G protein-coupled receptor kinase 5 regulates thrombin signaling in platelets.

Background: Our prior genome-wide association study of thrombin-induced platelet aggregation identified a G protein-coupled receptor kinase 5 (GRK5) noncoding variant (rs10886430-G) that is strongly associated with increased platelet reactivity to thrombin. This variant predisposes to increased risk of stroke, pulmonary embolism, and venous thromboembolism. Objectives: To determine role of platelet specific GRK5 in platelet responses to agonists and injury. Methods: Platelets from GRK5 mutant mice have been shown to have increased thrombin sensitivity, indicating that GRK5 may be a negative regulator of platelet activation. However, this has not been studied in a platelet-specific manner. We therefore used platelet-specific GRK5 mutant mice and models of thrombosis and pulmonary embolism. Results: We now demonstrate that mice lacking GRK5 specifically in platelets had a mild increase in thrombin responses in vitro and a shortened time to arterial thrombosis in vivo. In addition, platelet GRK5 mutant mice had increased thrombin but not collagen-induced thrombus burden in a mouse model of pulmonary embolism. Conclusion: These data indicate that platelet GRK5 has a significant role in limiting platelet responses to thrombin.

Armond S. Goldman (1930-2023) and the development of the immunobiology of human milk.

The understanding of the immunobiology of human milk is primarily a 20th-century phenomenon, but, even with our contemporary understanding, it remains a bit of a mystery. Breastfeeding of human milk, although the most obvious and natural form of nutrition for human infants, has been hindered by cultural and societal norms since ancient times. Thus, not all infants have experienced the advantages this form of nutrition may offer. Although these advantages have been anecdotally suggested since ancient times, it was only in the late 19th and early 20th centuries that the superiority of human milk was scientifically documented. The underlying immunobiological properties of human milk underpinning its observed superiority only became appreciated with advances in immunology that occurred in the mid to late 20th century. Armond S. Goldman (1930-2023) was in the vanguard of those promoting and developing an understanding of the immunobiology of human milk and its superiority in promoting the health of human infants.

Long-lived lung megakaryocytes contribute to platelet recovery in thrombocytopenia models.

Lung megakaryocytes (Mks) are largely extravascular with an immune phenotype (1). Because bone marrow (BM) Mks are short-lived it has been assumed that extravascular lung Mks are constantly 'seeded' from the BM. To investigate lung Mk origins and how that impacts their functions, we developed methods to specifically label lung Mks using CFSE dye and biotin delivered oropharyngeal. Labeled lung Mks were present for up to four months, while BM Mks had a <1 week lifespan. In a parabiosis model, lung Mks were partially replaced over 1-month from a circulating source. Unlike tissue-resident macrophages, using MDS1-Cre-ERT2 TdTomato mice, we found that lung Mks arise from hematopoietic stem cells. However, studies with FlkSwitch mTmG mice showed that lung Mks are derived from a Flt3-independent lineage that does not go through a multipotent progenitor. CFSE labeling to track lung Mk-derived platelets showed that about 10% of circulating platelets are lung resident Mk-derived at steady state, but in sterile thrombocytopenia this was doubled (about 20%). Lung-derived platelets were similarly increased in a malaria infection model (Plasmodium yoelii) typified by thrombocytopenia. These studies indicate that lung Mks arise from a Flt3-negative BM source, are long-lived, and contribute more platelets during thrombocytopenia.

Platelet Angiopoietin-1 Protects Against Murine Models of Tumor Metastasis.

