Relationship Between Immune Response to Severe Acute Respiratory Syndrome Coronavirus 2 Vaccines and Development of Breakthrough Infection in Solid Organ Transplant Recipients: The CONTRAST Cohort.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination in solid organ transplant (SOT) recipients is associated with poorer antibody response (AbR) compared with non-SOT recipients. However, its impact on the risk of breakthrough infection (BI) has yet to be assessed. METHODS: Single-center prospective longitudinal cohort study enrolling adult SOT recipients who received SARS-CoV-2 vaccination during a 1-year period (February 2021 - January 2022), end of follow-up April 2022. Patients were tested for AbR at multiple time points. The primary end-point was BI (laboratory-confirmed SARS-CoV-2 infection ≥14 days after the second dose). Immunization (positive AbR) was considered an intermediate state between vaccination and BI. Probabilities of being in vaccination, immunization, and BI states were obtained for each type of graft and vaccination sequence using multistate survival analysis. Then, multivariable logistic regression was performed to analyze the risk of BI related to AbR levels. RESULTS: 614 SOT (275 kidney, 163 liver, 137 heart, 39 lung) recipients were included. Most patients (84.7%) received 3 vaccine doses. The first 2 consisted of BNT162b2 and mRNA-1273 in 73.5% and 26.5% of cases, respectively. For the third dose, mRNA-1273 was administered in 59.8% of patients. Overall, 75.4% of patients reached immunization and 18.4% developed BI. Heart transplant recipients showed the lowest probability of immunization (0.418) and the highest of BI (0.323); all mRNA-1273 vaccine sequences showed the highest probability of immunization (0.732) and the lowest of BI (0.098). Risk of BI was higher for non-high-level AbR, younger age, and shorter time from transplant. CONCLUSIONS: SOT patients with non-high-level AbR and shorter time from transplantation and heart recipients are at highest risk of BI.

Comparison between available early antiviral treatments in outpatients with SARS-CoV-2 infection: a real-life study.

PURPOSE: To investigate the clinical impact of three available antivirals for early COVID-19 treatment in a large real-life cohort. METHODS: Between January and October 2022 all outpatients tested positive for SARS-CoV-2 referring to IRCCS S. Orsola hospital treated with an early antiviral therapy were enrolled. A comparison between patients treated with nirmatrelvir/ritonavir (NTV/r), molnupiravir (MPV) and remdesivir (RDV) was conducted in term of indications and outcome. To account for differences between treatment groups a propensity score analysis was performed. After estimating the weights, we fitted a survey-weighted Cox regression model with inverse-probability weighting with hospital admission/death versus clinical recovery as the primary outcome. RESULTS: Overall 1342 patients were enrolled, 775 (57.8%), 360 (26.8%) and 207 (15.4%) in MPV, NTV/r and RDV group, respectively. Median age was 73 (59-82) years, male sex was 53.4%. Primary indication was immunosuppression (438, 32.6%), the median time from symptom onset to drug administration was 3 [2-4] days. Overall, clinical recovery was reached in 96.9% of patients, with hospital admission rate of 2.6%. No significant differences were found in clinical recovery nor hospitalization. Cox regression showed a decreased probability of hospital admission/ death among prior vaccinated patients compared with unvaccinated (HR 0.31 [95%CI 0.14-0.70], p = 0.005]). No difference in hospitalization rates in early treatment compared to late treatment were found. CONCLUSIONS: No differences among MPV, NTV/r and RDV in terms of clinical recovery or hospitalization were found. Patients not vaccinated had a significant increased risk of hospitalization.

Follow-up blood culture in Gram-negative bacilli bacteraemia: for whom is follow-up blood culture useful?

PURPOSE OF REVIEW: The aim of this narrative review is to examine available evidence about the diagnostic yielding of the follow-up blood cultures (FU-BCs) in patients with Gram-negative bloodstream infection (GN-BSI), the predictors of persistent GN-BSI, and the impact of the performance of FU-BCs on patient management and clinical outcome. RECENT FINDINGS: The rate of persistent GN-BSI varies from 2.6% to 38.5%, with higher percentages in studies where FU-BCs were obtained from selected patients. Risk factors for persistent GN-BSI were analysed and prediction tools were proposed to guide physicians in the selection of patients. The impact of FU-BCs on patient management is still controversial as several authors have shown that this practice was associated with prolonged treatment duration and longer hospital stay. However, when adjusted for indication and survival bias, the performance of FU-BCs was a strong predictor of survival in large cohorts of hospitalized patients with GN-BSI. Favourable outcome seemed to be associated with higher rate of source control in GN-BSI patients managed with FU-BCs. SUMMARY: The practice of FU-BCs in patients with GN-BSI should be individualised balancing cost/benefit ratio. The use of risk scores could be useful in selecting patients for whom FU-BCs are appropriate.

