Nasal Reservoir Research Articles

Efficacy and safety of oxygen-sparing nasal reservoir cannula for treatment of pediatric hypoxemic pneumonia in Uganda: a pilot randomized clinical trial

BackgroundOxygen is an essential therapy for hypoxemia but is scarce in low-income settings. Oxygen conserving devices optimize delivery, but to date have been designed for adults in high-income settings. Here we present the development and clinical pilot study of an oxygen-sparing nasal reservoir cannula (OSNRC) for pediatric use in low-income settings.Methods(1) Pre-clinical development of a novel OSNRC using a simulated respiratory circuit with metabolic simulator and anatomically accurate face-airway models. Simulated breathing waveforms were designed based on airway resistance, lung compliance, respiratory rate, and tidal volume of spontaneous breathing for three disease conditions. (2) Pilot, randomized, controlled, non-blinded, cross-over study of the OSNRC vs standard nasal cannula (SNC) among children hospitalized with hypoxemic pneumonia in Uganda. Eight children were randomized to OSNRC followed by SNC, and eight were randomized to SNC followed by OSNRC.ResultsThe laboratory simulation showed that the OSNRC provided the same or higher fraction of inspired oxygen at approximately 2.5-times lower flow rate compared to SNC. The flow savings ratio exhibited a linear relationship with the OSNRC volume to tidal volume ratio with a slope that varied with breathing waveforms. The range of performance from different breathing waveforms defined a performance envelope of the OSNRC. Two mask sizes (30 mL and 50 mL) provided sufficient coverage for patients between the 3rd and 97th percentile in our targeted age range. In the clinical pilot study, the rise in capillary blood pCO2 was similar in the OSNRC and SNC groups, suggesting that the OSNRC was not associated with CO2 retention. There were no significant differences between OSNRC and SNC with respect to clinical adverse events, lactate levels, pH, and SpO2. The OSNRC group had a higher mean SpO2 than the SNC group (adjusted mean difference, 1.4, 95% confidence interval 1.1 to 1.8), showing oxygen delivery enhancement.ConclusionThe OSNRC enhances oxygen delivery without causing CO2 retention and appears to be well-tolerated by pediatric patients. If safety, efficacy and tolerability are confirmed in larger trials, this device has the potential to optimize oxygen delivery in children in low-resource settings, reducing the global burden of pediatric pneumonia.Trial registrationThe trial was retrospectively registered (International Standard Registered Clinical/Social Study Number (ISRCTN): 15216845; Date of registration: 15 July 2020).

A Feasibility Study Evaluating a Novel Mask (Nasal Reservoir Cannula)

A Feasibility Study Evaluating a Novel Mask (Nasal Reservoir Cannula)

Low-level antimicrobial resistance of Enterobacteriaceae isolated from the nares of pig-exposed persons.

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) have recently emerged in livestock and humans. Therefore, this study assessed the carriage of Enterobacteriaceae in the anterior nares and associated antimicrobial resistance in pig-exposed persons. Nasal swabs were enriched in non-selective broth and then plated on MacConkey and ESBL-selective agars. Species was confirmed by matrix-assisted laser-desorption ionization-time-of-flight mass spectrometry (MALDI-ToF MS). Antimicrobial susceptibility testing was performed according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) guidelines. Of 114 pig-exposed persons tested, Enterobacteriaceae were detected in the nares of 76 (66·7%) participants. The predominant species were Proteus mirabilis (n = 17, 14·9%), Pantoea agglomerans (n = 13, 11·4%), Morganella morganii (n = 9, 7·9%), Citrobacter koseri (n = 9, 7·9%), Klebsiella pneumoniae, Escherichia coli and Proteus vulgaris (each n = 8, 7·0%). ESBL-E were not detected. Of all isolates tested, 3·4% were resistant against ciprofloxacin, 2·3% against gentamicin, 23·9% against trimethoprim-sulfamethoxazole and 44·3% against tigecycline. Despite the high prevalence of ESBL-E in livestock, pig-exposed persons did not carry ESBL-E in their nares. This finding is important, because colonization of the nasal reservoir might cause endogenous infections or facilitate transmission of ESBL-E in the general population.

Molecular and Immunological Characterization ofStaphylococcus aureusin Pediatric Atopic Dermatitis: Implications for Prophylaxis and Clinical Management

S. aureus represents a critical cofactor in atopic dermatitis (AD). In this paper, the prevalence of S. aureus infection/colonization was evaluated in 117 children as well as in their cohabitants, in order to assess the value of S. aureus characterization in predicting disease onset and severity and in providing indications for prophylaxis. Results showed that children with AD as well as their cohabitants had a significantly greater incidence of S. aureus infection/colonization as compared to controls. The genetic characterization showed a virtual identity of the bacteria strains collected at different sites of the patients with those found in the cohabitants, suggesting both a direct transmission between the nasal reservoir and the lesions in the same atopic subject and a risk for reinfection within family cohabitants. These data stress the need of preliminary laboratory assessment and posttherapy control in both AD patients and their close contacts for effective S. aureus eradication.

