Non-fermenting Bacteria Research Articles

Antimicrobial activities of sitafloxacin and comparators against the clinical isolates of less common nonfermenting Gram-negative bacteria

ObjectivesTo evaluate in vitro activities of sitafloxacin and comparators against the clinical isolates of less common nonfermenting Gram-negative bacteria (NFGNB). MethodsThe isolates of less common NFGNB were collected during a long period spanning five years from 2016 to 2020 in Huashan Hospital, Fudan University in Shanghai. A broth microdilution method was used to determine the minimum inhibitory concentrations (MICs) of sitafloxacin and comparators. ResultsIn terms of MIC50/90 values, sitafloxacin was highly active against Stenotrophomonas maltophilia (0.25/1 mg/L), Burkholderia cepacia complex (0.25/2 mg/L), Achromobacter xylosoxidans (0.25/1 mg/L), and Chryseobacterium gleum (1/2 mg/L), but less active for Elizabethkingia (1/8 mg/L) and Chryseobacterium indologenes (16/32 mg/L). Sitafloxacin was more active than other fluoroquinolones against these NFGNB except Chryseobacterium. ConclusionThe results are helpful for clinicians to be aware of the role of sitafloxacin in managing the infections caused by these NFGNB.

The Threat of Carbapenem-Resistant Gram-Negative Bacteria in Patients with Hematological Malignancies: Unignorable Respiratory Non-Fermentative Bacteria-Derived Bloodstream Infections.

BackgroundCarbapenem-resistant Gram-negative bacteria (CRGNB) bloodstream infection (BSI) pose a significant threat to the prognosis of hematologic malignancies (HM) patients. Understanding the distribution of pathogenic bacteria, changes in carbapenem-resistant trends, risk factors for CRGNB infections, and exploring the early detection measures can help reduce mortality.MethodsWe conducted a multicenter retrospective study of Gram-negative bacteria (GNB) BSI in patients with HM in three university-affiliated hospitals in Hunan Province, China, from January 2010 to December 2020. Demographic and clinical data were collected from the hospital electronic medical records system.ResultsCRGNB caused 138 (15.3%) of 902 GNB BSI. The detection rate of CRGNB increased from 6.4% in 2010–2012 to 35.4% in 2019–2020. The 7-day mortality rate was significantly higher in patients with CRGNB BSI than in patients with carbapenem-susceptible Gram-negative bacteria (CSGNB) BSI [31.9% (44/138) vs 9.7% (74/764), P < 0.001], and the mortality rate in patients with carbapenem-resistant non-fermenting bacteria (CRNFB) bloodstream infections was generally higher than that of carbapenem-resistant Enterobacteriaceae (CRE). Urinary catheter (OR, 2.814; CI=1.395–5.680; P=0.004) and prior exposure to carbapenem (OR, 4.372; CI=2.881–6.635; P<0.001) were independent risk factors for CRGNB BSI. Analysis of co-infections showed that 50%–85% of patients with CRGNB BSI had pulmonary infections, sputum culture results suggested that sputum culture positivity rate was as high as 57.1%–66.7% in patients with carbapenem-resistant Acinetobacter baumannii (CRAB) and Stenotrophomonas maltophilia BSI, and the results of antimicrobial susceptibility testing of sputum cultures were consistent with the blood cultures.ConclusionCarbapenem resistance has dramatically increased in HM patients with GNB BSI in recent years and is associated with a worse outcome, especially for non-fermenting bacteria. In high-risk patients, early screening of the respiratory tract specimens may help to detect CRNFB colonization and protect patients from breakthrough BSI.

Multicenter surveillance of antimicrobial susceptibilities and resistance mechanisms among Enterobacterales species and non-fermenting Gram-negative bacteria from different infection sources in Taiwan from 2016 to 2018

