Baumannii Complex Research Articles

Long-term effectiveness of infection and antibiotic control programs on the transmission of carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex in central Taiwan

ObjectivesA carbapenem-resistant Acinetobacter calcoaceticus-Acinetobacter baumannii complex (CRA complex) infection is one of most the difficult infections to control worldwide. We evaluated the long-term effects of infection control interventions on the incidence densities of healthcare-associated infection (HAI) and CRA complex infection, and the rates of Acinetobacter calcoaceticus-Acinetobacter baumannii complex bacteremia (AB). Patients and methodsWe performed a cross-sectional analysis at the Changhua Christian Hospital from January 2002 to December 2013. Interventions for infection control were implemented from 2002 to 2009 (period 1). From 2010 to 2013 (period 2), infection control programs were improved by in-service education and a hand hygiene campaign to prepare for international and national hospital accreditation. The effectiveness of infection and antibiotic control programs was assessed according to the incidence densities of HAI and CRA complex, rates of CRA complex and of AB, chlorhexidine consumption density, and defined daily dose of antibiotics. ResultsThe incidence density of HAI decreased from 4.56‰ to 1.52‰ from periods 1 to 2 (P<0.001). Likewise, the incidence of AB decreased from 177.79 to 137.76 per person-years per 100,000 admissions (P<0.001). The incidence density of CRA complex ranged from 3.17–7.38‰. The chlorhexidine consumption density increased from 5.5 to 45.5 L per 1000 patient-days (P<0.001). The consumption of piperacillin-tazobactam was lower in period 2 than in period 1 (P<0.001). ConclusionEducation for infection control programs, hand hygiene campaigns, and antibiotics control programs may decrease the incidence density of AB and HAI, and may help control CRA complex infection.

Phenotypic and Molecular Epidemiology of Acinetobacter calcoaceticus baumannii Complex Strains Spread at Nemazee Hospital of Shiraz, Iran.

BackgroundAcinetobacter calcoaceticus baumannii (ACB) complex are Gram-negative opportunistic bacteria with low virulence properties. Their resistance to antibiotics has become a matter of concern in hospital infections.ObjectivesThe present study aimed to determine the prevalence and antimicrobial susceptibility of ACB isolates collected from the Nemazee hospital of Shiraz. In addition, Pulsed Field Gel Electrophoresis (PFGE) was used to determine the genetic patterns of these strains.Patients and MethodsIn this cross-sectional study, 93 strains of ACB complex were isolated from patients of Nemazee hospital, Shiraz, Iran. The antibiotic susceptibility patterns of the isolates to the following 15 antibiotics were determined: gentamicin, ticarcillin, ceftazidime, co-trimoxazole, imipenem, piperacillin tazobactam, amikacin, aztreonam, sulbactam, meropenem, tobramycin, cefotaxime, ceftriaxone, colistin, polymyxin B. Pulsed Field Gel Electrophoresis was used to determine the clonal relationship of these strains.ResultsMost of the isolates were found to be resistant to cefotaxime, co-trimoxazole, ceftriaxone, aztreonam, ceftazidime and ticarcillin (90%), and the least resistance was observed to colistin and polymyxin B. Among the 93 tested samples, 35 antimicrobial susceptibility patterns and 47 PFGE patterns were obtained.ConclusionsHigh resistance to antibiotics was observed among the strains of ACB complex and the least resistance was towards colistin and polymyxin B, indicating that these antibiotics could be effective for treatment, in case there is no other choice. Using PFGE, the similarity between some strains of Acinetobacter was determined, which indicated epidemics in different parts of the hospital; such epidemics can in turn lead to increased incidence of Acinetobacter infections.

