[Advances in the diagnosis and treatment strategy of polymyxin resistant Klebsiella pneumoniae].

In recent years, the detection rate of multidrug-resistant and pandrug-resistant Klebsiella pneumoniae has increased year on year, so polymyxin has received increasing attention as an antibiotic that is still sensitive to most of the multidrug-resistant strains. However, widespread use of polymyxin is likely to lead to the emergence of polymyxin-resistant Klebsiella pneumoniae. At the same time, the polymyxin hetero-resistance has made clinical prevention and treatment difficult. In addition to relying on the combination of polymyxins with other antibiotics, the search for new antibacterial drugs has also become a research hotspot. Research into early detection methods for polymyxin resistance can also help to optimize and improve the diagnosis and treatment strategies. This article reviewed the epidemic status, mechanism, detection methods and prevention measures of polymyxin-resistant Klebsiella pneumoniae.

Rapid diagnostics and ceftazidime/avibactam for KPC-producing Klebsiella pneumoniae bloodstream infections: impact on mortality and role of combination therapy.

This study was aimed at investigating risk factors for mortality in patients suffering from KPC-producing Klebsiella pneumoniae (KPC-Kp) bloodstream infections (BSIs), evaluating the impact of rapid diagnostics and ceftazidime/avibactam use. This observational retrospective study (January 2017-May 2021) included all patients with a KPC-Kp BSI. Uni-multivariable analyses were carried out to evaluate the effect of clinical variables on both in-hospital death (IHD) and 30-day all-cause mortality, and the role of the combination of ceftazidime/avibactam plus polymyxin. One hundred and ninety-six patients met the study's inclusion criteria. Older age, having undergone renal replacement therapy during the 30 days preceding the KPC-Kp BSI onset, having an INCREMENT-CPE score ≥ 8, and having suffered from a superimposed and/or following KPC-Kp BSI treatment candidemia were found to be the main factors associated with both mortality rates. Among protective factors, the centrality of ceftazidime/avibactam in monotherapy (IHD: OR: 0.34; CI 95%: 0.11-1.00-30-day all-cause mortality: OR: 0.18; CI 95%: 0.04-0.77) or combination (IHD: OR: 0.51; CI 95%: 0.22-1.19-30-day all-cause mortality: OR: 0.62; CI 95%: 0.21-1.84) emerged and became even more evident once the effect of ceftazidime/avibactam plus polymyxin was removed. Rapid diagnostics may be useful to adopt more effective strategies for the treatment of KPC-Kp BSI patients and implement infection control measures, even if not associated with higher patient survival. Ceftazidime/avibactam, even when used alone, represents an important option against KPC-Kp, while combined use with polymyxin might not have altered its efficacy. Patient comorbidities, severity of BSI, and complications such as candidemia were confirmed to have a significant burden on survival.

Influence of Antimicrobial Stewardship and Molecular Rapid Diagnostic Tests on Antimicrobial Prescribing for Extended-Spectrum Beta-Lactamase- and Carbapenemase-Producing Escherichia coli and Klebsiella pneumoniae in Bloodstream Infection.

