Non-fermenting Gram-negative Bacilli Research Articles

Duration of Antimicrobial Treatment in Adult Patients with Pneumonia: A Narrative Review

Pneumonia remains a major global health concern, causing significant morbidity and mortality among adults. This narrative review assesses the optimal duration of antimicrobial treatment in adults with community-acquired pneumonia (CAP), hospital-acquired pneumonia (HAP), and ventilator-associated pneumonia (VAP). Current evidence about the impact of treatment duration on clinical outcomes demonstrates that shorter antibiotic courses are non-inferior, regarding safety and efficacy, compared to longer courses, particularly in patients with mild to moderate CAP, which is in line with the recommendations of international guidelines. Data are limited regarding the optimal antimicrobial duration in HAP patients, and it should be individually tailored to each patient, taking into account the causative pathogen and the clinical response. Shorter courses are found to be as effective as longer courses in the management of VAP, except for pneumonia caused by non-fermenting Gram-negative bacteria; however, duration should be balanced between the possibility of higher recurrence rates and the documented benefits with shorter courses. Additionally, the validation of reliable biomarkers or clinical predictors that identify patients who would benefit from shorter therapy is crucial. Insights from this review may lead to future research on personalized antimicrobial therapies in pneumonia, in order to improve patient outcomes.

Detection of carbapenem-resistant gram-negative bacilli in Japan using the fully automated bacterial testing device RAISUS S4

ObjectiveWe investigated a rapid detection method for carbapenemase-producing gram-negative bacilli (CP-GNR) using meropenem (MEPM) to assess the efficiency of the antimicrobial susceptibility testing. MethodsWe used the function that can monitor the growth curve with the resistant bacteria monitoring function (RAISUS S4). Rapid detection of CP-GNR was performed using RAISUS S4 in two types of antimicrobial susceptibility testing, the RAISUS 18-hour method (18-h method) and RAISUS rapid method (rapid method) for Enterobacterales (F-GNR) and non-fermenting Gram-negative bacilli (NF-GNR). ResultsWhen F-GNR were based on MEPM MIC ≥ 0.25 μg/mL, CP-GNR were detected with a sensitivity of 100% (58/58) for the 18-h method and 98.3% (57/58) for the rapid method; the shortest detection times were 5.3 and 4.0 h, respectively. When NF-GNR were based on MEPM MIC > 8 μg/mL, it was possible to detect CP-GNR with 100% sensitivity (58/58) in both methods. Furthermore, in the analysis using the 18-h method for monitoring resistant bacteria, when ≥ 2 µg/mL was used as the screening concentration for F-GNR, approximately 50% of the resistant genotypes, NDM, GES, and KPC, were detected in approximately 7 h. However, detecting the IMP and VIM took 11–12 h. ConclusionsThe 18-h and rapid methods with RAISUS S4 were highly correlated with the results of the microdilution method of CLSI, and CP-GNR detection was rapid using a function that can monitor the growth curve with RAISUS S4.

Bloodstream infections in a Brazilian Pediatric Tertiary Oncology Hospital: 30-month analysis regarding the classification of the infection, distribution of microorganisms and their resistance profile

Abstract Background Infections are a major cause of morbidity and mortality in pediatric oncology patients during their treatment. Bloodstream infections are the main site of infection in these patients. Bacteremia in these patients can be secondary to a primary infectious focus, result from central line associated bloodstream infections (CLABSIs) or mucosal barrier injury laboratory-confirmed bloodstream infection (MBI-LCBI). Methods Descriptive study of bloodstream infections in pediatric patients undergoing oncological treatment and hematopoietic stem cell transplantation in a tertiary pediatric oncology hospital in Brazil from January 1st, 2021 to June 30th, 2023. Infections were classified according to the Centers for Disease Control and Prevention/ National Healthcare Safety Network (CDC/NHSN) criteria into CLABSIs, MBI-LCBIs and secondary bloodstream infections. Among the bloodstream infections that met CDC/NHSN criteria for CLABSI, were analyzed separately those who also met the criteria of catheter-related bloodstream infection (CRBSI) according to Infectious Diseases Society of America (IDSA). Results During this period were diagnosed 335 episodes of bloodstream infection (123 episodes in 2021, 150 in 2022 and 62 episodes in the first 6 months of 2023). There were 378 microorganisms isolated. These infections were classified into: 35% CLABSIs, 27% MBI-LCBIs, 23% CRBSIs, and 15% secondary bloodstream infections. Among the CLABSIs, the most common microorganisms were non-fermenting gram negative bacilli (NFGNB) 38%, enterobacteriaceae 35% and coagulase-negative staphylococcus (CoNS) 11%. Between CRBSIs, there were 31% enterobacteriaceae, 22% CoNS and 19% NFGNB. Among the MBI-LCBIs there were 66% enterobacteriaceae and 23% group viridans streptococci (VGS). Streptococcus pneumoniae (33%) was the most common microorganism in secondary infections followed by Staphylococcus aureus (17%). Assessing all infections together, the main enterobacteriaceae were Klebsiella spp. (40%) and only 50% of them were sensitive to cefepime while 10% were carbapenems resistant. Among NFGNB, 13% of Pseudomonas spp. and 5% of Acinetobacter spp. were carbapenems resistant. Between the gram-positive bacteria, 77% of the S. aureus were methicillin sensitive, the same percentage of the VGS were sensitive to cefepime. Conclusion Among bloodstream infections, there were a predominance of CLABSI followed by MBI-LCBIs. Antimicrobial resistance between gram-positive bacteria, is of little concern in our institution. In the case of gram-negative bacteria, resistance to cefepime is becoming worrying among enterobacteriaceae.

