Imipenem-resistant Acinetobacter Baumannii Research Articles

Prevalence of Healthcare-Associated Infections in a Tertiary Hospital in Casablanca, Morocco, 2021.

During the COVID-19 pandemic, healthcare professionals experienced an increased workload, which may have affected infection prevention and control (IPC) programs and consequently healthcare-associated infection (HAI) rates. The objective of this study was to estimate the prevalence of HAI in Ibn Rochd University Hospital Center (IRUHC) and identify associated factors. A survey was conducted on November 30, 2021 at IRUHC, including all patients hospitalized for at least 48 hours. Data was collected using a questionnaire, and analyzed using SPSS IBM software version 16. The significance level was set at 0.05. Among 887 patients, the prevalence of HAI was 9.7% (7.7%; 11.6%). The highest prevalence was observed in intensive care units (ICUs) (44.2%). Nosocomial pneumonia was the most common site (26.8%). The main isolated microorganisms were Acinetobacter baumannii (18.0%) and Escherichia coli (16.0%). All Acinetobacter baumannii isolated strains were imipenem-resistant. The presence of HAI was significantly associated with the presence of an invasive medical device (p<0.001), a higher physical status score of American Society of Anesthesiologists (ASA) (p<0.001), and a longer hospital stay (p<0.001). Conclusion: The emergence of imipenem-resistant Acinetobacter baumannii(IRAB) represents a serious therapeutic and epidemiological problem requiring the establishment of a system for monitoring the microbial environment and the application of strict hygiene measures.

Isolation and Characterization of Werneria Chromene and Dihydroxyacidissimol from Burkillanthus malaccensis (Ridl.) Swingle

The secondary metabolites of endemic plants from the Rutaceae family, such as Burkillanthus malaccensis (Ridl.) Swingle from the rainforest of Malaysia, has not been studied. Burkillanthus malaccensis (Ridl.) Swingle may produce antibacterial and antibiotic-potentiating secondary metabolites. Hexane, chloroform, and methanol extracts of leaves, bark, wood, pericarps, and endocarps were tested against bacteria by broth microdilution assay and their antibiotic-potentiating activities. Chromatographic separations of hexane extracts of seeds were conducted to investigate effective phytochemicals and their antibacterial activities. Molecular docking studies of werneria chromene and dihydroxyacidissiminol against SARS-CoV-2 virus infection were conducted using AutoDock Vina. The methanol extract of bark inhibited the growth of Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa with the minimum inhibitory concentration of 250, 500, and 250 µg/mL, respectively. The chloroform extract of endocarps potentiated the activity of imipenem against imipenem-resistant Acinetobacter baumannii. The hexane extract of seeds increased the sensitivity of P. aeruginosa against ciprofloxacin and levofloxacin. The hexane extract of seeds and chloroform extract of endocarps were chromatographed, yielding werneria chromene and dihydroxyacidissiminol. Werneria chromene was bacteriostatic for P. aeruginosa and P. putida, with MIC/MBC values of 1000 > 1000 µg/mL. Dihydroxyacidissiminol showed the predicted binding energies of −8.1, −7.6, −7.0, and −7.5 kcal/mol with cathepsin L, nsp13 helicase, SARS-CoV-2 main protease, and SARS-CoV-2 spike protein receptor-binding domain S-RBD. Burkillanthus malaccensis (Ridl.) Swingle can be a potential source of natural products with antibiotic-potentiating activity and that are anti-SARS-CoV-2.

Chemical Composition and Synergistic Potential of Mentha pulegium L. and Artemisia herba alba Asso. Essential Oils and Antibiotic against Multi-Drug Resistant Bacteria.

The essential oils were obtained by hydrodistillation from aerial parts of Mentha pulegium L. (M. pulegium L.) and Artemisia herba alba (A. herba alba) Asso. and analyzed by gas chromatography–flame ionization detector chromatograpy (GC–FID) and gaz chromatography–mass spectrometry (GC–MS). The antibacterial activities of the oils were determined by the disk diffusion method and a microdilution broth assay against six bacteria stains. The combinations of these essential oils with antibiotics were evaluated against two multi-drug-resistant bacteria strains: imipenem-resistant Acinetobacter baumannii (IRAB S3310) and methicillin-resistant Staphylococcus aureus (MRSA S19). The chemical analysis of M. pulegium essential oil revealed the presence of pulegone (74.8%) and neoisomenthol (10.0%). A. herba alba essential oil was characterized by camphor (32.0%), α-thujone (13.7%), 1,8-cineole (9.8%), β-thujone (5.0%), bornéol (3.8%), camphene (3.6%), and p-cymene (2.1%). All strains tested except Pseudomonas aeruginosa were susceptible to these oils. The combinations of essential oils with antibiotics exerted synergism, antagonism, or indifferent effects. The best effect was observed with A. herba alba essential oil in association with cefoxitin (CX) against MRSA S19. However, for IRAB S3310, the strongest synergistic effect was observed with M. pulegium in association with amikacin (AK). This study demonstrated that M. pulegium and A. herba alba essential oils have antibacterial activities which could be potentiated by antibiotics especially in the case of IRAB S3310.

