Search Results (86)

Multi-drug-resistant Pseudomonas aeruginosa (P. aeruginosa) commonly causes infections that are difficult to treat, necessitating the development of new therapeutics. The search for more effective ways to combat the emergence of bacterial resistance has also led to research into phage-antibiotic synergy (PAS) as a potential therapeutic strategy. The aim of this study was to isolate and characterize virulent phages from water sources that are active against clinical carbapenem-resistant P. aeruginosa isolates, and to evaluate their in vivo efficacy using a Galleria mellonella larvae infection model. The biological and genomic characteristics of the isolated phages were determined using host range analysis, one-step growth curve analysis, transmission electron microscopy analysis and whole-genome sequencing. Two phages (vB_PaMB13 and vB_PaMB17) that demonstrated in vitro synergistic and bactericidal interactions with antipseudomonal antibiotics (tobramycin and ceftazidime) were selected for further investigation using the checkerboard method. The study revealed synergy between all phages and either antibiotic, tobramycin or ceftazidime, against P. aeruginosa. Similarly, the percentage survival rates increased in the in vivo model when both phages and antibiotics were used in combination. Overall, our study provides further support for the idea that phage-antibiotic synergy could be an effective strategy for improving treatment outcomes. Full article

Background/Objectives: The COVID-19 pandemic has been reported to impact antimicrobial consumption (AMC) and antimicrobial resistance (AMR) worldwide. We aimed to assess this correlation in Klebsiella pneumoniae before and during the COVID-19 pandemic and to estimate the burden of each antibiotic. Methods: We collected data on AMC of penicillins and beta-lactamase inhibitors (PBIs), anti-pseudomonal activity penicillins and beta-lactamase inhibitors (AAPBIs), cephalosporins, carbapenems, fluoroquinolones, aminoglycosides, and AMR in K. pneumoniae strains. The correlation between AMC and AMR was studied using dynamic regression models. Results: Overall, AMC of AAPBIs and fourth-generation cephalosporin increased, while fluoroquinolone consumption and AMR in the 2862 K. pneumoniae strains analyzed decreased. However, during the first year of the pandemic, we reported an increase in AMC and AMR. We found that 46% to 48% of the increase in cephalosporin, AAPBI, and fluoroquinolone resistance was explained by increased cephalosporin and fluoroquinolone consumption, 55% of the increase in PBI resistance was explained by increased PBI, cephalosporin, and fluoroquinolone consumption, and 58% of the increase in aminoglycoside resistance was explained by increased aminoglycoside consumption. Conclusions: During the COVID-19 pandemic, the increase in AMR in K. pneumoniae was correlated with the increase in AMC of several antibiotics, mainly cephalosporins and especially fluoroquinolones. Full article

Bacteriophages have been widely investigated as a promising treatment of food, medical equipment, and humans colonized by antibiotic-resistant bacteria. Phages pose particular interest in combating those bacteria which form biofilms, such as the medically important human pathogen Pseudomonas aeruginosa and several plant pathogens, including P. syringae. In an undergraduate lab course, P. putida was used as the host to isolate novel anti-pseudomonal bacteriophages. Environmental samples of soil and water were collected, and purified phage isolates were obtained. After Illumina sequencing, genomes of these phages were assembled de novo and annotated. Assembled genomes were compared with known genomes in the literature and GenBank to identify taxonomic relations and to refine their functional annotations. The thirteen phages described are sipho-, myo-, and podoviruses in several families of Caudoviricetes, spanning several novel genera, with genomes ranging from 40,000 to 96,000 bp. One phage (DDSR119) is unique and is the first reported P. putida siphovirus. The remaining 12 can be clustered into four distinct groups. Six are highly related to each other and to previously described Autotranscriptaviridae phages: Waldo5, PlaquesPlease, and Laces98 all belong to the Waldovirus genus, whereas Stalingrad, Bosely, and Stamos belong to the Troedvirus genus. Zuri was previously classified as the founding member of a new genus Zurivirus within the family Schitoviridae. Ebordelon and Holyagarpour each represent different species within Zurivirus, whereas Meara is a more distantly related member of the Schitoviridae. Dolphis and Jeremy are similar enough to form a genus but have only a few distant relatives among sequenced phages and are notable for being temperate. We identified the lysis cassettes in all 13 phages, compared tail spike structures, and found auxiliary metabolic genes in several. Studies like these, which isolate and characterize infectious virions, enable the identification of novel proteins and molecular systems and also provide the raw materials for further study, evaluation, and manipulation of phage proteins and their hosts. Full article

