Invasive group A streptococcal infections in Ontario, Canada. Ontario Group A Streptococcal Study Group

Secondary Bacterial Infections in Patients with Atopic Dermatitis or Other Common Dermatoses

Secondary bacterial infections of common dermatoses such as atopic dermatitis, ectoparasitosis, and varicella zoster virus infections are frequent, with Staphylococcus aureus and Streptococcus pyogenes being the bacteria most involved. There are also Gram-negative infections secondary to common dermatoses such as foot dyshidrotic eczema and tinea pedis. Factors favoring secondary bacterial infections in atopic dermatitis, ectoparasitosis, and varicella zoster virus infections mainly include an epidermal barrier alteration as well as itch. Mite-bacteria interaction is also involved in scabies and some environmental factors can promote Gram-negative bacterial infections of the feet. Furthermore, the bacterial ecology of these superinfections may depend on the geographical origin of the patients, especially in ectoparasitosis. Bacterial superinfections can also have different clinical aspects depending on the underlying dermatoses. Subsequently, the choice of class, course, and duration of antibiotic treatment depends on the severity of the infection and the suspected bacteria, primarily targeting S. aureus. Prevention of these secondary bacterial infections depends first and foremost on the management of the underlying skin disorder. At the same time, educating the patient on maintaining good skin hygiene and reporting changes in the primary lesions is crucial. In the case of recurrent secondary infections, decolonization of S. aureus is deemed necessary, particularly in atopic dermatitis.

Toxic Shock Syndrome (TSS) Caused by Group A Streptococcus: Novel Insights Within the Context of a Familiar Clinical Syndrome

The emergence of invasive infections attributed to group A Streptococcus (GAS) infections, has resurged since the 1980s. The recent surge in reports of toxic shock syndrome due to GAS in Japan in 2024, while sensationalized in the media, does not represent a novel infectious disease per se, as its diagnosis, treatment, and prevention are already well-established. However, due to signs of increasing incidence since 2011, further research is needed. Health authorities in neighboring countries like The Republic of Korea should not only issue travel advisories but also establish meticulous surveillance systems and initiate epidemiological studies on the genotypic variations of this disease while awaiting various epidemiological research findings from Japan.

The associations between invasive group A streptococcal disease and infection with influenza, varicella, or hepatitis C viruses: A data linkage study, Victoria, Australia

OBJECTIVES

To quantify the associations between invasive group A streptococcal disease (iGAS) incidence and influenza, varicella, and chronic hepatitis C virus (HCV).

METHODS

We used individual-level linked data of iGAS cases from Victoria, Australia (2007-2017) to assess associations between these viral infections and iGAS. A self-controlled case series method was used to estimate the relative incidence of iGAS following an influenza or varicella infection, while the relative incidence of iGAS among HCV cases, and HCV cases who inject drugs, was estimated using population-level data and a negative binomial regression model.

RESULTS

Of the 1949 individuals with at least one iGAS diagnosis, 82 were diagnosed with influenza at least once, 30 with varicella, and 118 with HCV during the study period. The relative incidence of iGAS increased substantially following infection with influenza (incidence rate ratio [IRR]: 34.5, 95% confidence interval [CI]: 21.3-55.8) or varicella (IRR: 22.4, 95% CI: 10.3-48.8). iGAS incidence was higher among HCV cases (IRR: 5.7, 95% CI: 4.4-7.3) compared to individuals without HCV. iGAS incidence was also higher among HCV cases who inject drugs (IRR: 17.9, 95% CI: 13.0-24.4) compared to individuals without HCV who did not inject drugs.

CONCLUSIONS

We found a significantly higher risk of iGAS following an influenza or varicella infection and for chronic HCV cases, particularly those who inject drugs. These findings are relevant to public health practice and support the timely identification of iGAS cases.

Antibiotics to eradicate Streptococcus pyogenes pharyngeal carriage in asymptomatic children and adults: A systematic review

Streptococcus pyogenes (S. pyogenes) is a Gram-positive bacteria which causes a spectrum of diseases ranging from asymptomatic infection to life-threatening sepsis. Studies report up to 2000 times greater risk of invasive S. pyogenes disease in close contacts of index cases within 30-days of symptom onset. Despite this, there is variability in the management of asymptomatic carriage of S. pyogenes and those at risk of secondary cases of invasive S. pyogenes infection.

OBJECTIVE

Our systematic review assessed the efficacy of different antibiotic regimens used for eradication of S. pyogenes from the pharynx in asymptomatic individuals.

METHODS

We searched Pubmed, EMBASE (1974-), OVID Medline (1948-) and the Cochrane CENTRAL registry. We included randomised controlled trials (RCTs) with asymptomatic participants with >50% with pharyngeal cultures positive with S. pyogenes at baseline. Only studies with microbiological methods including culture (+/- polymerase chain reaction, PCR) were included. We included studies published in English. Each included study was assessed by two independent reviewers for data extraction and risk of bias.

RESULTS

Of 1166 unique records identified, three RCTs were included in the review. Two of the three included RCTs found oral clindamycin for 10-days was the most efficacious regimen, compared to intramuscular benzathine penicillin G followed by 4 days of oral rifampicin, or monotherapy using benzathine penicillin, phenoxymethylpenicillin or erythromycin. Two RCTs were assessed as being at high risk of bias, with the third study demonstrating low/some risk of bias.

CONCLUSIONS

Current available evidence for the optimal antibiotic in eradicating pharyngeal S. pyogenes carriage is limited. Future RCTs should include penicillin, first-generation cephalosporins, rifampicin, macrolides (such as azithromycin) and clindamycin.