Characteristics of Two Crustins from Alvinocaris longirostris in Hydrothermal Vents.

Crustins are widely distributed among different crustacean groups. They are characterized by a whey acidic protein (WAP) domain, and most examined Crustins show activity against Gram-positive bacteria. This study reports two Crustins, Al-crus 3 and Al-crus 7, from hydrothermal vent shrimp, Alvinocaris longirostris. Al-crus 3 and Al-crus 7 belong to Crustin Type IIa, with a similarity of about 51% at amino acid level. Antibacterial assays showed that Al-crus 3 mainly displayed activity against Gram-positive bacteria with MIC50 values of 10–25 μM. However, Al-crus 7 not only displayed activity against Gram-positive bacteria but also against Gram-negative bacteria Imipenem-resistant Acinetobacter baumannii, in a sensitive manner. Notably, in the effective antibacterial spectrum, Methicillin-sensitive Staphylococcus aureus, Escherichia coli (ESBLs) and Imipenem-resistant A. baumannii were drug-resistant pathogens. Narrowing down the sequence to the WAP domain, Al-crusWAP 3 and Al-crusWAP 7 demonstrated antibacterial activities but were weak. Additionally, the effects on bacteria did not significantly change after they were maintained at room temperature for 48 h. This indicated that Al-crus 3 and Al-crus 7 were relatively stable and convenient for transportation. Altogether, this study reported two new Crustins with specific characteristics. In particular, Al-crus 7 inhibited Gram-negative imipenem-resistant A. baumannii.

Prospective study of the incidence density of multi-resistant microorganisms and Clostridioides difficile during the period 2012- 2019 in the Canary Islands

RESUMENIntroducciónEl Servicio Canario de Salud implementó a partir de 2012 un nuevo sistema de vigilancia de infecciones nosocomiales causadas por microorganismos multirresistentes y Clostridioides difficile. Este sistema permitirá conocer las tasas de incidencia de estos patógenos, contrastarlas periódicamente para vigilar su tendencia y compararlas con las de otras instituciones sanitarias nacionales y europeas.Pacientes y métodoEstudio observacional, prospectivo de la densidad de incidencia de patógenos multirresistentes y Clostridioides difficile en los centros sanitarios del Servicio Canario de la Salud desde 2012 hasta 2019.ResultadosLa densidad de incidencia de infecciones por Staphylococcus aureus resistente a meticilina para el año 2012 fue de 1,96 casos por 10.000 estancias y disminuyó a 0,80 en 2019, alcanzando la cifra más baja en el periodo de vigilancia. Las infecciones por enterobacterias productoras de carbapenemasas mostraron una tendencia ascendente, 0,47 (2014) y 2,35 (2019). Se ha corregido la ligera tendencia al alza de infecciones por Acinetobacter baumannii resistente a imipenem en las bacteriemias observadas 0,17 (2012) y 0,09 (2019). No se observaron casos de infección por enterococos resistentes a vancomicina. En cuanto a C. difficile, se ha consolidado una tendencia al alza que inició en 2012, produciéndose un incremento de un 216% en el número de casos detectados al final del periodo de estudio.ConclusiónEl problema más importante detectado en la actualidad son las enterobacterias productoras de carbapenemasas. Los datos analizados en este período muestran un cambio evidente en la tendencia de los patógenos multirresistentes estudiados. Este hecho debe confirmarse en el futuro.

Impact of an Intervention to Control Imipenem-Resistant Acinetobacter baumannii and Its Resistance Mechanisms: An 8-Year Survey.