Review of Association Between Urinary Tract Infections and Immunosuppressive Drugs after Heart Transplantation.

Management of infections in heart transplant recipients is complex and crucial. In this population, there is a need for a better understanding of immunosuppressive trough levels (C0), infectious complications, and urinary tract infections (UTIs). The purpose of this review was to understand the association between immunosuppressive trough levels and UTIs after heart transplantation. A review of scientific literature (n= 100) was conducted based on the topic of interest by searching PUBMED.Gov (https://pubmed.ncbi.nlm.nih.gov/), Web of Science, and Scopus. The analysis of bacterial pulmonary infection required the occurrence of new or deteriorating pulmonary infiltrates and the development of organisms in cultures of sputum specimens. The diagnosis of UTIs was based on the result of related signs, pyuria, and a positive urine culture. The incidence of UTIs was reported as 0.07 episodes/1000 regarding heart transplantation days. An eightfold increase in the rate of rejection was noted in heart transplant recipients with higher variability in tacrolimus C0. There are associations between C0 of immunosuppressive drugs and clinical presentation of infection complications. Recipients with a low metabolism of immunosuppressive drugs are more susceptible to infectious complications. Attention to the biology of herpes viruses, Escherichia coli, Enterococcus spp., Pseudomonas aeruginosa, and Staphylococcus saprophyticus after heart transplantation are important, in which some of them are the most common pathogens responsible for UTIs. Pneumocystis and cytomegalovirus affect all transplant recipients. Pneumonia due to bacterial, viral, protozoa, and fungal infections, in addition to UTIs, are more specific reported types of infections in heart transplant recipients. Bacterial infections produced by extensively drug-resistant Enterobacteriaceae, vancomycin-resistant enterococci, and non-fermenting gramnegative bacteria were reported to increase after transplantation.

Genomic characterization of an uncommon Delftia acidovorans isolate obtained from aBulgarian immunocompetent outpatient diagnosed with bronchitis.

Delftia acidovorans is an aerobic, non-fermenting Gram-negative bacterium (NFGNB), found in soil, water and hospital environments. It is rarely clinically significant, most commonly affecting hospitalized or immunocompromised patients. The present study aimed to explore the genomic characteristics of a Bulgarian clinical D. acidovorans isolate (designated Dac759) in comparison to all strains of this species with available genomes in the NCBI Genome database (n = 34). Dac759 was obtained in 2021 from the sputum of a 65-year-old female immunocompetent outpatient with bronchitis. Species identification using MALDI-TOF mass spectrometry, antimicrobial susceptibility testing, whole-genome sequencing (WGS), and phylogenomic analysis were performed. The isolate demonstrated high-level resistance to colistin (16 mg L-1); resistance to gentamicin; reduced susceptibility to piperacillin, piperacillin-tazobactam, ceftazidime, cefepime, ciprofloxacin, and levofloxacin; and susceptibility to imipenem, meropenem, amikacin, and tobramycin. The observed genome size (6.43 Mb) and GC content (66.76%) were comparable with the accessible data from sequenced D. acidovorans genomes. A limited number of resistance determinants were identified in the assembled genome as follows: blaOXA-459, emrE, oqxB, and mexCD-oprJ. The phylogenomic analysis indicated a high heterogenicity of the included D. acidovorans genomes. In conclusion, to the best of our knowledge, this is the first documented case of a clinically relevant D. acidovorans isolate in Bulgaria. Unlike the majority of reports in the literature, Dac759 affected a patient with no malignancies or other preexisting comorbidities. With this in mind, its genome sequence is a valuable resource for the fundamental study of uncommon bacterial pathogens of public health importance.

