Cefdinir vs cephalexin for the treatment of urinary tract infections: A retrospective evaluation.

PURPOSE: Cefdinir and cephalexin are cephalosporin antibiotics commonly used in the treatment of urinary tract infections (UTIs). Their efficacy depends on achieving sufficient time with concentrations exceeding the minimum inhibitory concentration (MIC). Despite being frequently prescribed for UTIs, cefdinir has markedly lower urine penetration compared to cephalexin. It is possible that differences in pharmacokinetics could result in dissimilar efficacy between these agents; however, comparative studies of cephalosporins in UTIs are lacking. METHODS: This was a retrospective comparative study of patients discharged from emergency departments within a community health system with a diagnosis of acute cystitis who were prescribed cefdinir or cephalexin. Treatment failure rates at 7 and 14 days were compared between the 2 agents using a χ2 or Fisher's exact test, as appropriate. RESULTS: There were no differences in overall treatment failure between the cefdinir and cephalexin groups. Treatment failure at 7 days occurred in 11.6% (n = 14) of patients in the cefdinir group and 8.3% (n = 10) of patients in the cephalexin group (P = 0.389). Treatment failure at 14 days was higher for cefdinir at 20.7% (n = 25) than for cephalexin at 11.8% (n = 14), but this difference was not statistically significant (P = 0.053). There were no differences in the rate of treatment failure in subgroup analyses of uncomplicated or complicated UTIs. CONCLUSION: The results of this study suggest that cefdinir and cephalexin have comparable efficacy for the treatment of lower UTIs. While there was a numerically higher rate of treatment failure with cefdinir, there were no significant differences in treatment failure between the agents.

Impact of reflex fosfomycin susceptibility testing on the utilization of carbapenems for definitive extended-spectrum ß-lactamase Escherichia coli urinary tract infection treatment.

PURPOSE: A protocol was started within a large health system to automatically test all confirmed extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli urine isolates for susceptibility to fosfomycin, an antibiotic not routinely included in such testing in most institutions. This study assessed the effectiveness of the protocol at reducing carbapenem use for the definitive treatment of ESBL E. coli urinary tract infection (UTI) through several endpoints. METHODS: Eighty and 99 patients were compared pre- and postintervention, respectively. The primary outcome was the proportion of patients who received definitive carbapenem therapy. Key secondary outcomes included median total carbapenem days of therapy (DOT), discharge on intravenous UTI antibiotics, and median total antibiotic DOT. RESULTS: Preprotocol vs postprotocol definitive carbapenem use was seen in 59 of 80 patients (73.8%) and 71 of 99 patients (71.7%) (95% confidence interval [CI] for difference, -11.1% to 15.1%; P = 0.76). The rates of step-down to oral agents pre- and postintervention were 15 of 59 (25.4%) and 35 of 71 (49.3%) (P = 0.004). Median carbapenem DOT in those receiving carbapenems decreased from 8 to 4 days (95% CI, -5 to -1 days; P = 0.001). Median total DOT decreased from 10 to 8 days (95% CI, -3 to -1 days; P = 0.002). CONCLUSION: Implementation of a laboratory policy to automatically test ESBL positive E. coli for fosfomycin susceptibility did not reduce the percentage of patients receiving at least 1 dose of carbapenem treatment. It did result in a larger percentage reduction in step-down use of intravenous antibiotics for UTI prior to discharge, reduction in carbapenem DOT, and reduction in total antibiotic DOT.

Biosensors for Monitoring Airborne Pathogens.

Airborne pathogens affect both humans and animals and are often highly and rapidly transmittable. Many problematic airborne pathogens, both viral (influenza A/H1N1, Rubella, and avian influenza/H5N1) and bacterial (Mycobacterium tuberculosis, Streptococcus pneumoniae, and Bacillus anthracis), have huge impacts on health care and agricultural applications, and can potentially be used as bioterrorism agents. Many different laboratory-based methods have been introduced and are currently being used. However, such detection is generally limited by sample collection, including nasal swabs and blood analysis. Direct identification from air (specifically, aerosol samples) would be ideal, but such detection has not been very successful due to the difficulty in sample collection and the extremely low pathogen concentration found in aerosol samples. In this review, we will discuss the portable biosensors and/or micro total analysis systems (µTAS) that can be used for monitoring such airborne pathogens, similar to smoke detectors. Current laboratory-based methods will be reviewed, and possible solutions to convert these lab-based methods into µTAS biosensors will be discussed.

Droplet-based immunoassay on a 'sticky' nanofibrous surface for multiplexed and dual detection of bacteria using smartphones.

