Comparison of culture, confocal microscopy and PCR in routine hospital use for microbial keratitis diagnosis.

Aims: To evaluate the sensitivity and specificity of polymerase chain reaction (PCR), in vivo confocal microscopy (IVCM) and culture for microbial keratitis (MK) diagnosis.

Methods: Retrospective review of PCR, IVCM and culture results for MK diagnosis at Moorfields Eye Hospital between August 2013 and December 2014.

Results: PCR results were available for 259 MK patients with concurrent culture for 203/259 and IVCM for 149/259.

How to use… Procalcitonin.

Diagnosing bacterial infection in the unwell or febrile child is a common challenge faced by all paediatricians. Despite the advent of novel molecular techniques, there is ongoing need for diagnostic assays with adequate performance and turnaround time to facilitate safe clinical decision-making when bacterial sepsis is suspected, such as whether to commence empirical treatment with antibiotics. Procalcitonin is an established marker of infection that has a potential role in the diagnosis and exclusion of serious or invasive bacterial infection in neonates and children.

Herpes simplex virus and varicella zoster virus: recent advances in therapy.

Purpose Of Review: The mainstay of antiviral therapy for the alpha-herpesviruses [herpes simplex virus (HSV)-1, HSV-2, and varicella zoster virus (VZV)] over the past 40 years has been the nucleoside analogues such as aciclovir. Although conventional antiviral therapy has reduced mortality in severe disease, novel agents are needed to address the emergence of resistance and toxicity associated with current second-line therapy. Treatment and prophylaxis of VZV and HSV reactivations remains a challenge.

How to use... blood cultures.

Positive blood culture is the gold standard for diagnosing bacteraemia and fungaemia, yet there is significant variability in aspects of performing and interpreting the test in children and neonates. Processing a blood culture can take several days, and includes use of semi-automated incubation with growth detection and a broad range of laboratory techniques such as Gram staining, phenotypic or molecular identification and antimicrobial susceptibility testing on a cultured isolate. Sensitivity and specificity of a blood culture and time-to-positivity depend on a number of factors related to host/pathogen interaction, collection and transport of the specimen to the laboratory and methods employed to process the specimen.