BackgroundThis study aimed to examine the impact of an intervention carried out in 2011 to combat multi-drug resistance and outbreaks of imipenem-resistant Acinetobacter baumannii (IRAB), and to explore its resistance mechanism.MethodsA total of 2572 isolates of A. baumannii, including 1673 IRAB isolates, were collected between 2007 and 2014. An intervention was implemented to control A. baumannii resistance and outbreaks. Antimicrobial susceptibility was tested by calculating minimal inhibitory concentrations (MICs), and outbreaks were typed using pulsed-field gel electrophoresis (PFGE). Resistance mechanisms were explored by polymerase chain reaction (PCR) and whole genome sequencing (WGS).ResultsFollowing the intervention in 2011, the resistance rates of A. baumannii to almost all tested antibiotics decreased, from 85.3 to 72.6% for imipenem, 100 to 80.8% for ceftriaxone, and 45.0 to 6.9% for tigecycline. The intervention resulted in a decrease in the number (seven to five), duration (8–3 months), and departments (five to three) affected by outbreaks; no outbreaks occurred in 2011. After the intervention, only blaAMPC (76.47 to 100%) and blaTEM–1 (75.74 to 96.92%) increased (P < 0.0001); whereas blaGES–1 (32.35 to 3.07%), blaPER–1 (21.32 to 1.54%), blaOXA–58 (60.29 to 1.54%), carO (37.50 to 7.69%), and adeB (9.56 to 3.08%) decreased (P < 0.0001). Interestingly, the frequency of class B β-lactamase genes decreased from 91.18% (blaSPM–1) and 61.03% (blaIMP–1) to 0%, while that of class D blaOXA–23 increased to 96.92% (P < 0.0001). WGS showed that the major PFGE types causing outbreaks each year (type 01, 11, 18, 23, 26, and 31) carried the same resistance genes (blaKPC–1, blaADC–25, blaOXA–66, and adeABC), AdeR-S mutations (G186V and A136V), and a partially blocked porin channel CarO. Meanwhile, plasmids harboring blaOXA–23 were found after the intervention.ConclusionThe intervention was highly effective in reducing multi-drug resistance of A. baumannii and IRAB outbreaks in the long term. The resistance mechanisms of IRAB may involve genes encoding β-lactamases, efflux pump overexpression, outer membrane porin blockade, and plasmids; in particular, clonal spread of blaOXA–23 was the major cause of outbreaks. Similar interventions may also help reduce bacterial resistance rates and outbreaks in other hospitals.

In vitro and in vivo Evaluation of Antibiotic Combination against Imipenem Resistant Acinetobacter baumannii Strains Isolated from Bangladeshi Patients

Acinetobacter baumannii is becoming a common etiological agent of nosocomial infections resulting in septicemia, meningitis, endocarditis, pneumonia, wound, and urinary tract infections within the healthcare setting. There are currently no defined optimal therapies available for multidrug-resistant (MDR) Acinetobacter baumannii infections. We evaluated the efficacy of imipenem, ceftazidime, amikacin and their combinations against imipenem resistant A. baumannii in experimental rat models. We also detected MBL encoding genes such as blaNDM-1, blaVIM and blaIMP and ESBL encoding genes such as blaCTX-M-15 and blaOXA-1 genes by Polymerase chain reaction (PCR). MBL encoding genes such as blaNDM-1 (83.33%), blaVIM (66.67%) and blaIMP (41.67%) and ESBL encoding genes such as blaCTX-M-15 (16.67%) and blaOXA-1 (12.50%) were detected among imipenem resistant Acinetobacter baumannii by PCR. In vitro activities of imipenem, ceftazidime, amikacin, ciprofloxacin, tigecycline and their combinations were tested using agar dilution method. The proportions of synergy observed in imipenem-ceftazidime, imipenem-amikacin, imipenem-ciprofloxacin and amikacin-tigecycline combinations were 25%, 54.17%, 12.50% and 41.67% respectively in vitro. Rat septicaemic models were evaluated using the imipenem resistant A. baumannii strain. Rats were treated with three antimicrobials and their combinations. For the rat model, the efficacies of imipenem, amikacin and imipenem plus ceftazidime and imipenem plus amikacin were assayed. In the septicaemic rat model, compared to the control group, (i) imipenem alone, (ii) ceftazidime alone (iii) imipenem plus ceftazidime (iv) imipenem plus amikacin showed increased sterile blood culture (50%, 16.67%, 66.67% and 83.33%). Imipenem plus amikacin or amikacin plus tigecycline may be appropriate for the treatment against imipenem resistant Acinetobacter baumannii infections.

