Effect of Fish Oil Parenteral Emulsion Supplementation on Inflammatory Parameters after Esophagectomy

(Background) Esophagectomy (EPG) presents high morbidity and mortality. Omega-3 fatty acids (ω-3FA) are a pharmaconutrient with benefits for postoperative morbidity. Studies of ω-3FA administered parenterally after esophagectomy are scarce. This study proposes to investigate the effect of combining fish oil lipid emulsions (LE) administered parenterally with enteral nutrition support. (Methods) Randomization was 1:1:1 in three groups: Group A received a LE mixture of 0.4 g/kg/day of fish oil and 0.4 g/kg/day of LCT/MCT 50:50, Group B received 0.8 g/kg/day of fish oil LE, and Group C received 0.8 g/kg/day of LCT/MCT 50:50. Variables were measured at recruitment time and day +1, +3, and +5. Inflammatory variables studied were Interlukin-6, C-reactive protein (CRP), tumoral necrosis factor-α (TNF-α), IL-10, IL-8 and CD25s. Safety, nutritional parameters and complications were analyzed. (Results) Administration of ω-3LE in the immediate postoperative period did not modulate the earlier inflammatory response. Statistically significant differences were found in IL-6 and CRP overall temporal evolution but were not found when studying the type of LE administered or in patients needing critical care. Administration of ω-3 resulted in safe and improved hypertriglyceridemia, depending on the dose. (Conclusions) ω-3FA has no impact on the early inflammatory postoperative response assessed for a short period but was safe. More studies for longer periods are needed.

Association between septic patient mortality and blood survivin concentrations

OBJECTIVE

Survivin is a member of inhibitors of apoptosis proteins family. There are not data about the association between mortality of septic patients and blood survivin concentrations. Therefore, the objective of this study was to determine whether exist that association.

DESIGN

Observational and prospective study.

SETTING

Three Spanish Intensive Care Units.

PATIENTS

Patients with sepsis or septic shock according to Sepsis-3 Consensus criteria.

INTERVENTIONS

Serum survivin concentrations were determined at moment of sepsis diagnosis.

MAIN VARIABLE OF INTEREST

Mortality at 30 days.

RESULTS

A total of 204 patients were included in the study, of which 75 (36.8%) died in the first 30 days. Lower age (p<0.001), serum lactic acid levels (p=0.001), rate of septic shock (p=0.001) and SOFA (p<0.001), and higher serum survivin levels (p=0.001) exhibited surviving (n=129) than non-surviving patients (n=75). We found in multiple logistic regression analysis an association between serum survivin concentrations and mortality independently of SOFA, lactic acid, age, INR, activated partial thromboplastin time (aPTT) and empiric antimicrobial treatment adequate (OR=0.968; 95% CI=0.946-0.990; p=0.005), and also independently of APACHE-II, lactic acid, platelet, INR, aPTT and empiric antimicrobial treatment adequate (OR=0.966; 95% CI=0.943-0.989; p=0.004).

CONCLUSIONS

There is an association between septic patient mortality and low blood survivin concentrations.

Robotic surgery for the treatment of achalasia

OBJECTIVE

To describe the experience of the robotic approach for achalasia surgery in a tertiary center.

MATERIAL AND METHODS

Patients with achalasia who underwent robotic surgery between May 2010 and April 2019 were analyzed. The study variables were collected in a prospective database and a descriptive analysis was performed.

RESULTS

45 patients (55.6% male) with a mean age of 44 years were included. The main symptom at diagnosis was dysphagia. 19 patients (42.2%) received endoscopic treatment prior to surgery, mostly pneumatic dilation (84.2%). Heller's myotomy associated with Toupet fundoplication was the surgical technique of choice, with a mean operative time of 211 min. The average stay was 5 days. There were 2 postoperative perforations (4.4%). Perioperative mortality was 0%. The mean follow-up was 64 months. At 3 and 5 years, a significant decrease in the Eckardt score was observed and the manometric study showed a decrease in the lower esophageal sphincter pressure at rest of 58% and 70%, respectively, with persistence of hypomotility of the esophageal body. Pathological gastroesophageal reflux was diagnosed in two patients (5.4%) and 4 (10.8%) presented recurrence of symptoms, requiring endoscopic pneumatic dilations. In 2 cases, the dilations were not effective, so an endoscopic myotomy was considered.

