A. baumannii in high-risk NH residents. A. baumannii exhibits widespread antibiotic resistance and a preference to colonize with other antibiotic-resistant organisms, meriting enhanced attention and improved infection control practices in these residents.

Antimicrobial Susceptibility and Clonal Relation Between Acinetobacter baumannii Strains at a Tertiary Care Center in Turkey

Background:

Acinetobacter baumannii is an opportunistic pathogen, related with nosocomial infections such as bacteremia, urinary tract infections, and ventilator-associated pneumonia. Multidrug resistant (MDR) A. baumannii strains are first line causes of infection, especially in patients hospitalized at intensive care units (ICUs). Infection with MDR A. baumannii strains has a longer duration at ICUs and hospitals. There are studies using molecular methods which can differentiate MDR A. baumannii strains at the clonal level. This helps controlling these resistant strains and prevents their epidemy.

Objectives:

The aim of our study was to investigate the antimicrobial susceptibility and clonal relationship between the A. baumannii strains isolated from our ICU.

Materials and Methods:

The identification and antimicrobial susceptibility of 33 A. baumannii strains were performed by automatized Vitek version 2.0. The clonal relationship among A. baumannii strains was analyzed using enterobacterial repetitive intergenic consensus (ERIC) polymerase chain reaction (PCR).

Results:

A total of 33 A. baumannii strains were included in this study. A. baumannii complex strains were classified into seven clusters based on the fingerprint results. Our results revealed that two main clusters were responsible for the prevalence of A. baumannii complex strains at the ICU.

Conclusions:

MDR A. baumannii strains cause an increment in morbidity and mortality, particularly in ICUs. The use of molecular epidemiological methods can help us with the detection of the pathogen and preventing from spreading of these resistant strains.

Epidemiology of Multidrug-Resistant Bacteria in Patients With Long Hospital Stays

Objective.

To determine rates of colonization with multidrug-resistant (MDR) bacteria (ie, methicillin-resistantStaphylococcus aureus[MRSA], vancomycin-resistantEnterococcus[VRE], extended-spectrum β-lactamase [ESBL]-producing Enterobacteriaceae, andAcinetobacter baumannii) after prolonged hospitalization and to assess the yield of surveillance cultures and variables associated with colonization with MDR bacteria.

Design.

Prospective observational cohort study conducted from February 6 to May 26, 2006.

Methods.

All patients who spent more than 30 days in our university hospital (Paris, France) were included. Rectal and nasal swab samples obtained during day 30 screening were examined for MRSA, VRE, ESBL-producing Enterobacteriaceae, andA. baumannii.

Results.

Of 470 eligible patients, 439 had surveillance culture samples available for analysis, including 51 patients (11.6%) with a history of colonization or infection due to 1 or more types of MDR bacteria (MRSA, recovered from 35 patients; ESBL-producing Enterobacteriaceae, from 16 patients;A. baumannii, from 6 patients; and VRE, from 0 patients) and 37 patients (9.5% of the 388 patients not known to have any of the 4 MDR bacteria before day 30 screening) newly identified as colonized by 1 or more MDR bacteria (MRSA, recovered from 20 patients; ESBL-producing Enterobacteriaceae, from 16 patients;A. baumannii, from 1 patient; and VRE, from 0 patients). A total of 87 (19.8%) of 439 patients were identified as colonized or infected with MDR bacteria at day 30. Factors that differed between patients with and without MRSA colonization included age, McCabe score, comorbidity score, receipt of surgery, and receipt of fluoroquinolone treatment. Patients with ESBL-producing Enterobacteriaceae colonization were younger than patients with MRSA colonization.

Conclusions.

Differences in the variables associated with MRSA colonization and ESBL-producing Enterobacteriaceae colonization suggest differences in the epidemiology of these 2 organisms. Day 30 screening resulted in a 72.5% increase in the number of patients identified as colonized with at least 1 type of MDR bacteria.

Institutional Control Measures to Curtail the Epidemic Spread of Carbapenem-Resistant Klebsiella pneumoniae: A 4-Year Perspective

Objective.