Background: Infections caused by carbapenemase-producing Pseudomonas aeruginosa (CPPA) isolates have become a worldwide clinical challenge for clinicians due to the limited treatment options. This study provides epidemiological data on CPPA clinical isolates recovered from one of the largest tertiary care hospitals in Athens, Greece, serving a diverse patient population during and after the COVID-19 pandemic. Materials and Methods: The study included all consecutive single-patient CPPA clinical isolates identified from January 2020 to December 2023 in the clinical laboratory. Identification and antimicrobial susceptibility testing were performed using the VITEK-2 automated system. A lateral flow immunoassay and the FilmArray system for blood cultures only were used for the detection of the five most prevalent carbapenemases. Their epidemiological and antimicrobial susceptibility trends were retrospectively analyzed. Results: During the study period, a total of 628 single-patient CPPA were identified among 902 carbapenem-resistant P. aeruginosa clinical isolates. An increasing number of CPPA was revealed during the survey, especially in the post-COVID period (rising from n = 102 in 2020, n = 105 in 2021, and n = 123 in 2022 to n = 298 in 2023; p < 0.05). Regarding the type of carbapenemase, VIM metallo-beta-lactamase was the only carbapenemase identified during the first two years of the study (2020 to 2021). In 2022, VIM- and NDM-producing isolates split almost evenly at proportions of 57% and 43%, respectively. In 2023, NDM-producing isolates seem to have surpassed VIM producers with rates of 54.4% and 45.6%, respectively. As far as antimicrobial resistance profiles, high rates of resistance were observed for most of the antipseudomonal drugs, exceeding 90% across all study years, with little significant variation. However, aztreonam exhibited moderate activity and colistin exhibited excellent activity, remaining the most viable drugs in this setting. Conclusions: Following the COVID-19 pandemic, an increase in CPPA pathogens was identified, while an epidemiological shift was also observed, with the carbapenemase NDM dominating over VIM since 2023. Continuous surveillance is required to track resistance patterns and guide empirical therapy. In this context, new antimicrobials and antimicrobial combinations are also urgently needed. Full article

Objective: The impact of a febrile neutropenia (FN) emergency department (ED) triage screening tool and protocol on time to antibiotic administration (TTA) and patient outcomes was evaluated. Methods: This was a retrospective, quasi-experimental study of adult FN patients admitted through the ED from April 2014 to April 2017. In March 2016 a triage screening tool and protocol were implemented. In patients who screened positive, nursing initiated a protocol that included laboratory diagnostics and a pharmacy consult for empiric antibiotics prior to evaluation by a provider. Patients were evaluated pre- and post-protocol for TTA, 30-day mortality, ED length of stay (LOS), and hospital LOS. Results: A total of 130 patients were included in the study, 77 pre-protocol and 53 post-protocol. Median TTA was longer in the pre-protocol group at 174 min (interquartile range [IQR] 105–224) vs. 109 min (IQR 71–214) post-protocol, p = 0.04. Thirty-day mortality was greater at 18.8% pre-protocol vs. 7.5% post-protocol, p = 0.12. There was no difference in hospital LOS. Pre-protocol patients compared to post-protocol patients who had a pharmacy consult demonstrated a further reduction in TTA (174 min [IQR 105–224] vs. 87.5 min [IQR 61.5–135], p < 0.01) and a reduced mortality (18% vs. 0%, p = 0.04). Conclusions: To our knowledge, this is the first report of a protocol for febrile neutropenia that allows pharmacists to order antibiotics based on a nurse triage assessment. Evaluation of the protocol demonstrated a significant reduction in TTA and trend toward improved mortality. Full article