Central venous catheter-related infection: does insertion site still matter? A French multicentric cohort study.

We aim to evaluate the association between central venous catheter (CVC) insertion site and microbiological CVC complications in a nationwide cohort. This study was conducted using the healthcare-associated infection surveillance cohort "REA-REZO" involving 193 intensive care units (ICUs). All CVC inserted and removed during the same ICU stay between January 1st 2018 and December 31st 2022 were eligible but only those whose tips were sent for microbiological analysis were included. Primary objective was to describe CVC insertion sites and subsequent catheter-related bloodstream infection (CRBSI). Out of 126,997 CVCs, 71,314 were not sent for tip culture, and only 55,663 CVCs were included, (30,548 in internal jugular [IJ], 14,423 in femoral and 10,692 in subclavian [SC] sites). The incidence of CRBSI was 0.7 [0.6-0.8] in the IJ site, 0.7 [0.6-0.9] in the femoral site, and 0.6 [0.4-0.7] CRBSI per 1000 CVC days in the SC site (p = 0.248). The multivariable Poisson regression model showed no differences of CRBSI incidence rates between the three insertion sites. Microorganisms observed in CRBSI were coagulase-negative Staphylococci (27.9%), Enterobacterales (27.5%), non-fermenting Gram-negative Bacilli (10.4%), Candida sp. (16.9%), and Staphylococcus aureus (16.9%). Low CRBSI incidence rates were reported. CRBSI incidences rates were similar in the three insertion sites. Uncertainty remains due to potential selection bias since many CVCs had to be excluded.

The role of non-fermenting gram-negative bacteria Stenotrophomonas maltophilia in the etiology of infectious diseases (review)

Gram-negative bacteria Stenotrophomonas maltophilia rank third among non-fermenting gram-negative bacteria in terms of detection frequency in various infectious pathologies. This review presents information on the various virulence factors, mechanisms used by S. maltophilia for colonization and infection of the human body, multiple drug resistance, clinical manifestations of the diseases caused, and methods of bacteriological diagnosis. The importance of early identification of this pathogen for practicing physicians is emphasized. The selection of treatment for infections caused by S. maltophilia is discussed, highlighting the challenges faced by both clinicians and microbiologists. To this end, current domestic and international scientific publications were reviewed using scientific electronic library search engines such as PubMed, Google Scholar, eLIBRARY.ru, and CyberLeninka.

A Five-Year Trend Analysis of Antibacterial Resistance Patterns Among Non-fermenting Gram-Negative Bacilli: A Retrospective Study From the ICU Settings of a Tertiary Care Hospital.

Non-fermenting gram-negative bacilli (NFGNB) infections have emerged as a serious health concern in ICUs. Multi-drug resistant (MDR) strains of NFGNB can evolve by acquiring resistance genes to at least one agent in three or more antibacterial categories. This study aimed to analyse the prevalence of NFGNB, the distribution of MDR strains, and antibiotic resistance trends of NFGNB in different ICUs of a tertiary care hospital over a period of five years. This retrospective study was conducted in a tertiary care teaching hospital in eastern India, including a total of 20,256 samples received from various ICUs over five years. Data retrieved from the Laboratory Information System (LIS) of the hospital, and repetitive isolates from the same patients, were excluded. All samples were processed according to standard microbiological protocols by automated systems. Data were entered into a Microsoft Excel spreadsheet (Microsoft® Corp., Redmond, WA, USA), analysed using Epi Info software, and presented using descriptive statistics. Chi-square and Fisher's exact tests (where appropriate) were used as tests of significance, with a p-value of <0.05 considered statistically significant. A total of 18,032 culture-positive samples out of 20,256 samples showed growth of 18,659 bacteria. Out of these, 952 isolates were NFGNB. The prevalence of NFGNB was found to be 5.10% among all isolated bacteria. The predominant sources were respiratory samples (37.3%). Acinetobacter spp. emerged as the most prevalent NFGNB (46.5%), followed by Pseudomonas spp. (31%) and Burkholderia spp. (14.3%). Among the NFGNB isolates, 61.76% exhibited MDR, with the highest prevalence of MDR strains seen in Elizabethkingia spp. (94.7%). Among the most prevalent NFGNB, Acinetobacter spp., 64.8% were MDR strains. Trend analysis of antibiotic resistance patterns of Acinetobacter spp. indicated a substantial increase for trimethoprim-sulfamethoxazole by 18.5%, minocycline (44.4%), amikacin (20.4%), and ceftazidime (7.4%), whereas there was a reduced trend in resistance to carbapenems (6.5%), ciprofloxacin (4.7%), and cefepime (3.7%) over five years. In Pseudomonas spp., resistance to meropenem increased by 17.4%, and for ceftazidime (11.8%), amikacin (10.6%), and piperacillin-tazobactam (7.9%), whereas resistance to aztreonam diminished by 13.9%. Burkholderia spp. exhibited a 23.5% escalation in resistance to meropenem and ceftazidime (5.9%), while resistance to levofloxacin experienced a decrease of 30.2%. The study showed the prevalence of various NFGNB as 5.10% in ICU settings, with Acinetobacter spp. (46.5%) being the most common isolated bacteria. Notably, 61.76% of the isolates were MDR. Antibiotic trend analysis over five years showed increasing resistance of Acinetobacter spp. to trimethoprim-sulfamethoxazole, minocycline, and ceftazidime, with improved susceptibility for carbapenems, ciprofloxacin, and cefepime. Pseudomonas spp. showed increased susceptibility to aztreonam and rising resistance for meropenem, piperacillin-tazobactam, ceftazidime, and amikacin. In Burkholderia spp., there was increased susceptibility to levofloxacin and rising resistance to meropenem and ceftazidime. These findings focus on the need for vigilant antibiotic stewardship, with the adoption of appropriate infection prevention and control practices to restrict the emergence and spread of MDR NFGNB infections in ICU settings of hospitals.