The challenge of infectious diseases consultations in the emergency department: an Italian nationwide survey.

Diagnosis and management of infectious diseases (ID) at the emergency department (ED) are challenging due to the peculiar setting and the available diagnostic tools. The involvement of an ID consultant has been described to improve clinical outcomes and antimicrobial stewardship (AMS) programs. An online survey was sent to 100 Italian Departments of Infectious Diseases affiliated with the Italian Society of Infectious Diseases and Tropical Medicine (SIMIT). The primary objective of our study was to describe the characteristics of ID services in Italian EDs to identify possible challenges and shortcomings and provide tips to improve the management of patients. Secondary objectives included the evaluation of diagnostic capability and the management of patients with suspected or confirmed ID. Seventy-six out of the 100 SIMIT centers, 32 (42.1%) of which were teaching hospitals, answered the survey. In 62 (82.7%) centers, consultations were performed by the IDs specialist on call. In 29 (38.2%) centers, there was a formal AMS program, and 32 (42.7%) had protocols for antibiotic use in the ED. Microbiological tests to be performed before starting antibiotic treatment in the ED were clearly defined in 44 (57.9%) hospitals. This survey highlighted several challenges in the current organization of ID consultations in Italian EDs.

Epidemiology of Invasive Pulmonary Aspergillosis Among Intubated Patients With COVID-19: A Prospective Study.

BACKGROUND: We evaluated the incidence of invasive pulmonary aspergillosis among intubated patients with critical COVID-19 and evaluated different case definitions of invasive aspergillosis. METHODS: Prospective, multicenter study in adult patients with microbiologically confirmed COVID-19 receiving mechanical ventilation. All included participants underwent a screening protocol for invasive pulmonary aspergillosis with bronchoalveolar lavage galactomannan and cultures performed on admission at 7 days and in case of clinical deterioration. Cases were classified as coronavirus-associated pulmonary aspergillosis (CAPA) according to previous consensus definitions. The new definition was compared with putative invasive pulmonary aspergillosis (PIPA). RESULTS: 108 patients were enrolled. Probable CAPA was diagnosed in 30 (27.7%) patients after a median of 4 (2-8) days from intensive care unit (ICU) admission. Kaplan-Meier curves showed a significantly higher 30-day mortality rate from ICU admission among patients with either CAPA (44% vs 19%, P = .002) or PIPA (74% vs 26%, P < .001) when compared with patients not fulfilling criteria for aspergillosis. The association between CAPA (OR, 3.53; 95% CI, 1.29-9.67; P = .014) or PIPA (OR, 11.60; 95% CI, 3.24-41.29; P < .001) with 30-day mortality from ICU admission was confirmed, even after adjustment for confounders with a logistic regression model. Among patients with CAPA receiving voriconazole treatment (13 patients; 43%) a trend toward lower mortality (46% vs 59%; P = .30) and reduction in galactomannan index in consecutive samples were observed. CONCLUSIONS: We found a high incidence of CAPA among critically ill COVID-19 patients and its occurrence seems to change the natural course of disease.

Non-fermentative gram-negative bloodstream infection in northern Italy: a multicenter cohort study.