Toxic Shock Syndrome: A Literature Review

Toxic shock syndrome (TSS) is a rare, life-threatening, toxin-mediated infectious process linked, in the vast majority of cases, to toxin-producing strains of Staphylococcus aureus or Streptococcus pyogenes. The pathophysiology, epidemiology, clinical presentation, microbiological features, management and outcome of TSS are described in this review. Bacterial superantigenic exotoxins induces unconventional polyclonal lymphocyte activation, which leads to rapid shock, multiple organ failure syndrome, and death. The main described superantigenic exotoxins are toxic shock syndrome toxin-1 (TSST-1) and enterotoxins for Staphylococcus aureus and Streptococcal pyrogenic exotoxins (SpE) A, B, and C and streptococcal superantigen A (SsA) for Streptococcus pyogenes. Staphylococcal TSS can be menstrual or nonmenstrual. Streptococcal TSS is linked to a severe group A streptococcal infection and, most frequently, to a necrotizing soft tissue infection. Management of TSS is a medical emergency and relies on early detection, immediate resuscitation, source control and eradication of toxin production, bactericidal antibiotic treatment, and protein synthesis inhibiting antibiotic administration. The interest of polyclonal intravenous immunoglobulin G administration as an adjunctive treatment for TSS requires further evaluation. Scientific literature on TSS mainly consists of observational studies, clinical cases, and in vitro data; although more data on TSS are required, additional studies will be difficult to conduct due to the low incidence of the disease.

Surviving the perilous: A case report on an urgent approach to necrotizing fasciitis

Necrotizing fasciitis is a rare, fatal, and rapidly progressing bacterial infection of fascia and subcutaneous tissues. Skin necrosis, pain, bullae, and erythema are the common manifestations. Early diagnosis and prompt treatment can improve outcome.

Streptococcus pyogenes emm98.1 variants activate inflammatory caspases in human neutrophils

ABBREVIATIONS

CovRS, control of virulence regulatory system; GAS, Group A Streptococcus; PMN, polymorphonuclear leukocyte.

Streptococcal species as a prognostic factor for mortality in patients with streptococcal bloodstream infections

PURPOSE

Streptococcal bloodstream infections (BSIs) are common, yet prognostic factors are poorly investigated. We aimed to investigate the mortality according to streptococcal species and seasonal variation.

METHODS

Patients with streptococcal BSIs from 2008 to 2017 in the Capital Region of Denmark were investigated, and data were crosslinked with nationwide registers for the identification of comorbidities. A multivariable logistic regression analysis was performed to assess mortality according to streptococcal species and season of infection.

RESULTS

Among 6095 patients with a streptococcal BSI (mean age 68.1 years), the 30-day mortality was 16.1% and the one-year mortality was 31.5%. With S. pneumoniae as a reference, S. vestibularis was associated with a higher adjusted mortality both within 30 days (odds ratio (OR) 2.89 [95% confidence interval (CI) 1.20-6.95]) and one year (OR 4.09 [95% CI 1.70-9.48]). One-year mortality was also higher in S. thermophilus, S. constellatus, S. parasanguinis, S. salivarius, S. anginosus, and S. mitis/oralis. However, S. mutans was associated with a lower one-year mortality OR 0.44 [95% CI 0.20-0.97], while S. gallolyticus was associated with both a lower 30-day (OR 0.42 [95% CI 0.26-0.67]) and one-year mortality (OR 0.66 [95% CI 0.48-0.93]). Furthermore, with infection in the summer as a reference, patients infected in the winter and autumn had a higher association with 30-day mortality.

CONCLUSIONS

The mortality in patients with streptococcal BSI was associated with streptococcal species. Further, patients with streptococcal BSIs infected in the autumn and winter had a higher risk of death within 30 days, compared with patients infected in the summer.

Group A Streptococcus Meningitis in Adults, Denmark

We report a 21-fold increase in group A Streptococcus meningitis in adults in Denmark during October 13, 2022-April 12, 2023, concurrent with an outbreak of invasive streptococcal disease. We describe clinical characteristics of the outbreak cases and prognosis for patients in comparison to those for previous sporadic cases.

Outcomes and management of pregnancy and puerperal group A streptococcal infections: A systematic review

INTRODUCTION

Group A streptococcus (Streptococcus pyogenes) is one of the most lethal bacterial pathogens of humans, with increased risk of progression to septic shock and multiorgan failure in the pregnant population. The objective of this study is to systematically review the outcomes and management strategies for pregnancy and puerperal group A streptococcus infections in an effort to provide further guidance for prevention and treatment of a rare but lethal infection worldwide.

MATERIAL AND METHODS

A comprehensive search using puerperium and streptococcus pyogenes terms was completed across several registered databases. A total of 902 articles investigating pregnancy and puerperal group A streptococcus infection were identified, with 40 studies fulfilling inclusion criteria of original research articles in humans published from 1990 onwards reporting four or more unique cases of group A streptococcus in pregnancy or postpartum. This study was registered in PROSPERO: CRD42020198983.

RESULTS

A total of 1160 patients with pregnancy and puerperal group A streptococcus infection were identified. Most infections occurred postpartum (91.9%), with 4.7% reported antepartum and 0.6% intrapartum. Bacteremia was present in 49.0% of patients and endometritis in 45.9%. Puerperal sepsis was described in 28.2% of cases and progressed to streptococcal toxic shock syndrome in one-third of such cases. Overall, the case fatality ratio was 2.0%, with one-third of the deaths from antenatal cases including 3/22 (13.6%) cases of septic abortion and 10/46 (21.7%) antenatal cases of group A streptococcus infection.

CONCLUSIONS

Group A streptococcus infection remains an important contributor to pregnancy and puerperal morbidity and mortality. Early recognition, diagnosis and aggressive management are important for favorable outcomes given the serious risk of sepsis and streptococcal toxic shock syndrome.

Not so uncommon, yet neglected 'Severe Streptococcus pyogenes infections at a tertiary care center in south India

Streptococcus pyogenes (SP) causes uncomplicated infections of throat & skin to severe life-threatening invasive diseases and poststreptococcal sequelae. Despite being common, it hasn't been studied much in recent times. Data of 93 adult patients >18 years, culture proven (SP) infections from 2016 to 2019 was studied in south India. Irrespective of comorbidities, SSTI were most common followed by surgical site infections& bacteremia. Isolates were susceptible to penicillin, cephalosporins but 23% were resistant to clindamycin. Timely surgical interventions and appropriate antibiotics reduced morbidity& limb salvage by 9 times. Larger studies, worldwide, to see the current trend of SP need to be conducted.

