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Background: Recurrent urinary tract infections (rUTIs) occur in over 20% of patients, with postmenopausal women (over 50 years old) carrying the highest risk for recurrence compared to younger women. Virulence factors such as type 1 fimbriae adhesin FimH, the outer membrane protease OmpT, and the secreted pore-forming toxin α-hemolysin (HlyA) have been shown to support the formation of intracellular bacterial communities (IBCs) within bladder epithelial cells (BECs), facilitating persistence. This study aims to characterize the virulence expression and intracellular persistence of ESBL-producing uropathogenic E. coli (E-UPEC) strains isolated from postmenopausal women with recurrent or single episode infections. Methods: Study strains included 72 E-UPEC strains collected from patients (36 recurrent; 36 single episode) with a confirmed UTI diagnosis and control UPEC strains (CFT073 and UTI89). Patient demographics and clinical course were collected. Presence of hlyA, ompT, and fimH genes were confirmed by colony PCR, and qRT-PCR was performed using extracted RNA from a subset of 18 strains (12 recurrent; 6 single episode) grown in Luria-Bertani media and isolated from infected BECs to characterize gene expression. Bladder cell line 5637 was infected with study strains at MOI 15 for 2 h, treated with amikacin for 2 h to remove extracellular bacteria, then lysed to enumerate intracellular CFU counts. Results: No differences in clinical characteristics between patient groups were observed. Overall prevalence of fimH, ompT, and hlyA was 99% (71/72), 82% (59/72), and 26% (19/72) respectively; presence of all three genes did not differ between recurrent and single-episode strains. Notably, all recurrent strains had significantly more intracellular CFUs compared to single episode strains (median 16,248 CFU/mL vs. 4,118 CFU/mL, p = 0.018). Intracellular expression ompT was significantly increased (p = 0.0312) in the recurrent group compared to LB media, while fimH was significantly decreased (p = 0.0365) in the single episode group compared to expression in LB media. Conclusion: Our findings indicate strain-specific ability to persist inside BECs with the recurrent strains exhibiting increased ompT expression inside BECs and higher intracellular bacterial burden compared to strains causing single episode UTI. These results emphasize the potential microbial contributions to recurrence in postmenopausal women and warrant future investigations on the impact of antibiotic therapy and host response on IBC-supportive UPEC virulence. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus is a leading cause of bloodstream infection (SAB), with up to 30% mortality. Despite treatment with standard antibiotics, one in three patients develops a persistent infection, which portends a five-fold increase in the risk of death. Persistent SAB has been attributed in part to the inability of antistaphylococcal antibiotics to eradicate intracellular S. aureus surviving inside macrophages. (-)- Epigallocatechin gallate (EGCG) is a catechin found in green tea that has been widely studied for its broad biological activities, ranging from anticancer to antibacterial activity. However, EGCG is greatly limited by its poor drug-like properties in terms of stability, membrane permeability, and bioavailability. In this study, we established through a series of in vitro experiments that structural modifications of EGCG enhanced drug-like properties while maintaining or improving its antistaphylococcal activity. Our lead EGCG analogs (MCC-1 and MCC-2) showed improved biochemical properties along with increased potency against extracellular S. aureus and restored susceptibility of β-lactam agents to methicillin-resistant S. aureus (MRSA). Importantly, the lead analogs but not EGCG potentiated macrophage- and antibiotic-mediated clearance of intracellular bacteria. Overall, EGCG analogs showed promise for further development as adjunctive therapy candidates for the treatment of SAB. [ABSTRACT FROM AUTHOR]