Drug Resistance in Biofilm and Planktonic Cells of Achromobacter spp., Burkholderia spp., and Stenotrophomonas maltophilia Clinical Isolates.

Background: Biofilm production in nonfermenting Gram-negative bacteria influences drug resistance. The aim of this work was to evaluate the effect of different antibiotics on biofilm eradication of clinical isolates of Achromobacter, Burkholderia, and Stenotrophomonas maltophilia. Methods: Clinical isolates were identified by matrix-assisted laser desorption ionization-time of flightmass spectrometry in a third-level hospital in Monterrey, Mexico. Crystal violet staining was used to determine biofilm production. Drug susceptibility testing was determined by broth microdilution in planktonic cells and biofilm cells. Results: Resistance in planktonic cells was moderate to trimethoprim-sulfamethoxazole, and low to chloramphenicol, minocycline, levofloxacin (S. maltophilia and Burkholderia), ceftazidime, and meropenem (Burkholderia and Achromobacter). Biofilm eradication required higher drug concentrations of ceftazidime, chloramphenicol, levofloxacin, and trimethoprim-sulfamethoxazole than planktonic cells (p < 0.05). Levofloxacin showed biofilm eradication activity in S. maltophilia, minocycline and meropenem in Burkholderia, and meropenem in Achromobacter. Conclusions: Drug resistance increased due to biofilm production for some antibiotics, particularly ceftazidime and trimethoprim-sulfamethoxazole for all three pathogens, chloramphenicol for S. maltophilia and Burkholderia, and levofloxacin for Burkholderia. Some antibiotics could be used for the treatment of biofilm-associated infections in our population, such as levofloxacin for S. maltophilia, minocycline and meropenem for Burkholderia, and meropenem for Achromobacter.

Identification, Antibiotic Profiling of Potential Pathogenic Bacteria from Fomites in Neonatal Intensive Care Units in a Tertiary Teaching Hospital of North Karnataka

This study was taken up to determine the prevalence of potential pathogens in most touched fomites in Neonatal Intensive Care Units (NICUs) and to determine their antibiogram. Fifty swabs each were collected from fomites from In-born (for babies born in our center) and out-born (for babies born elsewhere, brought to our center) NICUs, before and after cleaning. Samples were processed using standard Microbiological techniques. Antibiogram was determined by Kirby-Bauer disc diffusion method. From In-born NICU, before cleaning, 42 (84%) samples yielded growth with 48 bacterial isolates of which 31 (64.6%) were pathogens and after cleaning, 40 (80%) samples yielded growth with 41 bacterial isolates, of which 30 (73.1%) were pathogens. Most frequent isolates were non-fermenting gram-negative bacilli (NFGNB) and Klebsiella pneumoniae before and after cleaning, respectively. Prevalence of bacteria from In-born NICU before and after the cleaning was statistically significant (p = 0.025). From Out-born NICU, before cleaning, 42 (84%) samples yielded growth with 45 bacterial isolates, of which 25 (55.55%) were pathogens. Samples collected after cleaning; 42 (84%) samples yielded growth with 43 bacterial isolates of which 19 (44.18%) were pathogens. Most frequent isolates were NFGNB and Klebsiella pneumoniae from In-born NICU and K. pneumoniae and Escherichia coli from Out-born NICU before and after cleaning, respectively. Overall prevalence of pathogens was significant (p = 0.007). Staphylococcal isolates were resistant to Methicillin. NFGNB exhibited highest resistance (55.9%) towards Gentamicin. Significant decrease in the frequency of pathogens after cleaning indicates stringent practice of sterilization protocol would be essential in hospital environment.