BACKGROUND: In addition to their fundamental roles in preserving vascular integrity, platelets also contribute to tumor angiogenesis and metastasis. However, despite being a reservoir for angiogenic and metastatic cytokines, platelets also harbor negative regulators of tumor progression. Angpt1 (angiopoietin-1) is a cytokine essential for developmental angiogenesis that also protects against tumor cell metastasis through an undefined mechanism. Although activated platelets release Angpt1 from α-granules into circulation, the contributions of platelet Angpt1 to tumor growth, angiogenesis, and metastasis have not been investigated. METHODS: Using cytokine arrays and ELISAs, we first compared platelet Angpt1 levels in breast and melanoma mouse tumor models to tumor-free controls. We then assessed tumor growth and metastasis in mice lacking megakaryocyte and platelet Angpt1 (Angpt1Plt KO). The spontaneous metastasis of mammary-injected tumor cells to the lungs was quantified using RT-PCR (reverse transcription-polymerase chain reaction). The lung colonization of intravenously injected tumor cells and tumor cell extravasation were determined using fluorescent microscopy and flow cytometry. RESULTS: Platelet Angpt1 is selectively upregulated in the PyMT (polyoma middle tumor antigen) breast cancer mouse model, and platelets are the principal source of Angpt1 in blood circulation. While primary tumor growth and angiogenesis were unaffected, Angpt1Plt KO mice had both increased spontaneous lung metastasis and tumor cell lung colonization following mammary or intravenous injection, respectively. Although platelet Angpt1 did not affect initial tumor cell entrapment in the lungs, Angpt1Plt KO mice had increased tumor cell retention and extravasation. Serum from Angpt1Plt KO mice increased endothelial permeability and reduced VE (vascular endothelial)-cadherin expression at endothelial junctions compared with serum from control mice (Angpt1WT). CONCLUSIONS: Platelets provide an intravascular source of Angpt1 that restrains tumor metastasis by preserving the lung microvasculature to limit tumor cell extravasation.

Applying the standardized infection ratio for reporting surgical site infections in Australian healthcare facilities.

Objective: We explored the utility of the standardized infection ratio (SIR) for surgical site infection (SSI) reporting in an Australian jurisdiction. Design: Retrospective chart review. Setting: Statewide SSI surveillance data from 2013 to 2019. Patients: Individuals who had cardiac bypass surgery (CABG), colorectal surgery (COLO), cesarean section (CSEC), hip prosthesis (HPRO), or knee prosthesis (KPRO) procedures. Methods: The SIR was calculated by dividing the number of observed infections by the number of predicted infections as determined using the National Healthcare Safety Network procedure-specific risk models. In line with a minimum precision criterion, an SIR was not calculated if the number of predicted infections was <1. Results: A SIR >0 (≥1 observed SSI, predicted number of SSI ≥1, no missing covariates) could be calculated for a median of 89.3% of reporting quarters for CABG, 75.0% for COLO, 69.0% for CSEC, 0% for HPRO, and 7.1% for KPRO. In total, 80.6% of the reporting quarters, when the SIR was not calculated, were due to no observed infections or predicted infections <1, and 19.4% were due to missing covariates alone. Within hospitals, the median percentage of quarters during which zero infections were observed was 8.9% for CABG, 20.0% for COLO, 25.4% for CSEC, 67.3% for HPRO, and 71.4% for KPRO. Conclusions: Calculating an SIR for SSIs is challenging for hospitals in our regional network, primarily because of low event numbers and many facilities with predicted infections <1. Our SSI reporting will continue to use risk-indexed rates, in tandem with SIR values when predicted number of SSI ≥1.

An evaluation of influenza, pneumococcal and herpes zoster vaccination coverage in Australian aged care residents, 2018 to 2022.