To explore the invitro antimicrobial susceptibility among clinically important Gram-negative bacteria (GNB) in Taiwan. From 2016 through 2018, a total of 5458 GNB isolates, including Escherichia coli (n=1545), Klebsiella pneumoniae (n=1255), Enterobacter species (n=259), Pseudomonas aeruginosa (n=1127), Acinetobacter baumannii complex (n=368), and Stenotrophomonas maltophilia (n=179), were collected. The susceptibility results were summarized by the breakpoints of minimum inhibitory concentration (MIC) of CLSI 2020, EUCAST 2020 (for colistin), or published articles (for ceftolozane/tazobactam). The resistance genes among multidrug-resistant (MDR) or extensively drug-resistant (XDR)-GNB were investigated by multiplex PCR. Significantly higher rates of non-susceptibility (NS) to ertapenem and carbapenemase production, predominantly KPC and OXA-48-like beta-lactamase, were observed in Enterobacterales isolates causing respiratory tract infection than those causing complicated urinary tract or intra-abdominal infection (12.7%/3.44% vs. 5.7%/0.76% or 7.7%/0.97%, respectively). Isolates of Enterobacter species showed higher rates of phenotypic extended-spectrum β-lactamase and NS to ertapenem than E. coli or K. pneumoniae isolates. Although moderate activity (54-83%) was observed against most potential AmpC-producing Enterobacterales isolates, ceftolozane/tazobactam exhibited poor invitro (44.7-47.4%) activity against phenotypic AmpC Enterobacter cloacae isolates. Additionally, 251 (22.3%) P. aeruginosa isolates exhibited the carbapenem-NS phenotype, and their MDR and XDR rate was 63.3% and 33.5%, respectively. Fifteen (75%) of twenty Burkholderia cenocepacia complex isolates were inhibited by ceftolozane/tazobactam at MICs of ≤4μg/mL. With the increase in antibiotic resistance in Taiwan, it is imperative to periodically monitor the susceptibility profiles of clinically important GNB.

MICROBIOLOGICAL ISOLATES AND IT’S RESISTOTYPE FROM CLINIC OF VASCULAR SURGERY FOR THE FIRST QUATER OF 2022

One of the most common complications of surgical exposures is the surgical site infection (SSI). Although it varies between different surgical profiles, it can reach up to one third of all complications. In vascular surgery patients ischemic ulcers are very common, as well as factors, compromising the immune system such as diabetes, chronic kidney disease etc. One of the main surgical exposures in vascular surgery is inguinal, providing access to the femoral artery and its bifurcation. Although it allows a wide range of reconstructions, implanting different types of prosthetic materials, stents and providing anastomosis site, it contains lymph nodes, which can contaminate the reconstruction and cause SSI with severe consequences. Patients, prone to SSI due to concomitant diseases, are threatened by sepsis, limb loss and even death, which makes prevention of those type of complications essential. Aim: To investigate etiological spectrum of microbiological isolates and their resistance against most common antimicrobials among vascular surgery patients. Materials and methods: The study is retrospective, conducted in the period 01 January 2022 – 31 March 2022. All of the samples were obtained from patients of Clinic of Vascular Surgery. After isolation of pure culture from the samples, the strains were identified by MALDI TOF MS and Vitec – 2 Compact. Antibiotic resistance was determined with Bauer-Kirby disk diffusion method. Results: From all 419 of the patients, hospitalized in the Clinic of Vascular surgery for this period, 28 isolates from 26 (6,21%) patients were obtained, of which Gram-negative were 19 (67,86%) and Gram-positive - 9 (32,14%). From Gram-negative - enterobacteria – 14 (73,68%), and non-fermenting gram-negative bacteria (NFGNB) were 5 (26,32%). Only 3 (21,43%) from all enterobacteria were extended spectrum beta-lactamases producing strains (ESBLs). No strains, resistant to carbapenems (RCP) were isolated. Five (55,55%) of the Gram-positive isolates were Staphylococcus aureus, 4 (80%) of which were methicillin resistant Staphylococcus aureus (MRSA). Two of the Gram-positive species isolated were Enterococcus faecalis, of which 1 with a high-level aminoglycoside resistance (HLAR). No Vancomycin resistant enterococci (VRE) were discovered. There were no colistin-resistant Acinetobacter baumannii and Pseudomonas aeruginosa strains. Conclusion: From all 28 isolates 8 (28,57%) were with acquired types of antimicrobial resistance. With almost one third of the isolates that are problematic in terms of antibiotic susceptibility, treatment of those patients can be challenging. Prevention of in hospital contamination with polyresistant strains, associated with medical care it is crucial for reducing the number of severe complications, decreasing of hospital stay and cost for treatment.