BACKGROUND: The management of non-fermentative gram-negative bloodstream infection (NFGN-BSI) offers numerous challenges. In this study the aim is to analyse a large cohort of patients with NFGN-BSI recruited in the northern Italy to describe epidemiology, etiological and susceptibility pattern, therapeutic management and outcome. METHODS: Multicentre retrospective cohort study of patients hospitalised at three large teaching hospitals in northern Italy in a fourth year period. RESULTS: 355 BSI episodes were analyzed, due to P. aeruginosa (72.7%), A. baumannii (16.6%), and Stenotrophomonas maltophilia (10.7%). Overall, 21.4% of isolates were defined as DTR, highest rate among A. baumannii (64.4%). All-cause 30-day mortality rate was 17.5%. Rates of XDR or DTR A. baumannii isolation were significantly higher in non-surviving patients. Independent risk factors for 30-day mortality were: age (HR 1.03, 95%CI 1.00-1.04, p = 0.003), septic shock (HR 2.84, 95%CI 1.67-4.82, p < 0.001) and BSI due to Acinetobacter baumannii (HR 2.23, 95%CI 1.27-3.94, p = 0.005). CONCLUSION: The overall prevalence of DTR was high in the NFGN BSI cohort analyzied, mainly among Acinetobacter baumannii episodes (64.4%). Acinetobacter baumannii is showed to be an independent predictor of mortality. These evidences marked the urgent need of new therapeutic options against this pathogen. TRIAL REGISTRATION NUMBER: 79/2017/O/OssN. Approved: March14th, 2017.

COVID-19 in solid organ transplant recipients: No difference in survival compared to general population.

Coronavirus disease 2019 (COVID-19) may be associated with worse outcome in solid organ transplant (SOT) recipients. We performed a prospective cohort study of hospitalized patients with confirmed diagnosis of COVID-19, from March 15 to April 30, 2020, at two tertiary hospitals in Emilia-Romagna Region. SOT recipients were compared with non-SOT patients. Primary endpoint was all-cause 30-day mortality. Relationship between SOT status and mortality was investigated by univariable and multivariable Cox regression analysis. Patients were assessed from COVID-19 diagnosis to death or 30-day whichever occurred first. Study cohort consisted of 885 patients, of them 24 SOT recipients (n = 22, kidney, n = 2 liver). SOT recipients were younger, had lower BMI, but higher Charlson Index. At admission they presented less frequently with fever and respiratory failure. No difference in 30-day mortality between the two groups (19% vs 22.1%) was found; however, there was a trend toward higher rate of respiratory failure (50% vs 33.1%, P = .07) in SOT recipients. Superinfections were more represented in SOT recipients, (50% vs 15.5%, P < .001). At multivariate analysis adjusted for main covariates, there was no association between SOT and 30-day mortality HR 1.15 (95% CI 0.39-3.35) P = .79. Our data suggest that mortality among COVID-19 SOT recipients is similar to general population.

Breakthrough invasive fungal infection after liver transplantation in patients on targeted antifungal prophylaxis: A prospective multicentre study.

OBJECTIVE: To investigate the rate of and the risk factors for breakthrough-IFI (b-IFI) after orthotopic liver transplantation (OLT) according to the new definition proposed by Mycoses-Study-Group-Education-and-Research-Consortium (MSG-ERC) and the European-Confederation-of-Medical-Mycology (ECMM). METHODS: Multicenter prospective study of adult patients who underwent OLT at three Italian hospitals, from January 2015 to December 2018. Targeted antifungal prophylaxis (TAP) protocol was developed and shared among participating centers. Follow-up was 1-year after OLT. B-IFI was defined as infection occurring during exposure to antifungal prophylaxis. Risk factors for b-IFI were analyzed among patients exposed to prophylaxis by univariable analysis. RESULTS: We enrolled 485 OLT patients. Overall compliance to TAP protocol was 64.3%, 220 patients received antifungal prophylaxis, 172 according to TAP protocol. Twenty-nine patients were diagnosed of IFI within 1 year after OLT. Of them, 11 presented with b-IFI within 17 (IQR 11-33) and 16 (IQR 4-30) days from OLT and from antifungal onset, respectively. Then out of 11 patients with b-IFI were classified as having high risk of IFI and were receiving anti-mould prophylaxis, nine with echinocandins and one with polyenes. Comparison of patients with and without b-IFI showed significant differences for prior Candida colonization, need of renal replacement therapy after OLT, re-operation, and CMV infection (whole blood CMV-DNA >100 000 copies/mL). Although non-significant, a higher rate of b-IFI in patients on echinocandins was observed (8.2% vs 1.8%, P = .06). CONCLUSIONS: We observed 5% of b-IFI among OLT patients exposed to antifungal prophylaxis. The impact of echinocandins on b-IFI risk in this setting should be further explored.