Analysis of microbial load on surgical instruments after clinical use and following manual and automated cleaning

We aimed to monitor the microbial load and identify the microorganisms recovered from surgical instruments after clinical use and following manual and automated cleaning. This experimental study was carried out in the Laboratory of Oral Microbiology and Anaerobes at the Federal University of Minas Gerais in Brazil. Microbial samples were taken from 125 surgical instruments used in 25 types of gastrointestinal surgeries. The average microbial load was 93.1 CFU/100 mL after clinical use and 41 CFU/100 mL and 8.24 CFU/100 mL on instruments following 2 sequential steps of manual cleaning, respectively, and 75 CFU/100 mL and 16.1 CFU/100 mL on instruments after automated cleaning. Surgical wound classification significantly affected the microbial load recovered on instruments. Coagulase-negative Staphylococcus, Escherichia coli, Pseudomonas spp, Stenotrophomonas maltophilia, and Acinetobacter baumannii complex were recovered. The average microbial load observed after the cleaning steps decreased, and the decrease in microbial load was more pronounced using the manual method compared with that observed using the automated method.

A distinct alleles and genetic recombination of pmrCAB operon in species of Acinetobacter baumannii complex isolates

To investigate pmrCAB sequence divergence in 5 species of Acinetobacter baumannii complex, a total of 80 isolates from a Korean hospital were explored. We evaluated nucleotide and amino acid polymorphisms of pmrCAB operon, and phylogenetic trees were constructed for each gene of prmCAB operon. Colistin and polymyxin B susceptibility was determined for all isolates, and multilocus sequence typing was also performed for A. baumannii isolates. Our results showed that each species of A. baumannii complex has divergent pmrCAB operon sequences. We identified a distinct pmrCAB allele allied with Acinetobacter nosocomialis in gene trees. Different grouping in each gene tree suggests sporadic recombination or emergence of pmrCAB genes among Acinetobacter species. Sequence polymorphisms among Acinetobacter species might not be associated with colistin resistance. We revealed that a distinct pmrCAB allele may be widespread across the continents such as North America and Asia and that sporadic genetic recombination or emergence of pmrCAB genes might occur.

Sulbactam treatment for pneumonia involving multidrug-resistant Acinetobacter calcoaceticus–Acinetobacter baumannii complex

Background: Multidrug-resistant (MDR) Acinetobacter calcoaceticus–Acinetobacter baumannii (Acb) complex has become an important cause of nosocomial pneumonia. Sulbactam is a β-lactamase inhibitor with antimicrobial activity against MDR Acb complex. Methods: To investigate outcomes of pneumonia involving MDR Acb complex treated with sulbactam or ampicillin/sulbactam for at least 7 days, we conducted a retrospective study of 173 adult patients over a 34 month period. Results: Of 173 patients, 138 (79.8%) received combination therapy, mainly with carbapenems (119/138, 86.2%). The clinical response rate was 67.6% and the 30 day mortality rate was 31.2%. The independent predictors of clinical failure were malignancy, bilateral pneumonia and shorter duration of treatment. In patients with sulbactam-susceptible strains, there was no difference in clinical and microbiological outcome between combination therapy and monotherapy. Compared to the sulbactam-susceptible group, the sulbactam-resistant group had a lower rate of airway eradication, a longer duration of treatment and a higher rate of combination therapy with predominantly carbapenems (p < 0.05). There was no significant difference between the two groups in clinical resolution and 30 day mortality rates. Conclusions: Sulbactam could be a treatment option for pneumonia involving MDR Acb complex, and combination therapy with carbapenems could be considered for sulbactam-resistant cases.

Acinetobacter seifertii sp. nov., a member of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex isolated from human clinical specimens.

This study aimed to define the taxonomic status of a phenetically distinct group of 16 strains that corresponds to Acinetobacter genomic species 'close to 13TU', a provisional genomic species of the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex recognized by Gerner-Smidt and Tjernberg in 1993. These strains have been isolated in different countries since the early 1990s and were mostly recovered from human clinical specimens. They were compared with 45 reference strains representing the known taxa of the ACB complex using taxonomic methods relevant to the genus Acinetobacter. Based on sequence analysis of the concatenated partial sequences (2976 bp) of seven housekeeping genes, the 16 strains formed a tight and well-supported cluster (intracluster sequence identity of ≥98.4 %) that was clearly separated from the other members of the ACB complex (≤94.7 %). The species status of the group was supported by average nucleotide identity values of ≤91.7 % between the whole genome sequence of representative strain NIPH 973(T) (NCBI accession no. APOO00000000) and those of the other species. In addition, whole-cell matrix-assisted laser desorption ionization-time-of-flight (MALDI-TOF) MS analyses indicated the distinctness of the group at the protein level. Metabolic and physiological tests revealed several typical features of the group, although they did not allow its reliable differentiation from the other members of the ACB complex. We conclude that the 16 strains represent a distinct novel species, for which we propose the name Acinetobacter seifertii sp. nov. The type strain is NIPH 973(T) ( = CIP 110471(T) = CCUG 34785(T) = CCM 8535(T)).