Background: Aspiration pneumonia is increasingly recognized as a fatal pulmonary disease among older people. Although antipseudomonal antibiotics are commonly used in clinical practice, their efficacy in this population remains uncertain. Methods: Nationwide data collected from patients aged ≥65 years who were hospitalized due to aspiration pneumonia from January 2018 to December 2018 were analyzed. The in-hospital mortality between patients who received antipseudomonal antibiotics within 3 days of hospital admission and those who did not were compared. A logistic regression analysis was performed to assess the effect of antipseudomonal antibiotics on in-hospital mortality after adjusting for potential prognostic confounders. Results: This study included 46,980 patients, and 13,340 (28.4%) patients received antipseudomonal antibiotics. In total, 7011 (14.9%) patients died during hospitalization. Advanced age, male sex, a lower body mass index, decreased Barthel Index, impaired consciousness, interstitial pneumonia, malignancy, renal failure, and use of immunosuppressive agents were significantly associated with increased in-hospital mortality. After adjusting for the confounders, the use of antipseudomonal antibiotics was found to be associated with an elevated in-hospital mortality (odds ratio: 1.33; 95% confidence interval: 1.26–1.41; p < 0.001). Conclusions: In this nationwide data analysis of older patients with aspiration pneumonia, early antipseudomonal antibiotic administration did not improve prognosis. Therefore, the routine use of antipseudomonal antibiotics should be avoided in older patients with aspiration pneumonia. Full article

Background/Objectives: The optimal therapy for polymicrobial wound infections is poorly defined. We sought to characterize the ability of linezolid to combat mixed cultures of Staphylococcus aureus and Pseudomonas aeruginosa. Methods: The antistaphylococcal activity of linezolid was assessed in 24-h time-killing experiments that used S. aureus and P. aeruginosa isolated from polymicrobial wound infections. Clindamycin was also evaluated as a comparator. A Hill-type mathematical model was used to assess the maximum killing of S. aureus (E_max). The ability of linezolid to potentiate the activity of host defense peptides against P. aeruginosa was evaluated using LL-37. Results: In the presence of P. aeruginosa, the E_max of linezolid decreased in 5/9 co-culture experiments and increased in 4/9 co-culture experiments in comparison to linezolid against S. aureus alone. The potency of linezolid was not significantly impacted by the presence of P. aeruginosa. In comparison, the maximal S. aureus killing achieved by clindamycin decreased in eight out of nine experiments, and somewhat paradoxically, the potency increased in nine out of nine experiments. In the host defense peptide assay, the supratherapeutic linezolid concentration of 64 mg/L did not significantly enhance the killing of the LL-37 peptides (p ≥ 0.121), but the concentration of linezolid was significantly associated with the killing of one of three P. aeruginosa isolates (p = 0.005). Conclusions: P. aeruginosa had a minimal impact on the antistaphylococcal activity of linezolid in comparison to clindamycin. Linezolid did not exert a consistent ability to enhance the antipseudomonal activity of host defense peptides. These data may help inform antimicrobial selection during polymicrobial wound infections. Full article

Background: Prevention of an irreversible sequalae in neurosyphilis patients requires immediate high-dose intravenous benzylpenicillin administered for a prolonged period of time. However, life-threatening neutropenia has been reported as one of the complications following extended usage of benzylpenicillin. Case presentation: We report a 54-year-old male patient with HIV who developed high-dose benzylpenicillin-induced febrile neutropenia during neurosyphilis treatment. The patient developed a fever of up to 39.8 °C, severe leukopenia (<1 × 10⁹/L), and neutropenia (0.2 × 10⁹/L). He also presented with slightly elevated C-reactive protein and procalcitonin levels but had no clear symptoms of other infections. The diagnosis was confirmed by excluding other possible causes of neutropenia: flu, measles, sepsis, and HIV-related neutropenia. Third-generation antipseudomonal cephalosporin in combination with vancomycin and granulocyte colony-stimulating factor were administered, and the patient saw a rapid improvement in clinical symptoms and laboratory findings. Conclusions: High-dose benzylpenicillin-induced neutropenia should be considered a complication after prolonged periods of neurosyphilis treatment with high-dose benzylpenicillin when there is no evidence of other potential causes of neutropenia. Early diagnosis and proper treatment are critical in order to prevent this dangerous condition from deteriorating further. Full article

