In June 2021, a national incident team was formed due to an increased detection of Staphylococcus capitis in samples from hospitalised infants. Staphylococcus capitis has been known to cause outbreaks in neonatal units across the globe, but the extent of the UK spread was unclear. A literature review was undertaken to support case identification, clinical management and environmental infection control. A literature search was undertaken on multiple databases from inception to 24 May 2021, using keywords such as “Staphylococcus capitis”, “NRCS-A”, “S. capitis”, “neonate”, “newborn” and “neonatal intensive care unit” (NICU). After screening, 223 articles of relevance were included. Results show incidences of S. capitis outbreaks have frequently been associated with the outbreak clone (NRCS-A) and environmental sources. The NRCS-A harbours a multidrug resistance profile that includes resistance to beta-lactam antibiotics and aminoglycosides, with several papers noting resistance or heteroresistance to vancomycin. The NRCS-A clone also harbours a novel SCCmec-SCCcad/ars/cop composite island and increased vancomycin resistance. The S. capitis NRCS-A clone has been detected for decades, but the reasons for the potentially increased frequency are unclear, as are the most effective interventions to manage outbreaks associated with this clone. This supports the need for improvements in environmental control and decontamination strategies to prevent transmission.

Many bacterial species are known to recover peptidoglycan (PG) fragments released from remodelling of their cell walls during growth and cell division. These PG fragments not only provide an essential energy resource, especially in nutrient restricted environments, but also play a critical role in influencing infection. Yet whether mycobacteria have the capacity to recycle their PG, or not, has still not been resolved. In this study we show that NagA, an N-acetylglucosamine-6-phosphate (GlcNAc-6-P) deacetylase, is essential for coordinating the remodelling and recycling of an amino sugar component released from the mycobacterial cell wall. We show that NagA is exclusively responsible for GlcNAc-6-P deacetylation and is pivotal for the de novo synthesis of core cell wall building blocks. Indeed, a nagA deletion mutant exhibited an altered composition of the cell envelope, smaller overall cell size, defective biofilm formation, and enhanced susceptibility to cell wall targeting agents. Moreover, uptake analysis and profiling of the amino-sugar pool revealed that NagA inactivation blocks N-acetylglucosamine (GlcNAc) import and has a pronounced effect on the fate and levels of the intracellular amino sugar pool. Loss of NagA led to the up- and down-regulation of proteins involved in cell wall biosynthesis, thereby altering cell wall homeostasis. Overall, our data highlights the importance of an overlooked yet conserved component in an important PG salvage pathway in mycobacteria, in which NagA provides a unique GlcNAc sensing mechanism, thus acting as a checkpoint for regulating the recovery and reuse of PG fragments.

Antimicrobial resistance remains a global existential threat. Given that antimicrobial therapy commonly starts before pathogen identification, rapid and scalable methods capable of determining effective antimicrobial compounds are needed. In this paper, we demonstrate a 2 × 2 array of parallelised microscopes that uses low numerical aperture (NA=0.25) detection optics and LED excitation to determine bacterial viability based on their fluorescence response to an electrical stimulus. Following a 2-hour incubation, the fluorescent viability readout requires less than one minute. We use K-means clustering to classify pixels in a time lapse sequence of widefield fluorescence images and extract changes seen within bacterial clusters. We demonstrate sufficient sensitivity to measure fluorescence changes after electrical stimulation in a bacterial monolayer. To capture these subtle fluorescence changes at high signal-to-background ratios, we place a limit on the minimum optical density of the bacterial sample. This novel approach is scalable to 96-well formats using a suitable consumable electrode array.