Review of studies of the impact on Gram-negative bacterial resistance on outcomes in the intensive care unit. Crit Care Med. 2009;37:1463-1469. [PMID: 19242341 DOI: 10.1097/ccm.0b013e31819ced02]

Intrapulmonary and Systemic Pharmacokinetics of Colistin Following Nebulization of Low-Dose Colistimethate Sodium in Patients with Ventilator-Associated Pneumonia Caused by Carbapenem-Resistant Acinetobacter baumannii

Colistimethate sodium (CMS) nebulization is associated with reduced systemic toxicity compared to intravenous injection, with potentially enhanced clinical efficacy. This study aimed to assess the pharmacokinetic (PK) properties of colistin during low-dose CMS nebulization in patients with ventilator-associated pneumonia (VAP) caused by carbapenem-resistant Acinetobacter baumannii. A nonlinear mixed-effects modeling approach was applied to develop population PK models for colistin in both epithelial lining fluid (ELF) and plasma. Twenty patients participated, and 80 ELF and 100 plasma samples were used for model development. Median colistin concentrations measured in ELF were 614-fold, 408-fold, and 250-fold higher than in plasma at 1, 3, and 5 h, respectively. Time courses in both ELF and plasma were best described by a one-compartment model with a Weibull absorption process. When the final model was simulated, the maximum free concentration and area under the free colistin concentration-time curve at steady state over 24 h in the plasma were approximately 1/90 and 1/50 of the corresponding values in ELF at steady state, respectively. For an A. baumannii MIC of 1 mg/L, inhaling 75 mg of CMS at 6 h intervals was deemed appropriate, with dose adjustments needed for MICs exceeding 2 mg/L. Using a nebulizer for CMS resulted in a notably higher exposure of colistin in the ELF than plasma, indicating the potential of nebulization to reduce systemic toxicity while effectively treating VAP.

The Prevalence of Carbapenemase-Producing Microorganisms and Use of Novel Cephalosporins for the Treatment of Severe Infections Caused by Carbapenem-Resistant Gram-Negative Bacteria in a Pediatric Cardiac Intensive Care Unit

BACKGROUND

The spread of carbapenem-resistant organisms (CROs) is an increasingly serious threat globally, especially in vulnerable populations, such as intensive care unit (ICU) patients. Currently, the antibiotic options for CROs are very limited, particularly in pediatric settings. We describe a cohort of pediatric patients affected by CRO infections, highlighting the important changes in carbapenemase production in recent years and comparing the treatment with novel cephalosporins (N-CEFs) to Colistin-based regimens (COLI).

METHODS

All patients admitted to the cardiac ICU of the Bambino Gesù Children's Hospital in Rome during the 2016-2022 period with an invasive infection caused by a CRO were enrolled.

RESULTS

The data were collected from 42 patients. The most frequently detected pathogens were Pseudomonas aeruginosa (64%), Klebsiella pneumoniae (14%) and Enterobacter spp. (14%). Thirty-three percent of the isolated microorganisms were carbapenemase producers, with a majority of VIM (71%), followed by KPC (22%) and OXA-48 (7%). A total of 67% of patients in the N-CEF group and 29% of patients in the comparative group achieved clinical remission (p = 0.04).

CONCLUSION

The increase over the years of MBL-producing pathogens in our hospital is challenging in terms of therapeutic options. According to the present study, N-CEFs are a safe and effective option in pediatric patients affected by CRO infections.

Point Prevalence Survey of Antimicrobial Utilization in a Tertiary Care Teaching Hospital and a Comprehensive Comparative Analysis of PPS across India

This study assessed antimicrobial prescription at our institute to promote rational antimicrobial use and implement customized antimicrobial stewardship programs. This study is a cross sectional point-prevalence survey on antimicrobial utilisation conducted at HAH Centenary hospital, New Delhi in April, 2019, over a period of 3 days. All in-patients were included in the analysis. However, neonates, emergency room patients and palliative care patients, orders for anti-viral, anti-fungal, anti-tubercular and anti-parasitic medications were excluded. SPSS version 13.0 was planned to be used for analysis of the statistical data. The number of patients admitted at the point of time of our survey was 217, out of which 101 (46.54%) patients were receiving antimicrobial agents (AMA) with 160 (73.73%) AMAs prescribed. 50 patients (49.5%) were prescribed AMAs for infections, whereas, 49 patients (48.51%) were prescribed AMAs prophylactically and 2 (1.98%) patients received AMAs for reasons not defined. The intensive care units exhibited 93.33% patients receiving antimicrobials. The most common indication was intra-abdominal infections (32.40%). The most commonly used antibiotics were beta-lactam antibiotics (60.62%). The study suggests a high rate of antimicrobial use and highlights areas for intervention for rational antimicrobial use. We propose to sensitise the government on initiating a national antimicrobial stewardship program such as the Global Point Prevalence Survey and facilitate evidence-based antimicrobial practice.

An optimal extended-infusion dosing of cefepime and ceftazidime in critically ill patients with continuous renal replacement therapy

PURPOSE

This study aimed to determine optimal extended-infusion dosing regimens for cefepime and ceftazidime in critically ill patients receiving continuous renal replacement therapy using Monte Carlo Simulations (MCS).

MATERIALS AND METHODS

Pharmacokinetic models were built using published pharmacokinetic/demographic data to predict drug disposition in 5000 virtual critically ill patients receiving continuous venovenous hemofiltration (CVVH) with the standard (20-30 mL/kg/h) and a higher (40 mL/kg/h) effluent rates. MCS was performed to assess the probability of target attainment (PTA) of four cefepime and ceftazidime doses administered over 4-h with the target of ≥60% fT > 4×MIC. The lowest dose attaining PTA ≥90% during the first 48-h was considered optimal. Additionally, risk of drug toxicity was assessed at 48-h using suggested neurotoxicity thresholds.

RESULTS

Cefepime 2 g loading dose (LD), then extended-infusion of 2 g q8hr was optimal in CVVH at 20 mL/kg/h and the same ceftazidime dose was optimal in CVVH at 20-30 mL/kg/h. Higher cefepime and ceftazidime doses were required to be optimal at higher effluent rates. This optimal dose particularly for cefepime likely increases neurotoxicity risk in most virtual patients with all CVVH settings.

CONCLUSIONS

Cefepime and ceftazidime 2 g LD, followed by extended-infusion 2 g q8hr may be optimal in CVVH with standard effluent rates.

Characteristic of Extended Spectrum β-Lactamase-Producing Enterobacteriaceae from Fecal Carriage Isolates of Intensive Care Unit Patients at Sanglah Hospital, Bali, Indonesia

Background:

The increasing Extended-Spectrum β-Lactamases-producing Enterobacteriaceae (ESBL-PE) infections in the Intensive Care Unit (ICU) needs an early warning system for the detection of these bacteria. The ESBL-PE fecal carriage analysis is a screening method that can be used to detect and characterize these bacteria. Furthermore, it aids in assessing an ICU patient’s risk of possible infection and prevent its transmission to the other patients within the period of hospitalization; therefore, enhancing the quality of patient care while alsoreducing morbidity and mortality due to ESBL-PE infection in ICU.

Objective:

The study aimed to determine the antibiogram and molecular characteristics of ESBL-PE fecal carriage from ICU patients at Sanglah Hospital, Denpasar, Bali.

Methods:

This cross-sectional retrospective study involved 30 stored-bacterial isolates of ESBL-PE from a rectal swab of ICU patients who had just been admitted to the ICU of Sanglah General Hospital from February to March 2019, consecutively. The identification and antimicrobial susceptibility test of the isolates were conducted using Vitek-2 Compact (bioMérieux®, Marcy-l'Etoile, France), while genotype identification was conducted using PCR for the detection of blaTEM, blaSHV, blaCTX-M genes.

Results:

Thirty bacterial isolates were identified as Escherichia coli (24/30) and Klebsiella spp. (6/30) and detected as ESBL-producing isolates by Vitek-2 Compact. All isolates were susceptible to piperacillin-tazobactam, meropenem, and amikacin. Twenty-two (73.3%) isolates harbored ESBLs blaTEM, blaSHV, blaCTX-M genes, either individually or in combination. Most of the isolates had the combination of ESBL genes. About 20% (6/30) of isolates had a combination of blaTEM and blaCTX-M, while 10% (3/30) of them possessed all of the three genes detected in this study. Only 3.3% (1/30) of the isolates had each combination of blaTEM and blaSHV as well as blaSHV and blaCTX-M. Meanwhile, 16.7% (5/30) of the isolates were detected to have each single gene of blaCTX-M or blaTEM, and only one isolate (3.3%) harbored blaSHV.

