Approach to the Patient with a Skin and Soft Tissue Infection.

The diagnosis of a skin and soft tissue infection (SSTI) requires careful attention to a patient's history, physical examination, and diagnostic test results. We review for many bacterial, viral, fungal, and parasitic pathogens that cause SSTIs the clues for reaching a diagnosis, including reported past medical history, hobbies and behaviors, travel, insect bites, exposure to other people and to animals, environmental exposures to water, soil, or sand, as well as the anatomic site of skin lesions, their morphology on examination, and their evolution over time. Laboratory and radiographic tests are discussed that may be used to confirm a specific diagnosis.

The clinical value of metagenomic next-generation sequencing in the microbiological diagnosis of skin and soft tissue infections.

BACKGROUND: Metagenomic next-generation sequencing (mNGS), with its comprehensiveness, is widely applied in microbiological diagnosis. Etiological diagnosis is of paramount clinical importance in patients with skin and soft tissue infections (SSTIs). However, the clinical application of mNGS in SSTIs is relatively less studied. MATERIALS AND METHODS: From April 1, 2017 to December 31, 2019, 96 SSTI cases were collected. The positive rates of pathogens detected by mNGS and culture were compared by analyzing tissue samples, pus, swabs, and/or interstitial fluids obtained from the infected parts. Modification of the antibiotic treatment strategy due to mNGS was also assessed. RESULTS: The sensitivity of mNGS for detecting pathogens in SSTI cases was superior to that of culture testing (67.7% vs 35.4%; p < 0.01). Significantly higher identification rates for viruses (10.4% vs 0.0%; p < 0.01) and anaerobes (11.5% vs 1.0%; p < 0.01) were obtained with mNGS compared to culture. Of note, rare pathogens such as Vibrio vulnificus and Bartonella henselae were also detected by mNGS. Importantly, the proportion of multi-pathogen SSTIs detected by mNGS was higher than that of multi-pathogen SSTIs detected by culture (16.7% vs 6.3%; p = 0.035). The rate of targeted antibiotic treatment was significantly higher in mNGS-positive cases than in mNGS-negative cases (41.7% vs 3.8%; p < 0.01). In culture-negative and mNGS-positive cases, the improvement rate was higher than that in mNGS-negative cases, but this was not statistically significant (75.0% vs 73.1%; p = 0.864). CONCLUSIONS: mNGS is a promising tool for the etiological diagnosis of SSTIs, particularly in identifying viruses, anaerobes, and multi-pathogen infections. The application of mNGS testing in clinical practice could change antibiotic treatment strategies and partly benefit clinical outcomes.

Hand Infections in the Immunocompromised Patient: An Update.

Physicians are increasingly caring for immunocompromised individuals owing, in part, to the improved treatments and the increased life expectancy in these patients. Presentation of a patient with hand infection can vary greatly depending on the patient's underlying immune status. It is important to recognize and treat the infections quickly and effectively owing to the higher morbidity and mortality that may result from ineffective or delayed treatment in this patient population. The purpose of this article is to provide an outline of the most common and some of the more exotic organisms causing hand infections in patients with human immunodeficiency virus/acquired immunodeficiency syndrome, diabetes, and patients on immunosuppressive treatment. We discuss presentation, clinical picture, evidence-based approaches in treatment, and possible complications. It is important to inform surgeons of the atypical presentation of hand infections and systemic infections with hand manifestation in immunocompromised patients in order to shorten time to accurate diagnosis and effective treatment.

Acute hand infections.

The continued emergence of antibiotic-resistant bacteria and the development of only a few new classes of antibiotics over the past 50 years have made the treatment of acute hand infections problematic. Prompt diagnosis and treatment are important, because hand stiffness, contractures, and even amputation can result from missed diagnoses or delayed treatment. The most common site of hand infections is subcutaneous tissue and the most common mechanism is trauma. An immunocompromised state, intravenous drug abuse, diabetes mellitus, and steroid use all predispose to infections.

Increased risk of deep neck infection among HIV-infected patients in the era of highly active antiretroviral therapy--a population-based follow-up study.

BACKGROUND: Deep neck infections (DNIs) in HIV-infected patients often produce severe complications, even death. Data on the incidence rates and risks of DNI among HIV-infected patients are scarce, particularly with the widespread use of highly active antiretroviral therapy (HAART). We evaluated the incidence rates and risks for DNI among HIV-infected patients and observed the long-term trends. METHODS: A total of 9888 new HIV-infected patients diagnosed in 2001-2007 were included and matched with 49440 randomly selected subjects. The HIV-infected subjects were offered free access to HAART. All subjects were traced until December 2009. A Kaplan-Meier analysis generated the cumulative DNI incidence rate. The adjusted hazard ratio was computed using Cox proportional hazard regressions. RESULTS: From the HIV-infected and comparison cohorts, 222 individuals (57.01 cases per 10000 person-years) and 735 individuals (35.54 cases per 10000 person-years) developed DNI, respectively. The log rank test indicated that patients with HIV had a significantly higher 8-year incidence rate of DNI than the control group (P < 0.0001). The adjusted hazard ratio for developing DNI after an HIV attack during the mean 3.94 years follow-up period was 1.59. The incidence rate and relative risk of DNI were 74.58 (per 10000 person-years) and 2.05 (P < 0.0001). Both figures were highest in the first follow-up year and decreased year-by-year thereafter. CONCLUSION: The risk of developing DNI is significantly elevated among HIV-infected patients, even with free access to HAART. Additional research is needed to examine the role of HAART in reducing the risk.