BACKGROUND: For older persons, vaccination mitigates the harmful impact of vaccine preventable infections. Our study objectives were to evaluate in the Victorian public sector residential aged care services (PSRACS) (1) the existence of local vaccination policies and admission assessment practices, (2) the current documented status of resident influenza, pneumococcal and herpes zoster vaccination uptake and (3) changes in documented resident vaccination uptake over time. METHODS: Standardised data were annually reported by all PSRACS between 2018 and 2022. The influenza, pneumococcal and herpes zoster vaccination status of each resident was classified as vaccinated, declined, contraindicated or unknown. Annual trends in vaccination status were assessed using Spearman's correlation. RESULTS: In 2022, most PSRACS reported an influenza immunisation policy existed (87.1%) and new residents were assessed for their influenza vaccination status (97.2%); fewer PSRACS reported the same for pneumococcal disease (73.1% and 78.9%) and herpes zoster (69.3% and 75.6%). The median resident influenza, pneumococcal and herpes zoster (70-79 years old) vaccination uptake was 86.8%, 32.8% and 19.3% respectively. The median unknown status was 6.9%, 63.0% and 76.0% respectively. Statistical evidence of an increase in annual uptake was observed for the herpes zoster (all resident) surveillance module (rs = 0.900, p = 0.037). CONCLUSIONS: Our study showed local influenza vaccination policies and practices exist and influenza vaccination uptake was consistently high. Pneumococcal and herpes zoster vaccination uptake were lower. Quality improvement strategies that at least determine the status of those residents classified as unknown are required.

Hepatitis B immune status of staff in smaller acute healthcare facilities.

Objective To determine the proportion of staff employed in smaller Victorian public acute healthcare facilities with evidence of immunity to hepatitis B. Methods For optimal long-term immunity, a completed hepatitis B vaccination course and post vaccination hepatitis B surface antibody (anti-HBs) level ≥10 mIU/mL is desirable for all high-risk staff employed in healthcare facilities. For the financial years 2016/17-2019/20, a standardised surveillance module developed by the Victorian Healthcare Associated Infection Surveillance System (VICNISS) Coordinating Centre was completed by the smaller Victorian public acute healthcare facilities (individual hospitals with Results A total of 88 healthcare facilities reported hepatitis B immunity status of high-risk (Category A) staff (n = 29 920) at least once over 5 years; 55 healthcare facilities reported more than once. The aggregate proportion with evidence of optimal immunity was 66.3%. Healthcare facilities with 100-199 Category A staff employed reported the lowest evidence of optimal immunity (59.6%). Of all Category A staff with no evidence of optimal immunity, the majority had 'unknown' status (19.8%), with only 0.6% overall who declined vaccination. Conclusions Our study found evidence of optimal staff hepatitis B immunity in only two-thirds of Category A staff working in surveyed healthcare facilities.

The same but different: a comparison of Staphylococcus aureus bloodstream infections in metropolitan and non-metropolitan hospitals (2010-2020).

BACKGROUND: Variation of infection rates between hospitals must be identified; differences may highlight opportunities for quality improvement in healthcare delivery to specific hospitals groups. AIMS: To analyse burden, time trends and risks of healthcare-associated (HA) Staphylococcus aureus bloodstream infections (SABSI) in patients admitted to Victorian metropolitan and non-metropolitan public acute care hospitals. METHODS: SABSI surveillance data submitted between 1 July 2010 and 30 June 2020 by all 118 Victorian public acute care hospitals were analysed. Aligned with the Australian Statistical Geography Standard Remoteness Structure, these hospitals were classified as metropolitan (major cities) or non-metropolitan (inner regional, outer regional, remote or very remote). RESULTS: Most SABSI were community associated: 66.9% and 75.0% of metropolitan (n = 9441) and non-metropolitan (n = 2756) hospital SABSI respectively. The overall HA-SABSI rate was statistically higher in metropolitan hospitals (1.13 per 10 000 occupied bed days (OBD)) compared with non-metropolitan hospitals (0.82 per 10 000 OBD; P < 0.001). In metropolitan and non-metropolitan hospitals, there was a statistically significant decline in the overall HA-SABSI rate (incidence rate ratio = 0.96; 95% confidence interval: 0.95-0.97; P < 0.001; and incidence rate ratio = 0.98; 95% confidence interval: 0.97-1.00; P = 0.044, respectively). In metropolitan and non-metropolitan hospitals, HA-SABSI were frequently associated with central venous (52.8%) and peripheral intravenous (62.2%) catheter use respectively. CONCLUSION: To reduce risks for SABSI and improve patient outcomes, hospital infection prevention and control programmes should be tailored according to local epidemiology. In common geographic locations, networking of hospitals should be considered as a means of strengthening delivery of these programmes.