Conclusion:

High prevalence of blaTEM, blaSHV, and blaCTX-M ESBL genes harbored by fecal flora of patients who had just been admitted in ICU give rise to the risk for transmission among critically ill patients in ICU. Fecal screening of ESBL-PE besides infection control can be considered for those patients who have a risk factor of ESBL-PE colonization before they are being admitted to the ICU.

Adipose-Derived Mesenchymal Stem Cells Ameliorating Pseudomonas aeruginosa-induced Acute Lung Infection via Inhibition of NLRC4 Inflammasome

Background

Pseudomonas aeruginosa (PA) is one of the most common Gram-negative bacteria causing hospital-acquired pulmonary infection, with high drug resistance and mortality. Therefore, it is urgent to introduce new non-antibiotic treatment strategies. Mesenchymal stem cells (MSCs), as important members of the stem cell family, were demonstrated to alleviate pathological damage in acute lung injury. However, the potential mechanism how MSC alleviate acute lung infection caused by PA remains unclear.

Objective

The purpose of this study was to investigate the effects of Adipose-derived mesenchymal stem cells (ASCs) on acute pulmonary infections and the possible mechanisms how ASCs reduce pulmonary inflammation induced by PA.

Methods

The therapeutic and mechanistic effects of ASCs on PA pulmonary infection were evaluated respectively in a murine model as well as in an in vitro model stimulated by PA and co-cultured with ASCs.

Results

1. ASCs treatment significantly reduced the bacterial load, inflammation of lung tissue and histopathological damage by PA. 2. PA infection mainly activated Nod-like receptor containing a caspase activating and recruitment domain 4 (NLRC4) inflammasome in the lung of mice. ASCs attenuated acute lung infection in mice by inhibiting NLRC4 inflammasome activation. 3. NLRC4^-/- mice showed a significant improvement in survival rate and lung bacterial load after PA infection. 4. ASCs mainly increased expression and secretion of STC-1 in response to PA-stimulated NLRC4 inflammasome activation.

Conclusions

PA infection attenuated macrophage phagocytosis through activation of NLRC4 inflammasome in macrophages, which eventually led to pulmonary inflammatory damage in mouse; ASCs reduced the activation of NLRC4 inflammasome in macrophages induced by PA infection, thereby increasing the phagocytic ability of macrophages, and ultimately improving lung tissue damage in mouse; ASCs may inhibit NLRC4 inflammasome through the secretion of STC-1.

Role of miR-466 in mesenchymal stromal cell derived extracellular vesicles treating inoculation pneumonia caused by multidrug-resistant Pseudomonas aeruginosa

RATIONALE

The effects of mesenchymal stromal cells (MSCs) and MSC-derived extracellular vesicles (MSC EVs) on multidrug-resistant pseudomonas aeruginosa (MDR-PA)-induced pneumonia remain unclear.

MATERIALS AND METHODS

MicroRNA array and RT-PCR were used to select the major microRNA in MSC EVs. Human peripheral blood monocytes were obtained and isolated from qualified patients. The crosstalk between MSCs/MSC EVs and macrophages in vitro was studied. MDR-PA pneumonia models were further established in C57BL/6 mice and MSC EVs or miR-466 overexpressing MSC EVs were intratracheally instilled.

RESULTS

MiR-466 was highly expressed in MSC EVs. MSCs and miR-466 promoted macrophage polarization toward Type 2 phenotype through TIRAP-MyD88-NFκB axis. Moreover, cocultured macrophages with miR-466 overexpressing MSCs significantly increased the phagocytosis of macrophages. MSC EVs significantly reduced mortality and decreased influx of BALF neutrophils, proinflammatory factor levels, protein, and bacterial load in murine MDR-PA pneumonia. Administration of miR-466 overexpressing MSC EVs further alleviated the inflammatory severity.

CONCLUSIONS

MSC-derived EVs containing high levels of miR-466 may partly participate in host immune responses to MDR-PA. Both MSCs and MSC EVs have therapeutic effects in treating MDR-PA-induced pneumonia.

The hypothetical periplasmic protein PA1624 from Pseudomonas aeruginosa folds into a unique two-domain structure

The crystal structure of the 268-residue periplasmic protein PA1624 from the opportunistic pathogen Pseudomonas aeruginosa PAO1 was determined to high resolution using the Se-SAD method for initial phasing. The protein was found to be monomeric and the structure consists of two domains, domains 1 and 2, comprising residues 24-184 and 185-268, respectively. The fold of these domains could not be predicted even using state-of-the-art prediction methods, and similarity searches revealed only a very distant homology to known structures, namely to Mog1p/PsbP-like and OmpA-like proteins for the N- and C-terminal domains, respectively. Since PA1624 is only present in an important human pathogen, its unique structure and periplasmic location render it a potential drug target. Consequently, the results presented here may open new avenues for the discovery and design of antibacterial drugs.

Some Suggestions from PK/PD Principles to Contain Resistance in the Clinical Setting-Focus on ICU Patients and Gram-Negative Strains

The containment of the phenomenon of resistance towards antimicrobials is a priority, especially in preserving molecules acting against Gram-negative pathogens, which represent the isolates more frequently found in the fragile population of patients admitted to Intensive Care Units. Antimicrobial therapy aims to prevent resistance through several actions, which are collectively known as "antimicrobial stewardship", to be taken together, including the application of pharmacokinetic/pharmacodynamic (PK/PD) principles. PK/PD application has been shown to prevent the emergence of resistance in numerous experimental studies, although a straight translation to the clinical setting is not possible. Individualized antibiotic dosing and duration should be pursued in all patients, and even more especially when treating intensive care unit (ICU) septic patients in whom optimal exposure is both difficult to achieve and necessary. In this review, we report on the available data that support the application of PK/PD parameters to contain the development of resistance and we give some practical suggestions that can help to translate the benefit of PK/PD application to the bedside.

Characterization of Amikacin Drug Exposure and Nephrotoxicity in an Animal Model

Despite excellent in vitro activity, aminoglycosides are used conservatively to treat multidrug-resistant bacterial infections due to their associated nephrotoxicity. Aminoglycosides are known to accumulate in the kidneys, but the quantitative relationship between drug exposures and nephrotoxicity is not well established. To bridge the knowledge gap, the objective of this study was to develop an animal model with clinically relevant conditions to mimic human disease progression. Single-dose pharmacokinetics were studied in Sprague-Dawley rats dosed either with 100 or 500 mg/kg of body weight of amikacin subcutaneously. Serial blood samples were collected, and serum amikacin concentrations were measured using liquid chromatography tandem mass spectrometry. Rats were also dosed with amikacin once daily for up to 10 days; blood samples were taken at baseline and daily to detect nephrotoxicity (defined as doubling of serum creatinine from baseline). Kidneys from both studies were harvested from selected rats, and amikacin concentrations in renal tissues were measured. A dose-dependent increase in systemic area under the curve (AUC) was observed, which ranged from approximately 1/3 (AUC of 53 mg·h/liter) to 3 times (AUC of 650 mg·h/liter) the expected exposure resulting from standard dosing in humans. Nephrotoxicity was significantly higher in rats given 500 mg/kg (100% versus 30%, P = 0.003). Kaplan-Meier analysis also showed a significant difference in nephrotoxicity onset between the two groups (P = 0.001). Finally, analysis of the renal tissues showed that the accumulation of amikacin could be associated with nephrotoxicity. These results are consistent with clinical observations, which support using this model in the future to investigate an intervention(s) that can be used clinically to alleviate nephrotoxicity.

Does inappropriate initial antibiotic therapy affect in-hospital mortality of patients in the emergency department with Escherichia coli and Klebsiella pneumoniae bloodstream infections?

Extended-spectrum β-lactamase (ESBL)-positive bloodstream infection (BSI) is on the rise worldwide. The purpose of this study is to evaluate the impact of inappropriate initial antibiotic therapy (IIAT) on in-hospital mortality of patients in the emergency department (ED) with Escherichia coli and Klebsiella pneumoniae BSIs. This retrospective single-center cohort study included all adult patients with E. coli and K. pneumoniae BSIs between January 2007 and December 2013, who had undergone a blood culture test and initiation of antibiotics within 6 h of ED registration time. Multiple logistic regression was used to adjust for bacterial species, IIAT, time to antibiotics, age, sex, quick Sepsis Related Organ Failure Assessment (qSOFA) score ⩾ 2, and comorbidities. A total of 3533 patients were enrolled (2967 alive and 566 deceased, in-hospital mortality rate 16%). The patients with K. pneumoniae ESBL-positive BSI had the highest mortality rate. Non-survivors had qSOFA scores ⩾ 2 (33.6% vs 9.5%, P < 0.001), more IIAT (15.0% vs 10.7%, P = 0.004), but shorter mean time to antibiotics (1.70 vs 1.84 h, P < 0.001). A qSOFA score ⩾ 2 is the most significant predictor for in-hospital mortality; however, IIAT and time to antibiotics were not significant predictors in multiple logistic regression analysis. In subgroup analysis divided by qSOFA scores, IIAT was still not a significant predictor. Severity of the disease (qSOFA score ⩾ 2) is the key factor influencing in-hospital mortality of patients with E. coli and K. pneumoniae BSIs. The time to antibiotics and IIAT were not significant predictors because they in turn were affected by disease severity.

