Cefazolin susceptibility of coagulase-negative staphylococci (CoNS) causing late-onset neonatal bacteraemia.

BACKGROUND: CoNS bacteraemia causes significant neonatal morbidity. Previous work has suggested that ß-lactam antibiotics vary in their binding affinity to PBP2a (produced by the mecA gene) present in most CoNS. OBJECTIVES: We evaluated cefazolin MICs for CoNS isolated in an Australian neonatal ICU (NICU) and correlated them with isolate genotype and phenotype. METHODS: Significant blood isolates from 2009 to 2017 were speciated and underwent broth microdilution testing for cefazolin, cefoxitin, oxacillin and flucloxacillin. Correlation with mecA presence and PBP2a expression was evaluated. A selection of Staphylococcus capitis isolates underwent WGS. RESULTS: The CoNS (n = 99) isolates were confirmed as S. capitis (n = 57), Staphylococcus epidermidis (n = 32), Staphylococcus haemolyticus (n = 2) and Staphylococcus warneri (n = 8). The MIC of cefazolin was ≤2 mg/L for 30% of isolates and 75% had an MIC of ≤8 mg/L (MIC90 = 16 mg/L). This contrasted with MIC90s of cefoxitin, oxacillin and flucloxacillin, which were all ≥32 mg/L. WGS found a number of S. capitis isolates closely related to the globally established NRCS-A clone. CONCLUSIONS: CoNS displayed distinctly lower MIC values of cefazolin than of other agents tested. MIC variation may be related to binding affinity of PBP2a or regulation of expression of mecA by mecR1-mecI functional genes. Further, NRCS-A S. capitis strains were present in this Australian NICU before and after the unit underwent physical relocation, which raised questions about a common environmental source. It is considered justified to conduct a randomized clinical trial that assesses cefazolin versus vancomycin for management of late-onset neonatal sepsis.

Liquid crystal alignment on carbonaceous surfaces with orientational order.

We used near-edge x-ray absorption fine structure (NEXAFS) spectroscopy to link the orientational bond order at three carbonaceous surfaces-rubbed polyimide, ion beam-irradiated polyimide, and ion beam-irradiated diamondlike carbon films-with the direction of liquid crystal (LC) alignment on these surfaces. We show that, in general, LC alignment can be created on any carbonaceous substrate by inducing orientational order at its surface. Our results form the scientific basis for LC alignment layers consisting of amorphous carbon films in which orientational order near the surface is induced by a directional low-energy ion beam.

A statistical review of 100 consecutive "U.C.I." low friction knee arthroplasties with analysis of results.

In 100 U.C.I. low friction knee arthroplasties, the primary goal of relief from pain was accomplished in most patients. However, the precise evaluation of the result of a knee arthroplasty can be difficult. Many of the patients who rated good or better within an average follow up time of one year had patellofemoral complaints to some extent. Cold flow deformation and prosthetic loosening is a definite concern about the tibial component. A longer follow-up study is needed to better evaluate the significance of the 1-2 mm radiolucent line at the bone cement interface of the tibial component. Although most patients in this series were greatly relieved of their pain, even better results are possible if the arthroplasty would include the patellofemoral joint and tibial component more substantially bonded to cancellous bone.

Failure of total knee arthroplasty due to loosening and deformation of the tibial component.

A series of 100 consecutive UCI knee replacements showed a 7 per cent incidence of reoperation due to loosening of the prosthesis associated with permanent deformation of the tibial component. Analysis of the clinical data, roentgenograms, and removed implants showed associations between failure and radiolucency at the cement-bone interface, prosthetic obliquity, collapse of trabecular bone, change of the alignment of the extremity, and permanent deformation of the tibial component. Although no one of these factors by itself can be responsible for the mechanical failure of the arthroplasty, a predominant failure pattern exists. We think that the sequence of events is as follows: implantation of the tibial component with medial or lateral tilt; lack of firm skeletal stabilization; continual microtrabecular fractures; change in alignment of the extremity; and permanent deformation of the plastic component.

Test strip meconium screening for cystic fibrosis.

The Boehringer-Mannheim Corporation (BMC) strip test is extremely reliable in indicating an albumin content above 20 mg/gm of dried meconium. All infants born during one year in 14 Milwaukee area hospitals were tested. Of 16,224 newborns, two were diagnosed correctly as suffering from cystic fibrosis and two were missed. False-positive tests were obtained in 0.9% of infants (prematurity, melena, gastroschisis, and intrauterine infection). The strip test is, at present, the best available but not the perfect screening method for cystic fibrosis.