“You Can’t Always Get What You Want…” The Mycobacterium abscessus Issue. Name versus Function

“You Can’t Always Get What You Want…” The <i>Mycobacterium abscessus</i> Issue. Name versus Function

Characteristics and prognosis of pulmonary infection in patients with neurologic disease and hypoproteinemia

Objective: To examine the characteristics and the prognostic influence of pulmonary infections in neurologic disease patients with mild-to-severe hypoproteinemia. Methods: We used a retrospective survey method to analyze the characteristics and prognoses of 220 patients with hypoproteinemia complicated with pulmonary infection in the Internal Medicine-Neurology Intensive Care Unit at the First Affiliated Hospital of Chongqing Medical University from January 2010 to December 2013. The patients were divided into mild, moderate and severe hypoproteinemia groups according to their serum albumin levels. The analysis included patient age, sex, acute physiology and chronic health evaluation (APACHE II score), and characteristics of the pulmonary infection, nutritional support and prognosis, among others. Results: Differences in the general information of the 220 cases of hypoalbuminemia patients complicated with varying degrees of pulmonary infection (APACHE II score, age, disease distribution) were statistically significant. The pulmonary infection onset time and pathogen susceptibility in the patients with mild-to-severe hypoalbuminemia were not significantly different. Pulmonary infection onset was more frequently observed within the first 3–11 days following admission in all groups. The nutritional support method did not significantly influence serum albumin protein levels. However, the neurological intensive care unit stay length, total hospitalization cost and disease distribution were significantly different among the patient groups. Conclusions: Patients with cerebrovascular disease, intracranial infections and epilepsy complicated with pulmonary infection represent the high-risk groups for hypoalbuminemia. The Acinetobacter baumannii complex represents the main group of pathogenic bacteria causing lung infections, and the high-risk period for lung infections is 3–11 days after the occurrence of hypoalbuminemia. Patients with severe hypoalbuminemia complicated with pulmonary infection have the worst prognoses.

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.

Contaminated open fracture and crush injury: a murine model.

Modern warfare has caused a large number of severe extremity injuries, many of which become infected. In more recent conflicts, a pattern of co-infection with Acinetobacter baumannii and methicillin-resistant Staphylococcus aureus has emerged. We attempted to recreate this pattern in an animal model to evaluate the role of vascularity in contaminated open fractures. Historically, it has been observed that infected bones frequently appear hypovascular, but vascularity in association with bone infection has not been examined in animal models. Adult rats underwent femur fracture and muscle crush injury followed by stabilization and bacterial contamination with A. baumannii complex and methicillin-resistant Staphylococcus aureus. Vascularity and perfusion were assessed by microCT angiography and SPECT scanning, respectively, at 1, 2 and 4 weeks after injury. Quantitative bacterial cultures were also obtained. Multi-bacterial infections were successfully created, with methicillin-resistant S. aureus predominating. There was overall increase in blood flow to injured limbs that was markedly greater in bacteria-inoculated limbs. Vessel volume was greater in the infected group. Quadriceps atrophy was seen in both groups, but was greater in the infected group. In this animal model, infected open fractures had greater perfusion and vascularity than non-infected limbs.

Isolation and identification of Acinetobacter species with special reference to antibiotic resistance.