Genetic Diversity of Imipenem-ResistantAcinetobacter baumanniiInfections at an Intensive Care Unit

Introduction. Imipenem-resistant Acinetobacter baumannii (IRAB) represents a major clinical threat. Dissemination in critical care areas necessitates effective action measures including genotyping tools to study the clonality of these strains and trace their origin. The main aim of this study is to assess the genetic relatedness between IRAB isolates in our institution intensive care units (ICU) which are at a particular risk of outbreaks. Methods Nonreplicate IRAB strains were serially collected over 3 years period (January 2016–December 2018) from patients admitted to the ICU. The isolates were phenotypically identified by a matrix-assisted laser desorption/ionization time-of-flight- (MALDI-TOF-) based system (VITEK MS), and their susceptibility was tested by the phenotypic-based VITEK 2 system. Molecular fingerprinting was performed by enterobacterial repetitive intergenic consensus (ERIC-PCR) followed by hierarchal clustering. The patterns were analysed by the software of BioNumerics package version 7.6.3 (Applied Maths, Belgium). Results A total of eighty IRAB were isolated from 31 colonization and 59 infection sites in patients admitted to the ICU. Sixty-two samples were respiratory in origin (77.5%). The generated dendrogram revealed distinct patterns for majority (95%) of the strains. Meropenem maintained activity against 43.8% of the imipenem-resistant A. baumannii. Conclusion Meropenem can be a therapeutic option for imipenem-resistant A. baumannii.

Identification of carbonylated proteins in a bactericidal process induced by curcumin with blue light irradiation on imipenem-resistant Acinetobacter baumannii.

Antimicrobial photodynamic treatment is potentially an alternative to antibiotics and is also effective against viruses, fungi and some cancers. Our previous studies have shown that blue light combined with curcumin, a chemical from the turmeric plant, exerted effective antimicrobial activity via photodynamic treatment. The study reported in this paper investigates which target proteins are affected after the treatment. We treated imipenem-resistant Acinetobacter baumannii with blue light and curcumin and used protein carbonylation as a marker for oxidative damage. After treatment, the bacterial proteins were extracted and the protein carbonyls marked using dinitrophenylhydrazide. After enzyme digestion, we used liquid chromatography/nano-electrospray ionization (LC/nano-ESI) ion trap mass spectrometry to identify bacterial peptides from a customized database. The functional enrichment analyses of the identified proteins were performed using gene ontology annotation and the STRING protein-protein interaction network. The application of curcumin with blue light showed good antibacterial activity against imipenem-resistant A. baumannii. Using a shotgun proteomics approach, the carbonylated proteins in A. baumannii caused by the photolytic curcumin were identified. The results showed that the proteins related to membrane structures, translation and response to oxidative stress were preferentially modified. The photolytic curcumin treatment could be a potential alternative to antibiotics for bacterial infection. In this study, the shotgun proteomics strategy allows us to explore the possible bactericidal mechanisms under this oxidative stress. The result provides a reference for future studies on the enhancement of the action of photolytic curcumin.

Circulation of imipenem-resistant Acinetobacter baumannii ST10, ST2 and ST3 in a university teaching hospital from Tehran, Iran.

Multi-drug resistant (MDR) Acinetobacter baumannii has introduced a worldwide health crisis. The purposes of this study were to characterize the clonal relatedness among MDR clinical strains and to introduce a new two-locus typing method confirmed by multi-locus sequence typing (MLST). In this study, we determined antimicrobial resistance, detected genes associated with carbapenem resistance and characterized clonal relatedness among 99 clinical isolates extracted from 82 hospitalized inpatients in a university hospital. Of the 99 A. baumannii isolates, 92.9% (92/99) were resistant to imipenem and 97.9% (97/99) had an MDR profile. We found that the high prevalence of blaVIM [94.9% (94/99)] and blaOXA-23-like [93.93% (93/99)] is the main mechanism of carbapenem resistance. This study proposes a new two-locus typing (blaOXA-51-like and ampC) method for the rapid identification of clonal complexes (CCs). The results of this method and confirmation by MLST show that clinical isolates carry blaOXA-68 as well as ampC-10 or ampC-20 genes belonging to CC10 (ST10); blaOXA-66 and ampC-2 belonging to CC2 (ST2); and blaOXA-71 and ampC-3 belonging to CC3 (ST3). One isolate had blaOXA-90 with an undetermined allele number of ampC belonging to ST513. The high prevalence of MDR strains and the circulation of four limited clones, including ST10 (45/99), ST2 (41/99), ST3 (12/99) and ST513 (1/99), in the clinical setting highlights the importance of a rigorous infection control programme. The two-locus typing method has more discrimination than the application of each method separately and it could be applied for the rapid determination of the CC without performing MLST.

