Genomic epidemiology of global Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli.

The dissemination of carbapenem resistance in Escherichia coli has major implications for the management of common infections. bla KPC, encoding a transmissible carbapenemase (KPC), has historically largely been associated with Klebsiella pneumoniae, a predominant plasmid (pKpQIL), and a specific transposable element (Tn4401, ~10 kb). Here we characterize the genetic features of bla KPC emergence in global E. coli, 2008-2013, using both long- and short-read whole-genome sequencing. Amongst 43/45 successfully sequenced bla KPC-E. coli strains, we identified substantial strain diversity (n = 21 sequence types, 18% of annotated genes in the core genome); substantial plasmid diversity (≥9 replicon types); and substantial bla KPC-associated, mobile genetic element (MGE) diversity (50% not within complete Tn4401 elements). We also found evidence of inter-species, regional and international plasmid spread. In several cases bla KPC was found on high copy number, small Col-like plasmids, previously associated with horizontal transmission of resistance genes in the absence of antimicrobial selection pressures. E. coli is a common human pathogen, but also a commensal in multiple environmental and animal reservoirs, and easily transmissible. The association of bla KPC with a range of MGEs previously linked to the successful spread of widely endemic resistance mechanisms (e.g. bla TEM, bla CTX-M) suggests that it may become similarly prevalent.

Multi-site and nasal swabbing for carriage of Staphylococcus aureus: what does a single nose swab predict?

BACKGROUND: Carriage of Staphylococcus aureus is a risk for infections. Targeted decolonization reduces postoperative infections but depends on accurate screening. AIM: To compare detection of S. aureus carriage in healthy individuals between anatomical sites and nurse- versus self-swabbing; also to determine whether a single nasal swab predicted carriage over four weeks. METHODS: Healthy individuals were recruited via general practices. After consent, nurses performed multi-site swabbing (nose, throat, and axilla). Participants performed nasal swabbing twice-weekly for four weeks. Swabs were returned by mail and cultured for S. aureus. All S. aureus isolates underwent spa typing. Persistent carriage in individuals returning more than three self-swabs was defined as culture of S. aureus from all or all but one self-swabs. FINDINGS: In all, 102 individuals underwent multi-site swabbing; S. aureus carriage was detected from at least one site from 40 individuals (39%). There was no difference between nose (29/102, 28%) and throat (28/102, 27%) isolation rates: the combination increased total detection rate by 10%. Ninety-nine patients returned any self-swab, and 96 returned more than three. Nasal carriage detection was not significantly different on nurse or self-swab [28/99 (74%) vs 26/99 (72%); χ2: P=0.75]. Twenty-two out of 25 participants with first self-swab positive were persistent carriers and 69/71 with first self-swab negative were not, giving high positive predictive value (88%), and very high negative predictive value (97%). CONCLUSION: Nasal swabs detected the majority of carriage; throat swabs increased detection by 10%. Self-taken nasal swabs were equivalent to nurse-taken swabs and predicted persistent nasal carriage over four weeks.

Limited internal fixation of the tibia with external fixation: an in vivo canine study.

This study reports the results of the healing of canine tibial osteotomies with external fixation alone or in combination with a single lag screw. Twelve dogs had a midshaft tibial osteotomy performed at a 45 degree obliquity. Half of the dogs had a six-pin, unilateral, medial, external half-frame applied after the osteotomy. The remaining six had an identical frame plus a lag screw placed perpendicular to the osteotomy site. When compared with their contralateral controls, the fixator-alone group had a 16.3% (p < 0.05) decrease in bone density, whereas no significant density change was seen in the group with the additional lag screw. Torsional stiffness was 29% higher in the osteotomies treated, and tested, with the lag screw, but this did not achieve statistical significance. Computed tomography scanning revealed that the surface area was increased by an average of 30-40% in both groups, relative to contralateral controls, but there was no difference between the two treatment groups. Three tibias in the group with external fixation alone, and two tibias in the screw group showed primary bone healing without evidence of callus formation. The combination of a semirigid external fixation construct with a lag screw resulted in increased torsional stiffness but healing equal to that seen with external fixation alone.

Malunions.