Efficacy of oral isotretinoin in the control of skin and nasal colonization by antibiotic-resistant propionibacteria in patients with acne

Skin colonization by antibiotic-resistant propionibacteria is commonplace among acne patients globally. Increasing attention is now being paid to how resistance rates might be reduced to preserve the future efficacy of antibiotics, especially erythromycin and clindamycin in acne therapy. To assess the efficacy of oral isotretinoin in the control of antibiotic-resistant propionibacteria. Acne patients (72 in the U.K., 62 in the U.S.A.) colonized with high numbers of antibiotic-resistant propionibacteria were sampled before, during and 12 weeks after oral isotretinoin therapy. Propionibacterial samples were collected from five acne-prone skin surface sites using a detergent scrub method and from the anterior nares using moistened swabs. Total and antibiotic-resistant propionibacteria were enumerated by viable counting on media with and without selective antibiotics. After 16 weeks of oral isotretinoin therapy, mean population densities of viable propionibacteria and variants resistant to erythromycin, clindamycin or tetracycline had fallen by more than 90% at all skin sites and in the nares. The sole exception was a smaller reduction in tetracycline-resistant strains on the lower back. In general, greater reductions were observed on skin than in the nares. By the end of the treatment period only three patients (all in Philadelphia) yielded no antibiotic-resistant strains from any site. Post-treatment, propionibacterial counts remained well below pretreatment levels but had begun to recover on the face and in the nares. The recovering propionibacterial population included both susceptible and resistant strains. Changes during and post-treatment at the two centres were similar but not identical. Oral isotretinoin effectively reduced skin and nasal colonization by antibiotic-resistant propionibacteria. However, viable populations of resistant isolates persisted post-treatment at multiple sites. Novel methods are required to eradicate antibiotic-resistant propionibacteria completely, especially from the nasal reservoir.

Strategy to control methicillin-resistant Staphylococcus aureus post-operative infection in orthopaedic surgery.

In the year 2000 the rate of infection after arthroplasty in our hospital was 9.75% and methicillin-resistant Staphylococcus aureus (MRSA) was the organism in 33% of the infected joints. In an attempt to overcome this unacceptable situation, we changed our prophylaxis regime over a period of 6 months. This involved modifying the precautionary measures for preventing surgical infections, active prophylaxis against any nasal reservoir of infection in joint implant patients, the control of health care personnel, the strict application of standard and contact precautions in all patients with MRSA, and the use of teicoplanin as prophylaxis during this 6-month period. This resulted in a definite decrease in the incidence of orthopaedic wound infections by MRSA, while the level of MRSA infection elsewhere in the hospital remained constant. Only one infection was detected during this 6-month trial, and this beneficial effect was maintained during the following 6 months. Since then, only sporadic new infections have been detected. Patients with arthroplasties performed during the study were followed for 12 months, and no new cases of MRSA infection were detected.

Prevalence of antibiotic-resistant propionibacteria on the skin of acne patients: 10-year surveillance data and snapshot distribution study.

Cutaneous propionibacteria are implicated in acne pathogenesis, although their exact role in the genesis of inflammation is still poorly understood. Agents, including antibiotics, that reduce the numbers of propionibacteria on skin are therapeutic. Resistance in the target organism is a well-recognized consequence of antibiotic therapy for acne but formal prevalence and distribution data are lacking. To monitor the prevalence of skin colonization by antibiotic-resistant propionibacteria in acne patients attending the dermatology out-patient clinic at Leeds General Infirmary over a 10-year period beginning in 1991, and to examine the distribution of resistant strains on acne-prone skin and in the nares. Propionibacterial samples were obtained from the skin surface of the worst affected site (usually the face) of 4274 acne patients using a moistened swab. The swab was used to inoculate agar plates with and without selective antibiotics. After anaerobic incubation at 37 degrees C for 7 days, the amount of growth in the presence of each antibiotic was scored on a scale from 0 to 5+. A small number of patients (72) were selected for more detailed quantitative sampling at six different sites to examine the distribution of resistant propionibacteria on acne-prone skin and in the anterior nares. The proportion of patients carrying strains resistant to one or more commonly used antiacne antibiotics rose steadily from 34.5% in 1991 to a peak of 64% in 1997. The prevalence dropped to 50.5% during 1999 and then rose again to 55.5% in 2000. Resistance to erythromycin was the most common and the majority of erythromycin-resistant strains were cross-resistant to clindamycin. Resistance to tetracyclines was less common in all years and with little increase over time. The more detailed quantitative study in 72 patients showed that population densities of resistant propionibacteria varied considerably between sites and between individuals. Almost invariably, patients were colonized with resistant strains at multiple sites, including the nares. Skin colonization with antibiotic-resistant propionibacteria is much more common now than a decade ago. Resistant propionibacteria are widely distributed on acne-prone skin and in the nares. This suggests that they will be very difficult to eradicate using existing therapeutic regimens, especially from the nasal reservoir.

Staphylococcus aureus infections in dialysis patients: focus on prevention.

Staphylococcus aureus infections are a major cause of morbidity and hospitalization in dialysis patients. The risk of infection relates to the type of access. Patients with acute hemodialysis (HD) catheters are at the greatest risk of S. aureus bacteremia, followed by tunneled HD catheters, and grafts. Patients with a fistula have a rate similar to that of peritoneal (PD) patients. In PD patients, however, S. aureus is the second most common cause of peritonitis, is often associated with a catheter infection, and frequently requires catheter removal for resolution. S. aureus infections in dialysis patients are much more common in nasal carriers. S. aureus moves from the nasal reservoir to the hands and skin, and from there to infect the access. Therefore, prevention of infection can be aimed at treating the carriage or in applying antibiotics at the catheter exit site, thus preventing colonization and subsequent infection of the catheter. For HD patients with a permanent access (either fistula or graft), intranasal mupirocin, twice a day for 5 days followed by a once weekly application, is effective in reducing the risk of S. aureus bacteremia. Cost analysis indicates that treating all patients would result in more cost savings than treating just carriers. For patients with acute HD catheters, exit site mupirocin applied as part of routine care during each HD treatment, reduces the risk of S. aureus exit site infection and bacteremia. For PD patients, S. aureus infections can be diminished by using mupirocin at the exit site as part of daily exit site care. Prophylaxis against S. aureus is under utilized in dialysis patients and, if implemented, could lower the rate of these serious infections.