To describe the implementation of an institution-wide, multiple-step intervention to curtail the epidemic spread of carbapenem-resistant Klebsiella pneumoniae (CRKP).

Design.

Consecutive intervention analyses.

Patients and Setting.

All patients admitted to a 775-bed tertiary care medical center in Jerusalem, Israel, from 2006 through 2010.

Interventions.

The effects of 4 interventions were assessed: (1) a policy of isolation for patients colonized or infected with CRKP in single rooms, which was started in March 2006; (2) cohorting of CRKP patients with dedicated nursing staff and screening of patients neighboring a patient newly identified as a carrier of CRKP, which was started in March 2007; (3) weekly active surveillance of intensive care unit patients, which was started during August 2008; and (4) selective surveillance of patients admitted to the emergency department, which was started in March 2009. Interrupted regression analysis and change-point analysis were used to assess the effect of each intervention on the CRKP epidemic.

Results.

Patient isolation alone failed to control the spread of CRKP, with incidence increasing to a peak of 30 new cases per 1,000 hospital beds per month. Institution of patient cohorting led to a steep decline in the incidence of CRKP acquisition (P< .001). Introduction of active surveillance interventions was followed by a decrease in the incidence of CRKP-positive clinical cultures but an increase in the incidence of CRKP-positive screening cultures. The mean prevalence of CRKP positivity for the period after cohorting began showed a statistically significant change from the mean prevalence in the preceding period (P< .001).

Conclusions.

The cohorting of patients with dedicated staff, combined with implementation of focused active surveillance, effectively terminated the epidemic spread of CRKP. Cohorting reduced cross-infection within the hospital, and active surveillance allowed for earlier detection of carrier status. Both interventions should be considered in attempts to contain a hospital epidemic.

Attributable Mortality of Nosocomial Acinetobacter Bacteremia

Objective.

To determine the attributable mortality and outcome of nosocomial Acinetobacter bacteremia.

Design.

Matched, retrospective cohort study.

Setting.

Large, university-based, tertiary care center.

Patients.

Of 219 patients with nosocomial Acinetobacter bacteremia identified by prospective surveillance during a 3-year period, 52 met the criteria for the study and were matched to a control patient by age, sex, primary and secondary diagnosis, operative procedures, and date of admission.

Results.

A 100% success rate was achieved in the proportion of case patients and control patients matched for the compared criteria, except for major operative procedures (88%) and the presence of an important secondary underlying disease (54.5%). Twenty-nine (55.7%) of the case patients died, compared with 10 (19.2%) of the control patients (P < .001). The attributable mortality was 36.5% (95% CI, 27%-46%) and the risk ratio for death was 2.9 (95% CI, 1.58-5.32). In a multivariate survival analysis, older age, mechanical ventilation, renal failure, and Acinetobacter bacteremia (hazard ratio [HR], 4.41; 95% confidence interval [CI], 1.97-9.87; P < .001) were found to be independent predictors of mortality. There was a trend for a longer median duration of hospitalization among case patients, compared with control patients (11.5 vs. 6.5 days; P = .06). Three isolates were resistant to all but 1 antibiotic tested (colistin), and 45 isolates (86.5%) were resistant to 4 or more different antibiotic classes.

Conclusions.

When adjusted for risk-exposure time and severity of disease at admission, nosocomial Acinetobacter bacteremia is associated with mortality in excess of that caused by the underlying diseases alone.

Update on the Epidemiology, Treatment, and Outcomes of Carbapenem-resistant Acinetobacter infections

Carbapenem-resistant Acinetobacter species are increasingly recognized as major nosocomial pathogens, especially in patients with critical illnesses or in intensive care. The ability of these organisms to accumulate diverse mechanisms of resistance limits the available therapeutic agents, makes the infection difficult to treat, and is associated with a greater risk of death. In this review, we provide an update on the epidemiology, resistance mechanisms, infection control measures, treatment, and outcomes of carbapenem-resistant Acinetobacter infections.