Costs of healthcare-associated infections to the Brazilian public Unified Health System in a tertiary-care teaching hospital: a matched case-control study

BACKGROUND

Little is known about the economic burden of healthcare-associated infections (HAIs) in Brazil.

AIM

To analyse the costs of hospitalization by reimbursement from the Brazilian government, via the Brazilian Unified Health System (SUS) affiliation, and direct costs in the adult Intensive Care Unit (ICU).

METHODS

The matched-pairs case-control study (83 patients with HAIs and 83 without HAIs) was performed at a referral tertiary-care teaching hospital in Brazil in January 2018. In order to calculate the HAI costs from the perspective of the payer, the total cost for each hospitalization was obtained through the Hospital's Billing Sector. Direct costs were calculated annually for 949 critical patients during 2018.

FINDINGS

The reimbursement cost per hospitalization of patients with HAIs was 75% (US$2721) higher than patients without HAIs (US$1553). When a patient has an HAI, in addition to a longer length of stay (15 days), there was an extra increase (US$996) in the reimbursement cost per hospitalization. An HAI in the ICU was associated with a total direct cost eight times higher compared with patients who did not develop infections in this unit, US$11,776 × US$1329, respectively. The direct cost of hospitalization in the ICU without HAI was 56.5% less than the reimbursement (US$1329 × US$3052, respectively), whereas for the patient with an HAI, the direct cost was 111.5% above the reimbursement (US$11,776 × US$5569, respectively).

CONCLUSION

HAIs contribute to a longer stay and an eight-fold increase in direct costs. It is necessary to reinforce programmes that prevent HAIs in Brazilian hospitals.

Prevalence of multidrug-resistant Gram-negative bacteria cases at admission in a multispeciality hospital

OBJECTIVES

The prevalence of drug-resistant cases is increasing globally. The present study aimed to investigate the prevalence of cases of blood culture positive for multidrug-resistant Gram-negative bacteria (MDR-GNB) at the time of admission, i.e. within 24h of admission to hospital from primary or secondary care centres.

METHODS

This record-based retrospective cross-sectional study was designed to analyze MDR-GNB-positive cases at Fortis Hospital, Mumbai, India. Fortis Hospital is a 500-bed referral tertiary care centre. An increase of MDR-GNB was seen from January 2012 to June 2014 in the hospital. A retrospective analysis of blood culture GNB-positive samples was performed to evaluate MDR-GNB-positive cases at admission.

RESULTS

The total number of positive blood cultures in January to December 2012, January to December 2013 and January to June 2014 were 221, 236 and 116, respectively, with 77.83%, 79.66% and 69.83% GNB-positive. Total MDR-GNB-positive cases were 26.16%, 32.98% and 33.33%, respectively, and amongst these MDR-GNB, 22%, 32% and 37% where positive at time of admission to the hospital. The MDR-GNB were Escherichia coli, Klebsiella, Acinetobacter, Pseudomonas and Enterobacter.

CONCLUSION

MDR-GNB blood cultures positive at admission rose from January 2012 to June 2014 and hence there is an urgent need for possible contact isolation of all patients coming from primary and secondary to tertiary health care centres which should be made compulsory until screening rules out MDR-GNB to prevent spread of MDR organisms in the hospital.

A Study of Multidrug-Resistant, Colistin-Only-Sensitive Infections in Intubated and Mechanically Ventilated Patients Over 2 Years

Background and Aims

Multidrug-resistant, Gram-negative infections are increasingly common in the intensive care unit (ICU). This study compares the occurrence and outcome of colistin-only-sensitive (COS) infections among mechanically ventilated patients at a tertiary hospital ICU.

Methods

The study included adult patients admitted over a period of 2 years, who were intubated and mechanically ventilated for more than 48 h. They were divided into two groups, those with COS infections and those without, and their GCS and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores, ICU length of stay, leukocyte count, and mortality were compared. COS patients were divided into neurosurgery, neurology, respiratory, and sepsis with bacteremia groups. The COS organisms in each group, their sources, ICU length of stay, ventilator-free days, and mortality were analyzed.

Results

Three hundred and one patients were selected, of whom 41 (13.6%) had COS infections. COS patients had a longer ICU length of stay than non-COS patients (P = 0.001) but comparable APACHE II and GCS scores, leukocyte count, and mortality. The sepsis group accounted for 8 out of 15 (53%) deaths among COS patients (P = 0.03). Acinetobacter baumannii accounted for 61% of the COS infections, Klebsiella pneumonia: 24.4%, Pseudomonas aeruginosa: 12.2%, and Escherichia coli: 2.4%. Endotracheal secretion cultures accounted for 65.8% of COS isolates, urine cultures 17%, pus cultures 7.3%, and blood cultures 4.9%. ICU length of stay, ventilator-free days, and mortality were similar between each COS organism.

Conclusion

Intubated patients with multidrug-resistant, COS infections have a longer stay in ICU than non-COS patients. COS infections associated with bacteremia have high mortality.

Population pharmacokinetics of piperacillin in plasma and subcutaneous tissue in patients on continuous renal replacement therapy

OBJECTIVES

Piperacillin is a β-lactam antimicrobial frequently used in critically ill patients with acute kidney injury treated with continuous renal replacement therapy (CRRT). However, data regarding piperacillin tissue concentrations in this patient population are limited. A prospective observational study was conducted of free piperacillin concentrations during a single 8-h dosing interval in plasma (8 samples) and subcutaneous tissue (SCT) (13 samples), in 10 patients treated with CRRT following piperacillin 4 g given every 8 h as intermittent administration over 3 min.

METHODS

A population pharmacokinetic model was developed using NONMEM 7.4.3, to simulate alternative administration modes and dosing regimens. SCT concentrations were obtained using microdialysis. Piperacillin concentrations were compared to the clinical breakpoint minimum inhibitory concentration (MIC) for Pseudomonas aeruginosa (16 mg/l), with evaluation of the following pharmacokinetic/pharmacodynamics targets: 50% fT > 1 × MIC, 100% fT > 1 × MIC, and 100% fT > 4 × MIC.

RESULTS

SCT concentrations were generally lower than plasma concentrations. For the target of 50% free time (fT) > 1 × MIC and 100% fT > 1 × MIC, piperacillin 4 g every 8 h resulted in probability of target attainment (PTA) >90% in both plasma and SCT. PTA > 90% for the target of 100% fT > 4 × MIC was only achieved for continuous infusion.

CONCLUSIONS

Piperacillin 4 g every 8 h is likely to provide sufficient exposure in both plasma and SCT to treat P.aeruginosa infections in critically ill patients on CRRT, given that targets of 50% fT > 1 × MIC or 100% fT > 1 × MIC are adequate. However, if a more aggressive target of 100% fT > 4 × MIC is adopted, continuous infusion is needed.

The BACH classification of long bone osteomyelitis

Objectives

The aim of this study was to assess the clinical application of, and optimize the variables used in, the BACH classification of long-bone osteomyelitis.

Methods

A total of 30 clinicians from a variety of specialities classified 20 anonymized cases of long-bone osteomyelitis using BACH. Cases were derived from patients who presented to specialist centres in the United Kingdom between October 2016 and April 2017. Accuracy and Fleiss’ kappa (Fκ) were calculated for each variable. Bone involvement (B-variable) was assessed further by nine clinicians who classified ten additional cases of long bone osteomyelitis using a 3D clinical imaging package. Thresholds for defining multidrug-resistant (MDR) isolates were optimized using results from a further analysis of 253 long bone osteomyelitis cases.

Results

The B-variable had a classification accuracy of 77.0%, which improved to 95.7% when using a 3D clinical imaging package (p < 0.01). The A-variable demonstrated difficulty in the accuracy of classification for increasingly resistant isolates (A1 (non-resistant), 94.4%; A2 (MDR), 46.7%; A3 (extensively or pan-drug-resistant), 10.0%). Further analysis demonstrated that isolates with four or more resistant test results or less than 80% sensitive susceptibility test results had a 98.1% (95% confidence interval (CI) 96.6 to 99.6) and 98.8% (95% CI 98.1 to 100.0) correlation with MDR status, respectively. The coverage of the soft tissues (C-variable) and the host status (H-variable) both had a substantial agreement between users and a classification accuracy of 92.5% and 91.2%, respectively.