Pro-inflammatory megakaryocyte gene expression in murine models of breast cancer.

Despite abundant research demonstrating that platelets can promote tumor cell metastasis, whether primary tumors affect platelet-producing megakaryocytes remains understudied. In this study, we used a spontaneous murine model of breast cancer to show that tumor burden reduced megakaryocyte number and size and disrupted polyploidization. Single-cell RNA sequencing demonstrated that megakaryocytes from tumor-bearing mice exhibit a pro-inflammatory phenotype, epitomized by increased Ctsg, Lcn2, S100a8, and S100a9 transcripts. Protein S100A8/A9 and lipocalin-2 levels were also increased in platelets, suggesting that tumor-induced alterations to megakaryocytes are passed on to their platelet progeny, which promoted in vitro tumor cell invasion and tumor cell lung colonization to a greater extent than platelets from wild-type animals. Our study is the first to demonstrate breast cancer-induced alterations in megakaryocytes, leading to qualitative changes in platelet content that may feedback to promote tumor metastasis.

The limits of viability of extremely preterm infants.

Shaeffer and Avery's textbook, Diseases of the Newborn (1971), estimated the limit of viability to be around 28 weeks' gestation and/or 1000 g. Contemporarily, however, attempts are being made to resuscitate infants as early as 22 weeks' gestation. Clearly the "limit of viability" is a moving target, and the acceptable risk of intervening to attempt to "save" these small infants/fetuses is a value judgment and not one that can be answered by science. Even though the dilemma is not one that can be resolved empirically, the emphasis on resolution continues to be one of demands for "further research" by critics as well as advocates for the care of these small infants. Patrick Romanell (1912-2002) was a major philosopher in the critical naturalist movement in the United States and internationally. His observations on the tragic quality of human life and the dilemmas associated between the conflicts of good vs good rather than the epic quality of good vs evil lend themselves well to understanding the conflicts involved in determining the limits of viability of extremely preterm infants.

Prophylactic Antimicrobial Prescribing in Australian Residential Aged-Care Facilities: Improvement is Required.

BACKGROUND AND OBJECTIVE: Inappropriate antimicrobial use can lead to adverse consequences, including antimicrobial resistance. The objective of our study was to describe patterns of prophylactic antimicrobial prescribing in Australian residential aged-care facilities and thereby provide insight into antimicrobial stewardship strategies that might be required. METHODS: Annual point prevalence data submitted by participating residential aged-care facilities as part of the Aged Care National Antimicrobial Prescribing Survey between 2016 and 2020 were extracted. All antimicrobials except anti-virals were counted; methenamine hippurate was classified as an antibacterial agent. RESULTS: The overall prevalence of residents prescribed one or more prophylactic antimicrobial on the survey day was 3.7% (n = 4643, 95% confidence interval 3.6-3.8). Of all prescribed antimicrobials (n = 15,831), 27.1% (n = 4871) were for prophylactic use. Of these prophylactic antimicrobials, 87.8% were anti-bacterials and 11.4% antifungals; most frequently, cefalexin (28.7%), methenamine hippurate (20.1%) and clotrimazole (8.8%). When compared with prescribing of all antimicrobial agents, prophylactic antimicrobials were less commonly prescribed for pro re nata administration (7.0% vs 20.3%) and more commonly prescribed greater than 6 months (52.9% vs 34.1%). The indication and review or stop date was less frequently documented (67.5% vs 73.8% and 20.9% vs 40.7%, respectively). The most common body system for which a prophylactic antimicrobial was prescribed was the urinary tract (54.3%). Of all urinary tract indications (n = 2575), about two thirds (n = 1681, 65.3%) were for cystitis and 10.6% were for asymptomatic bacteriuria. CONCLUSIONS: Our results clearly identified immediate antimicrobial stewardship strategies that aim to improve prophylactic antimicrobial prescribing in Australian residential-aged care facilities are required.