Potential role of T2Candida in the management of empirical antifungal treatment in patients at high risk of candidaemia: a pilot single-centre study.

Objectives: We estimated the diagnostic accuracy of T2Candida, with blood culture (BC) as the gold standard, and compared turnaround time between these two techniques in order to investigate the potential role of T2Candida in the management of empirical antifungal treatment (EAT). Methods: We performed a single-centre prospective observational study in patients with severe sepsis or septic shock and multiple risk factors for candidaemia. Results: We analysed 46 out of 50 screened patients. All patients received an echinocandin as EAT; the median EAT duration was 7 days (IQR 4-13 days). BCs were negative in 31 (67.4%) patients, positive for bacteria in 14 (30.4%) patients and positive for Candida albicans in 1 (2.2%) patient. T2Candida was negative, invalid and positive in 37, 5 and 4 patients, respectively. T2Candida and BC results were concordant in all but three patients, where T2Candida was positive and BCs were negative. Two of them were on antifungal prophylaxis at the time of enrolment. T2Candida reduced time to a negative result by 5 days. T2Candida performance was: sensitivity = 100% (95% CI 2.5%-100%), specificity = 91.8% (95% CI 78%-98%), positive predictive value = 25% (95% CI 0.63%-80.6%) and negative predictive value = 100% (95% CI 89.7%-100%). Conclusions: In patients with multiple risk factors for candidaemia and severe sepsis or septic shock, T2Candida may be helpful to reduce the length of EAT.

Management of immunosuppressive therapy in liver transplant recipients who develop bloodstream infection.

BACKGROUND: Data about the optimal management of immunosuppressive therapy in liver transplant (LT) recipients with bloodstream infection (BSI) are missing. We aimed to describe the management of immunosuppressive therapy at diagnosis of BSI in LT recipients and to assess its impact on 28-day mortality. METHODS: We performed a single-center retrospective study of all LT recipients diagnosed with BSI, over 10-year period. Multivariate Cox regression analysis of risk factors for all cause 28-day mortality was adjusted for the propensity score of being managed with "any reduction" in immunosuppressive therapy at the diagnosis of BSI. RESULTS: We identified 209 episodes of BSI in 157 LT recipients: 107 (68%) male, median age 54 (IQR 48-63) years. "Any reduction" was made in 90 (43%) cases including: dosage reduction of ≥1 immunosuppressive drug in 31 (15%), discontinuation of ≥1 immunosuppressive drug in 28 (13%), both dosage reduction and discontinuation in 13 (6%), complete withdrawal of immunosuppressive therapy in 18 (9%) cases. All-cause 28-day mortality rate was 13.4%, varying from 22% to 7% (P = .002) in cases with and without "any reduction". Cox regression showed septic shock (aHR 3.15, P = .007) and "any reduction" (aHR 2.50, P = .02) as independent risk factors for all-cause 28-day mortality, while Escherichia coli (aHR 0.38, P = .03) and source control (aHR 0.43, P = .04) were protective factors. The final model did not change after the introduction of the propensity score for "any reduction". CONCLUSIONS: Any reduction in the immunosuppressive therapy was common and was associated with worse outcome in LT recipients developing BSI.

Real-Time TDM-Guided Optimal Joint PK/PD Target Attainment of Continuous Infusion Piperacillin-Tazobactam Monotherapy Is an Effective Carbapenem-Sparing Strategy for Treating Non-Severe ESBL-Producing Enterobacterales Secondary Bloodstream Infections: Findings from a Prospective Pilot Study.