Skin and soft tissue infections among HIV-infected persons in the late combination antiretroviral therapy era.

Skin and soft tissue infections (SSTIs) occur at higher rates among HIV-infected persons, but current trends and risk factors are largely undefined. We evaluated SSTIs among a prospective cohort of HIV-infected persons during the late combination antiretroviral therapy (cART) era (2006-2010). Of the 1918 HIV-infected persons evaluated, 379 (20%) developed an SSTI during a median of 3.7 years of follow-up; of these, 118 (31%) developed at least one recurrent SSTI. The incidence rate of SSTIs was 101 (95% confidence interval [CI] 93-109) cases per 1000 person-years, and rates did not significantly change during the study period. Compared with not receiving cART and having an HIV RNA level >1000 copies/mL, patients receiving cART with an HIV RNA level <1000 copies/mL had a reduced risk of an SSTI (hazard ratio 0.64, 95% CI 0.48-0.86, P < 0.01). In summary, initial and recurrent SSTIs are common among HIV-infected persons, and HIV control is associated with a lower risk of SSTIs.

Community-associated methicillin-resistant Staphylococcus aureus and HIV: intersecting epidemics.

BACKGROUND: Single-site studies have suggested a link between human immunodeficiency virus (HIV) and community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA). METHODS: Population-level incidence of HIV-infected patients with CA-MRSA versus community-associated methicillin-susceptible S. aureus (CA-MSSA) infection was assessed in the Cook County Health and Hospitals System (CCHHS), a multi-hospital and ambulatory care center. Rates in zip codes, including those with a high density of individuals with prior incarceration (ie, high-risk zip codes), were calculated. We did a nested case-control analysis of hospitalized HIV-infected patients with S. aureus skin and soft-tissue infections (SSTIs). RESULTS: In CCHHS, the incidence of CA-MRSA SSTIs was 6-fold higher among HIV-infected patients than it was among HIV-negative patients (996 per 100,000 HIV-infected patients vs 157 per 100,000 other patients; P < .001). The incidence of CA-MRSA SSTIs among HIV-infected patients significantly increased from 2000-2003 (period 1) to 2004-2007 (period 2) (from 411 to 1474 cases per 100,000 HIV-infected patients; relative risk [RR], 3.6; P<.001), with cases in period 1 clustering in an area 6.3 km in diameter (P=.035) that overlapped high-risk zip codes. By period 2, CA-MRSA SSTIs among HIV-infected patients were spread throughout Cook County. USA300 was identified as the predominant strain by pulsed-field gel electrophoresis (accounting for 86% of isolates). Among hospitalized HIV-infected patients, the incidence of CA-MRSA increased significantly from period 1 to period 2 (from 190 to 779 cases per 100,000 HIV-infected patients; RR, 4.1; P<.001). Risks for CA-MRSA by multivariate analysis were residence in alternative housing (eg, shelters), residence in high-risk zip codes, younger age, and infection in period 2. CONCLUSIONS: HIV-infected patients are at markedly increased risk for CA-MRSA infection. This risk may be amplified by overlapping community networks of high-risk patients that may be targets for prevention efforts.

Treatment of latent and tertiary syphilis.

Although the efficacy of penicillin treatment for syphilis has been amply demonstrated, the optimal, curative dosage is still undefined. Some patients experience a third stage of the disease long after secondary-stage symptoms have resolved. Treatment differs in early and late latency and with the specific manifestations of tertiary-stage disease.

Soft tissues and osteo-articular infections in HIV-infected patients and other immunodeficient states.

Soft tissue and osteo-articular infections are rarely seen in patients with HIV infection and other immunodeficiency states. When present in HIV-infected patients, they tend to occur in the presence of low CD4(+)cell counts, intravascular indwelling catheters, extra-articular infection and trauma, and in intravenous drug users and haemophiliacs. A wide spectrum of clinical manifestations is seen, ranging from cellulitis and soft tissue abscesses to septic arthritis and pyomyositis. In general, the clinical picture and response to therapy is similar to that of patients without HIV infection. Causal micro-organisms are also similar to those in non-HIV populations, Staphylococcus aureus being the most common aetiological agent.

Metacarpal osteomyelitis complicating varicella-associated cellulitis of the hand: report of 2 cases.

Hematogenous osteomyelitis is a known complication of varicella. Osteomyelitis accompanying adjacent soft tissue infection, however, has only been described once in the literature. We report 2 cases of metacarpal osteomyelitis complicating varicella-associated cellulitis of the hand. The cases illustrate that this diagnosis should be considered in a patient with varicella, soft tissue infection and lack of clinical improvement despite apparently appropriate therapy.

Upper extremity infections in patients with the human immunodeficiency virus.

Twenty-eight patients with upper extremity infections and positive for the human immunodeficiency virus (HIV) were identified. The risk factor for HIV infection was intravenous drug injection in 24 patients, homosexual contact in 3, and heterosexual contact in 1. Eight of the patients had the acquired immunodeficiency syndrome. Two of the cases were prolonged herpetic infections of more than 6 months' duration that did not respond to oral acyclovir. The other 26 cases were bacterial in origin. Twenty-six of 28 cases responded to therapy with resolution of the infection. One patient refused surgical treatment and one died of systemic illness before resolution of the hand infection.