The Profile of Bacterial Infections in a Burn Unit during and after the COVID-19 Pandemic Period.

Infections represent a major complication for burn-injured patients. The aim of this study was to highlight the changes in the incidence and antimicrobial resistance of bacterial strains isolated from burn patients, at the end of the COVID-19 pandemic, in relation to the antibiotics used during the pandemic. A comparative analysis of the demographic data and the microorganisms identified in the clinical samples of two groups of burn patients admitted to a university hospital in Romania was carried out. The first group consisted of 48 patients and the second of 69 patients, hospitalized in January-August 2020 and 2023, respectively. The bacterial species with the highest incidence were S. aureus, A. baumannii, Pseudomonas spp. The significant changes between 2023 and 2020 are reflected in the increase in the frequency of non-fermentative Gram-negative bacteria, especially S. maltophilia, and the increase in antimicrobial resistance of Pseudomonas and Klebsiella spp. Klebsiella spp. did not change in frequency (7%), but there was a significant increase in the incidence of K. pneumoniae strains with pan-drug resistant behaviour to antibiotics (40%), including colistin. The phenomenon can be explained by the selection of specimens carrying multiple resistance genes, as a result of antibiotic treatment during the COVID-19 period. The post-pandemic antimicrobial resistance detected in burn patients indicates the need for permanent surveillance of the resistance trends, primarily due to the limited therapeutic options available for these patients.

Evaluation of Direct Antimicrobial Susceptibility Testing of Gram-Negative Bacilli and Staphylococcus aureus from Positive Pediatric Blood Culture Bottles Using BD Phoenix M50.

Bloodstream infections (BSIs) are life-threatening infections for which a timely initiation of appropriate antimicrobial therapy is critical. Antibiotic susceptibility testing (AST) directly performed on positive blood culture broths can help initiate targeted antibiotic therapy sooner than the standard AST performed on colonies isolated on solid media after overnight incubation. Faster antimicrobial susceptibility testing (AST) results can improve clinical outcomes, and reduce broad-spectrum antimicrobial consumption and healthcare-associated costs in sepsis. In this study, we evaluated the accuracy of a direct AST inoculation method on the BD Phoenix M50 system using serum separator tubes to harvest bacteria from positive pediatric blood culture bottles. Direct AST was performed on 132 monomicrobial pediatric blood culture bottles that were positive for Enterobacterales (65; 49.2%), Staphylococcus aureus (46; 34.8%), and non-fermenting Gram-negative bacilli (21; 16%). Overall, the categorical and essential agreements between the direct method and standard method were 99.6% and 99.8%, respectively. Very major, major, and minor error rates were 0.1%, 0.09%, and 0.20% respectively. Direct AST performed on pediatric blood culture bottles using BD Phoenix M50 can quickly provide accurate susceptibility information to guide antimicrobial therapy in patients with BSI.

Epidemiological and Bacteriological Profile of Urinary Tract Infections Diagnosed at The Bacteriology Laboratory of the Centre Hospitalier Universitaire De Fann, Dakar from January 1er to December 31 2020

Introduction Urinary tract infections are extremely frequent and caused by bacteria whose treatment is based on the administration of antibiotics. The emergence and spread of acquired resistance mechanisms are limiting the indications for a number of antibiotics. It is in this context that this work is set, the main objective of which is to study the epidemiological and bacteriological profile of urinary tract infections at the CHNU de Fann, Dakar. Methodology: This is a retrospective study covering a one-year period from January 1er to December 31 2020. All patients received at the laboratory for an ECBU request were included. Data collection was based on information sheets and bench registers. The following information was collected : age, sex, germ isolated, antibiotic susceptibility profile. These data were processed using R. Studio software version 3.6.3, 2019. Results : We received 3697 requests for bacteriological examination of urine. The mean age of patients in our series was 48.7 years, with extremes of 15 days and 113 years. The 60 to 80 age group was the most affected. Women were more affected, with a rate of 51.03%, compared with 48.97% for men. A total of 3,697 urine samples were received during the study period, of which 776 were positive after analysis, representing a rate of 21%. 845 bacteria, with enterobacteria predominating (73.14%), followed by Gram-negative non-fermentative bacilli (13.37%) and Gram-positive cocci (13.27%). Escherichia coli was the most prevalent species, with a frequency of 36.09%, followed by Klebsiella pneumoniae (17.99%), Pseudomonas aeruginosa (8.16%), Staphylococcus aureus (6.63%), Enterobacter spp (6.50%), Citrobacter spp (4.02%), Acinetobacter spp (3.73%), Streptococcus spp (3.67%).Enterobacter spp (52.72%), Escherichia coli (47.53%) and Klebsiella pneumoniae (49.34%) showed a high prevalence of ESBL. Staphylococci showed a high rate of resistance to methicillin (55.71%).