Platelets upregulate tumor cell programmed death ligand 1 in an epidermal growth factor receptor-dependent manner in vitro.

Programmed death ligand 1 (PD-L1) is an immune checkpoint protein that suppresses cytotoxic T lymphocytes and is often overexpressed in cancers. Due to favorable clinical trial results, immune checkpoint inhibition (ICI) is part of Food and Drug Administration approved immuno-oncology therapies; however, not all patients benefit from ICI therapy. High blood platelet-to-lymphocyte ratio has been associated with failure of ICI treatment, but whether platelets have a role in hindering ICI response is unclear. Here, we report that coculturing platelets with cancer cell lines increased protein and gene expression of tumor cell PD-L1, which was reduced by antiplatelet agents, such as aspirin and ticagrelor. Platelet cytokine arrays revealed that the well-established cytokines, including interferon-γ, were not the main regulators of platelet-mediated PD-L1 upregulation. Instead, the high molecular weight epidermal growth factor (EGF) is abundant in platelets, which caused an upregulation of tumor cell PD-L1. Both an EGF-neutralizing antibody and cetuximab (EGF receptor [EGFR] monoclonal antibody) inhibited platelet-induced increases in tumor cell PD-L1, suggesting that platelets induce tumor cell PD-L1 in an EGFR-dependent manner. Our data reveal a novel mechanism for platelets in tumor immune escape and warrant further investigation to determine if targeting platelets improves ICI therapeutic responses.

Evaluating peripheral intravascular catheter insertion, maintenance and removal practices in small hospitals using a standardized audit tool.

AIM: The aim of this study was to evaluate clinical practice about peripheral intravenous catheter (PIVC) insertion, maintenance and removal in a cohort of Victorian hospitals. DESIGN: A standardized PIVC audit tool was developed, and results from point prevalent surveys were conducted. METHODS: Hospitalized patients requiring a PIVC insertion were eligible for audit. Audit data submitted between 2015 and 2019 were extracted for the current study. RESULTS: 3566 PIVC insertions in 15 Victorian public hospitals were evaluated. 57.6% of PIVCs were inserted in wards, 18.7% in operating theatres and 11.6% in Emergency Departments (ED). 45.2% were inserted by nurses and 38.2% by medical staff. The preferred site for insertion was the dorsum of the hand and forearm (58.8%). 22.6% did not report a visual infusion phlebitis score at least daily, and 48% did not document a daily dressing assessment. Reasons for PIVC removal included no longer required (63%) and phlebitis (4.8%). No bloodstream infections were reported.

Patrick Romanell, William Osler, and philosophy in medicine.

In 1974, Patrick Romanell (1912-2002) published a paper in the Bulletin of the New York Academy of Medicine taking William Osler (1849-1919) to task for dismissing philosophy as a distinguishing feature of the nature of medicine. Osler had expressed this thought in the Silliman Lectures given at Yale in 1913 on the Evolution of Modern Medicine. That the nature of medicine is underpinned by an understanding of the nature of man requires that the pedagogy and practice of medicine incorporate not only the empirical science that is the basis for clinical practice, but also the logical and metaphysical concepts of the nature of man. These concepts are informed by the humanities that include history, literature, and the arts. Despite Romanell's critique of Osler's statement, Romanell ultimately corroborates other statements made by Osler in the lecture series, substantiating Osler's deep appreciation for the nature of man and a philosophy of medicine that deserves emulation.

Chester R. Burns (1937-2006) and the origins of the American Osler Society.