Staphylococcus aureus (SA) is a leading cause of bloodstream infection. The liver represents the sentinel immune organ for clearance of bloodstream pathogens and eradication of intracellular SA from liver-resident macrophages (Kupffer cells, KCs) eliminates the likely pathogenic reservoir that contributes to persistent bacteraemia. Objectives We assessed antimicrobial activity at phagolysosome-mimicking pH, intracellular penetration, and SA eradication within KCs in vitro for clinically prescribed antistaphylococcal agents alone or in combination: vancomycin, daptomycin, ceftaroline, ceftobiprole, oritavancin, oxacillin, cefazolin; rifampin and fosfomycin. Methods pH-adjusted broth microdilution assays, intracellular bioaccumulation assays, and intracellular killing assays against clinical bloodstream isolates were performed using a murine KC line with study agents. Results Rifampin and β-lactams exhibited enhanced activity [2- to 16-fold minimum inhibitory concentrations (MIC) decrease] at phagolysosomal pH while vancomycin, oritavancin, daptomycin and fosfomycin demonstrated reduced activity (2- to 32-fold MIC increase in order of least to greatest potency reduction). All agents evaluated had poor to modest intracellular to extracellular concentration ratios (0.024–7.8), with exceptions of rifampin and oritavancin (intracellular to extracellular ratios of 17.4 and 78.2, respectively). Finally, we showed that the first-line treatment for SA bacteraemia (SAB), vancomycin, performed worse than all other tested antibiotics in eradicating intracellular SA at human C max concentration (0.20 log cfu decrease), while oritavancin performed better than all other agents alone (2.05 versus 1.06–1.36 log cfu decrease). Conclusions Our findings raise concerns about the efficacy of commonly prescribed antibiotics against intracellular SA reservoirs and emphasize the need to consider targeting pathogen eradication from the liver to achieve early control of SAB. [ABSTRACT FROM AUTHOR]

ObjectivesChronic endobronchial infections with Pseudomonas aeruginosa contribute to bronchiectasis and progressive loss of lung function in patients with cystic fibrosis. This study aimed to evaluate the therapeutic potential of a novel macrocyclic peptide, rhesus θ-defensin-1 (RTD-1), by characterizing its in vitro antipseudomonal activity and in vivo efficacy in a murine model of chronic Pseudomonas lung infection.MethodsAntibacterial testing of RTD-1 was performed on 41 clinical isolates of P. aeruginosa obtained from cystic fibrosis patients. MIC, MBC, time-kill and post-antibiotic effects were evaluated following CLSI-recommended methodology, but using anion-depleted Mueller-Hinton broth. RTD-1 was nebulized daily for 7 days to cystic fibrosis transmembrane conductance regulator (CFTR) F508del-homozygous mice infected using the agar bead model of chronic P. aeruginosa lung infection. In vivo activity was evaluated by change in lung bacterial burden, airway leucocytes and body weight.ResultsRTD-1 exhibited potent in vitro bactericidal activity against mucoid and non-mucoid strains of P. aeruginosa (MIC90 = 8 mg/L). Cross-resistance was not observed when tested against MDR and colistin-resistant isolates. Time-kill studies indicated very rapid, concentration-dependent bactericidal activity of RTD-1 with ≥3 log10 cfu/mL reductions at concentrations ≥4× MIC. No post-antibiotic effect was observed. In vivo, nebulized treatment with RTD-1 significantly decreased lung P. aeruginosa burden (mean difference of -1.30 log10 cfu; P = 0.0061), airway leucocytes (mean difference of -0.37 log10; P = 0.0012) and weight loss (mean difference of -12.62% at day 7; P

Enterococci that are nonsusceptible (NS; MIC > 4 μg/ml) to daptomycin are an emerging clinical concern. The synergistic combination of daptomycin plus beta-lactams has been shown to be effective against vancomycin-resistant Enterococcus (VRE) species in vitro. This study systematically evaluated by in vitro time-kill studies the effect of daptomycin in combination with ampicillin, cefazolin, ceftriaxone, ceftaroline, ertapenem, gentamicin, tigecycline, and rifampin, for a collection of 9 daptomycin-NS enterococci that exhibited a broad range of MICs and different resistance-conferring mutations. We found that ampicillin plus daptomycin yielded the most consistent synergy but did so only for isolates with mutations to the liaFSR system. Daptomycin binding was found to be enhanced by ampicillin in a representative isolate with such mutations but not for an isolate with mutation to the yycFGHIJ system. In contrast, ampicillin enhanced the killing of the LL-37 human antimicrobial peptide against daptomycin-NS E. faecium with either the liaFSR or yycFGHIJ mutation. Antagonism was noted only for rifampin and tigecycline and only for 2 or 3 isolates. These data add support to the growing body of evidence indicating that therapy combining daptomycin and ampicillin may be helpful in eradicating refractory VRE infections.