Prognostic factors for streptococcal toxic shock syndrome: systematic review and meta-analysis

OBJECTIVES

To quantify the prognostic effects of demographic and modifiable factors in streptococcal toxic shock syndrome (STSS).

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

MEDLINE, EMBASE and CINAHL from inception to 19 September 2022, along with citations of included studies.

ELIGIBILITY CRITERIA

Pairs of reviewers independently screened potentially eligible studies of patients with Group A Streptococcus-induced STSS that quantified the association between at least one prognostic factor and outcome of interest.

DATA EXTRACTION AND SYNTHESIS

We performed random-effects meta-analysis after duplicate data extraction and risk of bias assessments. We rated the certainty of evidence using the Grading of Recommendations, Assessment, Development and Evaluation approach.

RESULTS

One randomised trial and 40 observational studies were eligible (n=1918 patients). We found a statistically significant association between clindamycin treatment and mortality (n=144; OR 0.14, 95% CI 0.06 to 0.37), but the certainty of evidence was low. Within clindamycin-treated STSS patients, we found a statistically significant association between intravenous Ig treatment and mortality (n=188; OR 0.34, 95% CI 0.15 to 0.75), but the certainty of evidence was also low. The odds of mortality may increase in patients ≥65 years when compared with patients 18-64 years (n=396; OR 2.37, 95% CI 1.47 to 3.84), but the certainty of evidence was low. We are uncertain whether non-steroidal anti-inflammatory drugs increase the odds of mortality (n=50; OR 4.14, 95% CI 1.13 to 15.14; very low certainty). Results failed to show a significant association between any other prognostic factor and outcome combination (very low to low certainty evidence) and no studies quantified the association between a prognostic factor and morbidity post-infection in STSS survivors.

CONCLUSIONS

Treatment with clindamycin and within clindamycin-treated patients, IVIG, was each significantly associated with mortality, but the certainty of evidence was low. Future research should focus on morbidity post-infection in STSS survivors.

PROSPERO REGISTRATION NUMBER

CRD42020166961.

Effectiveness and Safety of Antibiotic Prophylaxis for Persons Exposed to Cases of Invasive Group A Streptococcal Disease: A Systematic Review

Among close contacts of patients with invasive group A streptococcal (iGAS) infection, the benefits and harms of chemoprophylaxis are uncertain. We conducted a systematic review of studies that reported on persons who, after being exposed to a case of laboratory-confirmed or probable iGAS, received any antibiotic prophylaxis for the prevention of GAS infection or carriage. Thirty-seven studies including 26 outbreak investigations and 11 case series or reports were included with predominantly descriptive information that suggested that antibiotic prophylaxis may be effective in preventing GAS infection or GAS carriage, with very few serious adverse events. However, current available evidence is scant (with limited information on contacts of iGAS cases) and largely based on studies with weak design and small sample size. Therefore, definitive conclusions on effectiveness of antibiotic prophylaxis cannot be drawn. Well designed prospective studies are required to establish the benefit-harm profile of antibiotic prophylaxis for secondary prevention of GAS disease among close contacts of iGAS cases.

Case Report: Therapeutic Strategy With Delayed Debridement for Culture-Negative Invasive Group A Streptococcal Infections Diagnosed by Metagenomic Next-Generation Sequencing

Streptococcal toxic shock syndrome (STSS) caused by group A streptococcus is a rare condition that rapidly developed to multiple organ failure even death. Therefore, prompt diagnosis, initiate appropriate antibiotics and other supportive treatments are critical. Here we reported a case of STSS caused by group A streptococcus infection. A healthy 39-year-old man presented a sudden pain in the left lower extremity, followed by a high fever (40.0 °C) with dizziness, nausea, and shortness of breath. Twenty-four hours before the visit, the patient showed anuria. The patient was then admitted to the intensive care unit. Blood examination revealed elevated levels of inflammatory markers and creatinine. He suffered from septic shock, dysfunction of coagulation, acute kidney dysfunction, acute respiratory distress syndrome, and acute liver function injury. The diagnosis was obtained through clinical manifestation and metagenomic next-generation sequencing (mNGS) drawn from the pustule and deep soft tissue (lower limb) samples while all bacterial cultures came back negative. The pustule mNGS report detected a total of 132 unique group A streptococcus sequence reads, representing 96.3% of microbial reads while the soft tissue mNGS report identified a total of 142474 unique group A streptococcus sequence reads, representing 100% of microbial reads. The patient was treated with aggressive fluid resuscitation, antibiotics comprising piperacillin/tazobactam and clindamycin, respiratory support, following the delayed surgical debridement. Intravenous immunoglobulin was also used for 5 days. On the 14th day after admission, he was transferred to the general ward for follow-up treatment. Our case highlighted, for the first time, the key role of mNGS in the early diagnosis of culture-negative invasive group A streptococcal infection. The case also suggested that clindamycin combined with beta-lactam antibiotics and adjunction of intravenous immunoglobulin therapy with delayed debridement performed well in the management of unstable STSS patients.

Necrotizing Soft-Tissue Infections After Hip Arthroplasty

Necrotizing soft-tissue infections are a rare complication following hip arthroplasty procedures. These rapidly spreading infections have a high mortality rate and must be diagnosed and treated in an expeditious manner. This article discusses the epidemiology, classification, diagnosis, and treatment of these conditions and describes 2 related case reports.

Post-surgical staphylococcal toxic shock syndrome in pediatrics: A case report

Introduction

Toxic shock syndrome (TSS) is a rare but serious, life-threatening medical condition and potentially lethal if not detected and treated early. It is mainly caused by a toxin called toxin-1 produced by Staphylococcus aureus, and characterized by fever, hypotension, rash, skin desquamation and multisystem involvement.