CONCLUSIONS

In our experience, robotic surgery is a safe and effective procedure for the treatment of achalasia.

Association between blood caspase-8 levels and mortality of patients with malignant middle cerebral artery infarction

OBJECTIVE

High concentrations of caspase-8 (main initiator caspase of apoptosis extrinsic pathway) have been found in brain tissue from traumatic brain injury patients and in blood of patients with different diseases. However, there are not data on blood caspase-8 concentrations in ischemic stroke patients. Therefore, the objective of this study was to determine whether there is an association between blood caspase-8 concentrations and the probability and speed of mortality at 30 days in patients with malignant middle cerebral artery infarction (MMCAI).

DESIGN

Observational prospective study.

SETTING

Five Intensive Care Units (ICU).

PATIENTS

Patients with severe malignant middle cerebral artery infarction (MMCAI) defined as acute infarction in more than of 50% of that territory and Glasgow Coma Scale (GCS)<9.

INTERVENTIONS

Determination of serum caspase-8 levels when MMCAI was diagnosed.

MAIN VARIABLES OF INTEREST

Mortality at 30 days and time until this event.

RESULTS

Severe MMCAI patients (n=28) compared to survivor patients (n=28) showed higher serum caspase-8 concentrations (p<0.001), lower platelet count (p=0.01) and lower GCS (p=0.002). We found an area under the curve for mortality prediction of 78% (95% CI=65%-91%; p<0.001) by serum caspase-8 levels. Kaplan-Meier analysis found higher mortality rate in patients with serum caspase-8 levels >62.8ng/mL (hazard ratio=11.2; 95% CI=4.4-28.4; p<0.001).

CONCLUSIONS

The association of high blood caspase-8 concentrations with the rate and the velocity of 30-day mortality in MMCAI patients is the main new finding of our study.

Blood caspase-8 concentrations and mortality among septic patients

OBJECTIVE

No data are available on blood caspase-8 concentrations (the initiator caspase in the extrinsic apoptosis pathway) in septic patients. The present study thus describes the blood caspase-8 concentrations in survivors and non-survivors, and examines the possible association between blood caspase-8 concentrations and mortality in septic patients.

DESIGN

A prospective observational study was carried out.

SETTING

Three Spanish Intensive Care Units.

PATIENTS

Septic patients.

INTERVENTIONS

Serum caspase-8 concentrations were determined at the diagnosis of sepsis.

MAIN VARIABLE OF INTEREST

Mortality after 30 days.

RESULTS

Patients not surviving at day 30 (n=81) compared to surviving patients (n=140) showed higher serum caspase-8 levels (p<0.001). Multiple logistic regression analysis found an association between serum caspase-8 levels>43.5ng/ml and mortality (OR=3.306; 95%CI=1.619-6.753; p=0.001). The area under the curve (AUC) for mortality predicted by serum caspase-8 levels was 67% (95% CI=60-73%; p<0.001).

CONCLUSIONS

The novel findings of our study were that blood caspase-8 concentrations are higher in non-survivors than in survivors, and that there is an association between blood caspase-8 concentrations and mortality in septic patients.

Robotic surgery for the treatment of achalasia

OBJECTIVE

To describe the experience of the robotic approach for achalasia surgery in a tertiary center.

MATERIAL AND METHODS

Patients with achalasia who underwent robotic surgery between May 2010 and April 2019 were analyzed. The study variables were collected in a prospective database and a descriptive analysis was performed.