Impact of an Acinetobacter baumannii outbreak on kidney events in a burn unit: A targeted machine learning analysis

Multidrug-resistant (MDR) bacteria outbreaks represent a major threat in intensive care units. Patients may then be exposed to drug-related direct toxicity during such outbreaks. The objective of this study was to explore the impact of an outbreak of imipenem-resistant Acinetobacter baumannii (IR-AB) on renal outcomes. We performed a before-and-after observational study in a French burn intensive care unit during an IR-AB outbreak: a 13-month period before (period A, October 2013-October 2014) and a 13-month period after outbreak control (period B, December 2014-December 2015). A total of 409 patients were included, 195 during period A and 214 during period B. The main endpoint was major adverse kidney events at day 90 (MAKE 90). Secondary endpoints were acute kidney injury (AKI) and persistent renal dysfunction. Incidence of MAKE 90 was 15.9% during period A versus 11.2% during period B (P = .166) and AKI 28.2% versus 18.7% (P = .023). The use of colistin was associated with renal outcomes in univariate analysis. After adjustment of potential confounding factors using a targeted Machine Learning Analysis (ie, IR-AB-related infection, septic shock, severity scores, other nephrotoxics, chronic kidney disease, serum creatinine at admission, Staphylococcus aureus), colistin remained associated with the risk of MAKE and AKI (relative risk = 2.909, 95% confidence interval [CI] [1.364, 6.204], P = .006for MAKE 90, and relative risk = 2.14, 95% CI [1.52, 3.02], P<.0001 for AKI). The episode of IR-AB outbreak was associated with an increased risk of kidney events, which appears to be driven by the use of colistin.

In vitro activities of cefiderocol, ceftolozane/tazobactam, ceftazidime/avibactam and other comparative drugs against imipenem-resistant Pseudomonas aeruginosa and Acinetobacter baumannii, and Stenotrophomonas maltophilia, all associated with bloodstream infections in Taiwan.

We investigated the in vitro activities of cefiderocol, ceftazidime/avibactam, ceftolozane/tazobactam and other related drugs against imipenem-resistant Pseudomonas aeruginosa, imipenem-resistant Acinetobacter baumannii and Stenotrophomonas maltophilia isolates. Non-duplicated bacteraemia isolates (n = 300) of imipenem-resistant P. aeruginosa (n = 100), imipenem-resistant A. baumannii (n = 100) and S. maltophilia (n = 100) were evaluated. Imipenem-resistant P. aeruginosa and imipenem-resistant A. baumannii isolates were defined as isolates exhibiting imipenem MIC ≥8 mg/L, as determined using the VITEK 2 system. The MICs of 11 other antimicrobial agents for the isolates were determined by the broth microdilution method. Iron-depleted CAMHB was used to determine the MICs of cefiderocol. The rates of colistin resistance of imipenem-resistant P. aeruginosa and imipenem-resistant A. baumannii were 5% and 10%, respectively. The MIC90 values of cefiderocol, ceftolozane/tazobactam, ceftazidime/avibactam, tigecycline and colistin were as follows: imipenem-resistant P. aeruginosa: 1, 4, 16, >4 and 2 mg/L; imipenem-resistant A. baumannii: 8, >64, >64, 4 and 2 mg/L; and S. maltophilia: 0.25, >64, >64, 2 and >8 mg/L, respectively. For imipenem-resistant A. baumannii isolates, the MICs of cefiderocol, ceftolozane/tazobactam and ceftazidime/avibactam were ≤4 mg/L for 88%, 8% and 1% of the isolates, respectively. Cefiderocol MICs were ≤4 mg/L for the five colistin-resistant imipenem-resistant P. aeruginosa isolates and 70% of the 10 colistin-resistant imipenem-resistant A. baumannii isolates. Cefiderocol exhibited more potent in vitro activity than ceftolozane/tazobactam and ceftazidime/avibactam against imipenem-resistant P. aeruginosa, imipenem-resistant A. baumannii and S. maltophilia isolates.

Antimicrobial resistance of major clinical pathogens in South Korea, May 2016 to April 2017: first one-year report from Kor-GLASS.