The objective of this study was to evaluate whether the addition of the Verigene BC-GN molecular rapid diagnostic test to standard antimicrobial stewardship practices (mRDT + ASP) decreased the time to optimal and effective antimicrobial therapy for patients with extended-spectrum beta-lactamase (ESBL)- and carbapenemase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections (BSI) compared to conventional microbiological methods with ASP (CONV + ASP). This was a multicenter, retrospective cohort study evaluating the time to optimal antimicrobial therapy in 5 years of patients with E. coli or K. pneumoniae BSI determined to be ESBL- or carbapenemase-producing by mRDT and/or CONV. Of the 378 patients included (mRDT + ASP, n = 164; CONV + ASP, n = 214), 339 received optimal antimicrobial therapy (mRDT + ASP, n = 161; CONV + ASP, n = 178), and 360 (mRDT + ASP, n = 163; CONV + ASP, n = 197) received effective antimicrobial therapy. The mRDT + ASP demonstrated a statistically significant decrease in the time to optimal antimicrobial therapy (20.5 h [interquartile range (IQR), 17.0 to 42.2 h] versus 50.1 h [IQR, 27.6 to 77.9 h]; P < 0.001) and the time to effective antimicrobial therapy (15.9 h [IQR, 1.9 to 25.7 h] versus 28.0 h [IQR, 9.5 to 56.7 h]; P < 0.001) compared to CONV + ASP, respectively. IMPORTANCE Our study supports the additional benefit of molecular rapid diagnostic test in combination with timely antimicrobial stewardship program (ASP) intervention on shortening the time to both optimal and effective antimicrobial therapy in patients with ESBL- or carbapenemase-producing Escherichia coli and Klebsiella pneumoniae bloodstream infections, compared to conventional microbiological methods and ASP. Gram-negative infections are associated with significant morbidity and mortality, often resulting in life-threatening organ dysfunction. Both resistance phenotypes confer resistance to many of our first-line antimicrobial agents with carbapenemase-producing Enterobacterales requiring novel beta-lactam and beta-lactamase inhibitor combinations or other susceptible non-beta-lactam antibiotics for treatment. National resistance trends in a cohort of hospitalized patients at U.S. hospitals during our study period demonstrate the increasing incidence of both resistance phenotypes, reinforcing the generalizability and timeliness of such analysis.

Resistance patterns and clinical outcomes of Klebsiella pneumoniae and invasive Klebsiella variicola in trauma patients.

Recent reclassification of the Klebsiella genus to include Klebsiella variicola, and its association with bacteremia and mortality, has raised concerns. We examined Klebsiella spp. infections among battlefield trauma patients, including occurrence of invasive K. variicola disease. Klebsiella isolates collected from 51 wounded military personnel (2009-2014) through the Trauma Infectious Disease Outcomes Study were examined using polymerase chain reaction (PCR) and pulsed-field gel electrophoresis. K. variicola isolates were evaluated for hypermucoviscosity phenotype by the string test. Patients were severely injured, largely from blast injuries, and all received antibiotics prior to Klebsiella isolation. Multidrug-resistant Klebsiella isolates were identified in 23 (45%) patients; however, there were no significant differences when patients with and without multidrug-resistant Klebsiella were compared. A total of 237 isolates initially identified as K. pneumoniae were analyzed, with 141 clinical isolates associated with infections (remaining were colonizing isolates collected through surveillance groin swabs). Using PCR sequencing, 221 (93%) isolates were confirmed as K. pneumoniae, 10 (4%) were K. variicola, and 6 (3%) were K. quasipneumoniae. Five K. variicola isolates were associated with infections. Compared to K. pneumoniae, infecting K. variicola isolates were more likely to be from blood (4/5 versus 24/134, p = 0.04), and less likely to be multidrug-resistant (0/5 versus 99/134, p<0.01). No K. variicola isolates demonstrated the hypermucoviscosity phenotype. Although K. variicola isolates were frequently isolated from bloodstream infections, they were less likely to be multidrug-resistant. Further work is needed to facilitate diagnosis of K. variicola and clarify its clinical significance in larger prospective studies.

Low prevalence of hypervirulent Klebsiella pneumoniae in Anatolia, screened via phenotypic and genotypic testing.