Antibiotic-resistant bacterial pathogens threaten public health. Because many antibiotics target specific bacterial enzymes or reactions, corresponding genes may mutate under selection and lead to antibiotic resistance. Accordingly, antimicrobials that selectively target overall microbial cell integrity may offer alternative approaches to therapeutic design. Naturally occurring mammalian α- and θ-defensins are potent, non-toxic microbicides that may be useful for treating infections by antibiotic-resistant pathogens because certain defensin peptides disrupt bacterial, but not mammalian, cell membranes. To test this concept, clinical isolates of methicillin-resistant Staphylococcus aureus (MRSA), including vancomycin heteroresistant strains, and ciprofloxacin-resistant Pseudomonas aeruginosa (Cip(R)-PA) were tested for sensitivity to α-defensins Crp-4, RMAD-4 and HNPs 1-3, and to RTD-1, macaque θ-defensin-1. In vitro, 3 μM Crp-4, RMAD-4 and RTD-1 reduced MRSA cell survival by 99%, regardless of vancomycin susceptibility. For PA clinical isolates that differ in fluoroquinolone resistance and virulence phenotype, peptide efficacy was independent of strain ciprofloxacin resistance, site of isolation or virulence factor expression. Thus, Crp-4, RMAD-4 and RTD-1 are effective in vitro antimicrobials against clinical isolates of MRSA and Cip(R)-PA, perhaps providing templates for development of α- and θ-defensin-based microbicides against antibiotic resistant or virulent infectious agents.

Zusammenfassung: Hintergrund: Bei Patienten mit nosokomialer bakterieller Pneumonie ist die Mortalität am höchsten bei denjenigen, die so weit dekompensieren, dass eine mechanische Beatmung (vHABP) nötig wird, gefolgt von denen mit beatmungsassoziierter Pneumonie (VABP) und nicht beatmungsassoziierter, im Krankenhaus erworbener Pneumonie (nvHABP). Die Ziele dieser Studie waren die Identifizierung von Risikofaktoren, die mit der Entwicklung und der Mortalität von vHABP assoziiert sind, und die Bewertung der Antibiotikabehandlung. Methoden: Eine multizentrische retrospektive Kohortenstudie wurde bei erwachsenen hospitalisierten Patienten mit nosokomialer Pneumonie zwischen 2014 und 2019 durchgeführt. Die Gruppen wurden nach vHABP, nvHABP und VABP stratifiziert und hinsichtlich demografischer Daten, klinischer Merkmale, Behandlung und Ergebnissen verglichen. Mithilfe von maschinellem Lernen wurden multivariate Modelle erstellt, um Risikofaktoren für die Progression zur vHABP und die Mortalität durch Pneumonie für jede Kohorte zu identifizieren. Ergebnisse: 457 Patienten (32% nvHABP, 37% vHABP und 31% VABP) wurden untersucht. Die vHABP- und die nvHABP-Gruppe waren ähnlich alt (medianes Alter 66,4 Jahre), 77% wiesen mehrere Komorbiditäten auf, aber mehr vHABP-Patienten hatten eine Lebererkrankung (18,2% vs. 7,7%; p = 0,05) und eine Alkoholkonsumstörung (27% vs. 7,1%; p < 0,001) und waren in den vorausgehenden 30 Tagen im Krankenhaus gewesen (30,4% vs. 19,5%; p = 0,02). 70% der vHABP-Patienten benötigten am Tag der Diagnose eine sofortige Beatmung. Die Mortalität war in der vHABP-Gruppe am höchsten, gefolgt von der VABP- und der nvHABP-Gruppe (44,6% vs. 36% vs. 14,3%; p < 0,0001). Fast alle (96%) vHABP-Patienten hatten positive Kulturen, wobei Gram-negative Erreger 58,8% ausmachten und 33,0% resistent gegen β-Laktame mit breitem Wirkungsspektrum (ESBL), Ceftriaxon (17,5%), Fluorchinolone (20,6%) und Carbapeneme (12,4%) waren. Bis zur Hälfte der vHABP-Patienten mit ESBL-Enterobacteriaceae oder Pseudomonas aeruginosa erhielten keine wirksame empirische Therapie. Bei Patienten, bei denen eine wirksame Therapie erst nach dem Tag der Pneumoniediagnose begonnen wurde, war die Mortalität um mehr als 50% erhöht. Risikofaktoren, die mit der Entwicklung einer vHABP assoziiert waren, waren Alkoholkonsumstörung, APACHE-II-Score, eine Vasopressortherapie vor der Infektion und eine positive Kultur für ESBL-Enterobacteriales, während eine Krankenhausaufnahme in den letzten 30 Tagen, eine aktive maligne Erkrankung, die Isolierung von Ceftriaxon-resistenten Erregern oder P. aeruginosa und eine Vasopressortherapie Risikofaktoren für eine vHABP-assoziierte Mortalität waren. [ABSTRACT FROM AUTHOR]