RESULTS

45 patients (55.6% male) with a mean age of 44 years were included. The main symptom at diagnosis was dysphagia. 19 patients (42.2%) received endoscopic treatment prior to surgery, mostly pneumatic dilation (84.2%). Heller's myotomy associated with Toupet fundoplication was the surgical technique of choice, with a mean operative time of 211minutes. The average stay was 5 days. There were 2 postoperative perforations (4.4%). Perioperative mortality was 0%. The mean follow-up was 64 months. At 3 and 5 years, a significant decrease in the Eckardt score was observed and the manometric study showed a decrease in the lower esophageal sphincter pressure at rest of 58% and 70%, respectively, with persistence of hypomotility of the esophageal body. Pathological gastroesophageal reflux was diagnosed in two patients (5.4%) and 4 (10.8%) presented recurrence of symptoms, requiring endoscopic pneumatic dilations. In 2 cases, the dilations were not effective, so an endoscopic myotomy was considered.

CONCLUSIONS

In our experience, robotic surgery is a safe and effective procedure for the treatment of achalasia.

Association between blood caspase-8 levels and mortality of patients with malignant middle cerebral artery infarction

OBJECTIVE

High concentrations of caspase-8 (main initiator caspase of apoptosis extrinsic pathway) have been found in brain tissue from traumatic brain injury patients and in blood of patients with different diseases. However, there are not data on blood caspase-8 concentrations in ischemic stroke patients. Therefore, the objective of this study was to determine whether there is an association between blood caspase-8 concentrations and the probability and speed of mortality at 30 days in patients with malignant middle cerebral artery infarction (MMCAI).

DESIGN

Observational prospective study.

SETTING

Five Intensive Care Units (ICU).

PATIENTS

Patients with severe malignant middle cerebral artery infarction (MMCAI) defined as acute infarction in more than of 50% of that territory and Glasgow Coma Scale (GCS)<9.

INTERVENTIONS

Determination of serum caspase-8 levels when MMCAI was diagnosed.

MAIN VARIABLES OF INTEREST

Mortality at 30 days and time until this event.

RESULTS

Severe MMCAI patients (n=28) compared to survivor patients (n=28) showed higher serum caspase-8 concentrations (p<0.001), lower platelet count (p=0.01) and lower GCS (p=0.002). We found an area under the curve for mortality prediction of 78% (95% CI=65%-91%; p<0.001) by serum caspase-8 levels. Kaplan-Meier analysis found higher mortality rate in patients with serum caspase-8 levels >62.8ng/mL (hazard ratio=11.2; 95% CI=4.4-28.4; p<0.001).

CONCLUSIONS

The association of high blood caspase-8 concentrations with the rate and the velocity of 30-day mortality in MMCAI patients is the main new finding of our study.

HLA genetic polymorphisms and prognosis of patients with COVID-19

Objective

Different genetic polymorphisms of human leukocyte antigen (HLA) have been associated with the risk and prognosis of autoimmune and infectious diseases. The objectives of this study were to determine whether there is an association between HLA genetic polymorphisms and the susceptibility to and mortality of coronavirus disease 2019 (COVID-19) patients.

Design

Observational and prospective study.

Setting

Eight Intensive Care Units (ICU) from 6 hospitals of Canary Islands (Spain).

Patients

COVID-19 patients admitted in ICU and healthy subjects.

Interventions

Determination of HLA genetic polymorphisms.

Main variable of interest

Mortality at 30 days.