The Korean government established an antimicrobial resistance (AMR) surveillance system, compatible with the Global AMR Surveillance System (GLASS): Kor-GLASS. We describe results from the first year of operation of the Kor-GLASS from May 2016 to April 2017, comprising all non-duplicated clinical isolates of major pathogens from blood, urine, faeces and urethral and cervical swabs from six sentinel hospitals. Antimicrobial susceptibility tests were carried out by disk diffusion, Etest, broth microdilution and agar dilution methods. Among 67,803 blood cultures, 3,523 target pathogens were recovered. The predominant bacterial species were Escherichia coli (n = 1,536), Klebsiella pneumoniae (n = 597) and Staphylococcus aureus (n = 584). From 57,477 urine cultures, 6,394 E. coli and 1,097 K. pneumoniae were recovered. Bloodstream infections in inpatients per 10,000 patient-days (10TPD) were highest for cefotaxime-resistant E. coli with 2.1, followed by 1.6 for meticillin-resistant Sta. aureus, 1.1 for imipenem-resistant Acinetobacter baumannii, 0.8 for cefotaxime-resistant K. pneumoniae and 0.4 for vancomycin-resistant Enterococcus faecium. Urinary tract infections in inpatients were 7.7 and 2.1 per 10TPD for cefotaxime-resistant E. coli and K. pneumoniae, respectively. Kor-GLASS generated well-curated surveillance data devoid of collection bias or isolate duplication. A bacterial bank and a database for the collections are under development.

In vitro evaluation of antimicrobial combinations against imipenem-resistant Acinetobacter baumannii of different MICs

This study was designed to verify the effectiveness of antimicrobial combination therapy against Acinetobacter baumannii isolates with different degrees of resistance to imipenem. A total of twenty-one isolates with imipenem MICs of 16μg/ml (fifteen isolates) or 64μg/ml (six isolates), as identified using the Vitek II system, were included in this study. The MICs of all the isolates to each drug were confirmed again using the broth microdilution method, and a checkerboard assay was used for the assessment of the in vitro effectiveness of various antibiotic combinations. The results of susceptibility testing for single antibiotics indicated that imipenem-resistant Acinetobacter baumannii isolates exhibited good sensitivity to tigecycline and minocycline yet poor sensitivity to colistin, cefoperazone/sulbactam and levofloxacin. The distribution range of MICs for doripenem ranged from 0.5μg/ml to 128μg/ml, and the MICs ranged from 2μg/ml to 32μg/ml for levofloxacin. For combinations of imipenem and colistin, synergy was observed for the fourteen isolates with imipenem MICs of 16μg/ml and one isolate with an imipenem MIC of 64μg/ml. For the combinations of imipenem and cefoperazone/sulbactam, synergy was only observed for the fifteen isolates with imipenem MICs of 16μg/ml. The combinations of imipenem and fosfomycin showed synergy for twelve isolates with imipenem MICs of 16μg/ml. Other antimicrobial combinations based on colistin did not exhibit obvious synergy. The high sensitivity of tigecycline and minocycline in this study provides a reference for the clinical treatment of imipenem-resistant Acinetobacter baumannii infections in our region. The effectiveness of combination therapy may be predicted by the imipenem MICs of the isolates. The effect of fosfomycin in the combinations also reflects the clinical value of old drugs for new uses. These results suggest us that if we use carbapenem antibiotics in combination, more attention should be paid to the MICs of single drugs, and the economic costs should also be considered.

Nosocomial Neonatal Meningitis with Acinetobacter Baumannii on Myelomeningocele: A Real Therapeutic Challenge

Imipenem-resistant Acinetobacter baumannii meningitis is a hospital-acquired infection, the treatment of which constitutes a real therapeutic challenge. In this article, together with a review of the literature, we report two cases of imipenem-resistant Acinetobacter baumannii neonatal meningitis following ruptured myelomeningocele, treated with intravenous colistin with favorable results. In recent years, Acinetobacter baumannii has become a more and more commonly described pathogen in hospital-acquired infections. However, the cases of meningitis are mainly postoperative and are still not quite frequently described in the literature. Colistin appears to be preferably administered intravenously at a dose of 100.000 IU/kg/day.