Hypervirulent Klebsiella pneumoniae (hvKP) strains are associated with vigorous clinical presentation and relapses. Initially reported from Asia, these variants have spread globally and become an emerging agent of significant health threat. This study was carried out to identify hvKP strains in a previously uninvestigated region and to evaluate the impact of commonly-employed phenotypic and genotypic markers as diagnostic assays. A total of 111 blood culture isolates, collected at a tertiary care center was investigated. The hvKP strains were sought by a string test and the amplification of partial magA, rmpA, iucA and peg344. All products were characterized via sequencing. Evidence for hvKP was observed in 10.8% via iucA amplification (7.2%), string test (2.7%) and magA amplification (0.9%). Specific products were not produced by assays targeting rmpA and peg344 genes. Antibiotic susceptibility patterns compatible with possible extensive or pan-antimicrobial resistance was noted in 66.7% of the hvKP candidate strains. Capsule type in the magA positive strain was characterized as K5. We have detected hvKP in low prevalence at a region with no prior documentation. Targetting the aerobactin gene via iucA amplification provided the most accurate detection in this setting. The epidemiology of hvKP in Anatolia requires elucidation for effective control and management.

Multidrug-resistant Klebsiella oxytoca ventriculitis, successfully treated with intraventricular tigecycline: A case report.

A 38-year-old male presented to the hospital with headache, fever, and meningeal signs. He had undergone a surgical review of a ventriculoperitoneal shunt system one month earlier. A head computed tomography scan showed hydrocephalus. His medical history included a human immunodeficiency virus infection identified four years before and resolved cryptococcal meningitis, which had necessitated the implantation of the shunt system. Ventricular cerebrospinal fluid (CSF) was obtained, which showed inflammation and, in culture, grew a Gram-negative bacillus identified as multidrug-resistant Klebsiella oxytoca. The shunt was removed and a ventricular drain was installed. Treatment with meropenem and amikacin was established without a response; the CSF white blood cell count continued to increase, with cultures remaining positive. The patient's clinical condition deteriorated to stupor. With informed consent, intraventricular (ITV) treatment with tigecycline was initiated at a dose of 5 mg every 24 h and, three days later, the CSF cultures were negativized. Tigecycline levels in the CSF were quantified by liquid chromatography with ultraviolet detection and showed peak concentrations achieved at two hours after the dose of between 178 and 310 µg/mL. After 11 days of treatment with ITV tigecycline and eight negative CSF cultures, a new CSF shunt was installed. During follow-up review 10 months later, the patient reported he was working. The dose of tigecycline used in this study produced levels 15 to 20 times the minimum inhibitory concentration of the bacteria for up to six hours with adequate tolerance.

[The efficacy and safety of different antimicrobial regimens in carbapenem-resistant Klebsiella pneumoniae bloodstream infections].

Objective: To evaluate the efficacy and safety of different antimicrobial regimens in patients with bloodstream infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKP). Methods: The clinical date of patients with CRKP bloodstream infections were retrospectively analyzed at the First Affiliated Hospital of Zhejiang University Medical College between January 2017 and January 2018. All subjects were separated into three groups based on antibiotics regimens over 72 hours, including meropenem 2.0 g every 8 hours, tigecycline 200 mg as initial dose and 100 mg every 12 hours, and polymyxin B 1.25 mg/kg every 12 hours as salvage treatment of tigecycline. Results: A total of 86 patients were finally recruited, including 14, 52 and 20 patients in groups of meropenem, tigecycline and polymyxin B salvage, respectively. All of the strains were resistant to meropenem and susceptible to tigecycline and polymyxin B initially, while 2 of them became resistant to tigecycline during treatment. The 28-day mortality was significantly higher in meropenem group (13/14) than that in tigecycline group and polymyxin B salvage group (61.5%, 32/52) and (12/20), respectively (P<0.01), while as no significant difference was seen in the last two groups (χ(2)=0.014, P>0.05). The incidences of hepatic impairment [3.8%(2/52) vs. 1/20] and renal dysfunction (0 vs. 1/20) between tigecycline group and polymyxin B salvage group were both comparable (P>0.05). Conclusion: The meropenem-based therapy is not recommended for CRKP-related bloodstream infections. Tigecycline-based therapy is still disappointing despite salvage use of polymyxin B after 72 hours. Hepatic and nephretic toxicities caused by additional polymyxin B are acceptable.

