This study assessed the molecular epidemiology, resistance mechanisms, and susceptibility profiles of a collection of 150 extensively drug-resistant (XDR)
clinical isolates obtained from a 2015 ...Spanish multicenter study, with a particular focus on resistome analysis in relation to ceftolozane-tazobactam susceptibility. Broth microdilution MICs revealed that nearly all (>95%) of the isolates were nonsusceptible to piperacillin-tazobactam, ceftazidime, cefepime, aztreonam, imipenem, meropenem, and ciprofloxacin. Most of them were also resistant to tobramycin (77%), whereas nonsusceptibility rates were lower for ceftolozane-tazobactam (31%), amikacin (7%), and colistin (2%). Pulsed-field gel electrophoresis-multilocus sequence typing (PFGE-MLST) analysis revealed that nearly all of the isolates belonged to previously described high-risk clones. Sequence type 175 (ST175) was detected in all 9 participating hospitals and accounted for 68% (
= 101) of the XDR isolates, distantly followed by ST244 (
= 16), ST253 (
= 12), ST235 (
= 8), and ST111 (
= 2), which were detected only in 1 to 2 hospitals. Through phenotypic and molecular methods, the presence of horizontally acquired carbapenemases was detected in 21% of the isolates, mostly VIM (17%) and GES enzymes (4%). At least two representative isolates from each clone and hospital (
= 44) were fully sequenced on an Illumina MiSeq. Classical mutational mechanisms, such as those leading to the overexpression of the β-lactamase AmpC or efflux pumps, OprD inactivation, and/or quinolone resistance-determining regions (QRDR) mutations, were confirmed in most isolates and correlated well with the resistance phenotypes in the absence of horizontally acquired determinants. Ceftolozane-tazobactam resistance was not detected in carbapenemase-negative isolates, in agreement with sequencing data showing the absence of
mutations. The unique set of mutations responsible for the XDR phenotype of ST175 clone documented 7 years earlier were found to be conserved, denoting the long-term persistence of this specific XDR lineage in Spanish hospitals. Finally, other potentially relevant mutations were evidenced, including those in penicillin-binding protein 3 (PBP3), which is involved in β-lactam (including ceftolozane-tazobactam) resistance, and FusA1, which is linked to aminoglycoside resistance.
Data regarding the most efficacious and least toxic schedules for the use of colistin are scarce. The aim of this study was to determine the incidence and the potential risk factors of ...colistin-associated nephrotoxicity including colistin plasma levels.
A prospective observational cohort study was conducted for over one year in patients receiving intravenous colistin methanesulfonate sodium (CMS). Blood samples for colistin plasma levels were collected immediately before (Cmin) and 30 minutes after CMS infusion (Cmax). Renal function was assessed at baseline, on day 7 and at the end of treatment (EOT). Severity of acute kidney injury (AKI) was defined by the RIFLE (risk, injury, failure, loss, and end-stage kidney disease) criteria.
One hundred and two patients met the inclusion criteria. AKI related to CMS treatment on day 7 and at the end of treatment (EOT) was observed in 26 (25.5%) and 50 (49.0%) patients, respectively. At day 7, Cmin (OR, 4.63 2.33-9.20; P < 0.001) was the only independent predictor of AKI. At EOT, the Charlson score (OR 1.26 1.01-1.57; P = 0.036), Cmin (OR 2.14 1.33-3.42; P = 0.002), and concomitant treatment with ≥ 2 nephrotoxic drugs (OR 2.61 1.0-6.8; P = 0.049) were independent risk factors for AKI. When Cmin was evaluated as a categorical variable, the breakpoints that better predicted AKI were 3.33 mg/L (P < 0.001) on day 7 and 2.42 mg/L (P < 0.001) at EOT.
When using the RIFLE criteria, colistin-related nephrotoxicity is observed in a high percentage of patients. Cmin levels are predictive of AKI. Patients who receive intravenous colistin should be closely monitored and Cmin might be a new useful tool to predict AKI.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Highlights • A steady-state colistin plasma concentration ( Css ) > 2.42 mg/L is an independent risk factor of nephrotoxicity. • This has been validated in a prospective cohort of patients treated ...with colistin methanesulfonate. • Nephrotoxicity was significantly more frequent and occurred earlier in patients with Css > 2.42 mg/L. • Colistin has a narrow therapeutic window. • Therapeutic drug monitoring is recommended in patients receiving colistin therapy.
