Skin and Soft Tissue Infections (SSTIs) are common bacterial infections. We hypothesized that due to the COVID-19 pandemic, SSTI rates would significantly decrease due to directives to avoid unneeded care and attenuated SSTIs risk behaviours. We retrospectively examined all patients with an ICD-10 diagnosis code in the Los Angeles County Department of Health Services, the second largest U.S. safety net healthcare system between 16 March 2017 and 15 March 2022. We then compared pre-pandemic with intra-pandemic SSTI rates using an interrupted time series analysis. We found 72,118 SSTIs, 46,206 during the pre-pandemic period and 25,912 during the intra-pandemic period. Pre-pandemic SSTI rate was significantly higher than the intra-pandemic rate (3.27 vs. 2.31 cases per 1,000 empanelled patient-months, P < 0.0001). The monthly SSTI cases decreased by 1.19 SSTIs/1,000 empanelled patient-months between the pre- and intra-pandemic periods (P = 0.0003). SSTI subgroups (inpatient, observation unit, emergency department, and outpatient clinics), all had significant SSTI decreases between the two time periods (P < 0.05) except for observation unit (P = 0.50). Compared to the pre-COVID-19 pandemic period, medically attended SSTI rates in our large U.S. safety net healthcare system significantly decreased by nearly 30%. Whether findings reflect true SSTI decreases or decreased health system utilization for SSTIs requires further examination.

To determine the burden of skin and soft tissue infections (SSTI), the nature of antimicrobial prescribing and factors contributing to inappropriate prescribing for SSTIs in Australian aged care facilities, SSTI and antimicrobial prescribing data were collected via a standardised national survey. The proportion of residents prescribed ⩾1 antimicrobial for presumed SSTI and the proportion whose infections met McGeer et al. surveillance definitions were determined. Antimicrobial choice was compared to national prescribing guidelines and prescription duration analysed using a negative binomial mixed-effects regression model. Of 12 319 surveyed residents, 452 (3.7%) were prescribed an antimicrobial for a SSTI and 29% of these residents had confirmed infection. Topical clotrimazole was most frequently prescribed, often for unspecified indications. Where an indication was documented, antimicrobial choice was generally aligned with recommendations. Duration of prescribing (in days) was associated with use of an agent for prophylaxis (rate ratio (RR) 1.63, 95% confidence interval (CI) 1.08–2.52), PRN orders (RR 2.10, 95% CI 1.42–3.11) and prescription of a topical agent (RR 1.47, 95% CI 1.08–2.02), while documentation of a review or stop date was associated with reduced duration of prescribing (RR 0.33, 95% CI 0.25–0.43). Antimicrobial prescribing for SSTI is frequent in aged care facilities in Australia. Methods to enhance appropriate prescribing, including clinician documentation, are required.

The Infectious Disease Society of America (IDSA) publishes guidelines regularly for the management of skin and soft tissue infections; however, the extent to which practice patterns follow these guidelines and if this can affect treatment failure rates is unknown. We observed the treatment failure rates from a multicentre retrospective ambulatory cohort of adult emergency department patients treated for a non-purulent skin infection. We used multivariable logistic regression to examine the role of IDSA classification and whether adherence to IDSA guidelines reduced treatment failure. A total of 759 ambulatory patients were included in the cohort with 17.4% failing treatment. Among all patients, 56.0% had received treatments matched to the IDSA guidelines with 29.1% over-treated, and 14.9% under-treated based on the guidelines. After adjustment for age, gender, infection location and medical comorbidities, patients with a moderate infection type had three times increased risk of treatment failure (adjusted risk ratio (aRR) 2.98; 95% confidence interval (CI) 1.15–7.74) and two times increased risk with a severe infection type (aRR 2.27; 95% CI 1.25–4.13) compared with mild infection types. Patients who were under-treated based on IDSA guidelines were over two times more likely to fail treatment (aRR 2.65; 95% CI 1.16–6.05) while over-treatment was not associated with treatment failure. Patients ⩾70 years of age had a 56% increased risk of treatment failure (aRR 1.56; 95% CI 1.04–2.33) compared with those <70 years. Following the IDSA guidelines for non-purulent SSTIs may reduce the treatment failure rates; however, older adults still carry an increased risk of treatment failure.