Background: Pseudomonas aeruginosa (PSA) infections are associated with a high recurrence rate and high mortality in immuno-compromised patients. There are limited studies regarding pediatric hematopoietic cell transplantation recipients. Aim: The nationwide multicenter study was conducted to analyze the epidemiology of PSA infections in children treated with chemotherapy (PHO, pediatric hematology and oncology) or undergoing hematopoietic allogeneic or autologous cell transplantation (HCT) in the period 2014–2023. Methods: We retrospectively analyzed the clinical and microbiological data of children who underwent anticancer therapy or hematopoietic cell transplantation in 17 Polish PHO centers and six pediatric HCT centers. The data were collected in two-year intervals. Results: During the 10-year study period, a total of 1629 HCTs (both autologous and allogeneic) and 9614 children newly diagnosed with neoplasms were analyzed. The cumulative incidence of PSA infection was similar in both groups (6.71% in PHO vs. 6.32% in HCT, p = 0.624). The total number of PSA bloodstream infections was comparable in the PHO and HCT groups (31.9% vs. 26.2%; p = 0.223). In both analyzed groups, the antipseudomonal drugs of choice were as follows: meropenem, ceftazidime, and tazobactam/piperaciline in combination with other antibiotics. In the HCT group, high rates of meropenem (20.4%) and tazobactam/piperaciline (18.4%) non-susceptibility were observed. This led to colistin therapy in 5.3% of patients. There was no difference in the median antibiotic therapy time in both groups; however, the survival rates from PSA infection were significantly lower in the HCT group (89.3% vs. 96.0%, p = 0.004). Conclusions: Although the risk of infection and the occurrence of resistant bacterial strains in HCT patients were comparable with those in PHO patients, the outcome of PSA infections was better in the PHO setting. Full article

Introduction: Pseudomonas aeruginosa produces many exotoxins which are essential for the bacterial pathogenesis. The aim of this study was to identify Pseudomonas aeruginosa from clinical specimens, detect the sensitivity pattern, biofilm production, and the frequency of exogenes. Methods: Pseudomonas aeruginosa clinical isolates were identified by conventional and genotypic methods. Antibiotic susceptibility patterns and biofilm production were performed. Molecular detection of exotoxin genes exoS, exoT, exoU, and exoY in Pseudomonas aeruginosa isolates was performed by PCR. Results: Seventy-five Pseudomonas aeruginosa were identified in 400 clinical specimens. Sixty-six (88%) isolates were carbapenem-resistant. A total of 25 (33.3%) isolates were extensively drug resistant, 18 (24%) were multidrug resistant, and 11 (14.7%) were pandrug resistant. Sixty-three (84%) isolates were biofilm producers. Biofilm formation was detected in 56 (85%) of carbapenem-resistant isolates. Totally, 70 (93.3%) isolates carried exoS, 68 (90.7%) carried exoY, 65 (86.7%) carried exoT, and 28 (37.3%) carried exoU. Exogenes were highly expressed in carbapenem-resistant isolates. Coexistence of more than one gene was detected in nearly all isolates. Conclusions: Pseudomonas aeruginosa clinical isolates were resistant to many anti-pseudomonal antibiotics. Most of isolates were biofilm-producers. The genes exoT, exoS and exoY were identified in almost all P. aeruginosa strains and are considered an inevitable component of P. aeruginosa virulence. Full article