The aim of this study was to investigate the efficacy of ceftolozane-tazobactam in combination with meropenem against an extensively drug-resistant (XDR)
high-risk clone, sequence type 175, isolated ...in a Spanish university hospital. A 14-day hollow-fiber infection model was used to simulate clinical exposure of the two drug regimens alone and in combination, and serial samples were collected to determine drug concentrations and CFU counts. The untreated control failed, as did each study regimen when administered alone. However, when ceftolozane-tazobactam was administered in combination with meropenem, there was a >4-log
CFU/ml bacterial density reduction and suppression of resistance for the duration of the study. These data suggest that ceftolozane-tazobactam plus meropenem may be a useful combination for treating XDR
.
This study aimed to assess the impact of extensively drug-resistant (XDR) phenotype on mortality in
bacteremia. A retrospective cohort study was performed in a tertiary hospital from January 2000 to ...December 2018. All consecutive prospectively recorded
bacteremia in adult patients were assessed. In this study, 382 patients were included, of which 122 (31.9%) due to XDR
. Independent factors associated with 14-day mortality were as follows: high-risk source of bacteremia (hazard ratio (HR) 3.07, 95% confidence interval (CI), 1.73-5.46), septic shock (HR 1.75, 95% CI, 1.12-2.75), and higher Pitt scores (one-point increments; HR 1.25, 95% CI, 1.12-1.38). Otherwise, the appropriateness of definitive antibiotic therapy was a protective factor (HR 0.39, 95% CI, 0.24-0.62). The same variables were also associated with 30-day mortality. XDR phenotype was not associated with 14- or 30-day mortality. In a subanalysis considering only high-risk source cases, combined antimicrobial therapy was independently associated with 14-day favorable outcome (HR 0.56, 95% CI, 0.33-0.93). In conclusion, XDR phenotype was not associated with poor prognosis in patients with
bacteremia in our cohort. However, source of infection, clinical severity, and inappropriate definitive antibiotic therapy were risk factors for mortality. Combined antimicrobial therapy should be considered for high-risk sources.
Colistin has a narrow therapeutic window with nephrotoxicity being the major dose-limiting adverse effect. Currently, the optimal doses and therapeutic plasma levels are unknown.
Prospective ...observational cohort study, including patients infected by colistin-susceptible P. aeruginosa treated with intravenous colistimethate sodium (CMS). Clinical data and colistin plasma levels at steady-state (C
) were recorded. The primary and secondary end points were clinical cure and 30-day all-cause mortality.
Ninety-one patients were included. Clinical cure was observed in 72 (79%) patients. The mean (SD) C
was 1.49 (1.4) mg/L and 2.42 (1.5) mg/L (p = 0.01) in patients who achieved clinical cure and those who not, respectively. Independent risk factors for clinical failure were male sex (OR 5.88; 95% CI 1.09-31.63), APACHE II score (OR 1.15; 95% CI 1.03-1.27) and nephrotoxicity at the EOT (OR 9.13; 95% CI 95% 2.06-40.5). The 30-day mortality rate was 30.8%. Risk factors for 30-day mortality included the APACHE II score (OR 1.98; 95% CI 1-1.20), the McCabe score (OR 2.49; 95% CI 1.14-5.43) and the presence of nephrotoxicity at the end of treatment (EOT) (OR 3.8; 95% CI 1.26-11.47).