Following a cluster of serious pseudomonas skin infections linked to a body piercing and tattooing premises, a look-back exercise was carried out to offer clients a screen for blood-borne viruses. Of those attending for screening 72% (581/809) had a piercing procedure in the premises of interest: 94 (16%) were under 16 years of age at the time of screening. The most common site of piercing was ear (34%), followed by nose (27%), nipple (21%) and navel (21%). A small number (<5) tested positive for hepatitis B and C, with no evidence this was linked to the premises. However, 36% (211/581) of clients reported a skin infection associated with their piercing. Using data from client forms, 36% provided a false age. Those aged under 16 years (OR 4.5, 95% CI 2.7–7.7) and those receiving a piercing at an intimate site (OR 2.1, 95% CI 1.3–3.6) were more likely to provide a false age. The findings from this exercise were used to support the drafting of the Public Health (Wales) Bill which proposed better regulation of piercing premises and the need to provide proof of being 18 years of age or over before having a piercing of an intimate site.

Mycobacterium marinum, a bacterium found in freshwater and saltwater, can infect persons with direct exposure to fish or aquariums. During December 2013, the New York City Department of Health and Mental Hygiene learned of four suspected or confirmed M. marinum skin or soft tissue infections (SSTIs) among persons who purchased whole fish from Chinese markets. Ninety-eight case-patients with non-tuberculous mycobacteria (NTM) SSTIs were identified with onset June 2013–March 2014. Of these, 77 (79%) were female. The median age was 62 years (range 30–91). Whole genome sequencing of clinical isolates revealed two main clusters and marked genetic diversity. Environmental samples from distributors yielded NTM though not M. marinum. We compared 56 case-patients with 185 control subjects who shopped in Chinese markets, frequency-matched by age group and sex. Risk factors for infection included skin injury to the finger or hand (odds ratio [OR]: 15·5; 95% confidence interval [CI]: 6·9–37·3), hand injury while preparing fish or seafood (OR 8·3; 95% CI 3·8–19·1), and purchasing tilapia (OR 3·6; 95% CI 1·1–13·9) or whiting (OR 2·7; 95% CI 1·1–6·6). A definitive environmental outbreak source was not identified.

Since the 1990s, New Zealand (NZ) has seen an increasing incidence of paediatric skin infections leading to hospitalization. We sought to describe the epidemiology of these infections over time. Hospital discharge data were analysed for all children admitted to any NZ public hospital from 2004 to 2014. We found the age-standardized incidence of hospitalizations due to skin infections increased during this period from 522/100 000 in 2004 to a peak of 644/100 000 in 2011, after which it declined to 524/100 000 in 2014. This decline in incidence was driven primarily by the decline in hospitalization rates in high-risk groups including children living in the most deprived areas as well as Māori and Pacific children. Recent targeted policies focused on improving healthcare access through school-based and primary care-based interventions in these high-risk groups could potentially explain the decline in hospitalization rates. However, even with the closing of the inequality gap, significant socioeconomic and ethnic health disparities persist.

Skin and soft tissue infection (SSTIs) due to Staphylococcus aureus, particularly community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA), are common in human immunodeficiency virus (HIV)-infected populations in the United States. Studies have differed as to the importance of epidemiological and immunological factors in this relationship, and have employed conflicting strategies for variable selection in multivariate analyses. Developments in causal inference methods in epidemiology have emerged in the last decade to clarify relationships between variables and identify appropriate variables to include in and exclude from multivariate analysis. In this paper, we develop a causal diagram to clarify the pathways linking CA-MRSA and HIV. We focus on the role played by trimethoprim-sulfamethoxazole (TMP-SMX) prophylaxis, prescribed to many severely immunocompromised HIV patients and potentially protective against SSTIs, which both mediates and moderates the relationship between immunological parameters and SSTI risk. We demonstrate, using simulated data, that statistical models may yield biased results if they do not account for how HIV viral load may also be a marker of adherence to TMP-SMX prophylaxis. We conclude with a proposed causal model that includes both the epidemiological as well as immunological factors that may explain the increased risk of initial and recurrent SSTI risk in HIV-infected populations.