Background:Acinetobacter is clinically important pathogen with widespread resistance to various antibiotics. We assessed the incidence of Acinetobacter infection at a tertiary care hospital, analyze their resistance pattern and identify the production of extended spectrum β-lactamases (ESBLs) and metallo β-lactamases (MBLs).Materials and Methods:The study was conducted in tertiary care hospital, India over a period of 2 years. Acinetobacter species were isolated from various clinical samples received in Department of Microbiology. After identification, Acinetobacter isolates were speciated and antibiotic susceptibility was determined by the standard disc diffusion method. ESBL and MBL production was detected by the double disc synergy test and combined disc diffusion test respectively.Results:Of 3298 infected samples, 111 (3.36%) were found to be Acinetobacter. The most predominant species was Acinetobacter calcoaceticus-A. baumannii (Acb) complex (72%). High incidence of resistance was recorded for piperacillin (55%), followed by ceftriaxone (46%) and ceftazidime (46%). Isolation rate and antibiotic resistance was higher in the Intensive Care Units (ICUs) of the hospital. ESBL and MBL production was detected in 31.5% and 14.4% of the isolates respectively.Discussion and Conclusion:A high level of antibiotic resistance was observed in our study and maximum isolation rate of Acinetobacter was in the ICUs. Acb complex was the most predominant and most resistant species. The analysis of susceptibility pattern will be useful in understanding the epidemiology of this organism in our hospital setup, which will help in treating individual cases and controlling the spread of resistant isolates to other individuals.

Substitutions of Ser83Leu in GyrA and Ser80Leu in ParC Associated with Quinolone Resistance in Acinetobacter pittii.

To investigate the prevalence and the mechanism of quinolone-resistant Acinetobacter pittii, 634 Acinetobacter calcoaceticus-Acinetobacter baumannii complex isolates were collected throughout Zhejiang Province. Identification of isolates was conducted by matrix-assisted laser desorption ionization/time of flight mass spectrometry (MALDI-TOF MS), blaOXA-51-like gene, and partial RNA polymerase β-subunit (rpoB) amplification. Twenty-seven isolates of A. pittii were identified. Among the 634 isolates, A. baumannii, A. pittii, Acinetobacter nosocomialis, and A. calcoaceticus counted for 87.22%, 4.26%, 8.20%, and 0.32%, respectively. Antimicrobial susceptibility of nalidixic acid, ofloxacin, enoxacin, ciprofloxacin, lomefloxacin, levofloxacin, sparfloxacin, moxifloxacin, and gatifloxacin for 27 A. pittii were determined by the agar dilution method. Detection of quinolone-resistant determining regions of gyrA, gyrB, parC, and parE was performed for the A. pittii isolates. In addition, plasmid-mediated quinolone resistance (PMQR) determinants (qnrA, qnrB, qnrS, qnrC, qnrD, aac(6')-Ib-cr, qepA, oqxA, and oqxB) were investigated. All the 27 isolates demonstrated a higher minimum inhibitory concentration (MIC) to old quinolones than the new fluoroquinolones. No mutation in gyrA, gyrB, parC, or parE was detected in 20 ciprofloxacin-susceptible isolates. Seven ciprofloxacin-resistant A. pittii were identified with a Ser83Leu mutation in GyrA. Among them, six isolates with simultaneous Ser83Leu amino acid substitution in GyrA and Ser80Leu in ParC displayed higher MIC values against ciprofloxacin. Additionally, three were identified with a Met370Ile substitution in ParE, and two were detected with a Tyr317His mutation in ParE, which were reported for the first time. No PMQR determinants were identified in the 27 A. pittii isolates. In conclusion, mutations in chromosome play a major role in quinolone resistance in A. pittii, while resistance mechanisms mediated by plasmid have not been found. Ser83Leu substitution in GyrA and Ser80Leu substitution in ParC are associated with quinolone resistance in A. pittii. Whether Met370Ile and Tyr317His substitutions in ParE play a minor role requires further investigation.

Epidemiological characteristics of blaNDM-1 in Enterobacteriaceae and the Acinetobacter calcoaceticus-Acinetobacter baumannii complex in China from 2011 to 2012.