Piperacillin/tazobactam in modern clinical practice

Piperacillin/tazobactam represents a combination of the ureidopenicillin and the lactamase inhibitor. The antibiotic is the drug of choice for the treatment of severe infections, primarily in surgical and intensive care units. The area of clinical use of piperacillin/tazobactam includes intra-abdominal infections, skin and soft tissues infections, late nosocomial pneumonias, including ones in the context of the covid -19 pandemic, and infections of other localizations. The effectiveness of the intervention increases with intravenous administration of the drug by the method of prolonged infusions. A high susceptibility of most causative pathogens of wound infection to piperacillin/ tazobactam has been established in Ukraine (with the exception of Klebsiella spp. and non-fermenting bacteria). The drug can be used in patients with a history of allergic reactions to lactams; preliminary allergological testing is indicated only in cases of allergy to aminopenicillins and aminocephalosporins. The first domestic piperacillin/tazobactam under the name Refex is registered on the Ukrainian market.

Prevalence and temporal trends of critical infections due to multidrug-resistant bacteria (ESKAPE) in nine tertiary hospitals of Rio de Janeiro in the COVID-19 era

Introduction: Antimicrobial resistance is a serious threat to public health worldwide. This fact becomes more relevant in the COVID-19 era considering the inappropriate use of antimicrobials. An important representative of multidrug-resistant (MDR) bacteria is the ESKAPE group. The prevalence of these pathogens in Rio de Janeiro in COVID-19 patients is still unknown. The aim of the current study was to determine the prevalence and temporal trends of critical infections due to ESKAPE microorganisms in nine tertiary hospitals of Rio de Janeiro in the COVID-19 pandemic. Methods: Prospective study performed in nine tertiary private hospitals of Rio de Janeiro between March 2020 and October 2021. Electronic medical records were retrieved from the computerized database of the hospitals clinical microbiology laboratories. Bacterial identification/antibiotic susceptibility testing were performed by automated methodologies and statistical analyses were performed for comparative purposes. Results: In total, 1812 cultures from 1653 patients were evaluated. The data revealed that among the ESKAPE microorganisms, the highest prevalence was for Klebsiella pneumoniae and Acinetobacter baumannii. In the analysis of the temporal trends of the distribution of the MDR bacteria, we observed that the COVID-19 patients had a stable distribution during the study period, while the prevalence for these pathogens increased in the non-COVID-19 patients Conclusion: We confirmed an increase in the prevalence of MDR bacteria (including ESKAPE group) in COVID-19 patients, specifically of non-fermenting Gram-negative bacteria. We also observed that the indiscriminate use of antibiotics in COVID-19 patients had a cumulative impact on infections of non-COVID-19 patients.

Antibacterial Activity of Lactobacillus plantarum Supernatant on Non-Fermenting Gram-Negative Bacteria.

We studied the effect of the L. plantarum strain supernatant on the growth of culture and biofilm of non-fermenting bacteria of the genera Pseudomonas, Achromobacter, and Burkholderia. To obtain a supernatant, the culture of L. plantarum was grown for 48 h at 37°C on a Lactic broth nutrient medium with casein peptone, then centrifuged and filtered through a 0.22-μm Millipore filter. Antimicrobial activity was determined by broth microdilution assay. The inhibitory effect of the supernatant on the growth of bacteria of all three genera was demonstrated. The maximum inhibition was observed for P. aeruginosa (by 13 times compared to the control). For bacteria of the Achromobacter and Burkholderia genera, the inhibition was less pronounced: by 7 and 6 times, respectively. The supernatant also inhibited biofilm formation by P. aeruginosa and A. ruhlandii, but did not affect formed biofilm. Thus, the L. plantarum supernatant obtained by us exhibited pronounced antimicrobial activity against non-fermenting bacteria, the causative agents of nosocomial infections, especially in immunocompromised individuals, very often in cystic fibrosis patients.