Effect of chlorine exposure on the survival and antibiotic gene expression of multidrug resistant Acinetobacter baumannii in water

Acinetobacter baumannii is a multidrug resistant pathogen capable of causing a wide spectrum of clinical conditions in humans. Acinetobacter spp. is ubiquitously found in different water sources. Chlorine being the most commonly used disinfectant in water, the study investigated the effect of chlorine on the survival of A. baumannii in water and transcription of genes conferring antibiotic resistance. Eight clinical isolates of A. baumannii, including a fatal meningitis isolate (ATCC 17978) (~10⁸ CFU/mL) were separately exposed to free chlorine concentrations (0.2, 1, 2, 3 and 4 ppm) with a contact time of 30, 60, 90 and 120 second. The surviving pathogen counts at each specified contact time were determined using broth dilution assay. In addition, real-time quantitative PCR (RT-qPCR) analysis of the antibiotic resistance genes (efflux pump genes and those encoding resistance to specific antibiotics) of three selected A. baumannii strains following exposure to chlorine was performed. Results revealed that all eight A. baumannii isolates survived the tested chlorine levels during all exposure times (p > 0.05). Additionally, there was an up-regulation of all or some of the antibiotic resistance genes in A. baumannii, indicating a chlorine-associated induction of antibiotic resistance in the pathogen.

Mechanisms of resistance to β-lactams in some common Gram-negative bacteria causing nosocomial infections

Gram-negative bacilli remain major killers of hospitalized patients and continue to evolve new resistance mechanisms. This review describes the mechanisms of resistance to beta-lactam antibiotics from those Gram-negative pathogens most often isolated from nosocomial infections.

Laboratory to Clinical Investigation of Carbapenem Resistant Acinetobacter baumannii Outbreak in a General Hospital

Background:

The number of reported cases, infected with carbepenem resistant Acinetobacter baumannii (CRAb) and multi-drug resistant (MDR) Acinetobacter species had gradually increased in most PLA general hospital wards from April to June in 2007.

Objectives:

We have described the investigation of an outbreak of CRAb and MDR Acinetobacter in PLA general hospital, Beijing. The prospective and retrospective findings were identified and analyzed to study the infection causes.

Materials and Methods:

A. baumannii samples were collected from the patients and environment in each hospital unit. The onset times were recorded according to their case information. All samples were characterized by genotype and compared using pulsed-field gel electrophoresis (PFGE). The microorganism susceptibility was tested using the in vitro minimal inhibitory concentration (MIC) breakpoints method.

Results:

A total of 69 A. baumannii strains were successfully isolated from 53 patients. About 89.1% of them were resistant to ampicillin and 89.2% to cefotaxime and 75.4% to all standard antibiotics. PFGE analysis revealed that nine of the isolates had unique clones and the epidemic clone types were A, B and C.

Conclusions:

The A. baumannii outbreak, was caused by MDR A. baumannii. The strains had widely spread among 12 departments especially in surgical intensive care unit (SICU), emergency intensive care unit (EICU) and the department of respiratory disease. The outbreak was more likely caused by the A. baumannii infected or carrier patients and EICU was its origin.

Ampicillin/sulbactam: its potential use in treating infections in critically ill patients

The purpose of this paper was to review the potential utility of ampicillin/sulbactam (SAM) as a therapy for serious infections in critically ill patients. Data for this review were identified by searches of PubMed and of the reference lists of the included articles. We found that SAM appears to have a number of characteristics that support its use in the treatment of serious infections in critically ill patients. SAM demonstrates extensive penetration into many infection sites, supporting its use in a wide range of infection types. Microbiologically, sulbactam has strong intrinsic antibiotic activity against multidrug-resistant (MDR) bacteria, including Acinetobacter baumannii, which supports its use for the treatment of infections mediated by this pathogen. Of some concern, there have been reports showing a decline in susceptibility of some bacteria to SAM. As such, use of lower doses (4/2g/day), particularly for MDR A. baumannii, has been linked with a 30% reduced success rate in critically ill patients. The therapeutic challenges for ensuring achievement of optimal dosing of SAM result partly from bacterial susceptibility but also from the pharmacokinetic (PK) alterations common to β-lactam agents in critical illness. These PK changes are likely to reduce the ability of standard dosing to achieve the concentrations observed in non-critically ill patients. Optimisation of therapy may be more likely with the use of higher doses, administration by 4h infusion or by combination therapy, particularly for the treatment of infections caused by MDR pathogens.