Case presentation

Herein, we describe a nine-month-old male patient who presented to the hospital complaining of fever, vomiting and hypoactivity on day one post-orchidopexy. During hospitalization, his condition began to deteriorate with signs and symptoms of multisystemic failure. Laboratory tests and radiological images were done, leading to the decision to reopen and drain the surgical wound. Wound and nasal swabs were cultured and showed S. aureus infection, and the diagnosis of toxic shock syndrome was confirmed.

Discussion

TSS is a systemic illness resulting from overwhelming host response to bacterial exotoxins, that cause T cells activation and the release of pro-inflammatory cytokines (IL-1 and TNF-α causing fever, hypotension, and tissue injury). Also, it can present with CNS signs that may be misdiagnosed with meningitis in pediatrics.

It requires early identification and treatment despite its rarity with mortality rate of 81% even with treatment.

The patient's presentation, examination and laboratories tests with the blood and wound cultures were highly suggestive for this condition.

Conclusion

Physicians must maintain a high index of suspicion for TSS, as early diagnosis and treatment make a difference. This condition shouldn't be excluded even in young age patients or after simple procedure as in our case in which TSS occurred after orchidopexy.

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Toxic shock syndrome is a life-threatening condition that can be highly mortal even with treatment.

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Post-surgical TSS is very rare and according to the literature this is the first reported case post-orchidopexy.

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Broad spectrum antibiotics with debridement of the necrotic tissue as management are the best option to treat this condition.

Epidemiology and risk factors for pyogenic liver abscess in the Calgary Health Zone revisited: a population-based study

Background

Pyogenic liver abscess (PLA), although uncommon in North America, is associated with significant morbidity and mortality. We sought to re-examine the epidemiology, risk factors, and outcomes of PLA in a large, diverse Canadian health zone.

Methods

All Calgary Health Zone (CHZ) residents aged ≥20 with PLA between 2015 and 2017 were identified. Incidence and mortality rates were calculated using census data. Risk factors for PLA were identified using a multivariate analysis. Data was compared to 1999–2003 data, also collected in the CHZ.

Results

There were 136 patients diagnosed with PLA between 2015 and 2017. Incidence rate during this period increased significantly relative to 1999–2003 (3.7 vs 2.3 cases/100,000 population, p < 0.01), however, mortality rates remained similar. The microbiological composition of PLA did not change over this 15-year time period but the number of antimicrobial resistant isolates did increase (8% vs 1%, p = 0.04). The greatest risk factors for PLA relative to general populations included current malignancy, liver-transplant, end-stage renal disease, and cirrhosis. Thirty-day mortality was 7.4% and independent risk factors included polymicrobial bacteremia, absence of abscess drainage, congestive-heart failure, a history of liver disease, and admission bilirubin.

Conclusions

Pyogenic liver abscess is a health concern with rising incidence rate. The increasing prevalence of comorbidities in our population and factors that are associated with risk of PLA suggests this will continue to be an emerging diagnosis of concern. Increasing prevalence of antibiotic resistant organisms compounding unclear optimal treatment regimens is an issue that requires urgent study.

Unfolded protein response inhibitors cure group A streptococcal necrotizing fasciitis by modulating host asparagine

Group A streptococcus (GAS) is among the top 10 causes of mortality from an infectious disease, producing mild to invasive life-threatening manifestations. Necrotizing fasciitis (NF) is characterized by a rapid GAS spread into fascial planes followed by extensive tissue destruction. Despite prompt treatments of antibiotic administration and tissue debridement, mortality from NF is still high. Moreover, there is no effective vaccine against GAS, and early diagnosis of NF is problematic because its clinical presentations are not specific. Thus, there is a genuine need for effective treatments against GAS NF. Previously, we reported that GAS induces endoplasmic reticulum (ER) stress to gain asparagine from the host. Here, we demonstrate that GAS-mediated asparagine induction and release occur through the PERK-eIF2α-ATF4 branch of the unfolded protein response. Inhibitors of PERK or integrated stress response (ISR) blocked the formation and release of asparagine by infected mammalian cells, and exogenously added asparagine overcame this inhibition. Moreover, in a murine model of NF, we show that the inhibitors minimized mortality when mice were challenged with a lethal dose of GAS and reduced bacterial counts and lesion size when mice were challenged with a sublethal dose. Immunohistopathology studies demonstrated that PERK/ISR inhibitors protected mice by enabling neutrophil infiltration into GAS-infected fascia and reducing the pro-inflammatory response that causes tissue damage. Inhibitor treatment was also effective in mice when started at 12 hours after infection. We conclude that host metabolic alteration induced by PERK or ISR inhibitors is a promising therapeutic strategy to treat highly invasive GAS infections.

Invasive Group A Streptococcal Infections: Benefit of Clindamycin, Intravenous Immunoglobulins and Secondary Prophylaxis

Introduction: Mortality associated with invasive group A streptococcal infections (iGAS) remains high among adults, with lower mortality in children. The added value of both clindamycin and immunoglobulins in such treatment is still controversial, as is the need for antibiotic secondary prophylaxis. It is unlikely that conclusive randomized clinical studies will ever definitively end these controversies. Materials and Methods: A clinical and experimental literature review was conducted in Pubmed, Cochrane, and lay literature to determine the benefit of adding clindamycin and immunoglobulins to β-lactams in the management of iGAS, as well as the need for secondary prophylaxis measures in close contacts. Results: This review includes two meta-analyses, two randomized controlled trials, four prospective studies, five retrospective studies, and microbiological studies. To reduce mortality and morbidity, it appears useful to add clindamycin to β-lactams in severe clinical presentations, including necrotizing fasciitis or streptococcal toxic shock syndrome, and immunoglobulins for the latter two presentations. The high risk of secondary infection in household contacts justifies the need of taking preventive measures. Conclusions: Both clinical studies and available experimental evidence suggest that adding clindamycin and immunoglobulins as adjunctive therapies in the management of invasive group A streptococcal infections may reduce mortality. Household contacts should be warned about the increased risk of secondary infection, and chemoprophylaxis may be considered in certain situations.