Biochemical and Molecular Characterization of Klebsiella species isolated from neoplastic patients under Irradiation therapy

Neoplastic radiation therapy was able to alter the microbial flora of patients' bodies, as well as the microbial flora of radiation-exposed workers, and provided control for possible infectious consequences. Klebsiella aerogenes was a non-fermentative aerobic gram negative bacteria that was widely distributed in nature, requiring species identification in up to 25% of cases in the lab. Antibiotic susceptibility of Klebsiella species multi-resistant isolates is common, and all isolates were characterized in all cases of clinically significant infections caused by these organisms. Only 15 isolates showed significant antimicrobial activities against at least one of the tested indicator bacteria. Vancomycin is an anti-Klebsiella species antibiotic to which resistance is rarely seen, their use should be reserved for the treatment of species infections resistant to all other antibiotics, the emergence of widespread antibiotic-resistant bacteria enhanced the need for new sources of antimicrobial agents, and isolate SHM4-1 was active against all of them, with IC60 values of 3.3 and 1.1 g/ml against HCT-116 and HepG-2 cell lines, respectively. It was genotypically identified as a species with the PKS 4 biosynthetic gene cluster present. To enhance the production, mannitol, ammonium sulphate, pH 7, 2% inoculum size, and 2 days at 37°C were utilized.

INFLUENCE OF RESPIRATORY SYSTEM PROTECTION ON THE TREATMENT OF PATIENTS WITH CRANIOCEREBRAL TRAUMA

Introduction. Craniocerebral trauma (CCT) results in disorders of pharyngeal reflex, deglutition, breathing rhythm and frequency. All the mentioned conditions cause the development of respiratory complications. Whereas they become independent factors of negative therapeutic consequences in such category of patients.&#x0D; Aim of a paper. The research aims at evaluating protection/treatment possibilities of the respiratory system concerning the course of craniocerebral trauma in injured patients.&#x0D; Materials and methods. We examined 237 patients with CCT who underwent urgent surgical interventions in the form of a decompressive cranial trepanation and the removal of both subdural and epidural hematomata. All patients required prolonged mechanical ventilation of the lungs. The patients were retrospectively divided into two groups, namely: the first group (132 patients) – the patients with tracheostomy on the 5th-6th days of admission to the clinics of anesthesiology and intensive care; the second group (105 patients) – the patients with tracheostomy on the 1st-2nd days of hospitalization. Patients of both groups were not differentiated by gender, the severity of CCT and general condition. In addition to general clinical and biochemical blood markers, culturing of the secretion in the tracheostomy tube (at the moment of tracheostomy and further every 3-4 days), blood and urine were performed in all patients. Simultaneously we controlled the leucocyte count in the peripheral blood, number of immature forms, levels of CRP and procalcitonin. The evaluation of a neurological status of patients was carried out by the Glasgow and Richmond Agitation-Sedation Scale (RASS). The severity of CCT was visualized with the help of CT.&#x0D; Research results. Even at the moment of tracheostomy the frequency of colonization of tracheobronchial tree was significantly higher in the first group of patients compared to the second one. Such tendency was monitored in further stages as well. The phenomena of tracheobronchitis and pneumonia were detected more frequently in the group of patients with tracheostomy on the 5th-6th days of postoperative period in contrast to the patients with tracheostomy on the 1st-2nd days of postoperative period. Microorganisms of Enterobacteriaceae with the extended spectrum of ß-lactamase and non-fermenting Gram-negative bacteria were detected more frequently in the first group.&#x0D; Conclusion. Early tracheostomy in patients with CCT results in both the decrease in the frequency of positive culturing of secretions from the tracheobronchial tree and the reduction in a detection frequency of nosocomial pneumonia.

Cattle manure application triggers short-term dominance of Acinetobacter in soil microbial communities

Manure application improves soil productivity but also spreads microorganisms, some of which can be of clinical relevance. The ability of manure to spread common human pathogens has been widely studied but we lack understanding on whether it also disseminates opportunistic pathogens like Acinetobacter and other non-fermenting Gram-negative bacteria (NFGNB). We designed a microcosm experiment simulating the application of fresh manure to soil to analyse the effects on soil microbial communities (and vice versa), focusing on Acinetobacter and other NFGNB. We conducted two independent experiments with fresh cattle manure from a dairy farm and two pasture soils from different organic farms. We sampled the microcosms on days 2, 7, 14, 28 and 84, and characterized the microbial communities through sequencing of 16S rRNA amplicons from i) total communities and ii) those cultured on CHROMagar Acinetobacter (i.e., selective for NFGNB) after 24-h growth. Manure altered the community composition of soil microorganisms whereas the reverse effects were weaker, showing a transition to an environmentally structured community. Acinetobacter species increased their relative abundance in manure and soil under manure on day 2, especially in soils previously exposed to γ-irradiation to reduce the load of native microorganisms. Although manure spread most Acinetobacter phylotypes in the soil, it also stimulated a few from the soil that became occasionally abundant in manure. This study demonstrates that Acinetobacter species may dominate in soil and manure for a short time after deposition, and highlights their high responsiveness and competitiveness to changes likely associated with an increase in labile resources.