Results

A total of 3886 healthy controls and 72 COVID-19 patients (10 non-survivors and 62 survivor patients at 30 days) were included. We found a trend to a higher rate of the alleles HLA-A*32 (p = 0.004) in healthy controls than in COVID-19 patients, and of the alleles HLA-B*39 (p = 0.02) and HLA-C*16 (p = 0.02) in COVID-19 patients than in healthy controls; however, all these p-values were not significant after correction for multiple comparisons. Logistic regression analysis showed that the presence of certain alleles was associated with higher mortality, such as the allele HLA-A*11 after controlling for SOFA (OR = 7.693; 95% CI = 1.063-55.650; p = 0.04) or APACHE-II (OR = 11.858; 95% CI = 1.524-92.273; p = 0.02), the allele HLA-C*01 after controlling for SOFA (OR = 11.182; 95% CI = 1.053-118.700; p = 0.04) or APACHE-II (OR = 17.604; 95% CI = 1.629-190.211; p = 0.02), and the allele HLA-DQB1*04 after controlling for SOFA (OR = 9.963; 95% CI = 1.235-80.358; p = 0.03).

Conclusions

The new finding from our preliminary study of small sample size was that HLA genetic polymorphisms could be associated with COVID-19 mortality; however, studies with a larger sample size before definitive conclusions can be drawn.

High serum nitrates levels in non-survivor COVID-19 patients

OBJECTIVE

Higher blood nitrate and nitrite levels have been found in coronavirus disease 2019 (COVID-19) patients than in healthy subjects. The present study explores the potential association between serum nitrate levels and mortality in COVID-19 patients.

DESIGN

A prospective observation study was carried out.

SETTING

Eight Intensive Care Units (ICUs) from 6 hospitals in the Canary Islands (Spain).

PATIENTS

COVID-19 patients admitted to the ICU.

INTERVENTIONS

Determination of serum nitrate levels at ICU admission.

MAIN VARIABLE OF INTEREST

Mortality at 30 days.

RESULTS

Non-surviving (n=11) compared to surviving patients (n=42) showed higher APACHE-II (p<0.001) and SOFA scores (p=0.004), and higher serum nitrate levels (p=0.001). Logistic regression analyses showed serum nitrate levels to be associated to 30-day mortality after controlling for SOFA (OR=1.021; 95%CI=1.006-1.036; p=0.01) or APACHE-II (OR=1.023; 95%CI=1.006-1.041; p=0.01). There were no differences in the area under the curve (AUC) for mortality prediction by serum nitrate levels (AUC=83%; 95%CI=73-92%; p<0.001), APACHE II (AUC=85%; 95%CI=75-96%; p<0.001) and SOFA (AUC=78%; 95%CI=63-92%; p=0.005) based on the DeLong method. The Kaplan-Meier analysis found patients with serum nitrates levels>68.4μmol/l to have a higher mortality rate (hazard ratio=138.8; 95%CI=22.3-863.9; p<0.001).

CONCLUSIONS

The main novel finding was the association between serum nitrate levels and mortality in COVID-19 patients controlling for the SOFA or APACHE-II scores, though larger studies are needed to confirm this observation.

Blood caspase-8 concentrations and mortality among septic patients

OBJECTIVE

No data are available on blood caspase-8 concentrations (the initiator caspase in the extrinsic apoptosis pathway) in septic patients. The present study thus describes the blood caspase-8 concentrations in survivors and non-survivors, and examines the possible association between blood caspase-8 concentrations and mortality in septic patients.

DESIGN

A prospective observational study was carried out.

SETTING

Three Spanish Intensive Care Units.

PATIENTS

Septic patients.

INTERVENTIONS

Serum caspase-8 concentrations were determined at the diagnosis of sepsis.

MAIN VARIABLE OF INTEREST

Mortality after 30 days.

RESULTS

Patients not surviving at day 30 (n=81) compared to surviving patients (n=140) showed higher serum caspase-8 levels (p<0.001). Multiple logistic regression analysis found an association between serum caspase-8 levels>43.5ng/ml and mortality (OR=3.306; 95%CI=1.619-6.753; p=0.001). The area under the curve (AUC) for mortality predicted by serum caspase-8 levels was 67% (95% CI=60-73%; p<0.001).