Clinical and microbiological features of positive blood culture episodes caused by non-fermenting gram-negative bacilli other than Pseudomonas and Acinetobacter species (2020-2023).

Non-fermenting Gram-negative bacilli (NFGNB) other than Pseudomonas aeruginosa and Acinetobacter baumannii complex are pathogens of interest due to their ability to cause health-care associated infections and display complex drug resistance phenotypes. However, their clinical and microbiological landscape is still poorly characterized. Observational retrospective study including all hospitalized patients presenting with a positive positive blood culture (BC) episode caused by less common NFGNB over a four-year period (January 2020-December 2023). Clinical-microbiological features and factors associated with mortality were investigated. Sixty-six less common NFGNB isolates other than Pseudomonas and Acinetobacter species causing 63 positive BC episodes were recovered from 60 patients. Positive BC episodes were predominantly sustained by Stenotrophomonas maltophilia (49.2%) followed by Achromobacter species (15.9%) that exhibited the most complex resistance phenotype. Positive BC episodes had bloodstream infection criteria in 95.2% of cases (60 out 63), being intravascular device (30.2%) and respiratory tract (19.1%) the main sources of infection. Fourteen-day, 30-day, and in-hospital mortality rates were 6.4%, 9.5%, and 15.9%, respectively. The longer time from admission to the positive BC episode, older age, diabetes, admission due to sepsis, and higher Charlson Comorbidity Index were identified as the main predictors of in-hospital mortality. Positive BC episodes sustained by NFGNB other than Pseudomonas and Acinetobacter species were predominantly sustained by Stenotrophomonas maltophilia and Achromobacter species, having bloodstream infection criteria in the vast majority of cases. Factors that have emerged to be associated with mortality highlighted how these species may have more room in prolonged hospitalisation and at the end of life for patients with chronic organ diseases.

Analysis of the Class 1 Integrons, Carbapenemase Genes and Biofilm Formation Genes Occurrence in Acinetobacter baumannii Clinical Isolates.

Acinetobacter baumannii is a non-fermentative Gram-negative bacterium that can cause nosocomial infections in critically ill patients. Carbapenem-resistant A. baumannii (CRAB) has spread rapidly in clinical settings and has become a key concern. The main objective of this study was to identify the distribution of integrons and biofilm-formation-related virulence genes in CRAB isolates. A total of 269 A. baumannii isolates (219 isolates of CRAB and 50 isolates of carbapenem-sensitive A. baumannii (CSAB)) were collected. Carbapenemase genes (bla KPC, bla VIM, bla IMP, bla NDM, and bla OXA-23-like) and biofilm-formation-related virulence genes (abal, bfms, bap, and cusE) were screened with PCR. Class 1 integron was screened with PCR, and common promoters and gene cassette arrays were determined with restriction pattern analysis combined with primer walking sequencing. Whole-genome sequencing was conducted, and data were analyzed for a bla OXA-23-like-negative isolate. All 219 CRAB isolates were negative for bla KPC, bla VIM, bla IMP, and bla NDM, while bla OXA-23-like was detected in 218 isolates. The detection rates for abal, bfms, bap, and cusE in 219 CRAB were 93.15%, 63.93%, 88.13%, and 77.63%, respectively. Class 1 integron was detected in 75 CRAB (34.25%) and in 3 CSAB. The single gene cassette array aacA4-catB8-aadA1 with relatively strong PcH2 promoter was detected in class 1 integrons. The bla OXA-23-like-negative CRAB isolate was revealed to be a new sequence type (Oxford 3272, Pasteur 2520) carrying bla OXA-72, bla OXA-259, and bla ADC-26. In conclusion, bla OXA-23-like was the main reason for CRAB's resistance to carbapenems. A new (Oxford 3272, Pasteur 2520) CRAB sequence type carrying the bla OXA-72, bla OXA-259, and bla ADC-26 was reported.

