Optimizing antibiotic management for patients with acute appendicitis: A quality improvement study.

BACKGROUND: To decrease surgical site infections after appendectomy for acute appendicitis, preoperative broad-spectrum antibiotics are often used in clinical practice. However, this treatment strategy has come under scrutiny because of increasing rates of antibiotic-resistant infections. METHODS: The aim of this multisite quality improvement project was to decrease the treatment of uncomplicated acute appendicitis with piperacillin-tazobactam without increasing the rate of surgical site infections. Our quality improvement intervention had 2 distinct components: (1) updating electronic health record orders to encourage preoperative administration of narrow-spectrum antibiotics and (2) educating surgeons and emergency department clinicians about selecting appropriate antibiotic therapy for acute appendicitis. Patient demographics, clinical characteristics, and outcomes were compared 6 months before and after implementation of the quality improvement intervention. RESULTS: A total of 352 laparoscopic appendectomies were performed during the 6-month preintervention period, and 369 were performed during the 6-month postintervention period. The preintervention period and postintervention period groups had similar baseline demographics, vital signs, and laboratory test values. The rate of preoperative piperacillin-tazobactam administration significantly decreased after the intervention (51.4% preintervention period vs 20.1% postintervention period, P < .001). The rate of surgical site infections was similar in both groups (superficial surgical site infections = 1.4% preintervention period vs 0.8% postintervention period, P = .50; deep surgical site infections = 1.1% preintervention period vs 0.0% postintervention period, P = .06; and organ space surgical site infections = 3.1% preintervention period vs 3.0% postintervention period, P > .99). Rates of 30-day readmission, reoperation, and Clostridioides difficile infection also did not differ between groups. CONCLUSION: Our quality improvement intervention successfully decreased piperacillin-tazobactam administration without increasing the rate of surgical site infections in patients with acute appendicitis.

Cystoid Macular Edema in a 10-Year-Old Boy With Cohen Syndrome.

Cohen syndrome is an extremely rare disease with characteristic somatic and multi-system features that severely affect vision. Ophthalmologists must consider Cohen syndrome when developmental delay, high-grade myopia, and retinal dystrophy are present in a child. Here we report a case of Cohen syndrome in a 10-year-old boy presenting with cystoid macular edema (CME), only the second reported case of its kind. This case illustrates the phenotypic variability that can occur in Cohen syndrome, with rare features in addition to CME including trace posterior subcapsular cataracts, growth hormone deficiency, mild vermian hypoplasia, a nasolacrimal cyst, hearing loss, and high-functioning intelligence quotient (IQ). Our patient did not have an identifiable second mutation even after extensive genetic testing, which raises questions about whether the patient has a novel gene variant for the disease or an autosomal dominant mode of inheritance exists for Cohen syndrome. In addition to peripheral vision loss, the rare appearance of macular edema can threaten the remaining vision and requires intervention. This case also demonstrates that, without a high index of suspicion, there can be considerable delay in diagnosing Cohen syndrome. Though little is known about the prevalence of many of the clinical features seen in our case in the Cohen syndrome population, this case raises awareness of the syndrome and the need to recognize various clinical features, perform genetic testing, and direct appropriate treatment to prevent complications and help improve quality of life.

WITHDRAWN: Microsecond resolution of enzymatic conformational changes using dark-field microscopy.

We report a novel method to detect angular conformational changes of a molecular motor in a manner sensitive enough to achieve acquisition rates with a time resolution of 2.5mus (equivalent to 400,000fps). We show that this method has sufficient sensitivity to resolve the velocity of the F(1)-ATPase gamma-subunit as it travels from one conformational state to another (transition time). Rotation is detected via a gold nanorod attached to the rotating gamma-subunit of an immobilized F(1)-ATPase. Variations in scattered light intensity allow precise measurement of changes in angular position of the rod below the diffraction limit of light.

Single-molecule detection of DNA via sequence-specific links between F1-ATPase motors and gold nanorod sensors.

We report the construction of a novel biosensing nanodevice to detect single, sequence-specific target DNA molecules. Nanodevice assembly occurs through the association of an immobilized F1-ATPase molecular motor and a functionalized gold nanorod via a single 3',5'-dibiotinylated DNA molecule. Target-dependent 3',5'-dibiotinylated DNA bridges form by combining ligation and exonucleation reactions (LXR), with a specificity capable of selecting against a single nucleotide polymorphism (SNP). Using dark field microscopy to detect gold nanorods, quantitation of assembled nanodevices is sufficient to distinguish the presence of as few as 1800 DNA bridges from nonspecifically bound nanorods. The rotary mechanism of F1-ATPase can drive gold nanorod rotation when the nanorod is attached via the DNA bridge. Therefore, rotation discriminates fully assembled devices from nonspecifically bound nanorods, resulting in a sensitivity limit of one zeptomole (600 molecules).

Abundance of Escherichia coli F1-ATPase molecules observed to rotate via single-molecule microscopy with gold nanorod probes.

The abundance of E. coli F1-ATPase molecules observed to rotate using gold nanorods attached to the gamma-subunit was quantitated. Individual F1 molecules were determined to be rotating based upon time dependent fluctuations of red and green light scattered from the nanorods when viewed through a polarizing filter. The average number of F1 molecules observed to rotate in the presence of GTP, ATP, and without nucleotide was approximately 50, approximately 25, and approximately 4% respectively. In some experiments, the fraction of molecules observed to rotate in the presence of GTP was as high as 65%. These data indicate that rotational measurements made using gold nanorods provide information of the F1-ATPase mechanism that is representative of the characteristics of the enzyme population as a whole.

Microsecond time scale rotation measurements of single F1-ATPase molecules.

A novel method for detecting F(1)-ATPase rotation in a manner sufficiently sensitive to achieve acquisition rates with a time resolution of 2.5 micros (equivalent to 400,000 fps) is reported. This is sufficient for resolving the rate at which the gamma-subunit travels from one dwell state to another (transition time). Rotation is detected via a gold nanorod attached to the rotating gamma-subunit of an immobilized F(1)-ATPase. Variations in scattered light intensity allow precise measurement of changes in the angular position of the rod below the diffraction limit of light. Using this approach, the transition time of Escherichia coli F(1)-ATPase gamma-subunit rotation was determined to be 7.62 +/- 0.15 (standard deviation) rad/ms. The average rate-limiting dwell time between rotation events observed at the saturating substrate concentration was 8.03 ms, comparable to the observed Mg(2+)-ATPase k(cat) of 130 s(-)(1) (7.7 ms). Histograms of scattered light intensity from ATP-dependent nanorod rotation as a function of polarization angle allowed the determination of the nanorod orientation with respect to the axis of rotation and plane of polarization. This information allowed the drag coefficient to be determined, which implied that the instantaneous torque generated by F(1) was 63.3 +/- 2.9 pN nm. The high temporal resolution of rotation allowed the measurement of the instantaneous torque of F(1), resulting in direct implications for its rotational mechanism.