CONCLUSIONS

The novel findings of our study were that blood caspase-8 concentrations are higher in non-survivors than in survivors, and that there is an association between blood caspase-8 concentrations and mortality in septic patients.

Serum caspase-3 levels during the first week of traumatic brain injury

OBJECTIVE

Confluence between the intrinsic and extrinsic apoptosis pathways is reached at the point of caspase-3 activation, which induces death cell. Higher serum caspase-3 levels have been recorded on day 1 of traumatic brain injury (TBI) in 30-day non-survivors compared to survivors. The objectives of this study therefore were to determine whether serum caspase-3 levels are persistently higher in non-survivors than in survivors, and whether these levels may be used to predict 30-day mortality.

DESIGN

A prospective observational study was carried out.

SETTING

Six Spanish Intensive Care Units.

PATIENTS

Patients with severe isolated TBI (defined as Glasgow Coma Scale <9 points and non-cranial Injury Severity Score <10 points).

INTERVENTIONS

Serum caspase-3 concentrations were measured on days 1, 4 and 8 of TBI.

MAIN VARIABLES OF INTEREST

Thirty-day mortality was considered as the study endpoint.

RESULTS

In comparison with non-survivors (n=34), 30-day survivors (n=90) showed lower serum caspase-3 levels on days 1 (p=0.001), 4 (p<0.001) and 8 (p<0.001) of TBI. Analysis of the ROC curves showed serum caspase-3 concentrations on days 1, 4 and 8 of TBI to have an AUC (95% CI) in predicting 30-day mortality of 0.70 (0.61-0.78; p=0.001), 0.83 (0.74-0.89; p<0.001) and 0.87 (0.79-0.93; p<0.001), respectively.

CONCLUSIONS

The novel findings of our study were that serum caspase-3 levels during the first week of TBI were lower in survivors and could predict 30-day mortality.

DNA and RNA oxidative damage are associated to mortality in patients with cerebral infarction

OBJECTIVE

Secondary injury due to oxidation may occur during ischemic stroke, possibly leading to oxidative damage to deoxyribonucleic acid (DNA) and ribonucleic acid (RNA). Higher blood concentrations of 8-hydroxy-2'-deoxyguanosine (8-OHdG) (through the oxidation of guanosine from DNA) have been found in ischemic stroke patients than in healthy subjects, and in patients with versus without post-ischemic stroke depression. The present study was carried out to explore the possible association between serum DNA and RNA oxidative damage and mortality in patients with cerebral infarction.

METHODS

A prospective, multicenter observational study was carried out in the Intensive Care Units of 6 Spanish hospitals. We included patients with severe malignant middle cerebral artery infarction (MMCAI) defined as ischemic changes evidenced by computed tomography in more than 50% of the middle cerebral artery territory and a Glasgow Coma Score (GCS)<9. Serum concentrations of the three oxidized guanine species (OGS) (8-hydroxyguanine from DNA or RNA, 8-hydroxyguanosine from RNA, and 8-OHdG from DNA) on the day of MMCAI diagnosis were determined. The study endpoint was 30-day mortality.

RESULTS

We found higher serum OGS levels (p<0.001) in non-surviving (n=34) than in surviving patients (n=34). Logistic regression analyses showed serum OGS levels to be associated to 30-day mortality controlling for lactic acid, GCS and platelet count (OR=1.568; 95%CI=1.131-2.174; p=0.01).

CONCLUSIONS

The novel observation in this study is the association between global serum OGS concentration and mortality in ischemic stroke patients.