ObjectivesThe study aimed to investigate the prevalence and epidemiological characteristics of bla NDM-1 (encoding New Delhi metallo-β-lactamase 1) in Enterobacteriaceae and the Acinetobacter calcoaceticus-Acinetobacter baumannii complex (ABC) in China from July 2011 to June 2012.MethodsPCR was used to screen for the presence of bla NDM-1 in all organisms studied. For bla NDM-1-positive strains, 16S rRNA analysis and Analytical Profile Index (API) strips were used to identify the bacterial genus and species. The ABCs were reconfirmed by PCR detection of bla OXA-51-like. Antibiotic susceptibilities of the bacteria were assessed by determining minimum inhibitory concentration (MIC) of them using two-fold agar dilution test, as recommended by the Clinical and Laboratory Standards Institute (CLSI). Molecular typing was performed using pulsed-field gel electrophoresis (PFGE). S1 nuclease-pulsed-field gel electrophoresis (S1-PFGE) and Southern blot hybridization were conducted to ascertain the gene location of bla NDM-1. Conjugation experiments were conducted to determine the transmission of bla NDM-1-positive strains.ResultsAmong 2,170 Enterobacteriaceae and 600 ABCs, seven Enterobacteriaceae strains and two A. calcoaceticus isolates from five different cities carried the bla NDM-1 gene. The seven Enterobacteriaceae strains comprised four Klebsiella pneumoniae, one Enterobacter cloacae, one Enterobacter aerogen and one Citrobacter freundii. All seven were non-susceptible to imipenem, meropenem or ertapenem. Two A. calcoaceticus species were resistant to imipenem and meropenem. Three K. pneumoniae showed the same PFGE profiles. The bla NDM-1 genes of eight strains were localized on plasmids, while one was chromosomal.ConclusionsCompared with previous reports, the numbers and species containing the bla NDM-1 in Enterobacteriaceae have significantly increased in China. Most of them are able to disseminate the gene, which is cause for concern. Consecutive surveillance should be implemented and should also focus on the dissemination of bla NDM-1 among gram-negative clinical isolates.

Genomic epidemiology of a protracted hospital outbreak caused by multidrug-resistant Acinetobacter baumannii in Birmingham, England.

BackgroundMultidrug-resistant Acinetobacter baumannii commonly causes hospital outbreaks. However, within an outbreak, it can be difficult to identify the routes of cross-infection rapidly and accurately enough to inform infection control. Here, we describe a protracted hospital outbreak of multidrug-resistant A. baumannii, in which whole-genome sequencing (WGS) was used to obtain a high-resolution view of the relationships between isolates.MethodsTo delineate and investigate the outbreak, we attempted to genome-sequence 114 isolates that had been assigned to the A. baumannii complex by the Vitek2 system and obtained informative draft genome sequences from 102 of them. Genomes were mapped against an outbreak reference sequence to identify single nucleotide variants (SNVs).ResultsWe found that the pulsotype 27 outbreak strain was distinct from all other genome-sequenced strains. Seventy-four isolates from 49 patients could be assigned to the pulsotype 27 outbreak on the basis of genomic similarity, while WGS allowed 18 isolates to be ruled out of the outbreak. Among the pulsotype 27 outbreak isolates, we identified 31 SNVs and seven major genotypic clusters. In two patients, we documented within-host diversity, including mixtures of unrelated strains and within-strain clouds of SNV diversity. By combining WGS and epidemiological data, we reconstructed potential transmission events that linked all but 10 of the patients and confirmed links between clinical and environmental isolates. Identification of a contaminated bed and a burns theatre as sources of transmission led to enhanced environmental decontamination procedures.ConclusionsWGS is now poised to make an impact on hospital infection prevention and control, delivering cost-effective identification of routes of infection within a clinically relevant timeframe and allowing infection control teams to track, and even prevent, the spread of drug-resistant hospital pathogens.

Role of aerosolized colistin methanesulfonate therapy for extensively-drug-resistant Acinetobacter baumannii complex pneumonia and airway colonization.