Antibiotic susceptibility patterns of gram-negative bacteria in the pediatric hematology-oncology ward of RSUD Dr. Soetomo, Surabaya

Infection is one of the causes of death in children with malignancy. Gram-negative bacteria with broad resistance to antibiotics are the cause of invasive infections in patients with malignancy. This prospective observational study was conducted by collecting medical record data, including the identity of patients, their diagnosis results, and the antibiotic susceptibility test results, from January to December 2020 in the pediatric hematology-oncology ward of Dr. Soetomo Regional General Hospital (hereinafter referred to as RSUD Dr. Soetomo), Surabaya. Positive cultures were obtained in 20.9% of the 196 samples. The growth of gram-negative bacteria was found in 48.8% of the positive culture test results, with a percentage of 50% in blood cultures, 30% in pus cultures, and 15% in urine cultures. The most common gram-negative bacteria isolates obtained in general were E. coli (40%) and K. pneumoniae (30%). The most commonly found non-fermenting gram-negative bacteria was P. aeruginosa (15%). The lowest antibiotic susceptibility was obtained to ampicillin (0%) and ampicillin-sulbactam 10%. The lowest antibiotic susceptibility was obtained to amikacin (85%) and cefepime (80%). The MDR resistance pattern was found in 80% of samples, 40% of which was found in ESBL-producing bacteria.

Identification of Salmonella sp. bacteria, antibiotic tetrasicline in cultivated silkworms using chicken manure media

ABSTRACT[Identification of Salmonella Sp. Bacteria, Antibiotic Tetrasicline in Cultivated Silkworms using Chicken Manure Media]Sustainability of farming activities is determined by the use of materials that are free from pathogens, residues of antibiotics and other chemicals. Prevention of pathogenic microorganisms can be done through the use of disease-free seed with a certificate Specific Pathogen Free guided by way of Good Aquaculture (CBIB). This study uses a completely randomized design (CRD) with 2 treatment (fermentation methods and non-fermented) and three replications. The identification results on the silkworms with fermentation methods and non-fermenting bacteria positive for Salmonella sp positive and tetracycline antibiotic residues (&gt; 32 ppb) in the silkworm cultivation. Productivity silkworms in the fermentation medium are higher than in non-fermented in the amount of 267.91 ± 113.18 g / m2 / cycle and for non-fermented 201.89 ± 16,85g / m2 / cycle. Absolute growth fermentation medium peak at 30.92 ± 2.9 g / m2 and non-fermented 9.12 ± 1.99 g / m2. KEYWORDS: Antibiotics, silkworms, chicken manure, Salmonella sp.

Microflora in patients with community-acquired pneumonia and hospital environment in Blagoveshchensk during pandemic