(1) Objectives: To assess the impact of optimal joint pharmacokinetic/pharmacodynamic (PK/PD) target attainment of continuous infusion (CI) piperacillin-tazobactam monotherapy on the microbiological outcome of documented ESBL-producing Enterobacterlaes secondary bloodstream infections (BSIs). (2) Methods: Patients hospitalized in the period January 2022-October 2023, having a documented secondary BSI caused by ESBL-producing Enterobacterales, and being eligible for definitive targeted CI piperacillin-tazobactam monotherapy according to specific pre-defined inclusion criteria (i.e., absence of septic shock at onset; favorable clinical evolution in the first 48 h after starting treatment; low-intermediate risk primary infection source) were prospectively enrolled. A real-time therapeutic drug monitoring (TDM)-guided expert clinical pharmacological advice (ECPA) program was adopted for optimizing (PK/PD) target attainment of CI piperacillin-tazobactam monotherapy. Steady-state plasma concentrations (Css) of both piperacillin and tazobactam were measured, and the free fractions (f) were calculated based on theoretical protein binding. The joint PK/PD target attainment was considered optimal whenever the piperacillin fCss/MIC ratio was >4 and the tazobactam fCss/target concentration (CT) ratio was >1 (quasi-optimal or suboptimal if only one or neither of the two thresholds were achieved, respectively). Univariate analysis was carried out for assessing variables potentially associated with failure in achieving the optimal joint PK/PD target of piperacillin-tazobactam and microbiological eradication. (3) Results: Overall, 35 patients (median age 79 years; male 51.4%) were prospectively included. Secondary BSIs resulted from urinary tract infections as a primary source in 77.2% of cases. The joint PK/PD target attainment was optimal in as many as 97.1% of patients (34/35). Microbiological eradication occurred in 91.4% of cases (32/35). Attaining the quasi-optimal/suboptimal joint PK/PD target of CI piperacillin-tazobactam showed a trend toward a higher risk of microbiological failure (33.3% vs. 0.0%; p = 0.08) (4) Conclusions: Real-time TDM-guided optimal joint PK/PD target attainment of CI piperacillin-tazobactam monotherapy may represent a valuable and effective carbapenem-sparing strategy when dealing with non-severe ESBL-producing Enterobacterales secondary BSIs.

Gut microbiome dynamics and Enterobacterales infection in liver transplant recipients: A prospective observational study.

Background & Aims: The aim of this study was to investigate gut microbiome (GM) dynamics in relation to carbapenem-resistant Enterobacterales (CRE) colonization, CRE infection, and non-CRE infection development within 2 months after liver transplant (LT). Methods: A single-center, prospective study was performed in patients undergoing LT from November 2018 to January 2020. The GM was profiled through 16S rRNA amplicon sequencing of a rectal swab taken on the day of transplantation, and fecal samples were collected weekly until 1 month after LT. A subset of samples was subjected to shotgun metagenomics, including resistome dynamics. The primary endpoint was to explore changes in the GM in the following groups: (1) CRE carriers developing CRE infection (CRE_I); (2) CRE carriers not developing infection (CRE_UI); (3) non-CRE carriers developing microbial infection (INF); and (4) non-CRE carriers not developing infection (NEG). Results: Overall, 97 patients were enrolled, and 91 provided fecal samples. Of these, five, nine, 22, and 55 patients were classified as CRE_I, CRE_UI, INF, and NEG, respectively. CRE_I patients showed an immediate and sustained post-LT decrease in alpha diversity, with depletion of the GM structure and gradual over-representation of Klebsiella and Enterococcus. The proportions of Klebsiella were significantly higher in CRE_I patients than in NEG patients even before LT, serving as an early marker of subsequent CRE infection. CRE_UI patients had a more stable and diverse GM, whose compositional dynamics tended to overlap with those of NEG patients. Conclusions: GM profiling before LT could improve patient stratification and risk prediction and guide early GM-based intervention strategies to reduce infectious complications and improve overall prognosis. Impact and implications: Little is known about the temporal dynamics of gut microbiome (GM) in liver transplant recipients associated with carbapenem-resistant Enterobacterales (CRE) colonization and infection. The GM structure and functionality of patients colonized with CRE and developing infection appeared to be distinct compared with CRE carriers without infection or patients with other microbial infection or no infection and CRE colonization. Higher proportions of antimicrobial-resistant pathogens and poor representation of bacteria and metabolic pathways capable of promoting overall host health were observed in CRE carriers who developed infection, even before liver transplant. Therefore, pretransplant GM profiling could improve patient stratification and risk prediction and guide early GM-based intervention strategies to reduce infectious complications and improve overall prognosis.

Outcomes and Predictors of Mortality in Patients With KPC-Kp Infections Treated With Meropenem Vaborbactam: An Observational Multicenter Study.