The decision to attempt surgical correction of a malunion must be based on a careful preoperative assessment of the patient. The animal's gait must be observed. An animal that is not clinically affected by the malunion usually is not a candidate for surgery. Joint function and the condition of the bone, cartilage, and soft tissues must be noted. If the joints and soft tissues are irreversibly altered, surgical correction should not be performed. Accurate planning of any corrective osteotomy requires careful evaluation of the bony deformities that are present. Angular and rotational deformities may be present. Shortening of the limb also may be observed. Integration of these findings enables the surgeon to select the osteotomy technique best suited for a patient. External fixators or bone plates are most commonly used to stabilize the corrective osteotomy. When contemplating surgical correction of a malunion, critical preoperative assessment and planning are essential to achieving the desired goals. These goals are achieving normal limb function and preventing further damage to the joints of the limb.

Ultrasonic propagation in mammalian cell suspensions based on a shell model.

The interaction of ultrasonic waves with individual cells has been modelled on the basis that the cells can be represented by viscous liquid spheres surrounded by a viscoelastic shell (the membrane) immersed in a viscous fluid. The computational model includes thermal waves and requires 22 input parameters. Many of the parameters are not available in the literature and a detailed discussion is given on the procedures by which the values used in the model calculations were chosen. In spite of the arbitrariness of the choice of many of the parameter values, the computations show surprisingly good agreement with experimental measurements of ultrasonic attenuation in animal cell suspensions. The model has been used here to investigate different aspects of the interaction of ultrasound with the cells. It is found that the membrane is important only between 0.5 and 30 MHz and contributes less than 15% to the attenuation. Absorption is shown to be an important feature to include, while the scattering contribution to the attenuation is less than 1% at 3 MHz. The thermal effects are important at frequencies below 1 MHz and contribute some 65% to the attenuation at 100 MHz.

Clinical evaluation of canine acetabular fractures stabilized with an acetabular plate.

A retrospective study of 14 dogs with one or more acetabular fractures stabilized with an acetabular plate was conducted. Twelve of the 14 dogs had additional orthopedic injuries. Follow-up was longer than 6 months. Eleven dogs were evaluated by assessment of radiographs, lameness, mid-thigh circumference, coxofemoral joint range of motion, crepitus, and pain. Varying degrees of osteoarthrosis were noted radiographically at follow-up. Ten of 12 dogs examined had occasional or no clinical lameness. In 10 of 12 dogs, mid-thigh circumference was less on the limb that sustained the acetabular fracture. Nonunion was diagnosed in one plated acetabulum in which two screws had broken. A return to normal or nearly normal function was observed when there were no more than two orthopedic injuries.

A retrospective evaluation of the rectal pull-through technique. Procedure and postoperative complications.

Ten animals (8 dogs and 2 cats) with distal rectal lesions were treated by surgically resecting the affected segment of the rectum by the rectal pull-through technique. There were four malignant tumors, three benign tumors, two inflammatory lesions, and one malignant tumor that extended histologically to the margins of a previous surgical excision. Postoperative complications were tenesmus (7 animals), fecal incontinence (4 animals), rectal bleeding (4 animals), and abscess formation (1 animal). Dehiscence and stricture were not observed. The four animals with malignant tumors survived less than 12 months after surgery. One of the four animals still living has persistent fecal incontinence. The rectal pull-through technique is described and illustrated.

Fatal air embolism during anesthesia for laparoscopy in a dog.

A 13-year-old dog went into cardiopulmonary arrest after insufflation of the abdominal cavity with nitrogen for laparoscopy. Resuscitation was unsuccessful. Necropsy findings included a punctured spleen and confirmed the development of air embolism.

Idiopathic hyperaldosteronism in a dog.

Idiopathic hyperaldosteronism was diagnosed in an 8-year-old castrated male Yorkshire Terrier, based on increased concentration of plasma aldosterone, hypertension, hypernatremia, decreased natriuresis, hypokalemia, and hyperkaluria. Unilateral adrenalectomy was performed after visualization of a nodule on the right adrenal gland. Hyperplasia of the zona glomerulosa and increased postoperative aldosterone concentrations supported the diagnosis of idiopathic hyperaldosteronism.