Paradoxical increase in nasal airway resistance after topical nasal decongestion - does it really exist? A retro- and prospective study

OBJECTIVE

To explore the prevalence and reproducibility of paradoxically increased nasal airway resistance after decongestion of the nasal mucosa as well as to identify patient-related factors associated with it.

DESIGN

Retrospective analysis of all rhinomanometric measurements carried out at one ENT department in Sweden in the time between 1990 and 2010. In the baseline material, 207 of 4435 patients (4.7%) showed a paradoxically increased nasal airway resistance >20%. A follow-up rhinomanometry was performed in patients eligible for the study.

SETTING

Secondary care centre.

PARTICIPANTS

Patients with paradoxically increased nasal airway resistance >20% who returned a complete questionnaire and had not undergone any nasal- or sinus surgery. Thirty-six patients (33-72 years) were eligible for the study.

MAIN OUTCOME MEASURES

All patients answered a questionnaire and underwent rhinoscopy. Nasal airway resistance before and after decongestion with 0.1% xylometazoline hydrochloride was assessed by active anterior rhinomanometry.

RESULTS

Twelve of thirty-six patients (33%) showed a paradoxically increased nasal airway resistance in the follow-up rhinomanometry. No patient-related factors were identified.

CONCLUSION

The results indicate the existence and reproducibility of paradoxically increased nasal airway resistance.

Bone tissue and plasma concentrations of linezolid and vancomycin in rabbits with prosthesis-related infection due to MRSA

BACKGROUND

Due to its safety profile and ease of oral administration, linezolid became an alternative to vancomycin in the treatment of methicillin-resistant Staphylococcus aureus (MRSA) infections. The aim of our study was to compare bone tissue and plasma concentrations of linezolid and vancomycin in prosthesis-related MRSA infection in a rabbit model.

MATERIAL AND METHODS

During implantation of titanium cylinders into the femurs of nine rabbits, a bacterial suspension of MRSA was added to induce infection. Antibiotic treatment was started eight hours later. Antibiotic concentrations in plasma (day one, three and seven) and bone (day seven) were determined by HPLC analysis.

RESULTS

At steady state the mean peak and trough plasma levels of linezolid were 29.0 microg/mL and 8.2 microg/ mL and for vancomycin 39.1 microg/mL and 28.2 microg/mL. On day seven the mean peak concentration of linezolid in plasma was 28.5 microg/mL and after six hours 26.3 microg/mL and for vancomycin 53.8 microg/mL and 29.1 microg/mL after six hours. Vancomycin showed a penetration into the infected bone (femur) of 53% of plasma concentration, into the uninfected 28%, linezolid 11% (for both six hours after administration).

CONCLUSION

In conclusion, we observed a higher rate of tissue penetration for vancomycin than for linezolid into femur bone in this animal model. As linezolid offers the option for oral treatment of gram-positive organisms, results of further studies comparing vancomycin and linezolid are keenly awaited.

Identification of Marchfeld asparagus using Sr isotope ratio measurements by MC-ICP-MS

This work focuses on testing and application of Sr isotope signatures for the fast and reliable authentication and traceability of Asparagus officinalis originating from Marchfeld, Austria, using multicollector inductively coupled plasma mass spectrometry after optimised Rb/Sr separation. The major sample pool comprises freeze-dried and microwave-digested asparagus samples from Hungary and Slovakia which are compared with Austrian asparagus originating from the Marchfeld region, which is a protected geographical indication. Additional samples from Peru, The Netherlands and Germany were limited in number and allowed therefore only restricted statistical evaluation. Asparagus samples from Marchfeld were harvested within two subsequent years in order to investigate the annual variation. The results show that the Sr isotope ratio is consistent within these 2 years of investigation. Moreover, the Sr isotope ratio of total Sr in soil was found to be significantly higher than in an NH4NO3 extract, reflecting the mobile (bioavailable) phase. The isotope composition in the latter extract corresponds well to the range found in the asparagus samples in Marchfeld, even though the concentration of Sr in asparagus shows no direct correlation to the concentration of Sr in the mobile phase of the soil. The major question was whether the 'Marchfelder Spargel' can be distinguished from samples from the neighbouring countries of Hungary and Slovakia. According to our findings, they can be clearly (100%) singled out from the Hungarian samples and can be distinguished from the Slovakian asparagus samples with a probability of more than 80%.

Factors influencing caspofungin plasma concentrations in patients of a surgical intensive care unit

BACKGROUND

Co-morbidity, medical and surgical interventions often cause alterations to drug plasma concentrations and pharmacokinetic parameters in critically ill patients. In the present study, we investigated parameters influencing plasma caspofungin concentrations in patients of a surgical intensive care unit (SICU).

METHODS

In a monocentre open study, caspofungin trough concentrations (C(24)) were determined for a group of SICU patients. A linear-mixed model was then used to assess factors influencing caspofungin plasma concentrations.

RESULTS

A total of 40 SICU patients were enrolled. Age and body weight ranged from 22 to 76 years and 47 to 108 kg, respectively. All participants received a caspofungin loading dose of 70 mg and a maintenance dose of 50 mg/day. The median duration of therapy was 10 days. Caspofungin C(24) in SICU patients varied more than those determined for healthy subjects reported in previous studies (0.52-4.08 microg/mL versus 1.12-1.78 microg/mL). According to our model, caspofungin C(24) were predicted to be significantly higher in patients with body weight <75 kg (P=0.019) and patients with albumin concentration >23.6 g/L (P=0.030).

CONCLUSIONS

Our results show that body weight and albumin concentration influence caspofungin C(24) in SICU patients and should therefore be considered prognostic factors.