PurposeAn increase of community-acquired pneumonia (CAP) incidence has been detected during COVID-19 pandemic. Aim: to conduct analysis of bacterial microflora isolated from patients suffering from CAP and hospital environment in hospitals.Methods & MaterialsBacteriological survey of sputum obtained from 210 hospitalized patients with CAP was conducted from December 2020 - March 2021 in the Blagoveshchensk city. A simultaneous sanitary-bacteriological control of hospital environment was performed (210 environment samples and 24 air samples). The research was conducted during 12 weeks (6 cycles, one cycle lasted two weeks). Bacteriological assessment was performed via classical method. Identification of isolated pathogens and evaluation of drug-resistant strains were performed with bacteriological analyzer “Multiscan”.ResultsExamination of sputum that was obtained from 151 patients with CAP revealed 43 isolates and 8 bacterial species in 32 patients (21.2%). Candida spp. fungi (51.16±7.62%) and Gramm-positive microflora without drug-resistant strains (39.53±7.46%) were prevailing in the structure of detected isolates Gramm-negative enterobacteria were presented by one species of Klebsiella pneumoniae with multiple drug-resistance – ESBL (4.65±3.21%) and non-fermenting Gramm-negative bacteria – one species of Pseudomonas aeruginosa (2.33±2.30%). Evaluation of 210 environmental samples showed bacterial microflora in 49 samples (23.3% cases) that was comparable to frequency detection of bacterial pathogens from patients (21.2%). Microflora identified from environment was presented by 12 pathogenic species including Gramm-positive microflora (S. aureus, S. epidermidis, S. hominis, E.faecalis, E. Faecium) – 55.0%, Gramm-negative enterobacteria (K. pneumoniae, E. coli, E.agglomerans, E. cloacae, C. freundii) – 38.8%, non-fermenting Gramm-negative bacteria (A. baumannii, A. lwoffii) – 6.1%. Should be noted that during first three cycles bacterial contamination was detected in 19 out of 90 samples (21.1%) including 3 cases with multiple drug-resistance (3.3%). During following three cycles, bacterial contamination was revealed in 25.0% of samples (30 out of 120 samples) including 13 samples that had multiple drug-resistant bacteria (10.8%). Evaluation of 24 air samples showed no evidence of microbial contamination.ConclusionDynamic surveillance revealed wide circulation of bacterial pathogens in the hospital as well as build up of epidemiologically significant pathogen strains in hospital environment during observation period. These findings indicate considerable risk of nosocomial infections formation among patients.

Etiology of community-acquired and hospital-acquired pneumonia associated with COVID-19

PurposeThe COVID-19 pandemic is accompanied by a high incidence of community-acquired pneumonia (CAP). Patients with a new coronavirus infection have an increased risk of developing hospital-acquired pneumonia. Aim: to study the etiological structure of CAP during the epidemic spread of COVID-19, to assess the risks of joining the pathogens of pneumonia associated with the provision of medical care.Methods & MaterialsBiological material from 1085 hospitalized patients with CAP was conducted from August 2020 - June 2021 in Rostov-on-Don (Russia). Verification of respiratory viruses including SARS-CoV-2 RNA was performed by polymerase chain reaction in nasopharyngeal smears. Bacteriological analysis of sputum was performed via classical methods, identification of isolated pathogens was carried out using time-of-flight mass spectrometry on an Autoflex (Bruker Daltonics) with BioTyper 3.0 software.ResultsCases of type 3 parainfluenza virus (7.8±0.9%), other types of coronaviruses (HKU-1, OC43, HL-63 and 229Е) (2.7±0.5%), respiratory syncytial virus (1.9±0.5%) were detected in patients with COVID-19. Fungi of the genus Candida (35.6±1.8%) and Staphylococcus aureus (9.1±1.1%) were prevailing in the microbiota structure. Should be noted that the number of Streptococcus pneumoniae cultures decreased from 5.5 % in August 2020 to 1.1 % in June 2021, possibly due to pneumococcal vaccination. Gramm-negative enterobacteria were presented predominantly by Klebsiella pneumoniae (3.5±0.7%), Escherichia coli (2.9±0.6%), and non-fermenting Gramm-negative bacteria – Pseudomonas aeruginosa (1.5±0.5%) and Acinetobacter baumannii (1.2±0.4%). In 30.6% of patients treated in the hospital there was a secondary infection probably associated with compromised immune system and the transmission of infection from the hospital environment. Secondary infection with Candida spp., non-fermenting Gramm-negative bacteria (A. baumannii, and P. aeruginosa) and K. pneumoniae, including those characterized by multiple drug-resistance, prevailed. The most frequently registered resistance to penicillins, cephalosporins of 3rd generation.ConclusionA feature of CAP in patients with laboratory-confirmed COVID-19 is a higher incidence of mixed infection of both viral and bacterial etiology. Patients with COVID-19 represent a high risk group for the development of mycotic lung lesions, possibly against the background of treatment with antibacterial drugs. There is a significant risk of the formation of nosocomial infections in patients.