The American Osler Society (AOS) traces its origin to a 1970 symposium on Humanism in Medicine in Galveston, Texas. Although John P. McGovern (1921-2007) receives credit for conceiving the symposium and spearheading formation of the AOS, Chester Ray Burns (1937-2006) played a key role that has not been sufficiently recognized. Burns, the first American-born physician to receive a doctorate in the history of medicine from the Johns Hopkins University, did much and perhaps most of the organizational work and brought to the symposium a perspective on the crossroads between medicine and the humanities that proved essential to the nascent organization's success. Burns went on to a productive career at the University of Texas Medical Branch (UTMB) in Galveston, became the 35th president of the AOS, and is among the relatively few physician-historians to have published scholarly articles in the history of medicine, medical biography, medical ethics, and philosophy as related to medicine.

Images, science, and rights of the early modern fetus.

How do we define the beginnings of human life? Images, science, and culture have offered insight into this question. The early modern period (1500-1800) is particularly rich for examining the understanding of the human fetus. Using the 1712 Essay on the Possibility and Probability of a Child's Being Born Alive, and Live, in the Latter End of the Fifth Solar, or in the Beginning of the Sixth Lunar Month, this paper argues that evolving knowledge of the fetus failed to modify cultural norms for defining the beginning of human life. This compares with contemporary 21st century observations and how our definition of the beginning of human life has not been modified.

Topical antimicrobial prescribing patterns in residents of Australian aged-care facilities: use of a national point prevalence survey to identify opportunities for quality improvement.

BACKGROUND: Australian residential aged care facilities (RACFs) are encouraged to participate in an annual Aged Care National Antimicrobial Prescribing Survey. This data source was analysed to describe patterns of topical antimicrobial prescribing and thereby provide insight into antimicrobial stewardship (AMS) changes that might be required. METHODS: 2018 and 2019 survey data was analysed. RESULTS: The overall prevalence of the 52,431 audited residents (629 facilities) who were prescribed 1 or more topical antimicrobials was 2.9%. Of all prescribed antimicrobials (n=4899), 33.0% were for topical application. Most frequently prescribed topical antifungals were clotrimazole (85.3%) and miconazole (9.1%), and antibacterials chloramphenicol (64.1%) and mupirocin (21.8%). Tinea (38.3%) and conjunctivitis (23.8%) were the 2 most common indications. Topical antimicrobials were sometimes prescribed for pro re nata administration (38.8%) and greater than 6 months (11.3%). The review or stop date was not always documented (38.7%). CONCLUSIONS: To reduce the possibility of adverse consequences associated with antimicrobial use, antimicrobial stewardship programs in Australian residential aged care facilities should at least ensure mupirocin is appropriately used, first line antimicrobial therapy is prescribed for tinea, chloramphenicol is prescribed for conjunctivitis only if necessary, pro re nata orders for prescriptions are discouraged and to avoid prolonged duration of prescriptions, review or stop dates are always documented.

Network medicine framework shows that proximity of polyphenol targets and disease proteins predicts therapeutic effects of polyphenols.

Polyphenols, natural products present in plant-based foods, play a protective role against several complex diseases through their antioxidant activity and by diverse molecular mechanisms. Here we develop a network medicine framework to uncover mechanisms for the effects of polyphenols on health by considering the molecular interactions between polyphenol protein targets and proteins associated with diseases. We find that the protein targets of polyphenols cluster in specific neighbourhoods of the human interactome, whose network proximity to disease proteins is predictive of the molecule's known therapeutic effects. The methodology recovers known associations, such as the effect of epigallocatechin-3-O-gallate on type 2 diabetes, and predicts that rosmarinic acid has a direct impact on platelet function, representing a novel mechanism through which it could affect cardiovascular health. We experimentally confirm that rosmarinic acid inhibits platelet aggregation and α-granule secretion through inhibition of protein tyrosine phosphorylation, offering direct support for the predicted molecular mechanism. Our framework represents a starting point for mechanistic interpretation of the health effects underlying food-related compounds, allowing us to integrate into a predictive framework knowledge on food metabolism, bioavailability and drug interaction.