Use of Ceftazidime-avibactam for the Treatment of Extensively drug-resistant or Pan drug-resistant Klebsiella pneumoniae in Neonates and Children <5 Years of Age.

BACKGROUND: Emergence of extensively drug-resistant (XDR) or pan drug-resistant (PDR) Enterobacteriaceae is a major public threat especially for young patients. Treatment options for these bacteria are extremely limited with no safety data existing for neonates and children. Ceftazidime-avibactam has activity against Gram-negative bacteria producing Klebsiella pneumoniae carbapenemase, but virtually no data exist on its use in neonatal and pediatric patients. METHODS: We present a single-center case series of neonates and children <5 years treated with ceftazidime-avibactam for XDR or PDR K. pneumoniae infections until August 2018. Medical records of patients who received ceftazidime-avibactam for at least 2 days (6 doses) were reviewed. Clinical, laboratory and microbiologic data were collected using a prestructured form. Adverse events and clinical/microbiologic responses and 15- and 30-day outcome were assessed. RESULTS: In our case series, 8 patients (median age 53 days, range from 13 days to 4.5 years) received 9 courses of ceftazidime-avibactam at a dose of 62.5 mg/kg q8h for suspected or proven XDR/PDR K. pneumoniae infections including bloodstream infections (8 courses), central nervous system infections (2 courses) and urinary tract infection (1 course). All patients were critically ill and received other antibiotics prior and concomitantly with the administration of ceftazidime-avibactam. There was no treatment discontinuation due to adverse events. Clinical and microbiologic responses occurred in all patients, and no patient died by day 30. CONCLUSIONS: Administration of ceftazidime-avibactam appears to be well tolerated and efficacious against in vitro susceptible XDR or PDR Enterobacteriaceae without being associated with significant adverse events.

Emergence of ceftazidime-avibactam-resistant Klebsiella pneumoniae during treatment, Finland, December 2018.

In December 2018, a ceftazidime-avibactam (CAZ-AVI)-resistant KPC-2-producing Klebsiella pneumoniae strain was isolated in Finland. CAZ-AVI resistance was observed 34 days after CAZ-AVI treatment in a trauma patient transferred from a hospital in Greece who had been colonised with blaKPC-2-producing K. pneumoniae ST39, and later developed a bloodstream infection. The CAZ-AVI-resistant strain contained a novel 15 amino acid insertion in the KPC-2 protein causing structural changes proximal to the KPC-2 active site.

Preoperative urine culture is unnecessary in asymptomatic men prior to prostate needle biopsy.

PURPOSE: To determine the clinical utility of preoperative urine cultures in asymptomatic men undergoing prostate needle biopsy (PNB). METHODS: One hundred fifty asymptomatic men had urine cultures obtained 14-days prior to PNB. As per study protocol, positive cultures were not treated. Antibiotic prophylaxis prior to PNB included ciprofloxacin 500 mg the night before and morning of the biopsy. Repeat urine cultures were obtained immediately prior to PNB with colony-forming units (CFUs) annotated. Infectious complications post-biopsy were recorded. RESULTS: Of the 150 men, six patients (4%) had evidence of asymptomatic bacteriuria with > 10,000 CFU/mL on office urine culture. Repeat urine cultures on morning of biopsy in all 150 patients noted a mean bacterial count of 55 CFU/mL (range 0-1000). All six patients with positive office urine cultures had < 100 CFU/mL at time of PNB. Following biopsy, four patients (2.7%) developed an infectious complication including two with sepsis and two with culture-positive UTIs. The causative organism in all cases was quinolone-resistant E. coli. None of the six patients with preoperative positive urine cultures developed an infectious complication following PNB. CONCLUSIONS: In this prospective observational study, under 5% of asymptomatic men had positive office cultures prior to PNB. Furthermore, repeat urine culture on the morning of biopsy showed resolution in these patients, and none developed post-biopsy infectious complications. Routine office urine culture in the asymptomatic male prior to PNB was unnecessary.