Aerosolized colistin methanesulfonate (CMS) has been used for the treatment of extensively drug-resistant Acinetobacter baumannii (XDRAB) pneumonia and eradication of XDRAB colonization in the respiratory tract. The aims of this study were to compare the efficacy, adverse effects, clinical outcomes, and microbiological eradication of the cases of XDRAB pneumonia or colonization. We retrospectively reviewed the medical records of patients who received aerosolized CMS for the treatment of pneumonia and airway colonization due to XDRAB. Clinical data from 118 patients were studied. The mean age of 57 patients in the pneumonia group was 79.4 years, and that of 61 patients in the colonization group was 80.0 years. Patients with XDRAB pneumonia were more likely to be ventilator-dependent than colonized patients (46.5% vs. 21.3%; p=0.005), receive steroid therapy (49.1% vs. 31.1%; p=0.046), and be admitted to an intensive care unit (ICU) at the time of aerosolized CMS treatment (56.1% vs. 32.8%; p=0.011). The in-hospital mortality rate was higher in the pneumonia group than the colonization group (50.9% vs. 33.3%; p=0.05). Microbiological eradication of XDRAB in airway samples was achieved in 75% (89 of 118) patients. In pneumonia patients, XDRAB eradication was associated with resolution or improvement of presenting symptoms and signs of infection by the end of treatment relative to the noneradicated group (57.8% vs. 25%; p=0.044), but had no influence on 30-day mortality. In colonized patients, no difference in clinical outcomes was noted between the eradicated and noneradicated groups. Aerosolized CMS therapy has acceptable efficacy for XDRAB pneumonia, but no proven efficacy for XDRAB airway colonization.

Epidemiology and Prevalence of Bloodstream Infections in a Regional Hospital in Northern Taiwan During 2008–2013

Background Diagnosing bloodstream infections (BSIs) is a critical function of clinical microbiology laboratories. To reveal the prevalence of BSIs in a hospital in Northern Taiwan, which was established in July 2008, we investigated the clinical characteristics of patients with positive blood cultures from July 2008 to December 2013. Methods The medical records of the patients were retrospectively reviewed. In total, 104,641 blood culture sets were collected and analyzed. Results Microorganisms grew on 10.28% of these sets, as follows: 5.48% exhibited growth of a single microorganism; 1.56% exhibited growth of more than one microorganism; and 3.24% exhibited growth of contaminants. Furthermore, 5739 monomicrobial isolates included: Gram-positive cocci (22.02%); Enterobacteriaceae (56.51%); glucose nonfermentative Gram-negative bacteria (7.27%); yeast (6.22%); and anaerobic bacteria (6.64%). Most microorganisms were identified as follows: Escherichia coli (33.80%); Staphylococcus aureus (14.20%); Klebsiella pneumoniae (11.41%); Pseudomonas aeruginosa (3.17%); and the Acinetobacter calcoaceticus–Acinetobacter baumannii (Acb) complex (2.68%). Furthermore, among infants aged ≤3 months, Group B Streptococcus (GBS) and S. aureus were the leading pathogens causing bacteremia, whereas among infants 3–12 months old and children 1–4 years old, Salmonella species were the leading pathogens causing bacteremia. The prevalence of Streptococcus pneumoniae increased from the 3–12-month-old age group and reached a peak in the 5–12-year-old age group. For patients aged >13 years, the most common pathogens were E. coli, S. aureus, and K. pneumoniae. Conclusion We propose that the types and prevalence of BSIs vary according to age group and exhibit substantial geographical differences.

Influence of ACB complex genospecies on clinical outcomes in a U.S. hospital with high rates of multidrug resistance

Bacteria within the Acinetobacter calcoaceticus-Acinetobacter baumannii (ACB) complex commonly cause nosocomial infection and are often multidrug resistant. Advances in genospecies typing allow for speciation within the ACB complex; however, little is known about the effect of genospecies on patient outcomes. Adult patients with ACB complex bacteremia from Jan 2005-Oct 2012 were included. Bacterial isolates were speciated by rpoB gene sequence analysis, and clinical data were collected. Of 147 patients with ACB complex bacteremia, 116 had A. baumannii (78.9%), 28 had Acinetobacter pittii (19.0%), and 3 had Acinetobacter nosocomialis (2.0%). A. baumannii bacteremia was associated with greater comorbidity and was more frequently multidrug resistant (79% vs. 16%, p<0.01). Multidrug resistant A. baumannii but not susceptible A. baumannii was associated with worse outcomes compared to non-baumannii ACB complex bacteremia. Neither multidrug resistance nor genospecies was an independent predictor of mortality, but receipt of appropriate therapy was associated with decreased risk of mortality (OR, 0.13; 95% CI, 0.04-0.44; p<0.01). A. baumannii bacteremia is associated with worse clinical outcomes than non-baumannii ACB complex bacteremia. The difference, however, appears to be related to multidrug resistance and attendant receipt of appropriate therapy rather than genospecies.