Conclusions

The BACH classification system can be applied accurately by users with a variety of clinical backgrounds. Accuracy of B-classification was improved using 3D imaging. The use of the A-variable has been optimized based on susceptibility testing results.

Cite this article: A. J. Hotchen, M. Dudareva, J. Y. Ferguson, P. Sendi, M. A. McNally. The BACH classification of long bone osteomyelitis. Bone Joint Res 2019;8:459–468. DOI: 10.1302/2046-3758.810.BJR-2019-0050.R1

Clinical and Microbiological Outcomes in Obese Patients Receiving Colistin for Carbapenem-Resistant Gram-Negative Bloodstream Infection

Carbapenem-resistant infections are associated with poor outcomes, and treatment options are limited. Colistin is one of few antibiotics which retain in vitro activity against carbapenem-resistant pathogens. However, despite the availability of international consensus guidelines for the dosing of polymyxins, there are limited data on the effects of dosing on clinical outcomes among obese patients with carbapenem-resistant Gram-negative bacteremia. This retrospective study evaluated whether obesity was associated with day 7 global cure rates among patients with carbapenem-resistant Gram-negative bacteremia who were treated with an ideal body weight (IBW)-based colistin dosing regimen. Secondary outcomes included microbiological cure, clinical cure, length of hospital stay, in-hospital mortality, and day 7 acute kidney injury. After screening to identify 167 patients, 77 (46.1%) and 90 (53.9%) were classified as obese and nonobese, respectively. Patient characteristics were well balanced at baseline, except that obese patients were more often female and received a higher daily dose per IBW (3.7 versus 2.9 mg/kg/day, P = 0.03). Global cure rates were similar between groups (44.2% for obese versus 55.6% for nonobese, P = 0.14). After adjusting for baseline differences, obesity was not a significant predictor of global cure (adjusted odds ratio [AOR], 0.59; 95% confidence interval [CI], 0.31 to 1.11; P = 0.10). Obesity was associated with a lower likelihood of microbiological clearance (72.7% versus 91.1%, P = 0.02). No other secondary outcome differences were observed, though each outcome was numerically worse among obese patients. Obesity was not associated with differences in global cure rates. However, the difference in microbiological clearance warrants further investigation.

Impact of bloodstream infections caused by carbapenem-resistant Gram-negative pathogens on ICU costs, mortality and length of stay

Background

The aim of this study was to estimate the impact of bloodstream infections (BSIs) caused by carbapenem-resistant Gram-negative (CRGN) pathogens on hospital costs, mortality and length of stay (LOS).

Methods

All patients hospitalized for ≥3 days in the Intensive Care Unit (ICU) of a tertiary-care general hospital from 1/1/2015 to 31/12/2017 were included in the study. A retrospective case-control study was performed in order to examine the difference in medical, pharmaceutical and operating costs, LOS and in-hospital mortality between patients with BSI caused by CRGN/without BSI (cases/controls, respectively). The statistical analysis was performed using the SPSS software (v23.0).

Results

A total of 419 patients (67.5% males, median age 60.0 years) were included in the analysis (142 cases/277 controls); 10 patients with non-CRGN BSIs were excluded. Overall mortality was 33.7% (49.3/25.6% in cases/controls). The median LOS and total cost were 30.0 vs. 12.0 days and 20 359.1 vs. 8,509.3 €, respectively, between patients with/without CRGN BSIs. After adjusting for baseline demographics, underlying disease severity and patients' specialties, CRGN BSIs remained a significant factor in mortality (odds ratio 2.9; 95% confidence interval 1.8-4.8; p <0.001). Additionally, CRGN BSIs seem to result in significantly prolonged LOS and extra cost per infected patient (p <0.001).

Conclusions

ICU patients with CRGN BSI are at increased risk for mortality and prolonged hospitalization and incur higher costs, imposing a heavy burden on healthcare system. Infection control strategies, considering also the cost-efficacy of interventions, are crucial in order to control the expansion of CRGN infections.

Augmented renal clearance is associated with inadequate antibiotic pharmacokinetic/pharmacodynamic target in Asian ICU population: a prospective observational study

BACKGROUND

Augmented renal clearance (ARC) is common in critically ill patients and could result in subtherapeutic antibiotic concentration. However, data in the Asian population are still lacking. The aim of this study was to explore the incidence and risk factors of ARC and its effect on β-lactam pharmacokinetics/pharmacodynamics (PK/PD) in Asian populations admitted to a medical ICU. In addition, we evaluated the appropriateness of using three estimated glomerular filtration (eGFR) formulas [Cockcroft-Gault (CG), Modification of Diet in Renal Disease (MDRD), and the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI)] as screening tools.

METHODS

We measured 2-, 8-, and 24-hr creatinine clearance (CLCr) and calculated eGFR by using three formulas for each. ARC was defined as CLCr24hr >130 mL/min/1.73 m2. Concentrations at the mid-dosing interval and prior to the next dose were collected if patients received the β-lactam antibiotic of piperacillin/tazobactam, cefepime, and meropenem, to determine the PK/PD index of fT > MIC. Multiple logistic regression analysis was conducted to identify the risk factors for ARC. Pearson correlation coefficient and the Bland and Altman method were applied to assess the accuracy of CLCr2hr, CLCr8hr, and eGFR for predicting ARC.

RESULTS

Of 100 patients, 46 (46%) manifested ARC. Younger age (<50 years) and lower Sequential Organ Failure Assessment score increased the likelihood of ARC. ARC resulted in a low chance of achieving 50% fT >4MIC (33% vs 75%, p<0.01), 100% fT > MIC (23% vs 69%, p<0.01), and 100% fT >4MIC (3% vs 25%, p<0.02). CLCr8hr wielded the best correlation and agreement with CLCr24hr. eGFRCG was the most appropriate screening tool, and the optimal cutoff value for detecting ARC was 130.5 mL/min/1.73 m2.

CONCLUSION

ARC is associated with inadequate β-lactam PK/PD target in Asian ICU.

Carbapenem-Nonsusceptible Pseudomonas aeruginosa Isolates from Intensive Care Units in the United States: a Potential Role for New β-Lactam Combination Agents

Pseudomonas aeruginosa, a frequent pathogen in the intensive care unit (ICU), has the propensity to develop antibiotic resistance. In particular, carbapenem-nonsusceptible (NS) P. aeruginosa poses tremendous challenges, and new antibiotics will be needed to treat this phenotype. Here we determine carbapenem nonsusceptibility rates for contemporary P. aeruginosa isolates from U.S. ICUs and in vitro activities of new β-lactam combination agents. Between July 2017 and June 2018, consecutive nonduplicate P. aeruginosa isolates from blood and respiratory tract sources were recovered from patients admitted to the ICUs of 36 geographically diverse U.S. hospitals. Antimicrobial susceptibility to the following antipseudomonal agents was tested: ceftazidime, imipenem, meropenem, ceftazidime-avibactam, and imipenem-relebactam (an investigational β-lactam/β-lactamase inhibitor). MICs and susceptibility rates were measured using Clinical and Laboratory Standards Institute reference broth microdilution methodology. Among the 538 consecutive ICU P. aeruginosa isolates collected, carbapenem nonsusceptibility was observed for 35% of the isolates and was more common among respiratory tract versus bloodstream specimens. Susceptibility rates, MIC₅₀ values, and MIC₉₀ values were as follows: ceftazidime-avibactam, 92.8%, 2 μg/ml, and 8 μg/ml; imipenem-relebactam, 91.5%, 0.25 μg/ml, and 2 μg/ml; ceftazidime, 77.1%, 4 μg/ml, and 64 μg/ml; meropenem, 72.7%, 1 μg/ml, and 16 μg/ml; imipenem, 67.1%, 2 μg/ml, and 16 μg/ml. Most (>75%) of the carbapenem-NS isolates were susceptible to ceftazidime-avibactam and imipenem-relebactam. In these U.S. hospital ICUs, carbapenem-NS P. aeruginosa isolates from respiratory sources were frequently observed. Novel β-lactam combination agents appear to retain active in vitro susceptibility profiles against these isolates and may play a role in the treatment of infections caused by carbapenem-NS P. aeruginosa strains.

