Epidemiology, Management, and Outcomes of Large and Small Native Joint Septic Arthritis in Adults.

BACKGROUND: Native joint septic arthritis (NJSA) is poorly studied. We describe the epidemiology, treatment, and outcomes of large joint NJSA (LNJSA) and small joint NJSA (SNJSA) in adults at Middlemore Hospital, Auckland, New Zealand. METHODS: This was a coding-based retrospective study of patients ≥16 years old admitted between 2009 and 2014. Prosthetic joint infections were excluded. RESULTS: Five hundred forty-three NJSA episodes were included (302 LNJSA, 250 SNJSA). Only 40% had positive synovial fluid culture. Compared to SNJSA, LNJSA has higher incidence (13 vs 8/100 000 person-years [PY]), occurs in older, more comorbid patients, and is associated with greater rates of treatment failure (23% vs 12%) and mortality, despite longer antibiotic treatment. Total incidence is higher than previously reported (21/100 000 PY), with marked interethnic variation. Incidence rises with age (LNJSA only) and socioeconomic deprivation (LNJSA and SNJSA). Tobacco smokers and males are overrepresented. The most commonly involved joints were knee (21%) and hand interphalangeal (20%). Staphylococcus aureus was the most common pathogen (53%). Mean antibiotic duration was 25 days for SNJSA and 40 days for LNJSA, and the mean number of surgical procedures was 1.5 and 1.6, respectively. Treatment failure was independently associated with LNJSA, age, intra-articular nonarthroplasty prosthesis, and number of surgical procedures. CONCLUSIONS: This is the largest contemporary series of adult NJSA. SNJSA has better outcomes than LNJSA and may be able to be safely treated with shorter antimicrobial courses. Incidence is high, with significant ethnic and socioeconomic variation. Microbiological NJSA case ascertainment underestimates case numbers as it frequently excludes SNJSA.

Socioeconomic factors correlating with community antimicrobial prescribing.

BACKGROUND: Increasing antimicrobial resistance is a serious concern in New Zealand and worldwide. Antimicrobial resistance is tied to increased community antimicrobial consumption. Investigation of the drivers of antimicrobial prescribing in different locales is needed so that targeted interventions can be devised. Counties Manukau District Health Board (CMDHB) serves a diverse, relatively socio-economically deprived population that has the highest rate of community antimicrobial prescribing in New Zealand. We hypothesise that socio-economic factors are important in determining much of the prescribing of antimicrobials in the CMDHB population. METHODS: We collected data on the number of antibacterial prescriptions per person in each pre-defined geographical Area Unit in the CMDHB community in 2013, and compared these with demographic and socioeconomic parameters collected in the 2013 New Zealand census. Simple and multiple linear regression analyses were used to identify factors that correlated with antimicrobial prescribing. RESULTS: Multiple regression analysis showed that antimicrobial prescribing was strongly associated with a higher ratio of number of people to bedrooms in a dwelling (an index of crowding), with some added association with Maori ethnicity. When these factors were accounted for, there was no significant added influence from a range of other factors such as income, smoking or educational qualifications. CONCLUSIONS: Antimicrobial prescribing may be influenced by different factors within different communities. It is important to target the determinants of antimicrobial prescribing when addressing the issue of high community antimicrobial consumption. In the CMDHB community, crowding in homes is associated with higher rates of antimicrobial prescribing. This association may be because crowding directly increases infection rates, or that crowding serves as a proxy for other factors yet to be identified. Further investigation of the determinants of antimicrobial prescribing is needed.