Hypermucoviscous Klebsiella syndrome it's in the community!

Hypermucoviscous Klebsiella syndrome is a unique syndrome caused by a new variant of Klebsiella pneumoniae (KP), characterized by abscess formation at distant body sites. This emerging KP strain is different from the usual classic strains in having the rmp gene which increases capsule formation making this strain resistant to phagocytosis and helping in its dissemination to distant organs. A 50 years old diabetic man presented with facial swelling after dental procedure which progressively increased despite being on antibiotics. On examination he was febrile, had neck swelling with signs of inflammation and tender hepatomegaly. Ultrasonography showed submental and liver abscesses which were subsequently drained and both cultures isolated KP with hypermucoid colonies on agar plate and a positive string test indicating the presence of this new hypervirulent strain of KP. Therefore, a diagnosis of Hypermucoviscous Klebsiella syndrome should be considered in all patients who present with KP infection with multiple organ abscesses..

Childhood urinary tract infection caused by extended-spectrum ß-lactamase-producing bacteria: Risk factors and empiric therapy.

BACKGROUND: This study investigated risk factors of childhood urinary tract infection (UTI) associated with extended-spectrum ß-lactamase (ESBL)-producing bacteria (ESBL-positive UTI) and evaluated antimicrobial resistance as well as empiric treatment of childhood UTI. METHODS: The records of children with positive urine culture between 1 January 2008 and 31 December 2012 were evaluated. Patients with positive urine culture for ESBL-producing bacteria were defined as the ESBL-positive group, whereas patients of the same gender and similar age with positive urine culture for non-ESBL-producing bacteria were defined as the ESBL-negative group. Each ESBL-positive patient was matched with two ESBL-negative patients. RESULTS: The ESBL-positive and negative groups consisted of 154 and 308 patients, respectively. Potential risk factors for ESBL-positive UTI were identified as presence of underlying disease, clean intermittent catheterization (CIC), hospitalization, use of any antibiotic and history of infection in the last 3 months (P < 0.05). On logistic regression analysis, CIC, hospitalization and history of infection in the last 3 months were identified as independent risk factors. In the present study, 324 of 462 patients had empiric therapy. Empiric therapy was inappropriate in 90.3% of the ESBL-positive group and in 4.5% of the ESBL-negative group. Resistance to nitrofurantoin was similar between groups (5.1% vs 1.2%, P = 0.072); resistance to amikacin was low in the ESBL-positive group (2.6%) and there was no resistance in the ESBL-negative group. CONCLUSIONS: Clean intermittent catheterization, hospitalization and history of infection in the last 3 months should be considered as risk factors for ESBL-positive UTI. The combination of ampicillin plus amikacin should be taken into consideration for empiric therapy in patients with acute pyelonephritis who have the risk factors for ESBL-positive UTI. Nitrofurantoin seems to be a logical choice for the empiric therapy of cystitis.

Colistin Resistance in Carbapenem-Resistant Klebsiella pneumoniae: Laboratory Detection and Impact on Mortality.