Recent Advances in Investigation, Prevention, and Management of Healthcare-Associated Infections (HAIs): Resistant Multidrug Strain Colonization and Its Risk Factors in an Intensive Care Unit of a University Hospital

Active screening for resistant multidrug strain carriers remains an important component of infection control policy in any healthcare setting indifferent of financial and logistical costs. The objective of our study was to determine the spectrum of bacterial colonization individually among intensive care unit patients. A retrospective observational study was performed in the Intensive Care Unit of Emergency Clinical County Hospital of Oradea during 2017. Medical records of the patients were used for evaluation of source of ICU admission, previous antibiotic therapy, comorbidities, and length of hospital stay. Nasal and groin swabs for MRSA detection and rectal swabs for ESBL, VRE, and CRE detection were collected upon ICU admission of all patients in the first 24 hours and after 7 days. Swab samples were processed for isolation and identification of these resistant multidrug strains. Bacterial colonization on admission was detected in a quarter of patients included in the study. Carbapenemase-producing bacteria were the most common colonizers (21.16%). On admission, 12.06% of patients have been colonized by ESBL-producing members of the family Enterobacterales. Risk factors for colonization on admission to the ICU were chronic liver diseases and chronic renal failure for ESBL infection and chronic liver disease for CRE in male patients. Evaluation of Carmeli's score for male patients showed association only with CRE colonization. Chronic renal failure was found as risk factor for ESBL colonization in female patients. The prevalence of MRSA was 5.23% and less than 1% for VRE. There was no association between any risk factors studied and the presence of S. aureus or VRE upon admission. The 7-day ICU stay also proved to be an increased risk for ESBL and CRE infection.

Treatment of infections caused by multidrug-resistant Gram-negative bacteria: report of the British Society for Antimicrobial Chemotherapy/Healthcare Infection Society/British Infection Association Joint Working Party

The Working Party makes more than 100 tabulated recommendations in antimicrobial prescribing for the treatment of infections caused by multidrug-resistant (MDR) Gram-negative bacteria (GNB) and suggest further research, and algorithms for hospital and community antimicrobial usage in urinary infection. The international definition of MDR is complex, unsatisfactory and hinders the setting and monitoring of improvement programmes. We give a new definition of multiresistance. The background information on the mechanisms, global spread and UK prevalence of antibiotic prescribing and resistance has been systematically reviewed. The treatment options available in hospitals using intravenous antibiotics and in primary care using oral agents have been reviewed, ending with a consideration of antibiotic stewardship and recommendations. The guidance has been derived from current peer-reviewed publications and expert opinion with open consultation. Methods for systematic review were NICE compliant and in accordance with the SIGN 50 Handbook; critical appraisal was applied using AGREE II. Published guidelines were used as part of the evidence base and to support expert consensus. The guidance includes recommendations for stakeholders (including prescribers) and antibiotic-specific recommendations. The clinical efficacy of different agents is critically reviewed. We found there are very few good-quality comparative randomized clinical trials to support treatment regimens, particularly for licensed older agents. Susceptibility testing of MDR GNB causing infection to guide treatment needs critical enhancements. Meropenem- or imipenem-resistant Enterobacteriaceae should have their carbapenem MICs tested urgently, and any carbapenemase class should be identified: mandatory reporting of these isolates from all anatomical sites and specimens would improve risk assessments. Broth microdilution methods should be adopted for colistin susceptibility testing. Antimicrobial stewardship programmes should be instituted in all care settings, based on resistance rates and audit of compliance with guidelines, but should be augmented by improved surveillance of outcome in Gram-negative bacteraemia, and feedback to prescribers. Local and national surveillance of antibiotic use, resistance and outcomes should be supported and antibiotic prescribing guidelines should be informed by these data. The diagnosis and treatment of both presumptive and confirmed cases of infection by GNB should be improved. This guidance, with infection control to arrest increases in MDR, should be used to improve the outcome of infections with such strains. Anticipated users include medical, scientific, nursing, antimicrobial pharmacy and paramedical staff where they can be adapted for local use.

Surveillance of Antibiotic Use and Resistance in Intensive Care Units (SARI)

BACKGROUND

The project entitled Surveillance of Antibiotic Use and Resistance in Intensive Care Units (SARI) was initiated in Germany in 2000. In this article, we describe developments in antibiotic use and resistance rates in the participating intensive care units over the years 2001-2015.

METHODS

The intensive care units supplied monthly figures on patient days, antibiotic use (in defined daily doses, DDD), and resistance data for 13 pathogens. The density of antibiotic use per 1000 patient days was calculated on the basis of antibiotic use, DDD, and patient days, and the resistance density per 1000 patient days was calculated from the number of resistant pathogens.

RESULTS

In the years 2001-2015, data on 2 920 068 patient days were collected in 77 intensive care units. The average overall antibiotic use rose by 19% over this period, with a marked increase in the density of carbapenem use (from 76 to 250 DDD per 1000 patient days, +230%) and piperacillin-tazobactam use (from 42 to 146 DDD per 1000 patient days, +247%). The proportion of Escherichia coli and Klebsiella pneumoniae isolates that were resistant to third-generation cephalosporins increased markedly initially, then remained stable over the remainder of the observation period. The proportion of methicillin-resistant Staphylococcus aureus was stable over the entire period. The rates of vancomycin resistance among Enterococcus faecium isolates and imipenem resistance among gram-negative pathogens increased from 2.3% to 13.3% and from 0.1% to 0.3%, respectively.

CONCLUSION

The resistance density of gram-negative multiresistant pathogens in the participating intensive care units increased markedly. The rise in imipenem-resistant pathogens arouses particular concern. The increased use of broad-spectrum/reserve antibiotics may well have contributed to this development. Efforts to use antibiotics rationally, e.g., with the support of multidisciplinary "antibiotic stewardship" teams, are therefore vitally important. As participation in SARI is voluntary, these surveillance data cannot be considered representative of Germany as a whole.

Antibacterial Efficacy of Commercially Available Essential Oils Tested Against Drug-Resistant Gram-Positive Pathogens

The potential antibacterial activity of basil (Ocimum basilicum), chamomile (Matricaria chamomilla), origanum (Thymus capitatus), tea tree (Melaleuca alternifolia) and thyme (Thymus vulgaris) essential oils, was investigated against 29 Gram-positive bacterial strains isolated from wastewater treatment plants, clinical samples (n = 25) and American Type Culture Collection (ATCC) reference strains (n = 4). Wild bacterial strains included methicillin-resistant Staphylococcus aureus (n = 16) and vancomycin-resistant Enterococcus spp. (n = 9). The antimicrobial activity of the selected oils was studied using the broth macrodilution method. The Minimal Inhibitory Concentration (MIC) values for S. aureus ranged from 0.06 to 0.5% (v/v) for origanum oil, 0.06 to 1% (v/v) for thyme oil, 0.12 to 1% (v/v) for tea tree oil, 0.25 to 4% (v/v) for basil oil and 2 to >4% (v/v) for chamomile oil. For enterococci the MIC values were significantly higher ranging from 0.25 to 1% (v/v), 0.5 to 2% (v/v), 1 to 4% (v/v), 4 to >4% (v/v) and >4% (v/v) for the above-mentioned oils, respectively. The main compounds of the tested essential oils were: estragole (Ocimum basilicum), bisabolol and trans-b-farnesene (Matricaria chamomilla), carvacrol and thymol (Thymus capitatus), terpinen-4-ol and p-cymene (Melaleuca alternifolia), thymol, linalool, and p-cymene (Thymus vulgaris). Origanum essential oil yielded the best antimicrobial results followed by thyme, tea tree, and basil oil, while chamomile oil exhibited weak antibacterial properties.

After standard dosage of piperacillin plasma concentrations of drug are subtherapeutic in burn patients

Infections are a major problem in patients with burn diseases. Mortality is high despite antibiotic therapy as studies are controversial concerning drug underdosing. The aims of this prospective, observational study were to monitor plasma concentrations of piperacillin during standard piperacillin/tazobactam treatment in 20 burn patients and 16 controls from the intensive care unit (ICU) and to optimize doses by in silico analyses. Piperacillin/tazobactam (4/0.5 g, tid) was administered over 0.5 h. Blood samples were taken at 1, 4, and 7.5 h after the end of the infusion. Free piperacillin plasma concentrations were determined. Pharmacokinetic parameters and in silico analysis results were calculated using the freeware TDMx. The primary target was defined as percentage of the day (fT_>1xMIC; fT_>4xMIC) when piperacillin concentrations exceeded 1xMIC/4xMIC (minimum inhibitory concentration), considering a MIC breakpoint of 16 mg/L for Pseudomonas aeruginosa. In an off-label approach, two burn patients were treated with 8/1 g piperacillin/tazobactam, 3 h qid. fT_>1xMIC (55 ± 22% vs. 77 ± 24%) and fT_>4xMIC (17 ± 11% vs. 30 ± 11%) were lower in burn than in ICU patients after 4/0.5 g, 0.5 h, tid. In silico analyses indicated that fT_>1xMIC (93 ± 12% burn, 97 ± 4% ICU) and fT_>4xMIC (62 ± 23% burn, 84 ± 19% ICU) values increase by raising the piperacillin dosage to 8/1 g qid and prolonging the infusion time to 3 h. Off-label treatment results were similar to in silico data for burn patients (84%fT_>1xMIC and 47%fT_>4xMIC). Standard dosage regimens for piperacillin/tazobactam resulted in subtherapeutic piperacillin concentrations in burn and ICU patients. Dose adjustments via in silico analyses can help to optimize antibiotic therapy and to predict respective concentrations in vivo. Trial registration: NCT03335137, registered 07.11.2017, retrospectively.