Septischer Schock durch Vancomycin-resistente Enterokokken

Adequate antimicrobial therapy is of crucial importance for the survival of critically ill patients with severe nosocomial infections. Tigecycline is an important therapeutic option for the treatment of infections caused by multi-resistant Gram-positive and Gram-negative bacteria including vancomycin-resistant enterococci (VRE). A large randomised study (patients with APACHE-II-score >30 excluded/mean APACHE-II-score 6) demonstrated that tigecycline is not inferior to imipenem/cilastatin for treatment of complicated intra-abdominal infections. However, no case has been reported with microbiological eradication and clinical cure in a patient with septic shock due to peritonitis caused by VRE and treatment with tigecycline monotherapy. Clinical details of a patient suffering from postoperative peritonitis are presented. The patient developed severe septic shock after pancreatic surgery (multiple organ failure, APACHE-II-score 34). As the site of anastomotic leakage was very small and could not be exactly identified, irrigation-suction drains were placed followed by closed postoperative continuous lavage. The pathogen responsible was identified as a vancomycin-resistant Enterococcus faecium, therefore monotherapy with tigecycline was started which resulted in microbiological response and clinical cure. Tigecycline is a new therapeutic option for the treatment of intra-abdominal infections and from an economic point of view financially rewarding when used as monotherapy.

Tissue and serum levofloxacin concentrations in diabetic foot infection patients

OBJECTIVES

Levofloxacin has a high bioavailability and a broad antibacterial spectrum which covers the common pathogens found in acute and chronic diabetic foot infections. The purpose of our study was to determine the serum and tissue concentrations of levofloxacin when administered orally in patients with infected diabetic foot ulcers and to compare these values with microbiological findings.

PATIENTS AND METHODS

Ten outpatients with diabetes and ulcerations of the lower extremity were included. All patients received oral levofloxacin therapy at a dose of 500 mg once daily. Wound tissue and serum samples were collected and levofloxacin concentrations determined by HPLC with fluorescence detection. Additionally, microbiological cultures were performed from swabs and debrided wound tissue, both before and after treatment. MICs of levofloxacin for all bacterial isolates were determined using the Etest.

RESULTS

Following oral treatment with levofloxacin for an average of 10 +/- 3.8 days, all patients received debridement at the affected limbs. The levofloxacin concentrations in necrotic wound tissue were between 2.33-23.23 mg/kg and between 0.12-6.41 mg/L in serum. Tissue-to-serum ratios of levofloxacin concentrations for each patient were >1.0. The MIC values for all 17 initially isolated bacteria were < or = 2 mg/L. In half of our patients, fluoroquinolones were one of the few oral monotherapy options where the spectrum covered all initially isolated pathogens.

CONCLUSION

Our data showed good tissue penetration of levofloxacin in diabetic foot ulcers. In combination with adequate surgical debridement, levofloxacin seems well suited to the treatment of skin structure infections of diabetics caused by susceptible organisms.

Tissue and serum concentrations of levofloxacin 500 mg administered intravenously or orally for antibiotic prophylaxis in biliary surgery

OBJECTIVES

Levofloxacin is a third-generation fluoroquinolone with a broad spectrum of antibacterial activity, comprising enterobacteria, non-fermenters, Gram-positive cocci and some anaerobic species. Members of these species are common pathogens in acute and chronic cholecystitis. This suggests that levofloxacin may be used as peri-operative prophylaxis in gall-bladder surgery. The purpose of our study was to determine serum and tissue levels of levofloxacin in cholecystectomy patients following pre-operative dosing.

PATIENTS AND METHODS

Patients with gall-bladder surgery were given levofloxacin 500 mg as a single dose either intravenously (iv) or orally pre-operatively, at the treating physician's decision. Gall-bladder tissue and serum samples were collected, and drug concentrations were determined by HPLC with fluorescence detection. Additionally, all tissue samples underwent routine microbiological diagnostics. MICs for aerobic isolates were determined using the Etest.

RESULTS

A total of 61 patients (48 female, 13 male) were included. The medians of the levofloxacin concentrations in serum were 11.37 mg/L (iv) and 9.65 mg/L (oral), and in gall-bladder tissue they were 15.61 mg/kg (iv) and 17.93 mg/kg (oral). Eleven pathogens were isolated from gall-bladder samples. Post-operative wound infection was observed in two of the 61 patients.

CONCLUSION

Our data suggest that levofloxacin may be considered for peri-operative prophylaxis in biliary tract surgery.

Impact of altered aminoglycoside volume of distribution on the adequacy of a three milligram per kilogram loading dose. Critical Care Research Group

BACKGROUND

Sepsis is associated with an increased volume of distribution for aminoglycoside antibiotics. As a result of this increased volume of distribution, 2 mg/kg loading doses have previously been shown to be ineffective in producing adequate aminoglycoside peak plasma levels in critically ill patients. The main objective of this pharmacokinetic observational study was to determine the adequacy of a 3 mg/kg loading dose of gentamicin or tobramycin in attaining an initial peak level of 8 micrograms/ml or greater.

METHODS

Fifty-three consecutive patients given gentamicin or tobramycin for documented or suspected life-threatening gram-negative infections were enrolled. Loading doses of either aminoglycoside were administered during 30 minutes, and a peak level was obtained 1 hour after completed infusion.

RESULTS

The patient's mean age was 61 +/- 2 years, with a male/female ratio of 33:20. The loading dose of 3 mg/kg produced 1-hour peak aminoglycoside levels greater than 8 micrograms/ml in only 50% of the patients studied. The calculated aminoglycoside volume of distribution was increased by 34%.

CONCLUSIONS

An aminoglycoside loading dose of 3 mg/kg is inadequate in critically ill patients undergoing operation. The documented increase in volume of distribution is principally responsible for the inadequacy of this dose. Future studies should use a 4 mg/kg loading dose to maximize aminoglycoside bactericidal activity.