Background: Polymyxins including colistin are an important "last-line" treatment for infections caused by carbapenem-resistant Klebsiella pneumoniae (CRKp). Increasing use of colistin has led to resistance to this cationic antimicrobial peptide. Methods: A cohort nested within the Consortium on Resistance against Carbapenems in Klebsiella pneumoniae (CRACKLE) was constructed of patients with infection, or colonization with CRKp isolates tested for colistin susceptibility during the study period of December, 2011 to October, 2014. Reference colistin resistance determination as performed by broth macrodilution was compared to results from clinical microbiology laboratories (Etest) and to polymyxin resistance testing. Each patient was included once, at the time of their first colistin-tested CRKp positive culture. Time to 30-day in-hospital all-cause mortality was evaluated by Kaplan-Meier curves and Cox proportional hazard modeling. Results: In 246 patients with CRKp, 13% possessed ColR CRKp. ColR was underestimated by Etest (very major error rate = 35%, major error rate = 0.4%). A variety of rep-PCR strain types were encountered in both the ColS and the ColR groups. Carbapenem resistance was mediated primarily by blaKPC-2 (46%) and blaKPC-3 (50%). ColR was associated with increased hazard for in-hospital mortality (aHR 3.48; 95% confidence interval, 1.73-6.57; P < .001). The plasmid-associated ColR genes, mcr-1 and mcr-2 were not detected in any of the ColR CRKp. Conclusions: In this cohort, 13% of patients with CRKp presented with ColR CRKp. The apparent polyclonal nature of the isolates suggests de novo emergence of ColR in this cohort as the primary factor driving ColR. Importantly, mortality was increased in patients with ColR isolates.

The Clinical Characteristics of Neonatal Sepsis Infection in Southwest China.

OBJECTIVE: To identify the pathogens responsible for neonatal sepsis in a high-volume women and children's hospital in Southwest China. METHODS: We retrospectively studied 133 neonates who were admitted to the West China Women and Children's Hospital between 2008 and 2012 for sepsis. The clinical characteristics of the patients were recorded, and the antibiotic sensitivities of the isolated bacteria were determined. RESULTS: All of the included patients had clinical symptoms of sepsis, and subsequent blood cultures confirmed the infection. Almost 80% of patients were infected with coagulase-negative staphylococci (52.8%), Escherichia coli (23.6%), Klebsiella pneumoniae (16.0%) or Staphylococcus aureus (7.5%). Neonates who were infected with gram-negative bacteria, particularly K. pneumoniae, had lower birth weights and were admitted to hospital within 24 hours of birth. Additionally, 87.5% of the isolated K. pneumoniae strains were resistant to third generation cephalosporins. CONCLUSION: Coagulase-negative staphylococci were the most common pathogens found in neonatal sepsis. Moreover, neonatal sepsis caused by gram-negative bacteria was more often observed in newborns of low birth weight. The isolated strains of gram-negative bacteria were highly resistant to cephalosporins. This observation highlights the issue of antibiotic-resistant pathogens in the clinical setting, which poses an added risk to infants presenting with sepsis.

Efficacy of Appropriate Antimicrobial Therapy on the Survival of Patients With Carbapenem Nonsusceptible Klebsiella Pneumoniae Infection: A Multicenter Study in Taiwan.

The impact of antimicrobial treatment on the outcome of carbapenem nonsusceptible Klebsiella pneumoniae (CnsKP) infections needs to be elucidated. This nationwide, multicenter study was conducted to evaluate the impact of appropriate antimicrobial therapy on 14-day mortality among patients with CnsKP infection in Taiwan.Patients with CnsKP infections from 11 medical centers and 4 regional hospitals in Taiwan were enrolled in 2013. Carbapenem nonsusceptibility was defined as a minimum inhibitory concentration of ≥2 mg/L for imipenem or meropenem. Predictors of 14-day mortality were determined using the Cox proportional regression model. The influence of infection severity on the impact of appropriate use of antimicrobials on 14-day mortality was determined using the Acute Physiology and Chronic Health Evaluation (APACHE) II score.Overall 14-day mortality was 31.8% (49/154). Unadjusted mortality for appropriate antimicrobial therapy was 23.1% (18/78 patients). Appropriate therapy was independently associated with reduced mortality (hazard ratio [HR], 0.44; 95% confidence interval [CI], 0.24-0.80; P = 0.007). A subgroup analysis revealed that the benefit of appropriate therapy was limited to patients with higher APACHE II scores (HR for patients with scores >15 and ≤35, 0.46; 95% CI 0.23-0.92; and for those with scores >35, 0.14; 95% CI, 0.02-0.99).In conclusion, appropriate antimicrobial therapy significantly reduces 14-day mortality for CnsKP infections. Survival benefit is more notable among more severely ill patients.