Single-Center Pharmacokinetic Study and Simulation of a Low Meropenem Concentration in Brain-Dead Organ Donors

Meropenem is an ultrabroad-spectrum antibiotic of the carbapenem family. In brain-dead organ donors, administration of standard meropenem dosages does not reach therapeutic levels. Our objectives were to determine the plasma concentration of meropenem after the administration of standard meropenem dose and to estimate an improved dosage regimen for these patients. One gram of meropenem was administered as a 1-h infusion every 8 h for 1 to 3 days, and blood samples were collected. The plasma concentration of meropenem was measured and subjected to pharmacokinetic analysis. Simcyp simulation was performed to predict the optimum plasma levels and dosage based on the patients' individual pharmacokinetic parameters. The maximum plasma concentration of meropenem was 3.29 μg/ml, which was lower than four times the MIC of 8 μg/ml. Although the mean creatinine clearance of patients was moderately low (67.5 ml/min), the apparent volume of distribution at steady state (Vss) and time-averaged total body clearance (CL) of meropenem were markedly elevated (4.97 liters/kg and 2.06 liters/h/kg, respectively), owing to massive fluid loading to decrease the high sodium levels and to treat shock or dehydration. The simulation revealed that dose and infusion time of meropenem should be increased based on patients' Vss and CL, and a loading dose is recommended to reach rapidly the target concentration. In conclusion, a standard meropenem regimen is insufficient to achieve optimal drug levels in brain-dead patients, and an increase in dose and extended or continuous infusion with intravenous bolus administration of a loading dose are recommended for these patients.

Carbapenem-Nonsusceptible Gram-Negative Pathogens in ICU and Non-ICU Settings in US Hospitals in 2017: A Multicenter Study

Background

Infections caused by Gram-negative pathogens resistant to carbapenems have limited treatment options and are associated with increased morbidity and mortality. We evaluated the rates, infection sources, and pathogen types associated with carbapenem-nonsusceptible (Carb-NS) Gram-negative isolates in intensive care unit (ICU) and non-ICU settings in a large US hospital database.

Methods

We conducted a retrospective cross-sectional analysis of carbapenem susceptibility of all nonduplicate isolates of Gram-negative pathogens collected from January 1, 2017, to December 31, 2017, at 358 US hospitals in the BD Insights Research Database. Carb-NS isolates included all pathogens reported at the institutional level as intermediate or resistant.

Results

Of 312 075 nonduplicate Gram-negative isolates, 10 698 (3.4%) were Carb-NS. Respiratory samples were the most frequent source of Carb-NS isolates (35.2%); skin/wound accounted for 23.6%. Pseudomonas aeruginosa was the most common Carb-NS pathogen (58.5% of isolates), and about 30% were Enterobacteriaceae. The highest rates of Carb-NS were found in Acinetobacter spp. (35.6%) and P. aeruginosa (14.6%). The rate of Carb-NS was significantly higher in ICU (5.4%) vs non-ICU settings (2.7%; P < .0001 in univariate analysis). This difference remained significant in multivariable analysis after adjusting for infection and hospital characteristics (odds ratio, 1.35; 95% confidence interval, 1.17–1.56; P < .0001).

Conclusions

Infections caused by Carb-NS isolates pose a significant clinical problem across different sources of infection, species of pathogen, and hospital settings. Widespread infection prevention and antimicrobial stewardship initiatives, in combination with new treatment options, may be required to reduce the burden of carbapenem resistance in health care settings.

β-Lactam Dosage Regimens in Septic Patients with Augmented Renal Clearance

Augmented renal clearance is commonly observed in septic patients and may result in insufficient β-lactam serum concentrations. The aims of this study were to evaluate potential correlations between drug concentrations or total body clearance of β-lactam antibiotics and measured creatinine clearance and to quantify the need for drug dosage adjustments in septic patients with different levels of augmented renal clearance.

Augmented renal clearance is commonly observed in septic patients and may result in insufficient β-lactam serum concentrations. The aims of this study were to evaluate potential correlations between drug concentrations or total body clearance of β-lactam antibiotics and measured creatinine clearance and to quantify the need for drug dosage adjustments in septic patients with different levels of augmented renal clearance. We reviewed 256 antibiotic measurements (512 drug concentrations) from a cohort of 215 critically ill patients who had a measured creatinine clearance of ≥120 ml/min and who received therapeutic drug monitoring of meropenem, cefepime, ceftazidime, or piperacillin from October 2009 until December 2014 at Erasme Hospital. Population pharmacokinetic (PK) analysis of the data was performed using the Pmetrics software package for R. Fifty-five percent of drug concentrations showed insufficient β-lactam serum concentrations to treat infections due to Pseudomonas aeruginosa. There were significant, yet weak, correlations between measured creatinine clearance and trough concentrations of meropenem (r = −0.21, P = 0.01), trough concentrations of piperacillin (r = −0.28, P = 0.0071), concentrations at 50% of the dosage interval (r = −0.41, P < 0.0001), and total body clearance of piperacillin (r = 0.39, P = 0.0002). Measured creatinine clearance adequately explained changes in drug concentrations in population pharmacokinetic models for cefepime, ceftazidime, and meropenem but not for piperacillin. Therefore, specific PK modeling can predict certain β-lactam concentrations based on renal function but not on absolute values of measured creatinine clearance, easily available for clinicians. Currently, routine therapeutic drug monitoring is required to adjust daily regimens in critically ill patients receiving standard dosing regimens.

Clinical characteristics and outcome of critically ill patients with bacteremia caused by extended-spectrum β-lactamase-producing and non-producing Escherichia coli

The number of patients infected with extended-spectrum beta-lactamase (ESBL)-producing organisms has increased dramatically worldwide, and high mortality rates are seen in severely ill patients. This study retrospectively compared the clinical characteristics and outcomes of critically ill patients in an intensive care unit (ICU) at the Tsuyama Chuo Hospital (Okayama, Japan) who were hospitalized for bacteremia caused by ESBL-producing Escherichia coli (ESBL-EC) or non-ESBL-producing E. coli (non-ESBL-EC) between January 2006 and December 2016 (11 years). We analyzed the patients' age, sex, underlying disease(s), sequential organ failure assessment scores, primary focus of bacteremia, empiric antibiotics, rate of appropriateness of empiric antibiotics, and treatment duration, with 28-day mortality being the primary outcome. The study included 24 patients with ESBL-EC bacteremia and 77 with non-ESBL-EC bacteremia. The rate of appropriate initial antibiotic treatment was significantly lower (54.2% vs. 96.1%, respectively; P < 0.01) and the mortality due to bacteremia significantly higher (37.5% vs. 15.6%, respectively; P = 0.04) in the ESBL-EC than in the non-ESBL-EC bacteremia group. A subgroup analysis focusing on patients who were administered appropriate empiric antibiotics showed that the 28-day mortality rate did not differ significantly between the two groups (P = 0.23). To our knowledge, this is the first study to compare the outcomes of patients with ESBL-EC and non-ESBL-EC bacteremia in a Japanese ICU setting. Initial empiric antibiotic therapy covering ESBL-producing pathogens should be considered for critically ill patients in the ICU.