Clinical and laboratory characteristics of patients presenting to a tertiary care center emergency department with invasive group A streptococcal infections

OBJECTIVES

The aim of this study was to describe the clinical and laboratory characteristics of invasive group A streptococcal infections in a geographic area that sees a high volume of cases.

METHODS

We conducted a health records review of consecutive patients presenting to the Thunder Bay Regional Health Sciences Centre Emergency Department (ED) in 2016-2017 with a diagnosis of invasive group A streptococcal infection using ICD-10 codes. Patient demographics, host characteristics, triage vital signs, laboratory values, culture sites, and disposition were described using univariate and bivariate statistics.

RESULTS

Forty-four adult cases were identified over 2 years, with a median age of 44 years (interquartile range, 35-52). The most prevalent risk factors were diabetes mellitus (45%), current or previous alcohol abuse (39%), and current or previous intravenous drug use (34%). The two most abnormal triage vitals signs were a heart rate ≥ 100 beats per minute in 32 (73%) cases and a respiratory rate ≥ 20 breaths per minute in 27 (63%) cases. The temperature was ≥ 38°C in only 14 (32%) of cases. The C-reactive protein (CRP) was always elevated when measured, and greater than 150 mg/L in 20 (71%) of cases. One-third of patients had an ED visit in the preceding 7 days before the diagnosis of invasive group A Streptococcus.

CONCLUSIONS

Invasive group A streptococcal infections often present insidiously in adult patients with mild tachycardia and tachypnea at triage. The CRP was the most consistently abnormal laboratory investigation.

COVID Arm: Delayed Hypersensitivity Reactions to SARS-CoV-2 Vaccines Misdiagnosed as Cellulitis

The term “COVID arm” has been coined to describe a harmless delayed hypersensitivity reaction occurring approximately a week after administration of the novel SARS-CoV-2 mRNA vaccine. It appears as a red, warm, pruritic, indurated, or swollen area in the vicinity of the vaccine site. These reactions, especially if accompanied by systemic symptoms, have been mistaken for cellulitis. We report 3 cases of COVID arm, 2 of which were mistaken for cellulitis. Distinguishing features of COVID arm from cellulitis include pruritus as a common finding, occurrence approximately a week after vaccination, a lack of progression of symptoms, rapid response to topical steroids, and/or spontaneous resolution usually over 4 to 5 days.

Practice Points:

• Patients receiving SARS-CoV-2 vaccines may experience delayed hypersensitivity reactions characterized by erythema, swelling, and itching occurring near the vaccination site (COVID arm), approximately a week after vaccination.

• Clinicians can distinguish SARS-CoV-2 vaccine reactions from cellulitis by the time of onset (approximately a week vs 5 days), by the lack of progression of symptoms, and resolution over 4 to 5 days.

• Severe cases of COVID arm may be treated with topical steroids.

[Necrotizing Fasciitis]

Necrotizing fasciitis (NF) is a soft tissue infection spreading along the fasciae to the surrounding subcutaneous fat, overlying skin and finally musculature, that may rapidly lead to septic shock and death. In order to avoid a massive systemic spread of the infective process, an immediate and extensive radical debridement of necrotic tissues is mandatory complemented by a broad spectrum intravenous antibiotic therapy. Nevertheless, mortality is persistently high at 20-40 %. Because of the lack of specific clinical features in the initial stage of the disease, it is often underestimated or confused with cellulitis or abscess. Hence, early diagnosis is missed or delayed in 85 %-100 % of cases with the passage of valuable time.The aim of this review is to give an overview of the clinical and laboratory elements to be considered for diagnosis as well as the essential therapeutic patterns.

Genital Tract GAS Infection ISIDOG Guidelines

There has been an increasing worldwide incidence of invasive group A streptococcal (GAS) disease in pregnancy and in the puerperal period over the past 30 years. Postpartum Group A streptococci infection, and in particular streptococcal toxic shock syndrome (TSS) and necrotizing fasciitis, can be life threatening and difficult to treat. Despite antibiotics and supportive therapy, and in some cases advanced extensive surgery, mortality associated with invasive group A streptococcal postpartum endometritis, necrotizing fasciitis, and toxic shock syndrome remains high, up to 40% of postpartum septic deaths. It now accounts for more than 75,000 deaths worldwide every year. Postpartum women have a 20-fold increased incidence of GAS disease compared to non-pregnant women. Despite the high incidence, many invasive GAS infections are not diagnosed in a timely manner, resulting in potentially preventable maternal and neonatal deaths. In this paper the specific characteristics of GAS infection in the field of Ob/Gyn are brought to our attention, resulting in guidelines to improve our awareness, early recognition and timely treatment of the disease. New European prevalence data of vaginal GAS colonization are presented, alongside two original case histories. Additionally, aerobic vaginitis is proposed as a supplementary risk factor for invasive GAS diseases.

Diverse disease processes of group A Streptococcus infection including severe invasive infections among members of a family

We herein report three cases of group A Streptococcus (GAS) infection in a family. Patient 1, a 50-year-old woman, was transferred to our hospital in shock with acute respiratory distress syndrome, swelling in the right neck and erythemata on both lower extremities. She required intubation because of laryngeal oedema. At the same time, patient 2, a 48-year-old man, was admitted because of septic shock, pneumonia and a pulmonary abscess. Five days later, patient 3, a 91-year-old woman, visited our clinic with bloody stool. All three patients were cured by antibiotics, and GAS was detected by specimen cultures. During these patients' clinical course, an 84-year-old woman was found dead at home after having been diagnosed with type A influenza. All four patients lived in the same apartment. The GAS genotypes detected in the first three patients were identical. When treating patients with GAS, appropriate management of close contacts is mandatory.