Clonal dissemination of multilocus sequence type ST15 KPC-2-producing Klebsiella pneumoniae in Bulgaria.

A total of 36 consecutive clinical and two fecal-screening carbapenem-resistant Klebsiella pneumoniae isolates from two Bulgarian university hospitals (Varna and Pleven) were investigated. Susceptibility testing, conjugation experiments, and plasmid replicon typing were carried out. Beta-lactamases were characterized by isoelectric focusing, PCR, and sequencing. Clonal relatedness was investigated by RAPD and multilocus sequence typing (MLST). Most of the isolates demonstrated multidrug resistance profile. Amikacin and tigecycline retained good activity with susceptibility rates of 95 and 87%, respectively. The resistance rate to colistin was 63%. Six RAPD- and MLST-types were identified: the dominating MLST-type was ST15 (27 isolates), followed by ST76 (six isolates), and ST1350 (two isolates). ST101, ST258, and ST151 were detected once. All except one of the K. pneumoniae produced KPC-2, mostly in combination with CTX-M-15, while for one isolate (ST101) the enzymes OXA-48 and CTX-M-14 were found. All KPC-2-producing transconjugants revealed the presence of IncFII plasmid. The OXA-48- and CTX-M-14-producing isolate showed the presence of L/M replicon type. The dissemination of KPC-2-producing K.pneumoniae in Bulgaria is mainly due to the sustained spread of successful ST15 clone and to a lesser extent of ST76 clone. This is the first report of OXA-48 producing ST101 K. pneumoniae in Bulgaria.

Integrating rapid diagnostics and antimicrobial stewardship improves outcomes in patients with antibiotic-resistant Gram-negative bacteremia.

BACKGROUND: An intervention for Gram-negative bloodstream infections that integrated mass spectrometry technology for rapid diagnosis with antimicrobial stewardship oversight significantly improved patient outcomes and reduced hospital costs. As antibiotic resistance rates continue to grow at an alarming speed, the current study was undertaken to assess the impact of this intervention in a challenging patient population with bloodstream infections caused by antibiotic-resistant Gram-negative bacteria. METHODS: A total of 153 patients with antibiotic-resistant Gram-negative bacteremia hospitalized prior to the study intervention were compared to 112 patients treated post-implementation. Outcomes assessed included time to optimal antibiotic therapy, time to active treatment when inactive, hospital and intensive care unit length of stay, all-cause 30-day mortality, and total hospital expenditures. RESULTS: Integrating rapid diagnostics with antimicrobial stewardship improved time to optimal antibiotic therapy (80.9 h in the pre-intervention period versus 23.2 h in the intervention period, P < 0.001) and effective antibiotic therapy (89.7 h versus 32 h, P < 0.001). Patients in the pre-intervention period had increased duration of hospitalization compared to those in the intervention period (23.3 days versus 15.3 days, P = 0.0001) and longer intensive care unit length of stay (16 days versus 10.7 days, P = 0.008). Mortality among patients during the intervention period was lower (21% versus 8.9%, P = 0.01) and our study intervention remained a significant predictor of survival (OR, 0.3; 95% confidence interval [CI], 0.12-0.79) after multivariate logistic regression. Mean hospital costs for each inpatient survivor were reduced $26,298 in the intervention cohort resulting in an estimated annual cost savings of $2.4 million (P = 0.002). CONCLUSIONS: Integration of rapid identification and susceptibility techniques with antimicrobial stewardship resulted in significant improvements in clinical and financial outcomes for patients with bloodstream infections caused by antibiotic-resistant Gram-negatives. The intervention decreased hospital and intensive care unit length of stay, total hospital costs, and reduced all-cause 30-day mortality.