In this series of patients with infections caused by XDR P. aeruginosa infections, C
is not observed to be related to clinical outcome.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Time-kill curves are used to study antibiotic combinations, but the colony count method to obtain the results is time-consuming. The aim of the study was to validate an ATP assay as an alternative to ...the conventional colony count method in studies of antibiotic combinations. The cutoff point for synergy and bactericidal effect to categorize the results using this alternative method were determined in Pseudomonas aeruginosa. The ATP assay was performed using the GloMax 96 microplate luminometer (Promega), which measures bioluminescence in relative light units (RLU). To standardize this assay, background, linearity, and the detection limit were determined with one strain each of multidrug-resistant P. aeruginosa and Klebsiella pneumoniae. Twenty-four-hour time-kill curves were performed in parallel by both methods with 12 strains of P. aeruginosa. The conventional method was used as a “gold” standard to establish the pharmacodynamic cutoff points in the ATP method. Normal saline solution was established as washing/dilution medium. RLU signal correlated with CFU when the assay was performed within the linear range. The categorization of the pharmacodynamic parameters using the ATP assay was equivalent to that of the colony count method. The bactericidal effect and synergy cutoff points were 1.348 (93% sensitivity, 81% specificity) and 1.065 (95% sensitivity, 89% specificity) log RLU/mL, respectively. The ATP assay was useful to determine the effectiveness of antibiotic combinations in time-kill curves. This method, less laborious and faster than the colony count method, could be implemented in the clinical laboratory workflow. IMPORTANCE Combining antibiotics is one of the few strategies available to overcome infections caused by multidrug-resistant bacteria. Time-kill curves are usually performed to evaluate antibiotic combinations, but obtaining results is too laborious to be routinely performed in a clinical laboratory. Our results support the utility of an ATP measurement assay using bioluminescence to determine the effectiveness of antibiotic combinations in time-kill curves. This method may be implemented in the clinical laboratory workflow as it is less laborious and faster than the conventional colony count method. Shortening the obtention of results to 24 h would also allow an earlier guided combined antibiotic treatment.
•Extensively drug resistant (XDR) Pseudomonas aeruginosa causes severe infections.•There is a high risk of resistance selection in these clones.•Colistin has been the only available treatment but ...that is not an optimal treatment.•Combination regimens could suppress emerging resistance.•Colistin plus meropenem is synergistic in vitro against XDR Pseudomona aeruginosa.
Extensively drug-resistant (XDR) Pseudomonas aeruginosa (P. aeruginosa) and particularly P. aeruginosa high-risk clones, are of growing concern because treatment options are limited. For years, colistin monotherapy has been the only available treatment, but is well known that is not an optimal treatment. A combination of colistin with another antibiotic could be a possible therapeutic option.
This study aimed to investigate effective antibiotic combinations against 20 XDR P. aeruginosa isolates obtained in a Spanish multicentre study (2015).
Forty-five checkerboards with six antipseudomonal antibiotics (amikacin, aztreonam, ceftazidime, meropenem, colistin, and ceftolozane/tazobactam) were performed to determine whether combinations were synergic or additive by fractional inhibitory concentration indices. On average, 15 different regimens were evaluated in duplicate against the three most prevalent high-risk clones (ST175, ST235, ST111) by time-kill analyses over 24h. The combination showing synergism in the three high-risk clones was validated in all studied XDR isolates.
In time-kill curves, the untreated control failed, as did each study regimen when administered alone. Two combinations were synergistic in the three high-risk clones that were initially studied: amikacin plus ceftazidime and colistin plus meropenem, with the second being the most effective combination. The efficacy of colistin plus meropenem was then tested in all 20 isolates. A synergistic bacterial density reduction for the duration of the study occurred in 80% of the entire XDR collection.
These data suggest that colistin plus meropenem may be a useful combination for the treatment of infections due to XDR P. aeruginosa, including high-risk clones, which warrants evaluation in a clinical trial.
An outbreak of severe nosocomial Burkholderia cepacia infections in patients admitted to intensive care unit (ICU), including investigation of the reservoir, is described.
Over a period of 18 days, ...isolates of Burkholderia cepacia were recovered from different biological samples from five patients who were admitted to a multidisciplinary 18-bed intensive care unit. Isolation of B. cepacia was associated with bacteraemia in three cases, lower respiratory tract infection in one and urinary tract infection in one. Contact isolation measures were instituted; new samples from the index patients and adjacent patients were collected; and samples of antiseptics, eau de Cologne and moisturizing body milk available in treatment carts at that time were collected and cultured.
B. cepacia was isolated from three samples of the moisturizing body milk that had been applied to the patients. Three new hermetically closed units, from three different batches, were sent for culture; two of these were positive as well. All strains recovered from environmental and biological samples were identified as belonging to the same clone by pulsed-field gel electrophoresis. The cream was withdrawn from all hospitalization units and no new cases of B. cepacia infection developed.
Moisturizing body milk is a potential source of infection. In severely ill patients, the presence of bacteria in cosmetic products, even within accepted limits, may lead to severe life-threatening infections.
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