When All Else Fails: A Rare Case of Postoperative Toxic Shock Syndrome Arising from Surgical Site Infection after Decompressive Neurectomy Successfully Treated with Angiotensin-2

Toxic shock syndrome is a serious complication of Streptococcus pyogenes or Staphylococcus aureus infections associated with very high morbidity and mortality. Postoperative toxic shock syndrome is an extremely rare phenomenon which manifests as fevers, diffuse rash, septic shock, and death. We present the first reported case of toxic shock syndrome associated with a surgical site infection from a decompressive neurectomy for refractory migraines in a 41-year-old female as well as the first use of angiotensin-2 vasopressor therapy to treat persistent septic shock from toxic shock syndrome refractory to conventional therapies.

Streptococcus pyogenes M1T1 Variants Induce an Inflammatory Neutrophil Phenotype Including Activation of Inflammatory Caspases

Invasive infections due to group A Streptococcus (GAS) advance rapidly causing tissue degradation and unregulated inflammation. Neutrophils are the primary immune cells that respond to GAS. The neutrophil response to GAS was characterised in response to two M1T1 isolates; 5448 and animal passaged variant 5448AP. Co-incubation of neutrophils with 5448AP resulted in proliferation of GAS and lowered the production of reactive oxygen species when compared with 5448. Infection with both strains invoked neutrophil death, however apoptosis was reduced in response to 5448AP. Both strains induced neutrophil caspase-1 and caspase-4 expression in vitro, with inflammatory caspase activation detected in vitro and in vivo. GAS infections involving strains such as 5448AP that promote an inflammatory neutrophil phenotype may contribute to increased inflammation yet ineffective bacterial eradication, contributing to the severity of invasive GAS infections.

Pathogenic Mechanisms of Streptococcal Necrotizing Soft Tissue Infections

Necrotizing skin and soft tissue infections (NSTIs) are severe life-threatening and rapidly progressing infections. Beta-hemolytic streptococci, particularly S. pyogenes (group A streptococci (GAS)) but also S. dysgalactiae subsp. equisimilis (SDSE, most group G and C streptococcus), are the main causative agents of monomicrobial NSTIs and certain types, such as emm1 and emm3, are over-represented in NSTI cases. An arsenal of bacterial virulence factors contribute to disease pathogenesis, which is a complex and multifactorial process. In this chapter, we summarize data that have provided mechanistic and immuno-pathologic insight into host-pathogens interactions that contribute to tissue pathology in streptococcal NSTIs. The role of streptococcal surface associated and secreted factors contributing to the hyper-inflammatory state and immune evasion, bacterial load in the tissue and persistence strategies, including intracellular survival and biofilm formation, as well as strategies to mimic NSTIs in vitro are discussed.

Clinical Efficacy of Intravenous Immunoglobulins in Management of Toxic Shock Syndrome: An Updated Literature Review

Toxic shock syndrome (TSS) is an uncommon complication of infection caused by streptococci and staphylococci. It is associated with a high mortality rate. When evaluating patients with shock symptoms from skin or soft tissue sources, a high index of suspicion for TSS must be maintained. Prompt diagnosis and integrative management with surgical intervention, antibiotics, hemodynamic stabilization, and adjuvants like intravenous immunoglobulins improve survival.

A prospective survey of Streptococcus pyogenes infections in French Brittany from 2009 to 2017: Comprehensive dynamic of new emergent emm genotypes

Streptococcus pyogenes or group A Streptococcus (GAS) causes diseases ranging from uncomplicated pharyngitis to life-threatening infections. It has complex epidemiology driven by the diversity, the temporal and geographical fluctuations of the circulating strains. Despite the global burden of GAS diseases, there is currently no available vaccination strategy against GAS infections. This study, based on a longitudinal population survey, aimed to understand the dynamic of GAS emm types and to give leads to better recognition of underlying mechanisms for the emergence of successful clones. From 2009 to 2017, we conducted a systematic culture-based diagnosis of GAS infections in a French Brittany population with a prospective recovery of clinical data. The epidemiological analysis was performed using emm typing combined with the structural and functional cluster-typing system for all the recovered strains. Risk factors for the invasiveness, identified by univariate analysis, were computed in a multiple logistic regression analysis, and the only independent risk factor remaining in the model was the age (OR for the entire range [CI_95%] = 6.35 [3.63, 11.10]; p<0.0001). Among the 61 different emm types identified, the most prevalent were emm28 (16%), emm89 (15%), emm1 (14%), and emm4 (8%), which accounted for more than 50% of circulating strains. During the study period, five genotypes identified as emm44, 66, 75, 83, 87 emerged successively and belonged to clusters D4, E2, E3, and E6 that were different from those gathering “Prevalent” emm types (clusters A-C3 to 5, E1 and E4). We previously reported significant genetic modifications for emm44, 66, 83 and 75 types resulting possibly from a short adaptive evolution. Herein we additionally observed that the emergence of a new genotype could occur in a susceptible population having specific risk factors or probably lacking a naturally-acquired cluster-specific immune cross-protection. Among emergent emm types, emm75 and emm87 tend to become prevalent with a stable annual incidence and the risk of a clonal expansion have to be considered.

Necrotizing myositis case report and brief literature study

Necrotizing myositis is an extremely rare soft tissue infection, mainly caused by Group A Streptococci. Although its presentation is nonspecific and seems harmless, it quickly leads to death in almost all cases. Therefore, diagnosis and treatment of necrotizing myositis are considered as medical emergencies. The 27 years old patient we report benefited from early diagnosis and care. Necrotic tissues were surgically removed 24 hours after the appearance of the first clinical signs. Intravenous antibiotherapy as well as immunoglobulin therapy were also given on the first day. Starting from this clinical case, we present a brief explanation of the pathogenesis, the key clinical features and appropriate tools for diagnosis. Then, adequate antibiotherapy, role of immunoglobulin therapy and interest of hyperbaric oxygenotherapy will be discussed.