Evaluation of CHROMagar™ B. cepacia agar for the detection of Burkholderia cepacia complex species from sputum samples of patients with cystic fibrosis

IntroductionBurkholderia cepacia complex (BCC) are non-fermenting Gram-negative bacteria that can chronically colonize the lungs of people with cystic fibrosis (pwCF), causing a severe and progressive respiratory failure, post-transplant complications and epidemic outbreaks. Therefore, rapid and accurate identification of these bacteria is relevant for pwCF, in order to facilitate early eradication and prevent chronic colonization. However, BCCs are often quite difficult to detect on culture media as they have a slow growth rate and can be hidden by other fast-growing microorganisms, including Pseudomonas aeruginosa and filamentous fungi.Material and methodsWe evaluated the sensitivity of CHROMagar™ B. cepacia agar using 11 isolates from a well-characterized BCC collection, using BCA agar (Oxoid, UK) as a gold standard. We also studied 180 clinical sputum samples to calculate positive (PPV) and negative (NPV) predictive values. Furthermore, we used three of the well-characterized BCC isolates to determine the limit of detection (LOD).ResultsEleven isolates grew on CHROMagar™ B. cepacia at 37ºC after 48 h. The NPV and PPV of CHROMagar™ B. cepacia were 100% and 87.5%, respectively. The LOD of CHROMagar™ B. cepacia was around 1 × 103 CFU/ml, requiring a ten-fold dilution lower bacterial load than BCA for BCC detection.ConclusionCHROMagar™ B. cepacia agar proved to have a very good sensitivity and specificity for the detection of clinical BCCs. Moreover, the chromogenic nature of the medium allowed us to clearly differentiate BCC from other Gram-negative species, filamentous fungi and yeasts, thereby facilitating the identification of contaminants.

&lt;i&gt;Stenotrophomonas maltophilia&lt;/i&gt; as a causative agent of implant-associated infection in trauma and orthopedic patients

Objective. To evaluate an etiologic significance of S. maltophilia in the development of orthopedic implant-associated infections. Materials and methods. The study involved a retrospective analysis of the frequency of excretion of S. maltophilia in patients with periprosthetic infection and osteomyelitis, using the Microbe-2 program in period of 2005–2020. Clinical isolates were excreted according to standard methods. Identification was performed via Microlatest panels using iEMS Reader MF. Antibiotic susceptibility was studied in accordance with EUCAST. Results. Over 16 years 69 strains of S. maltophilia have been identified, comprising 0.33% of all isolated pathogens (n=20631). 50% of isolates were excreted from tissue biopsies, 30% – from wound exudates. In 89% of cases, S. maltophilia was isolated in microbial associations, including 65% of cases together with Grampositive bacteria, 18% with other non-fermenting Gram-negative bacteria, and 6% with other pathogens. 63% appeared sensitive to trimethoprim/sulfamethoxazole and 25.5% of isolates were resistant. The proportion of cultures sensitive to this drug was found to increase from 63% in 2011–2014 to 81% in 2015–2019 (p = 0.08). Conclusion. S. maltophilia should be considered as a causative etiologic agent of severe chronic orthopedic infections.

Controlling the hospital aquatic reservoir of multidrug-resistant organisms: a cross-sectional study followed by a nested randomized trial of sink decontamination

ObjectivesThe hospital water environment is an important reservoir of multidrug-resistant organisms (MDROs) and presents a risk for patient safety. We assessed the effectiveness of thermal and chemical interventions on sinks contaminated with MDRO in the hospital setting. MethodsWe conducted a cross-sectional assessment of MDRO contamination of sinks and toilets in 26 clinical wards of a tertiary care hospital. MDRO-contaminated sink traps were then replaced and randomized (1:1:1) to receive chemical (sodium hypochlorite), thermal disinfection (steam), or no intervention. Interventions were repeated weekly for 4 weeks. Sinks were resampled 7 days after the last intervention. The primary outcome was the proportion of decontaminated sinks. MDROs of interest were extended spectrum beta-lactamase (ESBL) producing and carbapenemase-producing Enterobacterales, and non-fermentative Gram-negative bacilli. ResultsIn the cross-sectional assessment, at least one MDRO was identified in 258 (36%) of the 748 samples and in 91 (47%) of the 192 water sources. In total, 57 (42%) of the 137 sinks and 34 (62%) of the 55 toilets were contaminated with 137 different MDROs. The most common MDRO were ESBL Enterobacterales (69%, 95/137), followed by Verona Integron-Borne Metallo-β-Lactamase (VIM) carbapenemase producing Pseudomonas aeruginosa (9%, 12/137) and Citrobacter spp. (6%, 5/137). In the nested randomized trial, five of the 16 sinks (31%) in the chemical disinfection group were decontaminated, compared with 8 of 18 (44%) in the control group (OR 0.58; 95% CI, 0.14–2.32) and 9 of 17 (53%) in the thermal disinfection group (OR 1.40; 95% CI, 0.37–5.32). DiscussionOur study failed to demonstrate an added benefit of repeated chemical or thermal disinfection, beyond changing sink traps, in the MDRO decontamination of sinks. Routine chlorine-based disinfection of sinks may need to be reconsidered.