We have developed a rapid, sensitive, and specific droplet-based immunoassay for the detection of Escherichia coli and Salmonella within a single-pipetted sample. Polycaprolactone (PCL) electrospun fibers on indium-tin-oxide (ITO) glass provide a sufficient surface to render a non-slip droplet condition, and while the PCL fibers lend a local hydrophilicity (contact angle θ=74°) for sufficient sub-micron particle adhesion, air pockets within the fibers lend an apparent hydrophobicity. Overall, the contact angle of water on this electrospun surface is 119°, and the air pockets cause the droplet to be completely immobile and resistant to movement, protecting it from external vibration. By using both anti-E. coli conjugated, 510 nm diameter green fluorescent particles (480 nm excitation and 520 nm emission) and anti-Salmonella conjugated, 400 nm diameter red fluorescent particles (640 nm excitation and 690 nm emission), we can detect multiple targets in a single droplet. Using appropriate light sources guided by fiber optics, we determined a detection limit of 10(2) CFU mL(-1). Immunoagglutination can be observed under a fluorescence microscope. Fluorescence detection (at the emission wavelength) of immunoagglutination was maximum at 90° from the incident light, while light scattering (at the excitation wavelength) was still present and behaved similarly, indicating the ability of double detection, greatly improving credibility and reproducibility of the assay. A power function (light intensity) simulation of elastic Mie scatter confirmed that both fluorescence and light scattering were present. Due to the size of the fluorescent particles relative to their incident excitation wavelengths, Mie scatter conditions were observed, and fluorescence signals show a similar trend to light scattering signals. Smartphone detection was included for true portable detection, in which the high contact angle pinning of the droplet makes this format re-usable and re-configurable.

Rapid and Sensitive Detection of H1N1/2009 Virus from Aerosol Samples with a Microfluidic Immunosensor.

Influenza A H1N1/2009 is a highly infectious, rapidly spreading airborne disease that needs to be monitored in near real time, preferably in a microfluidic format. However, such demonstration is difficult to find as H1N1 concentration in aerosol samples is extremely low, with interference from dust particles. In this work, we measured Mie scatter intensities from a microfluidic device with optical waveguide channels, where the antibody-conjugated latex beads immunoagglutinated with the target H1N1 antigens. Through careful optimizations of optical parameters, we were able to maximize the Mie scatter increase from the latex immunoagglutinations while minimizing the background scatter from the dust particles. The aerosol samples were collected from a 1:10 mock classroom using a button air sampler, where a nebulizer generated aerosols, simulating human coughing. The detection limits with real aerosol samples were 1 and 10 pg/mL, using a spectrometer or a cell phone camera as an optical detector, respectively. These are several orders of magnitudes more sensitive than the other methods. The microfluidic immunosensor readings are in concordance with the results of reverse transcription polymerase chain reaction. The assay time was 30 s for sampling and 5 min for the microfluidic assay.

Single-pipetting microfluidic assay device for rapid detection of Salmonella from poultry package.

A direct, sensitive, near-real-time, handheld optical immunoassay device was developed to detect Salmonella typhimurium in the naturally occurring liquid from fresh poultry packages (hereafter "chicken matrix"), with just single pipetting of sample (i.e., no filtration, culturing and/or isolation, thus reducing the assay time and the error associated with them). Carboxylated, polystyrene microparticles were covalently conjugated with anti-Salmonella, and the immunoagglutination due to the presence of Salmonella was detected by reading the Mie scatter signals from the microfluidic channels using a handheld device. The presence of chicken matrix did not affect the light scatter signal, since the optical parameters (particle size d, wavelength of incident light λ and scatter angle θ) were optimized to minimize the effect of sample matrix (animal tissues and blood proteins, etc.). The sample was loaded into a microfluidic chip that was split into two channels, one pre-loaded with vacuum-dried, antibody-conjugated particles and the other with vacuum-dried, bovine serum albumin-conjugated particles. This eliminated the need for a separate negative control, effectively minimizing chip-to-chip and sample-to-sample variations. Particles and the sample were diffused in-channel through chemical agitation by Tween 80, also vacuum-dried within the microchannels. Sequential mixing of the sample to the reagents under a strict laminar flow condition synergistically improved the reproducibility and linearity of the assay. In addition, dried particles were shown to successfully detect lower Salmonella concentrations for up to 8 weeks. The handheld device contains simplified circuitry eliminating unnecessary adjustment stages, providing a stable signal, thus maximizing sensitivity. Total assay time was 10 min, and the detection limit 10 CFU mL(-1) was observed in all matrices, demonstrating the suitability of this device for field assays.