A Monte Carlo Simulation Approach for Beta-Lactam Dosing in Critically Ill Patients Receiving Prolonged Intermittent Renal Replacement Therapy

Cefepime, ceftazidime, and piperacillin/tazobactam are commonly used beta-lactam antibiotics in the critical care setting. For critically ill patients receiving prolonged intermittent renal replacement therapy (PIRRT), limited pharmacokinetic data are available to inform clinicians on the dosing of these agents. Monte Carlo simulations (MCS) can be used to guide drug dosing when pharmacokinetic trials are not feasible. For each antibiotic, MCS using previously published pharmacokinetic data derived from critically ill patients was used to evaluate multiple dosing regimens in 4 different prolonged intermittent renal replacement therapy effluent rates and prolonged intermittent renal replacement therapy duration combinations (4 L/h × 10 hours or 5 L/h × 8 hours in hemodialysis and hemofiltration modes). Antibiotic regimens were also modeled depending on whether drugs were administered during or well before prolonged intermittent renal replacement therapy therapy commenced. The probability of target attainment (PTA) was calculated using each antibiotic's pharmacodynamic target during the first 48 hours of therapy. Optimal doses were defined as the smallest daily dose achieving ≥90% probability of target attainment in all prolonged intermittent renal replacement therapy effluent and duration combinations. Cefepime 1 g every 6 hours following a 2 g loading dose, ceftazidime 2 g every 12 hours, and piperacillin/tazobactam 4.5 g every 6 hours attained the desired pharmacodynamic target in ≥90% of modeled prolonged intermittent renal replacement therapy patients. Alternatively, if an every 6-hours cefepime regimen is not desired, the cefepime 2 g pre-prolonged intermittent renal replacement therapy and 3 g post-prolonged intermittent renal replacement therapy regimen also met targets. For ceftazidime, 1 g every 6 hours or 3 g continuous infusion following a 2 g loading dose also met targets. These recommended doses provide simple regimens that are likely to achieve the pharmacodynamics target while yielding the least overall drug exposure, which should result in lower toxicity rates. These findings should be validated in the clinical setting.

ICU mortality following ICU-acquired primary bloodstream infections according to the type of pathogen: A prospective cohort study in 937 Germany ICUs (2006-2015)

Objective

Mortality due to intensive care unit (ICU) acquired primary blood stream infections (PBSI) is related primarily to patient co-morbidities, types of pathogens and quality of care. The objective of this study is to determine the impact of various types of pathogen on ICU mortality.

Methods

Data from the German National Nosocomial Infection Surveillance System of patients with PBSI from 2006 to 2015 was used for this analysis. A BSI is primary when the pathogen recognized is not related to an infection on another site. Only mono-microbial infections stratified into the 13 pathogens most frequently causing PBSI were considered. Univariate and multivariate risk factor analyses were performed using the following risk factors: Sex, age, length of stay, device use, time until onset of PBSI, type and size of hospital, type of ICU and type of pathogen. ICU mortality following S.aureus PBSI was used as the reference value.

Results

A total of 4,556,360 patients with 16,978,882 patient days from 937 ICUs were considered in the analysis. Of 14,626 PBSI in total, 12,745 mono-microbial PBSI were included. The ICU mortality was 18.6%. Compared with S.aureus and adjusted by age, sex and type of ICU, S.maltophilia was associated with significantly higher ICU mortality (OR 1.71; 95%CI 1.19–2.47) as followed by Enterococci (OR 1.20; 95%CI 1.06–1.36), E.coli (OR 1.24; 95%CI 1.02–1.49), C.albicans (OR 1.37; 95%CI 1.16–1.61), non albicans Candida spp. (OR 1.49; 95%CI 1.18–1.88) and P.aeruginosa (OR 1.49; 95%CI 1.21–1.84). Coagulase negative Staphylococci were associated with significant lower ICU mortality (OR 0.86; 95%CI 0.75–0.99).

Conclusion

Because of the limitation of the study in adjusting for severity of illness and appropriateness of therapy, the differences between the pathogens may not only be explained by differences in virulence, but may reflect the prognosis after receiving the microbiological results and may therefore be useful for intensive care physicians.

Frequency, associated factors and outcome of multi-drug-resistant intensive care unit-acquired pneumonia among patients colonized with extended-spectrum β-lactamase-producing Enterobacteriaceae

Background

We assessed prevalence, associated factors and prognosis of extended-spectrum beta-lactamase-producing Enterobacteriaceae pneumonia acquired in intensive care unit (ESBL-PE pneumonia) among carriers. Variables associated with nosocomial pneumonia caused by carbapenem-resistant bacteria (CRB) were also assessed.

Methods

A 6-year prospective study (May 2009–March 2015) in the medical ICU of an 850-bed university-affiliated hospital was conducted.

Results

Of the 6303 patients admitted, 843 (13.4%) had ESBL-PE carriage detected. Among carriers, 111 (13%) patients developed ICU-acquired pneumonia of whom 48 (43%) had ESBL-PE pneumonia (6% of carriers). By multivariable analysis, SAPS II at admission >43 [OR 2.81 (1.16–6.79)] and colonization with Enterobacter sp. or K. pneumoniae species [OR 10.96 (2.93–41.0)] were independent predictive factors for ESBL-PE pneumonia in colonized patients, whereas receipt of >2 days of amoxicillin/clavulanic acid during the ICU stay [OR 0.24 (0.08–0.71)] was protective. Patients with ESBL-PE pneumonia had a higher SOFA score (p = 0.037) and more frequent septic shock at pneumonia onset (p = 0.047). However, ESBL-PE pneumonia was not an independent predictor of mortality. Twenty-five patients had pneumonia caused by CRB. Chronic renal insufficiency, administration of third-generation cephalosporin within the past 3 months, acute respiratory distress syndrome before pneumonia and prior therapy with a carbapenem or fluoroquinolones were associated with CRB pneumonia in this selected population.

Conclusions

Although few ESBL-PE carriers developed ESBL-PE pneumonia overall, a high proportion of pneumonia were caused by ESBL-PE in carriers developing ICUAP. ESBL-PE pneumonia was not an independent predictor of mortality. As pneumonia caused by CRB is increasing, knowledge of factors associated with ESBL-PE or CRB pneumonia may help empiric therapy of pneumonia among ESBL-PE carriers.

Electronic supplementary material

The online version of this article (doi:10.1186/s13613-017-0283-4) contains supplementary material, which is available to authorized users.

Target attainment with continuous dosing of piperacillin/tazobactam in critical illness: a prospective observational study

Optimal dosing of β-lactam antibiotics in critically ill patients is a challenge given the unpredictable pharmacokinetic profile of this patient population. Several studies have shown intermittent dosing to often yield inadequate drug concentrations. Continuous dosing is an attractive alternative from a pharmacodynamic point of view. This study evaluated whether, during continuous dosing, piperacillin concentrations reached and maintained a pre-defined target in critically ill patients. Adult patients treated with piperacillin by continuous dosing in the intensive care unit of a university medical centre in The Netherlands were prospectively studied. Total and unbound piperacillin concentrations drawn at fixed time points throughout the entire treatment course were determined by liquid chromatography-tandem mass spectrometry. A pharmacokinetic combined target of a piperacillin concentration ≥80 mg/L, reached within 1 h of starting study treatment and maintained throughout the treatment course, was set. Eighteen patients were analysed. The median duration of monitored piperacillin treatment was 60 h (interquartile range, 33-96 h). Of the 18 patients, 5 (27.8%) reached the combined target; 15 (83.3%) reached and maintained a less strict target of >16 mg/L. In this patient cohort, this dosing schedule was insufficient to reach the pre-defined target. Depending on which target is to be met, a larger initial cumulative dose is desirable, combined with therapeutic drug monitoring.

Impact of colistin plasma levels on the clinical outcome of patients with infections caused by extremely drug-resistant Pseudomonas aeruginosa

BACKGROUND

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.

METHODS

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_ss) were recorded. The primary and secondary end points were clinical cure and 30-day all-cause mortality.

RESULTS

Ninety-one patients were included. Clinical cure was observed in 72 (79%) patients. The mean (SD) C_ss 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).

CONCLUSION

In this series of patients with infections caused by XDR P. aeruginosa infections, C_ss is not observed to be related to clinical outcome.

Epidemiology of Klebsiella pneumoniae bloodstream infections in a teaching hospital: factors related to the carbapenem resistance and patient mortality

Background

Although Klebsiella pneumoniae bloodstream infections (KP-BSIs) have recently attracted attention due to an alarming raise in morbidity and mortality, there have been few reports on the epidemiology of KP-BSIs in mainland China. We sought to describe the epidemiological, microbiological, and clinical characteristics of KP-BSIs, focusing on the risk factors of carbapenem resistance and patient mortality.

Methods

A retrospective analysis of WHONET data of KP-BSI patients admitted to a teaching hospital in Shanghai, China, between January 1, 2011 and December 31, 2015 was performed, and the annual percentage of patients with carbapenem-resistant K. pneumoniae (CRKP) was determined. Risk factors related to the carbapenem resistance and patient mortality were analyzed using binary logistic regression model. The genetic relatedness of CRKP strains isolated from intensive care unit (ICU) patients was determined by pulsed-field gel electrophoresis (PFGE).

