Antibiotic pharmacokinetic and pharmacodynamic parameters in pediatric clinical practice

Progress in the knowledge of antibiotic mechanisms of action allows to determine the pharmacodynamics/pharmacokinetic (PK/PD) parameters predictive of antibiotic efficacy in bacterial infections. According to the antibiotic compound, the bacterial species implicated, the location of the infection, and the severity of the disease, these parameters may vary. The PK/PD parameters described in this paper, focus only on blood compartments. These PK/PD parameters best predict efficacy in the most frequent infections (e.g., respiratory, bacteremia, skin and soft tissue infections and intra-abdominal infections). Furthermore, they contribute to the determination of doses and number of administrations per day as well as the determination of minimum inhibitory concentration (MIC) breakpoints. The time above the MIC (T> MIC) is the main criterion for β-lactams: free drug serum levels of these drugs should be above the MIC for at least 40%-50% of the dosing interval to produce adequate clinical and microbiological efficacy. Peak/MIC ratio is the major determinant of the activity of aminoglycosides: in general, peak/MIC ratios should exceed 8-10. Area under the MIC curve (AUC/MIC) is considered for quinolones, macrolides, and vancomycin as the best predictor of efficacy.

Antibiotic treatment of lower respiratory tract infections

Lower respiratory tract infections, i.e., bronchitis, bronchiolitis, and pneumonia, are the second leading cause of antibiotic prescriptions. The vast majority of these infections are due to viruses and are self-limited diseases: most patients recover spontaneously. These two facts explain that antibiotic prescriptions must be limited to some clinical situations for which the diagnosis has to be done early. The first message of this manuscript is to strengthen non-antibiotic prescriptions in many situations such as bronchitis and bronchiolitis. Implementation of pneumococcal conjugate vaccines (PCVs) has reduced the incidence of pneumonia and empyema, and induced a dramatic decrease in the proportion of pneumococcus in these diseases. However, pneumococcus remains probably the leading cause of bacterial pneumonia and empyema and the main target of antibiotic treatment. Furthermore, the implementation of PCVs has reduced resistance to antibiotics including penicillins and macrolides antibiotics, explaining the de-escalation proposed in the last few years, with the reduction of the use if third generation cephalosporins and vancomycin. The therapeutic choices proposed in this article follow the previous official guidelines in France. Serious infections represented by empyema and severe pneumonia remain therapeutic emergencies, most often warranting hospitalization and IV antibiotics.

Principles of curative antibiotic treatment

Infectious diseases are constantly evolving for many reasons. New infectious agents are regularly discovered, mainly because of the development of identification methods, including the molecular tools and mass spectrometry. Changes in the epidemiology of infectious diseases are not always understood, but several factors undoubtedly play an important role, notably the impact of vaccination implementations, the ecological consequences of antibiotic treatments and their excessive use, and the secular epidemiological trends of pathogenic agents. Antibiotic resistance has been recognized as one of the major challenges for humanity and few new antibiotics with potent activity against resistant Gram-negative rods have been developed in recent years. The rationalization of antibiotic treatments is a key for reducing or limiting antimicrobial resistance. This guide takes into account the latest recommendations, the consensus conferences, and the guidelines of the Pediatric Infectious Diseases Group of the French Society of Pediatric, the French Infectious Diseases Society, and French official agencies. For each clinical situation, the main bacterial target of the antibiotic treatment, the first-choice antibiotic and the alternative treatment, as well as the most important findings for the diagnosis and treatment of the infection are detailed.

Comparison of Immunoassays for Tumor Markers CA 19-9, CA 15-3 and CA 125: Data from an International Quality Assessment Scheme

Data collected in the 1993 and 1994 cycles of an international external quality assessment (EQA) program and in a national multicenter collaborative study were cumulatively analyzed to evaluate the standardization of the methods currently in use for the assay of mucinous tumor markers CA 19-9, CA 15-3 and CA 125. On average the between-laboratory variability was 15.2 and 16.0 CV% for CA 15-3 and CA 125 respectively; the between-laboratory variability found for CA 19-9 was markedly worse (mean 28.3 CV%). The variability component attributable to systematic differences between different methods/kits was relatively small for CA 15-3 and CA 125 (18% and 24% of the total variability) but markedly larger for CA 19-9 (48% of the total variability). The agreement of CA 19-9 results worsened in the last few years when new nonisotopic techniques became available. The precision of the methods/kits most used in the survey ranged from 9.9 to 13.3 CV% for CA 125 and from 11.6 to 13.9 CV% for CA 15-3. For these two tumor markers the precision of the traditional IRMAs does not appear different from that of the new fully automated nonisotopic techniques. The precision of CA 19-9 methods was on average worse (from 11.7 to 19.6 CV%) although two automated systems exhibited a precision better than that of IRMAs. In conclusion, the results of this study indicate that CA 15-3 and CA 125 are satisfactorily assayed whereas CA 19-9 assay appears affected by larger differences between methods and by poorer precision of laboratories and kits.