Background/Objectives: Pseudomonas aeruginosa (Psa) can circumvent antimicrobial chemotherapy, an ability enhanced by cigarette smoking (CS). This study probed potential benefits of combinations of anti-pseudomonal agents, and potential augmentation by a macrolide, in the absence or presence of cigarette smoke condensate (CSC). Methods: Two susceptible (WT: wild-type and DS: drug-sensitive) and one multidrug-resistant (MDR) strains of Psa were treated with amikacin, cefepime, and ciprofloxacin, individually and in combination, and with and without clarithromycin, followed by the measurement of planktonic growth and biofilm formation by spectrophotometry. Antibiotic interactions were determined using the fractional inhibitory concentration index (FICI) method. Effects on preformed biofilm density were measured following the addition of antibiotics: all procedures were performed in the absence and presence of CSC. Results: The minimal inhibitory concentrations (MICs) of the three agents ranged from 0.125 mg/L to 1 mg/L (WT and DS strains) and 16 mg/L to 64 mg/L (MDR strain), with all resistant to clarithromycin (125 mg/L). MIC values closely correlated with the antibiotic concentrations required to inhibit biofilm formation. FICI revealed synergism between most combinations, with augmentation by clarithromycin. Amikacin had the greatest effect on biofilm density, which was potentiated by combination with the other antibiotics, particularly clarithromycin. Exposure to CSC had variable, albeit modest, effects on bacterial growth and biofilm formation, but low concentrations increased biofilm mass and attenuated synergistic antimicrobial interactions and effects on biofilm density. Conclusions: Amikacin, cefepime, and ciprofloxacin, especially with clarithromycin, exhibit synergistic anti-pseudomonal activity and decrease preformed biofilm density. CSC attenuated these effects, illustrating the pro-infective potential of CS. Full article

Background/Objectives: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is an important pathogen associated with high mortality and treatment failure rates. We aimed to assess the susceptibility of CRPA to antipseudomonal agents, identify its resistance mechanisms, and evaluate clinical outcomes in a sample of CRPA isolates. Methods: This was an in vitro study of a clinical isolate of CRPA from hospitalized patients with CRPA infection and a retrospective observational study of these patients, who were diagnosed between 14 February 2021 and 10 August 2023 at Songklanagarind Hospital in Songkhla, Thailand. In vitro experiments were conducted to determine the minimum inhibitory concentrations (MICs) of the antipseudomonal agents using the broth microdilution method. Resistance mechanisms were assessed using the modified carbapenem inactivation method, combined disk tests, and quantitative real-time reverse transcription polymerase chain reaction. Results: A total of 140 CRPA isolates were analyzed. Both traditional and novel β-lactams had high MICs. The most common resistance mechanism was the upregulation of the MexAB-OprM efflux pump (81.3%), followed by the downregulation of the OprD porin (48.9%) and metallo-β-lactamase (MBL) production (45.0%), and the overexpression of bla_AmpC (41.0%). The 30-day all-cause mortality rate was 30.5%. The risk factors associated with 30-day mortality included a Charlson Comorbidity Index of ≥5 (OR: 3.43; 95% CI: 1.07–10.99; p = 0.03), sepsis (OR: 10.62; 95% CI: 1.26–89.44; p = 0.03), and septic shock (OR: 4.39; 95% CI: 1.67–11.55; p < 0.01). In contrast, receiving active documented therapy was significantly associated with reduced mortality (OR: 0.17; 95% CI: 0.04–0.74; p = 0.01). Conclusions: This study revealed higher MIC values of all β-lactams for CRPA, while colistin and amikacin remained effective. The resistance mechanisms included MexAB-OprM overexpression, OprD downregulation, MBL production, and bla_AmpC overexpression, with a higher prevalence of MBL than in other regions of Thailand. High 30-day mortality was associated with comorbidities, sepsis, and septic shock, but active therapy reduced mortality. Full article