Understanding the participation of breast screening among women born in predominantly Muslim countries living in Victoria, Australia from record-linkage data.

BACKGROUND: Early detection of breast cancer can improve survival rates and decrease mortality rates. This study investigates whether there are significant differences in participation in breast screening among women born in Muslim countries compared to women born in Non-Muslim countries and Australia. METHODS: Screening data from January 1st, 2000 to December 31st, 2013 from the Breast Screen Victoria Registry (BSV) was linked with hospital records from the Victorian Admitted Episodes Dataset (VAED). Countries having more than 50% of their population as Muslim were categorised as Muslim countries. Age adjusted rates were calculated for women born in Muslim and Non-Muslim countries and compared with the Australian age adjusted rates. Logistic regression assessed the association between screening status and other factors which include country of birth, marital status, age and socio-economic status. RESULTS: Women born in Muslim countries (Odds Ratio (OR) = 0.70, 95%CI = 0.68-0.72) and in other Non-Muslim countries (OR = 0.87, 95%CI = 0.86-0.88) had lower odds of participation in breast screening than Australian born women. Women aged 60-64 years (OR = 1.42, 95%CI = 1.40-1.44) had higher odds of participation in the BreastScreen program than 50-54 age group. CONCLUSION: This study provides valuable insights to understanding breast screening participation among women born in Muslim countries residing in Victoria. This population level study contributes to the broader knowledge of screening participation of women born in Muslim countries, an understudied population group in Australia and across the world. This study has implications for breast screening programs as it highlights the need for culturally sensitive approaches to support breast screening participation among women born in Muslim countries.

HPV16/18 prevalence in high-grade cervical lesions in an Australian population offered catch-up HPV vaccination.

OBJECTIVES: Using laser capture microdissection (LCM) and sensitive human papillomavirus (HPV) genotyping, we aimed to determine the distribution of vaccine-preventable types in cervical intraepithelial neoplasia grade 3 (CIN3) lesions and adenocarcinoma in situ (AIS) in young women in Victoria, Australia, offered catch-up HPV vaccination, as a baseline for ongoing vaccine impact monitoring. We also compared findings with available pre-vaccination estimates from women with HPV detected on concurrently-collected cytology samples. METHODS: Consecutive histologically-confirmed CIN3/AIS biopsies were collected between May 2011 and December 2014 from vaccine-eligible women (born after 30th June 1981). Genotypes present in whole tissue sections (WTS) were determined by a sensitive reverse hybridisation assay; RHA kit HPV SPF10-LiPA25, v1 (Labo Bio-medical Products). Where multiple genotypes were detected, lesions were isolated using LCM and genotyped. Cervical cytology samples from a pre-vaccine cohort had been previously collected and genotyped using HPV Linear Array HPV Genotyping Test (Roche Diagnostics). Mixed-genotype detections in this cohort were resolved to single-lesion-attributable genotypes using hierarchical attribution. RESULTS: Overall, 213 and 530 cases were included from pre- and post-vaccine time-periods, respectively. In 18-25 year-olds, the proportion of HPV16/18-positive CIN3/AIS decreased significantly over time from 69% in 2001-2005 (pre-vaccine), to 62% in 2011-2012 (post-vaccine), to 47% in 2013-2014 (p-trend = 0.004). There was no significant change in HPV16/18 in 26-32 year-olds (p-trend = 0.15). In 2013/14, nonavalent vaccine types accounted for 80% of CIN3/AIS in 18-25 year old women and 90% in 26-32 year old women. CONCLUSION: Four to 8 years following implementation of HPV vaccination in Australia, approximately 70% of CIN3/AIS in young women was due to HPV16/18. Our data, despite some limitations due to change in methods between pre- and post-vaccine periods, suggests that for vaccine-eligible women aged 18-25 at the time of biopsy, the proportion of HPV16/18-attributable CIN3/AIS lesions is significantly declining post-vaccination.