Feasibility of fluorescence lymph node imaging in colon cancer: FLICC

BACKGROUND

In colon cancer, appropriate tumour excision and associated lymphadenectomy directly impact recurrence and survival outcomes. Currently, there is no standard for mesenteric lymphadenectomy, with a lymph node yield of 12 acting as a surrogate quality marker. Our goal was to determine the safety and feasibility of indocyanine green (ICG) fluorescence imaging to demonstrate lymphatic drainage in colon cancer in a dose-escalation study.

METHODS

A prospective pilot study of colon cancer patients undergoing curative laparoscopic resection was performed. At surgery, peritumoural subserosal ICG injection was done to demonstrate lymphatic drainage of the tumour. A specialized fluorescence system excited the ICG and assessed lymphatics in real time. The primary outcome was the feasibility of ICG fluorescent lymphangiography for lymphatic drainage in colon cancer. Secondary outcomes were the optimal protocol for dose, injection site, and ICG lymphatic mapping timing.

RESULTS

Ten consecutive patients were evaluated (six males, mean age 69.5 years). In all, lymphatic channels were seen around the tumour to a varying extent. Eight (80%) had drainage to the sentinel node. In all cases where the lymphatic map was seen, there was no further spread 10 min after injection. In 2 patients (20%), additional lymph nodes located outside of the proposed resection margins were demonstrated. In both cases the resection was extended to include the nodes and in both patients these nodes were positive on histopathology. Factors contributing to reduced lymphatic visualization were inadequate ICG concentrations, excess India ink blocking drainage, and inflammation from tattoo placement.

CONCLUSIONS

ICG can be safely injected into the peritumoural subserosal and demonstrate lymphatic drainage in colon cancer. This proof of concept and proposed standards for the procedure can lead to future studies to optimize the application of image-guided precision surgery in colon cancer. Furthermore, this technique may be of value in indicating the need for more extended lymphadenectomy.

Modelling of airborne particulate matter concentration in underground stations using a two size-class conservation model

This study presents an attempt of predictive modelling of airborne particulate matter in underground railway stations. The aerosol is represented by a set of simple, ordinary differential equations that describe apparent emission of two particles size-classes in relation with train traffic, ventilation and deposition. The parameters of the equations are identified numerically by a genetic algorithm and comply with their respective expected order of magnitude. A quantitative comparison of numerical results with experimental data from Paris underground station exhibits a good accordance. A qualitative comparison with results from the literature also supports the model.

Sexual dysfunction following rectal cancer surgery

INTRODUCTION

Sexual and urological problems after surgery for rectal cancer are common, multifactorial, inadequately discussed, and untreated. The urogenital function is dependent on dual autonomic sympathetic and parasympathetic innervation, and four key danger zones exist that are at risk for nerve damage during colorectal surgery: one of these sites is in the abdomen and three are in the pelvis. The aim of this study is to systematically review the epidemiology of sexual dysfunction following rectal cancer surgery, to describe the anatomical basis of autonomic nerve-preserving techniques, and to explore the scientific evidence available to support the laparoscopic or robotic approach over open surgery.

METHODS

According to the PRISMA guidelines, a comprehensive literature search of studies evaluating sexual function in patients undergoing rectal surgery for cancer was performed in Medline, Scopus, Web of Science, Embase, and Cochrane Central Register of controlled trials.

RESULTS

An increasing number of studies assessing the incidence and prevalence of sexual dysfunction following multimodality treatment for rectal cancer has been published over the last 30 years. Significant heterogeneity in the prevalence of sexual dysfunction is reported in the literature, with rates between 5 and 90%.

CONCLUSIONS

There is no evidence to date in favor of any surgical approach (open vs laparoscopic vs robotic). Standardized diagnostic tools should be routinely used to prospectively assess sexual function in patients undergoing rectal surgery.

Audit of appropriate use of platelet transfusions: validation of adjudication criteria

BACKGROUND AND OBJECTIVES

Platelet (PLT) transfusions must be used appropriately, as they are in chronic short supply, costly and risky to patients. The goals of this audit were to: (1) validate preset adjudication criteria through an audit of appropriateness at four large academic hospitals; (2) identify variability in appropriateness across medical services, physician specialties or hospital locations; and (3) inform logistical or educational interventions that may reduce inappropriate use.

MATERIALS AND METHODS

A chart review of two hundred patients receiving PLT transfusions was performed. Fifty consecutive transfusion episodes per site were audited in detail. Each transfusion episode was independently adjudicated as appropriate or inappropriate by two transfusion specialists based on predetermined criteria.

RESULTS

The adjudication criteria performed well with simple agreement of 95% (kappa statistic 0·83) between reviewers. Overall, 78% (95% CI: 72-84%) of PLT transfusions were adjudicated as appropriate, with results varying significantly by hospital site (range 62-94%). Prophylactic transfusions for non-bleeding patients had the highest proportion of appropriateness (85%, n = 80), and therapeutic transfusions for bleeding patients had the lowest (73%, n = 99). The lowest levels of appropriate platelet transfusions were observed in the operating rooms (60%) and when ordered by the general surgery service (55%).