Severe community-acquired pneumonia due to Streptococcus pyogenes in the Newcastle area

Background

An apparent increase in the incidence of severe community-acquired pneumonia (CAP) caused by Streptococcus pyogenes (group A Streptococcus - GAS) was observed during 2017 in the Newcastle area. The study was undertaken to establish whether there was a true increase in severe S. pyogenes pneumonia and to explore its epidemiology and clinical features.

Methods

The study was a retrospective descriptive study of S. pyogenes pneumonia set in two tertiary referral hospitals in Newcastle, a large regional city, during the period 2007 to 2018. Subjects were adults identified as having S. pyogenes pneumonia by searching a database of severe CAP (defined as requiring intensive care unit [ICU] admission) for the period 2007-2018. Laboratory records were also searched for sterile site isolates of S. pyogenes to identify patients not requiring ICU admission.

Results

There were 13 cases of S. pyogenes CAP identified during the study period, of whom 12 (92%) required ICU admission. S. pyogenes accounted for 12/728 (1.6%) cases of severe CAP during the study period. The severity of S. pyogenes pneumonia was high despite a mean patient age of 48 years and 7/13 (54%) having no significant past medical history. The mortality rate was 2/13 (15%). Viral co-infection was found in 6/12 (50%) of patients tested. Overall 7/12 (58%) of the patients with severe S. pyogenes CAP during the study period presented in the winter or spring of 2017.

Conclusions

Streptococcus pyogenes is a rare cause of severe CAP in the Newcastle area, but there was a marked increase in frequency observed during the 2017 influenza season. Further study of the epidemiology of invasive GAS (iGAS) disease in Newcastle is warranted to identify emerging trends in this severe infection.

Clinically Important Toxins in Bacterial Infection: Utility of Laboratory Detection

The elaboration of proteins that damage host cells is fundamental to the pathogenesis of many bacterial pathogens. The clinical significance of many bacterial toxins is well recognized, and routine detection is necessary to confirm definitive diagnosis for some types of infectious diseases. Determining the clinical significance of a toxin involves many factors, including the toxin's prevalence, virulence, and role in disease pathogenesis. While essential from a diagnostic perspective, toxin detection has the potential to be important for patient management decision making, as well as infection prevention and control measures. This review focuses on the history, epidemiology, pathogenesis, clinical presentation, and management of infections associated with well-defined, clinically important toxins (such as Shiga toxin-producing Escherichia coli), as well as those that are less well defined (such as Staphylococcus aureus' Panton-Valentine leukocidin) where detection may yield clinically important information.

An anti-perfringolysin O monoclonal antibody cross-reactive with streptolysin O protects against streptococcal toxic shock syndrome

Objective

Streptococcus pyogenes (Group A Streptococcus; GAS) causes a variety of infections that include life-threatening, severe invasive GAS infections, such as streptococcal toxic shock syndrome (STSS), with > 30% mortality rate, despite effective antibiotics and treatment options. STSS clinical isolates highly express streptolysin O (SLO), a member of a large family of pore-forming toxins called cholesterol-dependent cytolysins (CDCs). SLO is an important toxic factor for GAS and may be an effective therapeutic target for the treatment of STSS. Our aim was to identify a monoclonal antibody (mAb) that reacts with SLO and has therapeutic potential for STSS treatment.

Results

We focused on mAbs that had originally been established as neutralizing reagents to perfringolysin O (PFO), another member of the CDC family, as some cross-reactivity with SLO had been reported. Here, we confirmed cross-reactivity of an anti-PFO mAb named HS1 with SLO. In vitro analysis revealed that HS1 mAb sufficiently prevented human neutrophils from being killed by STSS clinical isolates. Furthermore, prophylactic and therapeutic injection of HS1 mAb into C57BL/6 mice significantly improved the survival rate following lethal infection with an STSS clinical isolate. These results highlight the therapeutic potential of HS1 mAb for STSS treatment.

Incidence and Outcomes of Staphylococcus aureus Bacteriuria: A Population-based Study

BACKGROUND

Staphylococcus aureus bacteriuria (SABU) may represent multiple processes ranging from asymptomatic colonization to a marker of S. aureus bacteremia (SAB). Our objective was to describe SABU at a population-based level and determine patient characteristics associated with SAB.

METHODS

A retrospective study was performed using electronic databases. All urine cultures positive for S. aureus between 2010 and 2013 within the Calgary Health Zone were included. Patient characteristics were compared among patients with and without SAB and risk factors identified using multiple logistic regression modeling.

RESULTS

A total of 2540 urine cultures positive for S. aureus from 2054 patients were analyzed. The incidence of SABU was greatest among geriatric males with multiple comorbidities. SAB occurred in 175 (6.9%) of SABU patients. Those with SAB were more likely to be hospitalized, male, have a recent urinary procedure, have pure S. aureus culture in urine, and have laboratory findings suggesting systemic infection. Patients with isolated SABU were more likely to be ≥65 years, have dementia, and have abnormal urinalyses with pyuria and urine nitrites. In-hospital mortality in patients with SABU and SABU+SAB was 9.2% and 17.5%, respectively. Patients with SABU detected ≥48 hours before SAB had the highest risk of death.

CONCLUSIONS

Less than 7% of patients with SABU have or will develop SAB. Characteristics associated with SABU were identified that established higher risk for systemic infection. Investigating SABU patients with these characteristics for systemic infection is warranted because a delay in diagnosis is associated with increased mortality.