Microbiology of French military casualties repatriated from overseas for an open traumatic injury

BackgroundThis study aimed to describe the microbiological epidemiology of repatriated French soldiers with an open traumatic injury, and to measure the proportion of multidrug-resistant bacteria (MDRB). MethodsRetrospective study including all French soldiers repatriated in 2011 and 2012 in Parisian military hospitals for open traumatic injury. Results of clinical samples and MDRB screening were collected. The antibiotic susceptibility was assessed using the agar disk diffusion method. Characterization of resistance mechanisms was performed using PCR. Genotyping of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) isolates was performed using rep-PCR. ResultsA total of 139 patients were included; 70% of them were repatriated from Afghanistan. At admission, 24/88 were positive for MDRB (28%), mainly ESBL-E but no carbapenemase-producing Enterobacteriaceae and vancomycin-resistant Enterococcus faecium were identified. Forty-five patients had lesion sample collection, and 28/45 had a positive culture. The most frequently isolated pathogens were Enterobacter cloacae, Pseudomonas aeruginosa, and Escherichia coli. For eight patients, a MDRB was isolated from the wound, mainly ESBL-E (7/8) but also one methicillin-resistant Staphylococcus aureus and one imipenem-resistant Acinetobacter baumannii. Among ESBL-E, the PCR evidenced the high prevalence of CTX-M15 enzymes. Rep-PCR performed on the 23 ESBL-producing E. coli isolates highlighted numerous profiles. ConclusionsControlling the spread of ESBL-E is currently challenging for French Armed Forces. Despite any evidence of an epidemic clone, a high-level compliance with hygiene precautions is required throughout the chain of care to avoid cross contamination.

Molecular characterization of carbapenem-resistant &lt;i&gt;Acinetobacter baumannii&lt;/i&gt; isolated from pediatric burns patients in an Iranian hospital

Purpose : To survey the molecular characteristics of imipenem-resistant Acinetobacter baumannii obtained from pediatric burns patients in a teaching hospital in Tehran, Iran. Methods : Over a 10-month period, 73 non-duplicate A. baumannii strains were collected from pediatric burns patients admitted to Motahari Burn and Reconstruction Center, Tehran, Iran. The resistance profile of several antimicrobials was determined. Metallo-β-lactamase (MBL)-producing isolates were identified using double-disk synergy and an MBL E-test. Polymerase chain reaction (PCR) was carried out to detect the following β-lactamase-encoding elements: blaVIM, blaIMP, blaSIM, blaSPM, blaGIM, blaNDM, blaAIM, blaDIM, blaKPC, blaOXA-23/24/51, and blaOXA-58. The types of integrons were also identified using PCR. Results : Out of the 73 collected strains, 92.4 and 38.3 % of the isolates were multidrug-resistant (MDR) and extensively drug-resistant (XDR), respectively. Colistin was the most effective antibiotic. It was found that 94.5 % of the strains were resistant to imipenem, as determined both by disk agar diffusion and MIC E-test methods. Based on double disk synergy and E-test, 78.1 and 83.5 % of the isolates, respectively, were MBL producers. The prevalence of blaOXA-23 and blaOXA-24 were 75.4 and 39.1 %, respectively. The results also indicate that 62.3, 30.4, and 4.3 % of the isolates were positive for blaVIM, blaIMP and blaNDM genes, respectively. Furthermore, 16.4, 76.1, and 7.5 % of the isolates carried intI, intII, and intIII genes, respectively. Conclusion : The increased frequency of carbapenem-resistant A. baumannii in burns cases underlines the importance of choosing an appropriate antibacterial regimen based on antibiotic susceptibility profile. Rapid identification of carbapenemase-producing strains would be helpful for selecting suitable antimicrobial therapy and preventing further spread of their encoding genes. Keywords : Carbapenem-resistant Acinetobacter baumannii, Pediatric burns, Integron, β-lactamase genes

Changes in antimicrobial susceptibility of commonly clinically significant isolates before and after the interventions on surgical prophylactic antibiotics (SPAs) in Shanghai.