Group B streptococcus (GBS) is an increasing cause of disease in adults. We present long-term trends in incidence of overall infections and identify characteristics of patients with GBS cellulitis, bone and joint infections. Active, population-based surveillance was conducted from 1995–2012 in three California counties and the data were analysed retrospectively. All cases had isolation of GBS from a normally sterile site. Cases of cellulitis were classified based on clinical diagnosis. GBS bone or joint infection was defined as isolation of GBS from a bone or joint or a diagnosis of osteomyelitis or septic arthritis. Medical charts were reviewed for demographic and clinical information. There were 3917 cases of GBS; the incidence of disease increased from 5·8 to 8·3 cases/100 000 persons (P < 0·001) from 1995 to 2012. In adults aged ⩾40 years, the overall incidence of GBS increased from 8·5 to 14·2 cases/100 000 (P < 0·001) persons during the study period. The incidence of cellulitis increased from 1·6 to 3·8 cases/100 000 (P < 0·001), bone infection increased from 0·7 to 2·6 cases/100 000 (P < 0·001), and the incidence of joint infection remained approximately constant at an average rate of 1·0 case/100 000. The highest incidence rates were observed in men, persons aged ⩾80 years, non-Hispanic blacks and Hispanics. Diabetes was the most common underlying condition (51·2% cellulitis cases, 76·3% bone infections, 29·8% joint infections).

Information on the risk factors for community-associated skin and soft-tissue infections (SSTIs) due to methicillin-resistant Staphylococcus aureus in Asian populations is scarce. To this end we performed a case-control study of patients treated at two hospital-affiliated outpatient clinics in Taiwan to determine potential risk factors for MRSA SSTIs. S. aureus was isolated from 39 of 100 eligible patients, and 74% were MRSA. Apart from resistance to clindamycin and erythromycin, most MRSA isolates were susceptible to appropriate antimicrobials. The significant risk factors identified by multivariate analysis for MRSA SSTIs were male gender (P = 0·09), nasal carriage of MRSA (P = 0·02), exposure to an individual who had surgery within a year before infection (P = 0·02), and antibiotic treatment for SSTI in the year before infection (P = 0·04). The identification of such factors may assist provision of appropriate treatment to patients with suspected S. aureus SSTIs particularly in Taiwan.

People who inject drugs are vulnerable to infections and injuries at injection sites, but these have rarely been studied in those injecting image- and performance-enhancing drugs (IPEDs). This study examined the factors associated with reported symptoms of injection site infections and injuries in IPED injectors. Of the 366 male IPED injectors surveyed, 42% reported ever having redness, swelling and tenderness (36% in the preceding year), and 6·8% had ever had an abscess or open wound at an injection site. Having these symptoms was associated with a range of factors related to drug use and healthcare utilization. One sixth (17%) of those reporting redness, tenderness and swelling had ever sought treatment, as had the majority (76%) of those reporting an abscess, sore or open wound. Most common sources of advice were emergency clinics and General Practitioners. Interventions are needed to support access to appropriate injecting equipment and provide targeted harm reduction advice.

People who inject drugs (PWID) are vulnerable to infections and injuries at injection sites. The factors associated with reporting symptoms of these, seeking related advice, and hospital admission are examined. PWID were recruited in Birmingham, Bristol and Leeds using respondent-driven sampling (N = 855). During the preceding year, 48% reported having redness, swelling and tenderness (RST), 19% an abscess, and 10% an open wound at an injection site. Overall, 54% reported ⩾1 symptoms, with 45% of these seeking medical advice (main sources emergency departments and General Practitioners). Advice was often sought ⩾5 days after the symptom first appeared (44% of those seeking advice about an abscess, 45% about an open wound, and 35% for RST); the majority received antibiotics. Overall, 9·5% reported hospital admission during the preceding year. Ever being diagnosed with septicaemia and endocarditis were reported by 8·8% and 2·9%, respectively. Interventions are needed to reduce morbidity, healthcare burden and delays in accessing treatment.