Monitoring of antibiotic resistance of non-fermenting bacteria circulating in hospitals in Rostov-On-Don (2012-2019)

Monitoring of antibiotic resistance of non-fermenting bacteria circulating in hospitals in Rostov-On-Don (2012-2019)

Dynamic Gene Clusters Mediating Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates.

Acinetobacter baumanni (A. baumannii), a nonfermenting Gram-negative bacterium, has recently been associated with a broad range of nosocomial infections. To gain more meaningful insight into the problem of nosocomial illnesses caused by the multidrug-resistant (MDR) A. baumannii, as well as the factors that increase the risk of catching these infections, this investigation included a total of 86 clinical A. baumannii infections. Repetitive extragenic palindromic (REP)-PCR was used to investigate imipenem-resistant A. baumannii isolates for dynamic gene clusters causing carbapenem resistance. Four distinct A. baumannii lineages were found in the REP-PCR-DNA fingerprints of all isolates, with 95% of the samples coming from two dominant lineages. Imipenem, amikacin, and ciprofloxacin were less effective against genotype (A) isolates because of enhanced antibiotic tolerance. Lastly, to gain more insight into the mode of action of imipenem, we explored the binding affinity of imipenem toward different Acinetobacter baumannii OXA beta-lactamase class enzymes.

New Antibiotics for Hospital-Acquired Pneumonia and Ventilator-Associated Pneumonia.

Hospital-acquired pneumonia (HAP) and ventilator-associated pneumonia (VAP) represent one of the most common hospital-acquired infections, carrying a significant morbidity and risk of mortality. Increasing antibiotic resistance among the common bacterial pathogens associated with HAP and VAP, especially Enterobacterales and nonfermenting gram-negative bacteria, has made the choice of empiric treatment of these infections increasingly challenging. Moreover, failure of initial empiric therapy to cover the causative agents associated with HAP and VAP has been associated with worse clinical outcomes. This review provides an overview of antibiotics newly approved or in development for the treatment of HAP and VAP. The approved antibiotics include ceftobiprole, ceftolozane-tazobactam, ceftazidime-avibactam, meropenem-vaborbactam, imipenem-relebactam, and cefiderocol. Their major advantages include their high activity against multidrug-resistant gram-negative pathogens.

Bedside risk prediction for positive follow-up blood culture in Gram-negative bacilli bacteremia: for whom is follow-up blood culture useful?

The value of follow-up blood culture (FUBC) in Gram-negative bacteremia (GNB) management is controversial. We evaluated bedside risk predictors and their probabilities of yielding positive FUBCs in GNB. All adult patients with GNB in a 2700-bed tertiary center were retrospectively enrolled between January 2019 and December 2019. Only one initial GNB episode was included per patient. Positive FUBC was defined as isolation of the same organism in blood culture 48-72h after the initial blood culture. A total of 2216 patients with GNB were identified, of whom 34.4% underwent FUBC. Of the 645 patients with FUBCs analyzed in the study, 89 (13.8%) had positive FUBCs. In multivariate analysis, hemodialysis [adjusted odds ratio (aOR), 2.6], fever on the day of FUBCs (aOR 3.6), intravascular device (aOR 2.4), no use of in vitro active antibiotic within 24h (aOR 2.5), non-fermenting bacteria (aOR 4.7), and multidrug resistance (aOR 5.4) were independent risk factors for positive FUBCs. If microbiological results were excluded in multivariate analysis, hemodialysis, immunosuppressive treatment, fever on the day of FUBCs, and intravascular device were independent bedside risk predictors for positive FUBCs. The yield of FUBCs increased from 3.0% (95% CI 1.0-7.0) to 63.6% (95% CI 25.6-100) as the number of bedside risk predictors increased from 0 to 4. In addition, positive FUBCs were significantly associated with 30day mortality. FUBCs may not need to be routinely used for patients with GNB bacteremia, and bedside risk predictors could be helpful in identifying patients for whom FUBC is likely to be useful.