Minimally invasive and robotic surgery in the surgical treatment of esophagogastric junction cancer

Minimally invasive surgery provides for the treatment of esophagogastric junction tumors under safe conditions, reducing respiratory and abdominal wall complications. Recovery is improved, while maintaining the oncological principles of surgery to obtain an optimal long-term outcome. It is important to have a sufficient volume of activity to progress along the learning curve with close expert supervision in order to guarantee R0 resection and adequate lymphadenectomy. Minimal invasiveness ought not become an objective in itself. Should total gastrectomy be performed, the risk of a positive proximal margin makes intraoperative biopsy compulsory, without ruling out a primary open approach. Meanwhile, minimally invasive esophagectomy has been gaining ground. Its main difficulty, the intrathoracic anastomosis, can be safely carried out either with a mechanical side-to-side suture or a robot-assisted manual suture, thanks to the 3-D vision and versatility of the instruments.

Influence of tracheostomy on the incidence of catheter-related bloodstream infection in the catheterization of jugular vein by posterior access

There are no data about the influence of tracheostomy in the incidence of catheter-related bloodstream infection (CRBSI) on the catheterization of the jugular vein by posterior access and there are no recommendations relating to this circumstance in the guidelines of the Centers for Disease Control and Prevention (CDC) and of Healthcare Epidemiology of America/Infectious Diseases Society of America (SHEA/IDSA) for the prevention of CRBSI. The novel finding of this observational study was that there was a higher incidence of CRBSI in the catheterization of jugular vein by posterior access in patients with tracheostomy than without it (13.24 vs 0 episodes of CRBSI per 1,000 catheter-day; odds ratio = 23.92; 95% CI = 1.86-infinite; p = 0.008). Thus, the presence of tracheostomy is a risk factor of CRBSI on the catheterization of jugular vein by posterior access.

Lower incidence of catheter-related bloodstream infection in subclavian venous access in the presence of tracheostomy than in femoral venous access: prospective observational study

Guidelines for the prevention of catheter-related bloodstream infection (CRBSI) recommend subclavian rather than femoral venous access to minimize the risk of CRBSI. However, they do not address the issue of CRBSI with subclavian venous access in the presence of tracheostomy, where the incidence of CRBSI has been found to be higher than without tracheostomy. In this study, we found lower CRBSI in subclavian venous access in the presence of tracheostomy than in femoral venous access (3.9 vs. 10.1 CRBSI per 1000 catheter-days; odds ratio = 0.39; 95% confidence interval ≤0.001-0.91; p 0.03).

Influence of tracheostomy on the incidence of central venous catheter-related bacteremia

Although there are many studies on catheter-related infection, there are scarce data about the influence of tracheostomy in the incidence of central venous catheter-related bacteremia (CRB). In this cohort study, we found a higher incidence of CRB in patients with tracheostomy than without (11.25 vs. 1.43 per 1,000 catheter-days; odds ratio [OR] = 7.99; 95% confidence interval [CI] = 4.38-infinite; P < 0.001). Besides, we found a higher incidence of CRB in patients with tracheostomy using the jugular access compared to subclavian access (21.64 vs. 5.11 per 1,000 catheter-days; OR = 4.23; 95% CI = 1.44-infinite; P = 0.0097).

[Work-related disabilities and workers' difficulties in rejoining the labor market]

This cross-sectional study was conducted on permanently disabled workers assisted by the Center for Occupational Rehabilitation (CRP) in Belo Horizonte, Minas Gerais, Brazil, to evaluate factors associated with their chances of readmission into the labor market. A logistic model was used to investigate workers' acceptance into the professional rehabilitation program and their return into the market. The most decisive factors for their acceptance were age, presence of repetitive strain injury (RSI), and educational level. The most favorable situation was that of workers with RSI under 40 years of age and with average schooling (75.6%). Results showed that young male workers with high educational levels were the ones with the best chances of rejoining the market (90.9%). A controversial issue relates to workers' acceptance and program results. In order to be accepted, the worker had to display a given age and educational profile. Workers with RSI had this profile, but once accepted they were the ones with the greatest difficulty in rejoining the work force. In addition, discrimination against female workers was observed, despite their characteristics being similar to those of males.