Co-infection with carbapenem-resistant Klebsiella pneumoniae (CRKP) and Pseudomonas aeruginosa (CRPA) is associated with poor outcomes and historically relied on combination therapy with toxic agents for management. However, several novel β-lactam/β-lactamase inhibitor combination agents have been developed, offering potential monotherapy options. Here, we compare the in vitro activity of ceftazidime-avibactam (CZA), imipenem-relebactam (IRL), and meropenem-vaborbactam (MVB) against both CRKP and CRPA clinical isolates. Minimum inhibitory concentrations (MICs) for each agent were determined using broth microdilution. Carbapenemase gene detection was performed for representative isolates of varying carbapenem resistance phenotypes. IRL demonstrated excellent activity against CRKP and CRPA with susceptibility rates at 95.8% and 91.7%, respectively. While CZA and MVB showed comparable susceptibility to IRL against CRKP (93.8%), susceptibility of CRPA to CZA was modest at 79.2%, whereas most CRPA strains were resistant to MVB. Of the 35 CRKP isolates tested, 91.4% (32/35) carried a blaKPC gene. Only 1 of 37 (2.7%) CRPA isolates tested carried a blaVIM gene, which conferred phenotypic resistance to all three agents. None of the CRKP strains were cross-resistant to all three agents. Source of infection and co-infection did not significantly influence antimicrobial activity for IRL and CZA; none of the CRPA isolates from co-infected patients were susceptible to MVB. Our results suggest that novel β-lactam agents with antipseudomonal activity and stability against carbapenemases, such as IRL and CZA, offer potential monotherapy options for the treatment of co-infection involving both CRKP and CRPA, but not MVB. [ABSTRACT FROM AUTHOR]

Background: Nearly 30% of patients infected with carbapenem-resistant Klebsiella pneumoniae (CRKP) were previously shown to be coinfected with carbapenem-resistant Pseudomonas aeruginosa (CRPA) or Acinetobacter baumannii (CRAB). Infections caused by multiple carbapenem-resistant pathogens present significant challenge to infection control and therapeutic management. The study objective was to identify risk factors for acquisition of multiple carbapenem-resistant pathogens and associated outcomes. Methods: A descriptive analysis of adults infected with either CRKP alone or coinfected with CRPA or CRAB was performed. Patient groups were compared on demographics, clinical characteristics, treatment, and outcome. Results: 86 patients with CRKP monoinfection and 60 patients with coinfections were evaluated. Respiratory tract was the predominant infection site for coinfected patients involving mostly CRPA whereas urinary tract was the primary site for CRKP-only group. More coinfected patients were severely debilitated, had prior carbapenem exposure (37% vs 13%, p<0.001) and history of pneumonia in the past year (67% vs 41%, p<0.01). More coinfected patients required direct ICU admission (45% vs 27%, p=0.02) and had prolonged length of stay (median 15 vs 10 days, p<0.01) than the CRKP-only group but mortality rates (18% vs 16%) were similar. Conclusions: CRKP coinfection with another carbapenem-resistant pathogen adds significant morbidity and healthcare burden overall. Empiric therapy with reliable activity against both CRKP and carbapenem-resistant Pseudomonas aeruginosa may be prudent for at risk patients with pneumonia. [ABSTRACT FROM AUTHOR]

Probiotics are defined by the Food and Agriculture Organization of the World Health Organization as live microorganisms that, when administered in adequate amounts, confer a health benefit on the host [...]