No U.S. general population-based study has characterized the epidemiology and risk factors, including skin and soft tissue infection (SSTI), for healthcare-associated (HA) and community-associated (CA) methicillin-resistant Staphylococcus aureus (MRSA). We estimated the incidence of HA- and CA-MRSA and SSTI over a 9-year period using electronic health record data from the Geisinger Clinic in Pennsylvania. MRSA cases were frequency-matched to SSTI cases and controls in a nested case-control analysis. Logistic regression was used to assess risk factors, while accounting for antibiotic administration. We identified 1713 incident CA- and 1506 HA-MRSA cases and 78 216 SSTI cases. On average, from 2005 to 2009, the annual incidence of CA-MRSA increased by 34%, HA-MRSA by 7%, and SSTI by 4%. Age, season, community socioeconomic deprivation, obesity, smoking, previous SSTI, and antibiotic administration were identified as independent risk factors for CA-MRSA.

The incidence of serious skin infections in New Zealand children is significantly higher than in comparative countries. This study aimed to describe the epidemiology of these infections and identify changes in disease distribution over time. Discharge data were analysed for all children admitted to a New Zealand public hospital with a serious skin infection during the period 1990–2007. Patient and admission variables were compared between 1990–1999 and 2000–2007. The incidence of serious skin infections almost doubled from 298·0/100 000 in 1990 to 547·3/100 000 in 2007. The highest rates were observed in boys, preschool-aged children, Māori and Pacific children, those living in deprived neighbourhoods, urban areas and northern regions. Over time there were disproportionate increases in infection rates in Māori and Pacific children and children from highly deprived areas. Serious skin infections are an increasing problem for New Zealand children. Worsening ethnic and socioeconomic health inequalities may be contributing to increasing rates.

Suppurative methicillin-resistant Staphylococcus aureus (MRSA) skin infections are common and associated with MRSA colonization, but little is known about non-suppurative cellulitis and its relationship with MRSA colonization in areas endemic for community-associated MRSA. We prospectively enrolled patients hospitalized for non-suppurative cellulitis (n=50) and matched controls (n=100) and found S. aureus colonization was similar in cases and controls (30% vs. 25%, P=0·95). MRSA was uncommon in cases (6%) and controls (3%) (P=0·39). All MRSA isolates were USA300 by pulsed-field gel electrophoresis. Independent risk factors for non-suppurative cellulitis were diabetes (OR 3·5, 95% CI 1·4–8·9, P=0·01) and homelessness in the previous year (OR 6·4, 95% CI 1·9–20·9, P=0·002). These findings suggest that MRSA may only rarely be causative of non-suppurative cellulitis.

Injection site infections in injecting drug users (IDUs) are associated with serious morbidity and healthcare costs. Factors associated with symptoms of these were examined through annual (2006–2008) unlinked-anonymous survey of IDUs in England, Wales and Northern Ireland. Overall 36% (1863/5209) self-reported having a symptom with no trend over time (35% 2006, 37% 2007, 34% 2008). Symptoms were less common in the North East of England; increased with years injecting; and were higher in women, those recently homeless, those recently using a needle exchange, and those injecting both opiates and stimulants. Of those injecting during the previous 4 weeks (n=3733) symptoms were associated with: injecting daily; injecting ⩾10 times a day; injecting into hands, groin, or legs; sharing filters; and reusing water to flush syringes. Symptoms of injection site infections are common in IDUs. Better-targeted preventive interventions are needed, and continued surveillance should assist with assessing the impact of new initiatives.

Hospital discharge reports have provided data for studies of methicillin-resistant Staphylococcus aureus (MRSA) skin and soft-tissue infection (SSTI) studies. This analysis determined the sensitivity and positive predictive value of International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) code combinations to calculate hospitalization incidence rates, representativeness of a set of three ICD-9-CM codes to define MRSA SSTI, and hospitalization incidence rate trends for paediatric MRSA SSTIs in Los Angeles County (LAC). Using 133 cases from 31 hospitals, we found that the set of three ICD-9-CM codes used to define laboratory-confirmed cases had one of the highest positive predictive values (49%). There was no difference in age and race between those categorized using three codes vs. other code combinations. A dramatic increase in paediatric MRSA SSTI cases occurred in LAC during 1998–2006. We conclude that this combination of codes may be used to determine the rise of MRSA SSTIs in paediatric populations.