Carriage of antibiotic-resistant bacteria and etiology of postoperative infectious complications in infants with congenital heart defects

Objective. To determine resistant microorganisms carriage, the frequency and etiology of postoperative infectious complications in high-risk infants with congenital heart defects (CHD). Materials and Methods. The retrospective analysis included 489 patients admitted for surgical treatment for CHD. The median age was 0.23 (0–12) months. Swabs were taken from the oropharynx and rectum for microbiological examination no later than 72 hours after admission (a total of 978 samples). The growth of resistant microorganisms (ESBL and/or carbapenemase-producing Enterobacterales, resistant non-fermentative Gram-negative bacteria, MRSA and VRE) was recorded. Results. Of 489 patients, 128 (26.2%) were colonized with resistant bacteria. The majority of patients were carriers of ESBL-producers (81.3%), in some cases (24%) with concomitant production of several carbapenemases. The rate of VRE carriage was 21.1%, in 8 cases – in combination with other resistant microorganisms. MRSA was detected in 1.6% of carriers, other multidrug-resistant microorganisms – in 3.9% of carriers. In early postoperative period, 145⁄489 (29.7%) patients developed infectious complications. The ventilator-associated respiratory tract infections were the most common. In most cases (73.8%) infectious complications were caused by ESBL producers, in 43.9% of cases those microorganisms also produced carbapenemases. Resistant non-fermentative Gram-negative bacteria caused postoperative infections in 4.8% of cases. The rates of MRSA and VRE in infants with infectious complications were 3.4% and 1.4%, respectively. There were no differences in the incidence of infectious complications in colonized and non-colonized patients – 42⁄128 (32.8%) versus 103⁄361 (28.5%), respectively (p = 0.6). Postoperative infectious complications were caused by resistant microorganisms in colonized patients significantly more often than in non-colonized patients – 41⁄42 (97.6%) and 82⁄103 (79.6%) cases, respectively (p = 0.008). Conclusions. It is confirmed the active process of the introduction of resistant microorganisms into the hospital with the possible development of complications of the corresponding etiology. Gram-negative bacteria with different mechanisms of antibiotic resistance present the greatest problem. In order to manage this process, it is advisable to screen hospitalizing patients with the implementation of the infection control measures.

Microbiological monitoring of COVID-19 patients in the ICU: a prospective observational study

Objective. To study spectrum of pathogens and the time to colonization of respiratory samples in patients with severe and critical COVID-19 as well as to analyze incidence of nosocomial infections and structure of prescribed antibacterial drugs. Materials and Methods. The prospective observational study included patients aged 18 years and older with confirmed severe and critical COVID-19 from December 2021 to February 2022. During the first 48 hours and then every 2–3 days of hospitalization, a respiratory sample was collected: sputum, tracheal aspirate (if intubated), bronchoalveolar lavage (if bronchoscopy was performed) for microscopy and microbiological examination. Some patients were screened for invasive aspergillosis. Clinical and demographic data, comorbidities, pathogenetic therapy for COVID-19, antibiotic therapy, cases of probable/documented bacterial nosocomial infections, antibiotic-associated diarrhea, and hospital treatment outcomes were recorded. Results. A total of 82 patients were included in this study. Patients with lung parenchyma involvement of more than 50% by computer tomography predominated; most of them (77%) required intubation and mechanical ventilation due to progression of respiratory failure, and 76% of patients had a lethal outcome. During the first 48 hours, a respiratory sample was obtained from 47 patients; the rest of the patients presented with non-productive cough. No growth of microorganisms was detected in 31 (36.8%) cases; clinically significant pathogens were detected in 16 (19.5%) patients. A subsequent analysis included data from 63 patients with a sufficient number of samples for dynamic observation were used. During the first 3 days of ICU stay, the most common bacterial pathogens were Klebsiella pneumoniae without acquired antibiotic resistance and methicillin-susceptible Staphylococcus aureus. From 3rd day and afterwards, an increase in the proportion of Acinetobacter baumannii, other non-fermenting bacteria, and carbapenemresistant Enterobacterales was noted. Among the pathogens causing lower respiratory tract infections, A. baumannii and carbapenem-resistant K. pneumoniae were predominant pathogens and accounted for 76% of cases. Positive galactomannan test results were obtained in 4 cases. Conclusions. The study confirmed importance of bacterial nosocomial infections in patients with severe and critical COVID-19. In the case of the development of nosocomial lower respiratory tract infections, empirical antimicrobial therapy should take into account the predominance of carbapenem-resistant Enterobacteria and A. baumannii, as well as the possibility of invasive aspergillosis.