CONCLUSIONS

One in five platelet transfusions may be unnecessary, suggesting that interventions to improve PLT transfusion practice are warranted.

Clinical and molecular characterisation of hereditary and sporadic metastatic colorectal cancers harbouring microsatellite instability/DNA mismatch repair deficiency

BACKGROUND

Patients treated with chemotherapy for microsatellite unstable (MSI) and/or mismatch repair deficient (dMMR) cancer metastatic colorectal cancer (mCRC) exhibit poor prognosis. We aimed to evaluate the relevance of distinguishing sporadic from Lynch syndrome (LS)-like mCRCs.

PATIENTS AND METHODS

MSI/dMMR mCRC patients were retrospectively identified in six French hospitals. Tumour samples were screened for MSI, dMMR, RAS/RAF mutations and MLH1 methylation. Sporadic cases were molecularly defined as those displaying MLH1/PMS2 loss of expression with BRAFV600E and/or MLH1 hypermethylation and no MMR germline mutation.

RESULTS

Among 129 MSI/dMMR mCRC patients, 81 (63%) were LS-like and 48 (37%) had sporadic tumours; 22% of MLH1/PMS2-negative mCRCs would have been misclassified using an algorithm based on local medical records (age, Amsterdam II criteria, BRAF and MMR statuses when locally tested), compared to a systematical assessment of MMR, BRAF and MLH1 methylation statuses. In univariate analysis, parameters associated with better overall survival were age (P < 0.0001), metastatic resection (P = 0.001) and LS-like mCRC (P = 0.01), but not BRAFV600E. In multivariate analysis, age (hazard ratio (HR) = 3.19, P = 0.01) and metastatic resection (HR = 4.2, P = 0.001) were associated with overall survival, but not LS. LS-like patients were associated with more frequent liver involvement, metastatic resection and better disease-free survival after metastasectomy (HR = 0.28, P = 0.01). Median progression-free survival of first-line chemotherapy was similar between the two groups (4.2 and 4.2 months; P = 0.44).

CONCLUSIONS

LS-like and sporadic MSI/dMMR mCRCs display distinct natural histories. MMR, BRAF mutation and MLH1 methylation testing should be mandatory to differentiate LS-like and sporadic MSI/dMMR mCRC, to determine in particular whether immune checkpoint inhibitors efficacy differs in these two populations.

Impact of pH on Urine Chemistry Assayed on Roche Analyzers

BACKGROUND

The pH may impact the concentration of certain urinary parameters, making urine pre-treatment questionable.

METHODS

1) Determining the impact of pH in vitro on the urinary concentration of chemistry parameters assayed on Roche Modular analyzers. 2) Evaluating whether concentrations depended on pH in non-pretreated urines from patients.

RESULTS

1) The optimal urinary pH values for each measurement were: 6.3 ± 0.8 (amylase), < 5.5 (calcium and magnesium), < 6.5 (phosphorus), > 6.5 (uric acid). Urinary creatinine, sodium and urea concentrations were not pH-dependent. 2) In urines from patients, the pH was negatively associated with the concentration of some urinary parameters. However, concentrations of all the parameters were strongly and positively correlated with urinary creatinine, and relationships with pH were no longer evidenced after creatinine-normalization.

CONCLUSIONS

The need for urine pH adjustment does not seem necessary when considering renal function. However, from an analytical and accreditation standpoint, the relationship between urine pH and several parameters justifies its measurement.

Reply to the Letter by S. Sorscher Regarding "Implications of BRAF Mutations in dMMR Colorectal Cancers"

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Quality of life following fistulotomy - short term follow-up

AIM

Anal fistula causes pain and discharge of pus and blood. Treatment by fistulotomy has the highest success, but can risk continence; treatment needs to balance cure with continence. This study assessed the impact of fistulotomy on quality of life (QOL) and continence.

METHOD

Patients selected for fistulotomy prospectively completed the St Mark's Continence Score (full incontinence = 24) and Short Form-36 questionnaires preoperatively at two institutions with an interest in anal fistula. Patients were reassessed 3 months' postoperatively.

RESULTS

There were 52 patients with a median age of 44 (range 19-82) years; 10 were women. Preoperative continence scores were median 0 (range 0-23) and there was no significant difference compared with postoperative scores (median 1, range 0-24). Following fistulotomy QOL was significantly improved in four of eight domains - Bodily Pain (P < 0.001), Vitality (P < 0.01), Social Functioning (P < 0.05) and Mental Health (P < 0.001) - and returned to that of the general population. QOL for patients with intersphincteric fistula improved postfistulotomy, and for those with trans-sphincteric fistula it remained the same. Data were further examined in two groups, with and without deterioration in continence score. Where continence improved postoperatively, QOL improved in three domains; where continence deteriorated QOL improved in two domains (P < 0.05). Patients with postoperative continence scores of < 5 had worse QOL than those scoring 4 or less.

CONCLUSION

QOL significantly improved at 3 months' follow-up after fistulotomy where continence was maintained or a small reduction occurred.