Background: Meropenem-vaborbactam is a recent and promising option for the treatment of KPC-producing Klebsiella pneumoniae (KPC-Kp) infections, including those resistant to ceftazidime-avibactam. Methods: We conducted a retrospective analysis of observational data from 19 Italian hospitals on use and outcomes of patients treated with meropenem-vaborbactam for at least ≥24 hours for KPC-Kp infections. Crude and propensity-weighted multiple Cox regression models were performed to ascertain risk factors independently associated with 30-day mortality. Results: The cohort included 342 adults with bloodstream infections (n = 172) and nonbacteremic infections (n = 170), of which 107 were lower respiratory tract infections, 30 were complicated urinary tract infections, and 33 were infections involving other sites. Most infections (62.3%) were managed with meropenem-vaborbactam monotherapy, or in combination with at least 1 other active drug (usually fosfomycin, tigecycline, or gentamicin) (37.7%). The 30-day mortality rate was 31.6% (108/342). In multiple Cox regression model, 30-day mortality was independently associated with septic shock at infection onset, Charlson comorbidity index ≥ 3, dialysis, concomitant COVID-19, and INCREMENT score ≥ 8. Administration of meropenem-vaborbactam within 48 hours from infection onset was a negative predictor of mortality. All predictors, except administration of meropenem-vaborbactam within 48 hours, remained significant when the multiple Cox regression model was repeated after adjustment for the propensity score for receipt of combination therapy. Conclusions: Despite the limits of a retrospective study, the data derived from this multicenter cohort provide additional evidence on the efficacy of meropenem-vaborbactam in treating severe KPC-Kp infections, even when used as monotherapy.

Sphingomonas paucimobilis osteomyelitis in an immunocompetent patient. A rare case report and literature review.

Sphingomonas paucimobilis occurs widely both in natural and nosocomial environments, including hospital water systems, respiratory therapy equipment, and laboratory instruments. It is an opportunistic pathogen that rarely causes infections in humans. Among S. paucimobilis nosocomial infections, osteomyelitis is particularly rare. Almost all infections occur in patients with comorbidities such as malignancy, immunosuppressant therapy, diabetes mellitus and acquired immunodeficiency syndrome. We present the first case of Sphingomonas paucimobilis osteomyelitis in an immunocompetent patient and include updated literature concerning infections by this microorganism.

Population Pharmacokinetic and Pharmacodynamic Analysis for Maximizing the Effectiveness of Ceftobiprole in the Treatment of Severe Methicillin-Resistant Staphylococcal Infections.

Ceftobiprole is a fifth-generation cephalosporin used for different Gram-positive bacterial infections. A population pharmacokinetic analysis was conducted in real-life clinical patients to assess the adequacy of current dosages. Population pharmacokinetics was conducted using non-linear mixed effect modeling. Monte Carlo simulations were performed to determine the probability of target attainment (PTA) of free trough or steady-state concentration over MIC (fCtrough/MIC or fCss/MIC) ≥ 1 or ≥4 associated with both the standard and intensified dosing regimens adjusted for renal function. Cumulative fraction of response (CFR) against methicillin-resistant Staphylococcus aureus (MRSA) and Staphylococcus epidermidis (MRSE) were also calculated. A total of 132 patients with 503 concentrations were included. Most of them (107/132, 81.1%) had hospital- or community-acquired pneumonia, endocarditis, and bacteremia. A three-compartment model adequately fitted ceftobiprole concentration-time data. Estimated glomerular filtration rate significantly affected drug clearance. Monte Carlo simulations showed that the optimal target of fCtrough/MIC or fCss/MIC ≥ 4 is achieved only with the use of the standard dosages administered by continuous infusion (CI) against MRSA infections in patients with preserved renal function. Intensified dosages administered by CI are needed in patients with impaired renal function and/or augmented renal clearance against MRSA and in patients with preserved renal functions against MRSE.

A descriptive pharmacokinetic/pharmacodynamic analysis of continuous infusion ceftazidime-avibactam in a case series of critically ill renal patients treated for documented carbapenem-resistant Gram-negative bloodstream infections and/or ventilator-associated pneumonia.

