Culex quinquefasciatus Mosquitoes Resist Acquisition of Methicillin-Resistant Staphylococcus aureus: Insights from Field and Laboratory Studies.

The emergence of antimicrobial resistance (AMR) in pathogens and their spillover into the environment have become a global public health menace. Insects can acquire these pathogens from the environment and would serve as mechanical and biological vectors. The current study assessed the ability of Culex quinquefasciatus mosquitoes to acquire methicillin-resistant Staphylococcus aureus (MRSA) through the exposure of the mosquitoes to the pathogen via rearing water, blood feed, or a feeding membrane under laboratory conditions. In addition, mosquito immatures collected from their habitat in the vicinity of hospitals, veterinary dispensaries, and butcher shops at 15 study sites in Puducherry were screened for MRSA infection. All samples were subjected to the culture-based isolation of S. aureus from the surface and homogenate. The presence of the S. aureus-specific nuc gene and the genes that confer resistance to methicillin (mecA and mecC) were screened using PCR tests. MRSA was not evident either on the external surface or in the homogenate of the mosquitoes emerging from the larvae reared in the MRSA-spiked water or those fed with MRSA through blood or smeared membranes. Furthermore, the presence of MRSA was not evident in any of the field-caught mosquitoes. Hence, we conclude that C. quinquefasciatus mosquitoes are impervious to MRSA colonization.

Age-related reduction in the functional properties of adult stem cells located in the peripheral region of human retinal pigment epithelium.

PURPOSE: Adult stem cells (SCs) with self-renewal and multilineage potential have been reported upon culturing human retinal pigment epithelial (RPE) cells. The current study aimed to identify the location of SCs in human RPE and to elucidate the age-related changes. METHODS: Peripheral, equatorial, and central RPE cells from donors of three age groups were analyzed for their sphere-forming, clonal, and label-retaining cell properties. Furthermore, native human RPE flatmounts were immunostained for SC and proliferating cell markers. RESULTS: Cells with higher sphere-forming and clonal ability were identified only in young donors (<30 years) and were restricted to the periphery. Upon culturing, cells from peripheral and equatorial regions had the label-retaining cell (LRC) property. With aging, the LRCs were restricted to the periphery and were reduced. In young donors, Ki67 + proliferating cells were not observed in native RPE. However, such cells were observed in the peripheral RPE of older donors correlating with the need for regeneration. The native RPE cells were negative for SC marker expression. CONCLUSION: The above findings highlighted the presence of SCs with the ability to proliferate in the peripheral RPE and a reduction in these functional properties of SCs with aging.

Comparative Evaluation of Different Tissues and Molecular Techniques for the Zoonotic Surveillance of Scrub Typhus.

Background and Objectives: Scrub typhus (ST) is detected in one-fourth of patients with acute febrile illnesses, confirming its nationwide re-emergence. The disease, if not diagnosed, can lead to multiple organ dysfunction and mortality. Being a vector-borne zoonotic disease, the molecular survey for pathogens in animal hosts is essential to predict the risk of its transmission to humans. Hence, this study aimed at identifying the effective animal tissue and molecular technique for zoonotic surveillance of ST infection in small animal hosts. Methods: Rodents/shrews were trapped from seventeen randomly selected villages in Puducherry between July and September, 2022. The presence of Orientia tsutsugamushi in ectoparasites and tissues including blood, lung, liver, spleen, kidney, heart, brain, and intestine retrieved from the animals was screened by nested PCR targeting 56 kDa, real-time PCR (qPCR) targeting 47 kDa and traD, and conventional PCR targeting groEL. The Weil-Felix test was carried out to detect antibodies against O. tsutsugamushi in rodent/shrew serum samples. Diagnostic accuracy measures of the molecular tests were calculated for each of the tissues by latent class modeling. Results: O. tsutsugamushi detected in the rodents/shrews were identified to be Karp-like and Kawasaki-like strains. Upon statistical analysis, qPCR targeting 47 kDa exhibited the highest accuracy measures in most of the tissues analyzed, with perfect sensitivity and specificity of 100% and 97% for intestine and lung samples for the epidemiological surveillance, respectively. Interpretation and Conclusion: The study recommends qPCR targeting 47 kDa gene and analysis of intestine and lung along with blood for the zoonotic surveillance of ST infection.