Surveillances and interventions on antibiotics use have been suggested to improve serious drug-resistance worldwide. Since 2007, our hospital have proposed many measures for regulating surgical prophylactic antibiotics (carbapenems, third gen. cephalosporins, vancomycin, etc.) prescribing practices, like formulary restriction or replacement for surgical prophylactic antibiotics and timely feedback. To assess the impacts on drug-resistance after interventions, we enrolled infected patients in 2006 (pre-intervention period) and 2014 (post-intervention period) in a tertiary hospital in Shanghai. Proportions of targeted pathogens were analyzed: methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus spp. (VRE), imipenem-resistant Escherichia coli (IREC), imipenem-resistant Klebsiella pneumoniae (IRKP), imipenem-resistant Acinetobacter baumannii (IRAB) and imipenem-resistant Pseudomonas aeruginosa (IRPA) isolates. Rates of them were estimated and compared between Surgical Department, ICU and Internal Department during two periods. The total proportions of targeted isolates in Surgical Department (62.44%, 2006; 64.09%, 2014) were more than those in ICU (46.13%, 2006; 50.99%, 2014) and in Internal Department (44.54%, 2006; 51.20%, 2014). Only MRSA has decreased significantly (80.48%, 2006; 55.97%, 2014) (p < 0.0001). The percentages of VRE and IREC in 3 departments were all <15%, and the slightest change were also both observed in Surgical Department (VRE: 0.76%, 2006; 2.03%, 2014) (IREC: 2.69%, 2006; 2.63%, 2014). The interventions on surgical prophylactic antibiotics can be effective for improving resistance; antimicrobial stewardship must be combined with infection control practices.

Outbreak of imipenem-resistant Acinetobacter baumannii in different wards at a regional hospital related to untrained bedside caregivers

This study describes an outbreak caused by imipenem-resistant Acinetobacter baumannii (IRAB) involving 2 general wards at the Penghu branch of Tri-Service General Hospital. Clinical data obtained from the patients with IRAB during an outbreak from May 2014-October 2014 were reviewed. Microbiologic sampling from the environment and the hands of health care workers (HCWs) was performed. Clinical isolates from case patients were genotyped using pulsed-field gel electrophoresis (PFGE). During the outbreak period, 12 patients were colonized or infected with IRAB. The hospital room environments of the case patients were contaminated with IRAB. Hands of nurses and physicians were not colonized with IRAB, but the hands of 2 bedside caregivers of case patients were colonized with IRAB. The PFGE analysis revealed that at least 2 major genetically distinct strains disseminated between 2 different wards. After implementation of infection control measures with a cohort of nursing patients, hand hygiene education for caregivers who had not received instructions before the outbreak, and a critical value alert system to notify case patients, the outbreak was controlled successfully. This outbreak study highlights the importance of adherence to hand hygiene by all HCWs to prevent the dissemination of multidrug-resistant organisms.

A study on antibiotics resistance and carbapenemase genotype of Acinetobacter baumannii in intensive care unit of Qingdao

Objective To investigate antibiotics resistant characteristics and carbapenemases genotype of Acinetobacter baumannii in Intensive Care Unit (ICU), so as to provide theoretical basis for clinical prevention and treatment. Methods Retrospective study was made on 90 non-duplicated clinical isolates of Acinetobacter baumannii, which were collected From January 2013 to January 2014 in three tertiary hospitals of Qingdao. All strains were identified by VITEK2 automated microbiology analyzer; K-B method was used to do drug susceptibility test; polymerase chain reaction (PCR) was used to amplify the OXA-23, OXA-24, OXA-51, OXA-58, KPC-2, VIM, IMP genes, and the positive products of genes were sequenced; the chi-square test was used to compare the difference of the resistance rates. Results The detection rate of multi-drug resistant A. baumannii (MDRAB)and Pan-drug resistant A. baumannii (PDRAB)was 61.11% (55/90) and 17.78% (16/90). In the 32 strains of imipenem-resistant Acinetobacter baumannii, the resistant rates to Cefoperazone/sulbactam, Polymyxin B was lower, while the resistant rates to other drugs tested were more than 85%. The difference of the resistance rates to 9 drugs between imipenem resistant group and Imipenem sensitive group were statistically significant (P≤0.05). PCR result showed: 32 strains detected OXA-51 gene, 28 strains detected OXA-23 gene, and 3 strains detected VIM gene, the detection rates of which were 100%, 87.50% and 9.38% respectively.All strains were not detected OXA-24, OXA-58, KPC-2 and IMP genes. The sequenced results were absolutely homology with the corresponding genes in genbank. Conclusions The resistance of A. baumannii in ICU is serious in this region, especially imipenem-resistant A. baumannii, which were nearly no-sensitive to most of the drugs commonly used in clinical. The gene existence of carbapenemase and carbapenemase producing is one of the main resistance mechanism of Acinetobacter baumannii to carbapenem antibiotics. OXA-23 was the major genotypes in this region.(Chin J Lab Med, 2017, 40: 216-220) Key words: Acinetobacter baumannii; Drug resistance, bacterial; Bacterial proteins; Beta-Lactamases; Genotype; Intensive care units