OBJECTIVES: To describe the pharmacokinetic/pharmacodynamic (PK/PD) behaviour of continuous infusion (CI) ceftazidime-avibactam and the microbiological outcome in a case series of critically ill renal patients treated for documented carbapenem-resistant Gram-negative (CR-GN) bloodstream infections (BSI) and/or ventilator-associated pneumonia (VAP). METHODS: Critically ill patients with different degrees of renal function who were treated with CI ceftazidime-avibactam for documented CR-GN infections, and who underwent therapeutic drug monitoring from April 2021 to March 2022, were retrospectively assessed. Ceftazidime and avibactam concentrations were determined at steady-state, and the free fraction (fCss) was calculated. The joint PK/PD target of ceftazidime-avibactam was considered as optimal when both Css/MIC ratio for ceftazidime ≥4 (equivalent to 100%fT>4xMIC) and Css/CT ratio for avibactam >1 (equivalent to 100% fT>CT of 4.0 mg/L) were simultaneously achieved (quasi-optimal if only one of the two was achieved, and suboptimal if neither of the two was achieved). The relationship between ceftazidime-avibactam PK/PD targets and microbiological outcome was assessed. RESULTS: Ten patients with documented CR-GN infections (5 BSIs, 4 VAP, 1 BSI+VAP) were retrieved. The joint PK/PD targets of ceftazidime-avibactam were optimal and quasi-optimal in eight and two cases, respectively. Microbiological failure occurred in two patients (one with VAP, one with BSI+VAP), one of whom developed ceftazidime-avibactam resistance. Both underwent renal replacement therapy, and failed despite attaining optimal joint PK/PD target and receiving fosfomycin co-treatment. CONCLUSION: CI administration may enable optimal joint PK/PD targets of ceftazidime-avibactam to be achieved in most critical renal patients with CR-GN infections, and may help to minimize the risk of microbiological failure.

Impact on clinical outcome of follow-up blood cultures and risk factors for persistent bacteraemia in patients with gram-negative bloodstream infections: a systematic review with meta-analysis.

BACKGROUND: The clinical usefulness of follow-up blood cultures (FUBCs) in gram-negative bloodstream infections (GN-BSIs) represents a debated issue. OBJECTIVE: To assess the impact on the clinical outcome of FUBCs in patients with GN-BSI and to predict risk factors for persistent bacteraemia. DATA SOURCES: PubMed-MEDLINE, Scopus, and the Cochrane Library Database were independently searched until 24 June, 2022. STUDY ELIGIBILITY CRITERIA: Randomized controlled trials, prospective, or retrospective observational studies, including patients affected by GN-BSIs. Primary endpoints were in-hospital mortality rate, and persistent blood stream infections were defined as FUBC-positive for the same pathogen isolated from index blood cultures (BCs). PARTICIPANTS: Hospitalized patients with documented GN-BSIs. INTERVENTION: Performance of FUBCs (defined as subsequent BCs collected at least 24 hours after index BCs). ASSESSMENT OF RISK OF BIAS: Quality of included studies was independently assessed according to the Cochrane Risk of Bias Tool and the Risk Of Bias In Non-randomized Studies of Interventions. METHODS OF DATA SYNTHESIS: Meta-analysis was performed by pooling odds ratio (OR) retrieved from studies providing adjustment for confounders using random-effect model with the inverse variance method. Risk factors for persistent blood stream infections were also assessed. RESULTS: A total of 3747 articles were screened, and 11 observational studies (6 assessing impact on outcome (N = 4631), and 5 investigating risk factors for persistent GN-BSI (N = 2566)), conducted between 2002 and 2020 were included. The execution of FUBCs was associated with a significantly lower risk of mortality (OR, 0.58; 95% CI, 0.49-0.70; I2 = 0.0%). The presence of end-stage renal disease (OR, 2.99; 95% CI, 1.77-5.05), central venous catheter (OR, 3.30; 95% CI, 1.82-5.95), infections due to extended-spectrum ß-lactamase-producing strains (OR, 2.25; 95% CI, 1.18-4.28), resistance to empirical treatment (OR, 2.70; 95% CI, 1.65-4.41), and unfavourable response at 48 hours (OR, 2.99; 95% CI, 1.44-6.24) emerged as independent risk factors for persistent bacteraemia. CONCLUSIONS: The execution of FUBCs is associated with a significantly low risk of mortality in patients with GN-BSIs. Our analysis could be useful to stratify patients at a high risk of persistent bacteraemia to optimize the use of FUBCs.