Postanitbiotic and sub-MIC effects of azithromycin and isepamicin against Staphylococcus aureus and Escherichia coli

Investigations of pharmacodynamic parameters (postantibiotic effect [PAE], sub-MIC effects [SMEs], etc.) have been progressively employed for the design of dosing schedules of antimicrobial agents. However, there are fewer in vivo than in vitro data, probably because of the simplicity of the in vitro procedures. In this study, we have investigated the in vitro PAE, SME, and previously treated (postantibiotic [PA]) SME (1/2 MIC, 1/4 MIC and 1/8 MIC) of azithromycin and isepamicin against standard strains of Staphylococcus aureus and Escherichia coli by using centrifugation to remove the antibiotics. In addition, the in vivo PAE and SME have been studied with the thigh infection model in neutropenic mice. Finally, in vivo killing curves with two dosing schedules were determined to examine whether the PAE can cover the time that antimicrobial agents are below the MIC. The two antimicrobial agents induced moderate-to-high in vitro PAEs, SMEs, and PA SMEs against S. aureus (>8 h) and E. coli (3.38 to >7.64 h). The in vivo PAEs were also high (from 3.0 to 3.6 h), despite the fact that isepamicin had lower times above the MIC in serum. Only azithromycin showed a high in vivo SME against the two strains (1.22 and 1.75 h), which indicated that the in vivo PAEs were possibly overestimated. In the killing kinetics, no great differences (<0.5 log10) were observed between the schedule that took the PAE into account and the continuous administration of doses. These results are comparable with those of other authors and suggest that these antimicrobial agents could be administered at longer intervals without losing effectiveness.

Pharmacodynamic effects of ciprofloxacin, fleroxacin and lomefloxacin in vivo and in vitro

The present study investigates the postantibiotic effect (PAE) in vivo, and the postantibiotic subinhibitory concentration effects (PA-SE) in vitro and SE in vivo of three 4-fluoroquinolones (ciprofloxacin, fleroxacin and lomefloxacin) against standard strains of Staphylococcus aureus and Escherichia coli. In vivo killing kinetics have also been performed using two different short administrations to study if the PAE duration could cover the time that the antibiotic was below the minimal inhibitory concentration (MIC) in serum. The results show that the three antimicrobial agents induced long PAEs (1.9-3.1 h) against the two microorganisms. Moderate but significant in vitro PA-SEs were also produced (1-->9 h). The in vivo SEs were not significant except when the effect of lomefloxacin on E. coli was assayed (0.54 h). Finally, the in vivo killing kinetics showed that the administrations that included the PAE duration were as effective as the schedule that maintained the antibiotic levels in serum above the MIC. Only when fleroxacin and S. aureus were assayed, this last administration was more effective (+0.9 log10 colony-forming units/thigh).

In vivo and in vitro study of several pharmacodynamic effects of meropenem

Several pharmacodynamic parameters are being studied and applied to the design of dosage regimens. The thigh infection model in neutropenic mice has been used in this study to investigate the in vivo postantibiotic effect (PAE) of meropenem against S. aureus, E. coli and P. aeruginosa. The sub-minimum inhibitory concentration (sub-MIC) postantibiotic effect (PA SME) of 1/2, 1/4 and 1/8 x MIC was also determined in vitro on S. aureus and E. coli after pre-exposure of these microorganisms to 10 x MIC of meropenem. The in vitro PAE was also determined. In vivo killing curves using 2 different short dosage regimens were also studied to relate the lethal effect to the time that serum levels were above the MIC. No significant in vivo and in vitro PAEs were observed. The PA SMEs were higher for S. aureus than for E. coli. The 2 short dosage regimens, in vivo, were equally effective in killing S. aureus, but not E. coli. These results suggest that the pharmacodynamics of meropenem on Gram-negative strains may need further study to elucidate the mechanisms and characteristics of these parameters. On the other hand, we need to standardize a reliable in vitro method to monitor regrowth with a good correlation with the in vivo conditions.