Acinetobacter sp. isolates from emergency departments in two hospitals of South Korea.

A total of 114 Acinetobacter sp. isolates were collected from patients in the emergency departments (EDs) of two Korean hospitals. Most isolates belonged to the Acinetobacter baumannii complex (105 isolates, 92.1 %). Imipenem resistance was found in 39 isolates (34.2 %) of the Acinetobacter sp. isolates, and 6 colistin-resistant isolates were also identified. Species distribution and antimicrobial-resistance rates were different between the two hospitals. In addition, two main clones were identified in the imipenem-resistant A. baumannii isolates from hospital B, but very diverse and novel genotypes were found in those from hospital A. Many Acinetobacter sp. isolates, including the imipenem-resistant A. baumannii, are considered to be associated with the community. The evidence of high antimicrobial resistance and different features in these Acinetobacter sp. isolates between the two EDs suggests the need for continuous testing to monitor changes in epidemiology.

Antibiotic susceptibility and molecular epidemiology of Acinetobacter calcoaceticus-baumannii complex strains isolated from a referral hospital in northern Vietnam.

Acinetobacter calcoaceticus–baumannii complex is a common cause of hospital-acquired infections (HAIs) globally, remarkable for its high rate of antibiotic resistance, including to carbapenems. There are few data on the resistance of A. baumannii in Vietnam, which are essential for developing evidence-based treatment guidelines for HAIs. Antibiotic susceptibility testing was conducted by VITEK®2, and pulsed-field gel electrophoresis (PFGE) was performed on 66 clinical A. baumannii complex isolates recovered during 2009 at the National Hospital of Tropical Diseases (NHTD), a referral hospital in Hanoi, Vietnam. Basic demographic and clinical data were collected and analysed using descriptive statistics. Most isolates came from lower respiratory tract specimens (59; 89.4%) from intensive care unit (ICU) patients [64/65 (98.5%) with available data] who had been admitted to NHTD for ≥2 days [42/46 (91.3%) with available data]. More than 90% of the isolates were resistant to the tested β-lactamase/β-lactamase inhibitors, cephalosporins, carbapenems, fluoroquinolones and trimethoprim/sulfamethoxazole. Moreover, 25.4% (16/63) were resistant to all tested β-lactams, quinolones and aminoglycosides. All isolates remained sensitive to colistin and 58.7% were susceptible to tigecycline. Of the 66 isolates, 49 could be classified into eight PFGE types (A–H). Every PFGE type, except D, had cluster(s) of three or more isolates with a temporal relationship. In conclusion, these data suggest a significant rise in A. baumannii antibiotic resistance in Vietnam. Clustering within PFGE types supports cross-transmission of A. baumannii within the ICU at NHTD. Increased research and resources in optimising treatment, infection control and antibiotic stewardship are needed.

MALDI-TOF MS and chemometric based identification of the Acinetobacter calcoaceticus-Acinetobacter baumannii complex species

MALDI-TOF MS is becoming the technique of choice for rapid bacterial identification at species level in routine diagnostics. However, some drawbacks concerning the identification of closely related species such as those belonging to the Acinetobacter calcoaceticus-Acinetobacter baumannii (Acb) complex lead to high rates of misidentifications. In this work we successfully developed an approach that combines MALDI-TOF MS and chemometric tools to discriminate the six Acb complex species (A. baumannii, Acinetobacter nosocomialis, Acinetobacter pittii, A. calcoaceticus, genomic species “Close to 13TU” and genomic species “Between 1 and 3”). Mass spectra of 83 taxonomically well characterized clinical strains, reflecting the breadth of currently known phenetic diversity within the Acb complex, were achieved from intact cells and cell extracts and analyzed with hierarchical cluster analysis (HCA) and partial least squares discriminant analysis (PLSDA). This combined approach lead to 100% of correct species identification using mass spectra obtained from intact cells. Moreover, it was possible to discriminate two Acb complex species (genomic species “Close to 13TU” and genomic species “Between 1 and 3”) not included in the MALDI Biotyper database.