Cefiderocol in Difficult-to-Treat Nf-GNB in ICU Settings

BackgroundThe efficacy and safety of cefiderocol in ICU patients with difficult-to-treat resistance (DTR) non-fermenting Gram-negative bacteria (Nf-GNB) are not as well-established. Consequently, we conducted a cohort study to compare Cefiderocol with the Best Available Therapy (BAT) in ICU patients.MethodsWe included adult patients from 9 different ICUs, including a burn ICU unit, from 2019 to 2023 treated with Cefiderocol for DTR Nf-GNB isolated from the blood or lungs. We matched each patient at a 1:2 ratio based on the same DTR Nf-GBN isolated pathogen, and when possible, within the same type of ICU (burn unit or not). The primary endpoint of the study was the clinical cure at 15 days, with secondary endpoints including clinical cure at 30 days, relapse, and in-ICU mortality. For each outcome, adjusted odds ratios were estimated using bidirectional stepwise regression in a final model, which included 13 preselected confounders.ResultsWe included 27 patients with cefiderocol, matched with 54 patients receiving the BAT. Four patients were not exactly matched on the type of ICU unit. Characteristics were comparable between groups, mostly male with a Charlson Comorbidity Index of 3 [1–5], and 28% had immunosuppression. Cefiderocol patients were most likely to have higher number of antibiotic lines. The main DTR Nf-GNB identified was Pseudomonas aeruginosa (81.5%), followed by Acinetobater baumanii (14.8%) and Stenotrophomonas maltophilia (3.7%). Pneumonia was the identified infection in 21 (78.8%) patients in the Cefiderocol group and in 51 (94.4%) patients in the BAT group (p = 0.054). Clinical cure at 15 and 30-day and the in-ICU mortality was comparable between groups, however relapse was higher in the cefiderocol group (8-29.6% vs. 4-7.4%;aOR 10.06[1.96;51.53])ConclusionCefiderocol did not show an improvement in clinical cure or mortality rates compared to BAT in the treatment of DTR Nf-GNB, but it was associated with a higher relapse rate.

Antimicrobial combination effects against multidrug-resistant Acinetobacter baumannii and Pseudomonas aeruginosa strains: A cross-sectional study.

Emergence of multidrug resistance in non-fermenting Gram-negative bacilli is a threat to public health. Combination therapy is a strategy for the treatment of antibiotic-resistant infections. In this cross-sectional study, a total of 63 nonduplicate clinical isolates of Acinetobacter baumannii and Pseudomonas aeruginosawere collected from various specimens. Identification of bacterial isolates was performed by phenotypic and molecular tests. Antibiotic susceptibility patterns and detection of β-lactamase genes were determined using the broth microdilution and polymerase chain reaction (PCR) techniques, respectively. Then, the combined effects analysis was determined by the checkerboard method. Based on the status of resistance to carbapenems (imipenem and meropenem), 25 isolates of each genus were selected for further investigation. For A. baumannii, bla OXA-23, bla OXA-58, and bla OXA-48 genes were positive in 21 (84%), 17 (68%), and 11 (44%) of isolates, respectively. In P. aeruginosa isolates, bla VIM was the most common gene (44%) and other genes including bla IMP, bla NDM, and bla OXA-23 were found in nine (36%), six (24%), and three (12%) isolates, respectively. Meropenem (MER)-tigecycline (TIG) had a significant synergistic effect against 20 (80%) A. baumannii (pvalue < 0.001). This combination was also efficient against 5 (20%) P. aeruginosa isolates. Moreover, the other combination, tigecycline-amikacin (TIG-AMK) was effective against 10 (40%) A. baumannii isolates. The combination of colistin (COL) and MER showed a significant synergistic effect against 21 (84%) A. baumannii (pvalue < 0.001) and 17 (68%) P. aeruginosa isolates (pvalue < 0.001). The MER-TIG and COL-MER combinations are promising options against resistant bacteria. Our study could be helpful for the development of a new treatment recommendation.