Results

A total of 293 incidences of KP-BSIs were identified in a 5-year period, 22.18% of these (65/293) were CRKP strains, and the proportion of CRKP-BSI in ICU was 59.62% (31/52), equaling the levels observed in the epidemic regions. A number of KP-BSIs (114), obtained from January 1, 2014, to December 31, 2015, were further investigated. Skin and soft tissue infection source (odds ratio [OR] 26.63, 95% confidence interval [CI] 4.8–146.8) and ICU-acquired infection (OR 5.82, 95% CI 2.0–17.2) was shown to be powerful risk factors leading to the development of CRKP-BSI. The crude 28-day mortality rates of KP-BSI and CRKP-BSI patients were 22.8% and 33.3%, respectively. Lung as the probable source of infection (OR 4.23, 95% CI 1.0–17.3), and high Sequential Organ Failure Assessment (SOFA) score (OR 1.40, 95% CI 1.2–1.6) were strong prognostic factors determining crude 28-day KP-BSI mortality rates. PFGE analysis demonstrated that 10/11 random CRKP isolates in ICU belonged to the same clonal type.

Conclusions

During the study period, we observed a significant increase in the occurrence of CRKP infections among the identified KP-BSIs in our hospital and especially in ICU, and we demonstrated that carbapenem resistance is associated with the increased mortality of KP-BSI patients.

E. coli bacteremia in comparison to K. pneumoniae bacteremia: influence of pathogen species and ESBL production on 7-day mortality

In a previous study, we demonstrated prolonged length of hospital stay in cases of extended-spectrum beta-lactamase (ESBL)-positive K. pneumoniae bacteremia compared to bacteremia cases due to E. coli (ESBL-positive and –negative) and ESBL-negative K. pneumoniae. The overall mortality was significantly higher in bacteremia cases resulting from ESBL-positive pathogens but also in K. pneumoniae cases disregarding ESBL-production. In order to examine whether pathogen species rather than multidrug resistance might affect mortality risk, we reanalyzed our dataset that includes 1.851 cases of bacteremia.

Clinical and Molecular Characteristics of Neonatal Extended-Spectrum β-Lactamase-Producing Gram-Negative Bacteremia: A 12-Year Case-Control-Control Study of a Referral Center in Taiwan

Extended-spectrum β-lactamase (ESBL)-producing Gram-negative bacteremia (GNB) in the neonatal intensive care unit was characterized by comparison with two control groups: a susceptible control group and a general base population group over 2001 to 2012. The influence of ESBL production on mortality was studied in all study subjects and ESBL-GNB isolates were microbiologically characterized. We identified 77 episodes of ESBL-GNB (14.2% of all neonatal late-onset GNB), which were caused by Klebsiella spp. (62.3%), E. coli (20.8%) and Enterobacter spp. (16.9%). Most ESBL-GNB strains were genetically unrelated and the SHV-type ESBLs were the most prevalent (67% of isolates). Comparison with both control groups disclosed previous usage of 3^rd generation cephalosporin (odds ratio [OR], 4.72; 95% confidence interval [CI], 2.03–10.97; P < 0.001), and underlying renal disease (OR, 4.07; 95% CI, 1.10–15.08; P = 0.035) as independent risk factors for ESBL-GNB. Inadequate empiric antibiotics, a higher illness severity, higher rates of infectious complications and sepsis-attributable mortality were more frequently seen in neonates with ESBL-GNB than those with non-ESBL GNB (20.8% and 15.6% vs. 9.2% and 7.9%, respectively; P = 0.008 and 0.049, respectively). Neonates with underlying secondary hypertension (OR, 7.22; 95% CI, 2.17–24.06) and infectious complications after bacteremia (OR, 6.66; 95% CI, 1.81–19.31) were identified as independent risk factor for in-hospital mortality. ESBL-GNB accounted for one-seventh of all neonatal gram-negative bacteremia, especially in neonates exposed to broad-spectrum cephalosporins. Neonates with ESBL-GNB bacteremia more frequently received inadequate empirical antibiotic therapy, which were associated with a higher rate of infectious complications and an adverse outcome.

Screening for Gram-negative bacteria: Impact of preanalytical parameters

Screening recommendations for multidrug-resistant Gram-negative bacteria comprise microbiological analyses from rectal swabs. However, essential specifications of the preanalytic steps of such screenings, i.e. the sampling technique, sampling devices and sampling site, are lacking. For standardized and optimum screening conditions these parameters are indispensable. Here, the optimum parameters were examined irrespective of the antibiotic resistance patterns of the target bacteria in order to establish a general basis for this type of screening. Swabs with rayon, polyurethane-cellular-foam and nylon-flocked tips were tested. Different sampling locations were evaluated, i.e. perianal, intraanal and deep intraanal. Subjects were swabbed and quantities of E. coli, K. pneumoniae, P. aeruginosa and A. baumannii were assessed. Overall prevalences of E. coli, K. pneumoniae, P. aeruginosa, and A. baumannii were 94%, 16%, 12%, and 2%, respectively. Bacterial recovery rates were independent from the sampling-timepoint during hospital stay. Polyurethane-cellular-foam or nylon-flocked swabs recovered significantly more bacteria as compared to rayon swabs. Intraanal swabbing resulted in significantly higher bacterial quantities as compared to perianal swabbing. In contrast, for the detection of A. baumannii, perianal swabbing seems more suitable than intraanal swabbing. Gender-related differences in bacterial recovery could be detected from perianal but not from intraanal swabs.

Association between infections caused by multidrug-resistant gram-negative bacteria and mortality in critically ill patients

The incidence of gram-negative multidrug-resistant (MDR) bacterial pathogens is increasing in hospitals and particularly in the intensive care unit (ICU) setting. The clinical consequences of infections caused by MDR pathogens remain controversial. The purpose of this review is to summarize the available data concerning the impact of these infections on mortality in ICU patients. Twenty-four studies, conducted exclusively in ICU patients, were identified through PubMed search over the years 2000-2015. Bloodstream infection was the only infection examined in eight studies, respiratory infections in four and variable infections in others. Comparative data on the appropriateness of empirical antibiotic treatment were provided by only seven studies. In ten studies the presence of antimicrobial resistance was not associated with increased mortality; on the contrary, in other studies a significant impact of antibiotic resistance on mortality was found, though, sometimes, mediated by inappropriate antimicrobial treatment. Therefore, a direct association between infections due to gram-negative MDR bacteria and mortality in ICU patients cannot be confirmed. Sample size, presence of multiple confounders and other methodological issues may influence the results. These data support the need for further studies to elucidate the real impact of infections caused by resistant bacteria in ICU patients.

Extended-spectrum beta-lactamase--producing enterobacteriaceae in the intensive care unit: acquisition does not mean cross-transmission

Background

In intensive care unit (ICU), infection and colonization by resistant Gram-negative bacteria increase costs, length of stay and mortality. Extended-spectrum beta-lactamase − producing Enterobacteriaceae (ESBL-E) is a group of pathogens increasingly encountered in ICU setting. Conditions that promote ESBL-E acquisition are not completely understood. The increasing incidence of infections related to ESBL-E and the unsolved issues related to ESBL-E cross-transmission, prompted us to assess the rates of referred and acquired cases of ESBL-E in ICU and to assess patient-to-patient cross-transmission of ESBL-E using a multimodal microbiological analysis.

Methods

During a 5-month period, all patients admitted to a medical ICU were tested for ESBL-E carriage. A rectal swab was performed at admission and then twice a week until discharge or death. ESBL-E strains were analyzed according to antibiotic susceptibility pattern, rep-PCR (repetitive-element Polymerase chain reaction) chromosomal analysis, and plasmid PCR (Polymerase chain reaction) analysis of ESBL genes. Patient-to-patient transmission was deemed likely when 2 identical strains were found in 2 patients hospitalized simultaneously in the ICU.

Results

Among the 309 patients assessed for ESBL-E carriage on admission, 25 were found to carry ESBL-E (importation rate: 8 %). During follow-up, acquisition was observed among 19 of them (acquisition rate: 6.5 %). Using the multimodal microbiological approach, we found only one case of likely patient-to-patient ESBL-E transmission.

Conclusions

In unselected ICU patients, we found rather low rates of ESBL-E referred and acquired cases. Only 5 % of acquisitions appeared to be related to patient-to-patient transmission. These data highlight the importance of jointly analyzing phenotypic profile and molecular data to discriminate strains of ESBL-E.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-016-1489-z) contains supplementary material, which is available to authorized users.