Bacterial Isolates from Severe Infections and Their Antibiotic Susceptibility Patterns in Italy: a Nationwide Study in the Hospital Setting

The most frequent agents of severe bacterial infections and their antibiotic susceptibility patterns were determined in patients admitted to 45 Italian hospitals over the years 2002-2003. The most common diagnoses were: sepsis (33.8%), pneumonia (9.4%), intravascular catheter-associated infections (9.3%) and ventilator-associated pneumonia (8.1%). Overall, 5115 bacterial isolates were identified from 4228 patients. Three bacterial species, Staphylococcus aureus, Pseudomonas aeruginosa and Escherichia coli, accounted for more than 50% of the isolates. Other prevalent bacterial isolates were Staphylococcus epidermidis and Enterococcus faecalis, while Acinetobacter baumanii ranked third among all Intensive Care Unit (ICU) isolates. 7% of S. aureus had intermediate resistance to vancomycin. Although E. faecalis displayed no vancomycin resistance, 34% of vancomycin-resistant isolates were found among Enterococcus faecium, one of the highest rates found to date, emphasizing the difference between these two enterococcal species. All the Gram-positive pathogens were susceptible to linezolid, with the exception of approximately 2% of the enterococcal isolates that were intermediate with a minimum inhibitory concentration (MIC)=4 microg/ml. Almost 10% of Escherichia coli, 14% of Klebsiella pneumoniae, 22% of Serratia marcescens and 50% of Enterobacter cloacae were non-susceptible to cefotaxime. Amikacin was the most active antibiotic against P. aeruginosa that showed lack of susceptibility to ceftazidime, gentamicin, piperacillin and ciprofloxacin ranging from 20 to 35%. Finally, Acinetobacter baumanii showed a high level of resistance to all the antibiotics tested including imipenem (58%). The results obtained in this study, the first of its kind in Italy, offer indications for guiding empirical therapy and implementing specific interventions to fight antibiotic-resistant bacterial infections and their transmission in the hospital setting in Italy.

Isolation and characterization of antimicrobial compounds in plant extracts against multidrug-resistant Acinetobacter baumannii

The number of fully active antibiotic options that treat nosocomial infections due to multidrug-resistant Acinetobacter baumannii (A. baumannii) is extremely limited. Magnolia officinalis, Mahonia bealei, Rabdosia rubescens, Rosa rugosa, Rubus chingii, Scutellaria baicalensis, and Terminalia chebula plant extracts were previously shown to have growth inhibitory activity against a multidrug-resistant clinical strain of A. baumannii. In this study, the compounds responsible for their antimicrobial activity were identified by fractionating each plant extract using high performance liquid chromatography, and determining the antimicrobial activity of each fraction against A. baumannii. The chemical structures of the fractions inhibiting >40% of the bacterial growth were elucidated by liquid chromatography/mass spectrometry analysis and nuclear magnetic resonance spectroscopy. The six most active compounds were identified as: ellagic acid in Rosa rugosa; norwogonin in Scutellaria baicalensis; and chebulagic acid, chebulinic acid, corilagin, and terchebulin in Terminalia chebula. The most potent compound was identified as norwogonin with a minimum inhibitory concentration of 128 µg/mL, and minimum bactericidal concentration of 256 µg/mL against clinically relevant strains of A. baumannii. Combination studies of norwogonin with ten anti-Gram negative bacterial agents demonstrated that norwogonin did not enhance the antimicrobial activity of the synthetic antibiotics chosen for this study. In conclusion, of all identified antimicrobial compounds, norwogonin was the most potent against multidrug-resistant A. baumannii strains. Further studies are warranted to ascertain the prophylactic and therapeutic potential of norwogonin for infections due to multidrug-resistant A. baumannii.