Background/Objectives: Although chronic infection by Pseudomonas aeruginosa among patients with bronchiectasis is associated with poor prognosis, the impact of antibiotics with P. aeruginosa coverage in patients with bronchiectasis who experienced bacterial pneumonia or exacerbation of bronchiectasis has not been fully investigated. Methods: This study targeted patients with bronchiectasis who were admitted to hospitals because of bacterial pneumonia or exacerbation of bronchiectasis between April 2018 and March 2020 using a national inpatient database in Japan. The association of antipseudomonal antibiotic treatment with in-hospital mortality was assessed after propensity score matching to adjust the patients’ backgrounds. Results: In total, 4943 patients with bacterial pneumonia and 1914 patients with exacerbation of bronchiectasis were included in this study. The in-hospital mortality rate did not differ between patients who did and did not receive antipseudomonal agents among patients with bacterial pneumonia (9.0% [185/2045] vs. 7.4% [151/2045]; p = 0.053) and those with exacerbation of bronchiectasis (5.2% [42/803] vs. 4.1% [33/803] group; p = 0.287). Conclusions: The use of antibiotics covering P. aeruginosa does not apparently improve prognosis in patients with bacterial pneumonia or exacerbation of bronchiectasis. A prospective study focusing on the impact of antibiotics covering P. aeruginosa among patients with bronchiectasis in whom P. aeruginosa is isolated is required. Full article

Background: Empirical antibacterial therapy for febrile neutropenia reduces mortality due to Gram-negative blood stream infections (BSIs). Pediatric guidelines recommend monotherapy with an antipseudomonal beta-lactam or a carbapenem and to add a second anti-Gram-negative agent in selected situations. We evaluated the changes in the proportions of resistance of beta-lactam monotherapies vs. their combination with amikacin, and the possible impact on ICU admission or death. Results: 797 BSIs due to Gram-negative bacteria in 685 patients were included. Combination therapies with amikacin had a lower percentage of isolates resistant to one or to both drugs compared with the respective monotherapy. The highest OR for ICU admission was observed when both drugs of the combination of meropenem–amikacin were resistant. Mortality was significantly associated with relapse or the progression of the underlying malignancy, and resistance to both drugs of the combinations of cefepime–amikacin or meropenem–amikacin. Methods: This study was based on data collected for a large multinational study, in which the susceptibility of Gram-negative bloodstream isolates was categorized following either EUCAST or CLSI according to local laboratory standards. An escalation antibiogram was generated for each selected drug. For resistant bacteria, the conditional susceptibility probability on resistance was calculated. Conclusions: In pediatric cancer patients with Gram-negative BSIs, the proportion of the resistant organism correlates with ICU admission or death, which may be reduced by combination therapy. In patients with suspected or confirmed Gram-negative BSIs that are not-improving or deteriorating under monotherapy, escalation to meropenem may represent the best option. Amikacin should be preferred when combination therapy is considered with ciprofloxacin as an alternative in the case of impaired renal function. Full article

Background: Antipseudomonal β-lactams (APBL) are commonly used for empirical therapy of Gram-negative bloodstream infections (BSI). This retrospective cohort study examines risk factors for prolonged APBL use (≥48 h) in patients with Enterobacterales BSI and compares 28-day mortality between early de-escalation of APBL and prolonged APBL therapy. Methods: Adult patients admitted to two community hospitals in South Carolina with Enterobacterales BSI from January 2010 to June 2015 were included in this study. Data were extracted manually from medical records. Multivariate logistic regression and Cox proportional hazards analyses were used to examine predictors of prolonged APBL therapy and mortality, respectively. Results: Among 993 patients with Enterobacterales BSI, 491 (49%) underwent early de-escalation of APBL and 502 (51%) received prolonged APBL therapy. Cancer, immune compromised status, residence at a skilled nursing facility, a high Pitt bacteremia score, non-urinary source of infection, and BSI due to AmpC-producing Enterobacterales were independently associated with prolonged use of APBL. Antimicrobial stewardship interventions were inversely associated with prolonged APBL use. Early de-escalation of APBL was not associated with increased mortality. Conclusions: This study exemplifies the safety and effectiveness of early de-escalation of APBL in Enterobacterales BSI. Antimicrobial stewardship strategies should be implemented to encourage the practice of early de-escalation of antimicrobial therapy, including in high-risk populations. Full article