Impact of multidrug-resistant organisms on patients considered for lung transplantation

Infections with multidrug-resistant organisms are a growing problem in lung transplant recipients. Carriage of drug-resistant bacteria and fungi before transplantation is an important risk factor for such infections. In that regard Pseudomonas aeruginosa and species of Burkholderia, Acinetobacter, non-tuberculous mycobacteria and Scedosporium are particularly important. An understanding of the impact of these organisms is essential to the evaluation of lung transplant candidates. The microbiology, epidemiology, clinical manifestations, and approach to these pathogens before transplant are reviewed in this article.

Polyclonal endemicity of Acinetobacter baumannii in ventilated patients in an intensive care unit in Uruguay

OBJECTIVES

To identify the mechanisms responsible for respiratory infections by Acinetobacter baumannii in intubated patients and risk factors for digestive colonization and infection by A. baumannii.

METHODS

We conducted a prospective study in an intensive care unit (ICU) between May 2005 and November 2006, including 175 consecutive patients at the beginning of invasive ventilation (day 1). We performed pharyngeal and rectal swabs on days 1, 4, 7, 10, 13, and 16. Respiratory samples were taken on days 1 and 7, or on suspicion of ventilator-associated pneumonia (VAP).

RESULTS

We detected 62 patients with A. baumannii digestive colonization and 20 cases of A. baumannii lower respiratory infection (14 VAP and six purulent tracheobronchitis (PTB)). Digestive colonization by A. baumannii was an independent risk factor for lower respiratory tract infections with that microorganism (p<0.0001; relative risk 8.71, 95% confidence interval 2.73-27.77). Respiratory and rectal A. baumannii isolates from the same patients were compared by enterobacterial repetitive intergenic consensus (ERIC)-PCR; in 9/11 cases (eight VAP and one PTB) results suggested events of exogenous pneumonia with previous colonization, whereas the remaining two cases (two PTB) were suggestive of exogenous infection without previous colonization.

CONCLUSIONS

In our unit the pathogenesis of VAP by A. baumannii is mixed, most cases corresponding to exogenous pneumonia with previous colonization.

Infection Associated with Hemophagocytic Lymphohisticytosis triggered by nosocomial Infection

Hemophagocytic lymphohistiocytosis (HLH) can occur as primary idiopathic syndrome or secondary to neoplastic, infection or autoimmune processes. It is characterized by the proliferation of histiocytes with phagocytosis of formed elements of blood. Clinical manifestations include signs and symptoms of immune activation and pancytopenia. This report presents a child with infection associated with HLH trigged by Acinetobacter baumannii sepsis. Multidrug-resistant Acinetobacter, an emergent nosocomial pathogen but so far in the literature, it has not been reported to cause HLH.

Outcome of ventilator-associated pneumonia due to multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa treated with aerosolized colistin in neonates: a retrospective chart review

Multidrug-resistant (MDR) gram-negative bacteria-related nosocomial infections and ventilator-associated pneumonia (VAP) presents an emerging challenge to clinicians. Older antimicrobial agents such as colistin have become life-saving drugs because of the susceptibility of these pathogens. We report our experience with aerosolized colistin in two preterm and one term neonate with Acinetobacter baumannii and Pseudomonas aeruginosa-related VAP who were unresponsiveness to previous antimicrobial treatment. All pathogens were isolated from tracheal aspirate. We used 5 mg/kg (base activity) aerosolized colistin methanesulfonate sodium in every 12 h as an adjunctive therapy for VAP. VAP was treated by 14, 14, and 16-day courses of aerosolized colistin in these patients, respectively. No adverse effect such as nephrotoxicity or neurotoxicity was observed. We found that aerosolized colistin was tolerable and safe, and it may be an adjunctive treatment option for MDR gram-negative bacterial VAP in neonates. Further studies are needed to determine appropriate doses for aerosolized colistin and its eligibility as an alternative treatment choice in newborns.

Three-dimensional human skin equivalent as a tool to study Acinetobacter baumannii colonization

Acinetobacter baumannii can colonize body surfaces of hospitalized patients. From these sites, invasion into the host and spread to other patients and the hospital environment may occur. The eradication of the organism from the patient's skin is an important infection control strategy during epidemic and endemic episodes. In this study, a three-dimensional (3D), air-exposed human epidermal skin equivalent was exploited to study Acinetobacter skin colonization. We characterized the adherence of A. baumannii ATCC 19606(T) and Acinetobacter junii RUH2228(T) to and biofilm formation on the skin equivalent and the responses to these bacteria. Furthermore, we assessed the ability of the disinfectant chlorhexidine to decolonize the skin equivalents. The results revealed that both strains replicated on the stratum corneum for up to 72 h but did not invade the epidermis. A. baumannii, in contrast to A. junii, formed large biofilms on the stratum corneum. Bacterial colonization did not affect keratinocyte activation, proliferation, or differentiation, nor did it induce a strong inflammatory response. Disinfection with chlorhexidine solution resulted in complete eradication of A. baumannii from the skin, without detrimental effects. This 3D model is a promising tool to study skin colonization and to evaluate the effects of novel disinfectant and antimicrobial strategies.

Ciprofloxacin-resistant Escherichia coli in hospital wastewater of Bangladesh and prediction of its mechanism of resistance

Hospital and agriculture wastewater is mostly responsible for causing environmental pollution by spreading un-metabolized antibiotics and resistant bacteria, especially in Bangladesh. Here, we studied the influence of the most frequently prescribed antibiotic, fluoroquinolone (~72%), on the development of antibiotic resistance in Escherichia coli. Out of 300, 24 ciprofloxacin resistant E. coli isolates were selected for the study that showed the MBC(100) higher than expected (600 μg/mL). Here, we profiled plasmid, sequenced gyr genes, screened mutations and analyzed the effect of mutation on drug-protein interaction through molecular docking approach. We found that (1) out of 10, most of them (n = 7) had large plasmid(s); (2) all ciprofloxacin-resistant isolates had gyrA double mutations (S83L and D87Y); (3) no isolate had qnr gene; and (4) docking of ciprofloxacin with DNA gyrase A subunit suggests that acquisition of double mutation leads to alteration of the ciprofloxacin binding pocket.

Molecular characterisation of multiple drug-resistant Acinetobacter baumannii isolates in southern Taiwan

The purpose of this study was to develop a multiplex polymerase chain reaction (mt-PCR) assay for synchronous detection of carbapenem resistance genes and/or pandrug resistance genes in clinical isolates of multidrug-resistant Acinetobacter baumannii (MDR-AB) and to investigate the association between the genetic make-up and a drug-resistant pattern. In total, 213 MDR-AB isolates were collected. All clinical isolates underwent antimicrobial susceptibility testing and were analysed for the presence of oxacillinase genes (bla(OXA-23), bla(OXA-24), bla(OXA-51)-like and bla(OXA-58)), class A and C β-lactamase genes (bla(TEM-1) and bla(AmpC), respectively), and an integron-associated antibiotic resistance gene (int1) by an in-house-designed mt-PCR assay. Of the 213 isolates, 73.87% harboured both bla(TEM-1) and bla(AmpC) and 83.92% carried at least three oxacillinase genes. Moreover, 64.82% of the isolates were significant in that they had two β-lactamase genes and three oxacillinase genes (P<0.001), indicating the complexity of the genetic make-up of carbapenem-resistant A. baumannii. The bla(OXA-51)-like allele was detected in the majority of these A. baumannii isolates (97.49%), whereas bla(OXA-23) was rarely prevalent in these isolates. In multivariate logistic regression, the presence of bla(OXA-23) and bla(TEM-1) had a statistically significant association with imipenem resistance [bla(OXA-23), P=0.004, odds ratio (OR)=10.52, 95% confidence interval (CI) 2.12-52.17; bla(TEM-1), P=0.005, OR=6.14, 95% CI 1.74-21.62]. These results suggest that detecting bla(OXA-23) and bla(TEM-1) genes could be used to predict imipenem resistance in MDR-AB isolates. A mt-PCR for detecting carbapenem resistance genes and pandrug resistance genes of A. baumannii isolates was developed to provide an assay to quickly screen for potential imipenem-resistant A. baumannii in the clinic.