Sequential Sensing by TLR2 and Mincle Directs Immature Myeloid Cells to Protect against Invasive Group A Streptococcal Infection in Mice

Severe invasive group A Streptococcus (GAS) infection evades anti-bacterial immunity by attenuating the cellular components of innate immune responses. However, this loss of protection is compensated for by interferon (IFN)-γ-producing immature myeloid cells (γIMCs), which are selectively recruited upon severe invasive GAS infection in mice. Here, we demonstrate that γIMCs provide this IFN-γ-mediated protection by sequentially sensing GAS through two distinct pattern recognition receptors. In a mouse model, GAS is initially recognized by Toll-like receptor 2 (TLR2), which promptly induces interleukin (IL)-6 production in γIMCs. γIMC-derived IL-6 promotes the upregulation of a recently identified GAS-sensing receptor, macrophage-inducible C-type lectin (Mincle), in an autocrine or paracrine manner. Notably, blockade of γIMC-derived IL-6 abrogates Mincle expression, downstream IFN-γ production, and γIMC-mediated protection against severe invasive GAS infection. Thus, γIMCs regulate host protective immunity against severe invasive GAS infection via a TLR2-IL-6-Mincle axis.

[Bibliometric analysis of the scientific evidence on violence perpetrated against the elderly]

The scope of this study is violence perpetrated against the elderly. It aims to analyze the international scientific production on violence against the elderly. It involved bibliometric research carried out in the ISI Web of Knowledge/Web of ScienceTM database, in which the search terms "elder,"violence" or "abuse" and "health care" were used, in the period between the years 1991 and 2016. The data were analyzed considering the evolution of the annual publications, the journals with the highest number of records, the authors with the highest number of publications, the number of articles distributed by authors' country of origin, and articles with the highest impact. A total of 267 published records in 174 different journals indexed to the database in question were identified and were written by 901 authors with links to 410 institutions located in 39 countries. In the descriptive analysis of the content of the top journals on the topic and of the most cited articles there was potential for the development of the topic, since there is a need for more data on interventions in cases of violence against the elderly, with a multidisciplinary approach, as well as conducting more research on clinical manifestations, quality of life and its economic impact on the use of health services.

Clinical Features of Group A Streptococcus in Children With Pharyngitis: Carriers versus Acute Infection

BACKGROUND

Among children with pharyngitis who test positive for group A Streptococcus (GAS), 10%-25% are GAS carriers. Current laboratory methods cannot distinguish acute infection from colonization.

METHODS

We examined 2 separate longitudinal studies of children with symptomatic pharyngitis associated with a positive GAS throat culture (illness culture). In cohort 1, children presented with pharyngitis symptoms to a clinician, then had follow-up cultures at regular intervals. In cohort 2, throat cultures were performed at regular intervals and with pharyngitis symptoms. Illness cultures were categorized as acute infection or carrier based on follow-up culture results. In cohort 2, carriers were further categorized as a GAS carrier with a new emm-type or a GAS carrier with a previous emm-type based on typing data from prior culture results. For each cohort, symptoms were compared at the time of illness culture between carriers and those with acute infection.

RESULTS

Cohort 1 (N = 75 illness cultures): 87% of the children were classified as acutely infected versus 13% carriers. Carriers were more likely to have upper respiratory (URI) symptoms [odds ratio (OR): 5.5; 95% confidence interval (CI): 1.4-22.1], headache (OR: 6.0; 95% CI: 1.2-40.5) or vomiting (OR: 5.5; 95% CI: 1.2-24.5). Cohort 2 (N = 122 illness cultures): 79% were acutely infected and 21% were carriers. Children determined to be carriers with a previous detected emm-type were more likely to have URI symptoms compared with those with acquisition of a new emm-type.

CONCLUSIONS

Children with symptomatic pharyngitis and GAS on throat culture identified as carriers were more likely to present with URI and atypical symptoms than children who were acutely infected.

Spontaneous Streptococcus pyogenes pelvic inflammatory disease; Case report and review of the literature

Streptococcus pyogenes gynecological infections generally occur in association with childbirth, intra-uterine devices, and other invasive gynecologic procedures, but rarely cause spontaneous pelvic inflammatory disease. We describe a case of a healthy young woman with spontaneous S. pyogenes pelvic inflammatory disease, bacteremia, and shock, and summarize an additional 13 cases found in the literature. The majority were bacteremic and a significant number were also hypotensive. The same proportion had presenting gastrointestinal symptoms as had genitourinary symptoms, masking the diagnosis in many. Many prior case reports postulate a connection with S. pyogenes pharyngitis in a close contact, and an oro-genital route of transmission has been proposed given the exceedingly low rates of genital colonization with S. pyogenes. A high index of suspicion is needed for an accurate and timely diagnosis of this rare but potentially fatal condition.

Integrated Univariate, Multivariate, and Correlation-Based Network Analyses Reveal Metabolite-Specific Effects on Bacterial Growth and Biofilm Formation in Necrotizing Soft Tissue Infections

Necrotizing soft-tissue infections (NSTIs) have multiple causes, risk factors, anatomical locations, and pathogenic mechanisms. In patients with NSTI, circulating metabolites may serve as a substrate having impact on bacterial adaptation at the site of infection. Metabolic signatures associated with NSTI may reveal the potential to be useful as diagnostic and prognostic markers and novel targets for therapy. This study used untargeted metabolomics analyses of plasma from NSTI patients (n = 34) and healthy (noninfected) controls (n = 24) to identify the metabolic signatures and connectivity patterns among metabolites associated with NSTI. Metabolite-metabolite association networks were employed to compare the metabolic profiles of NSTI patients and noninfected surgical controls. Out of 97 metabolites detected, the abundance of 33 was significantly altered in NSTI patients. Analysis of metabolite-metabolite association networks showed a more densely connected network: specifically, 20 metabolites differentially connected between NSTI and controls. A selected set of significantly altered metabolites was tested in vitro to investigate potential influence on NSTI group A streptococcal strain growth and biofilm formation. Using chemically defined media supplemented with the selected metabolites, ornithine, ribose, urea, and glucuronic acid, revealed metabolite-specific effects on both bacterial growth and biofilm formation. This study identifies for the first time an NSTI-specific metabolic signature with implications for optimized diagnostics and therapies.

Beta-Hemolytic Streptococci and Necrotizing Soft Tissue Infections

β-hemolytic streptococci are major causes of necrotizing soft tissue infections (NSTIs), Streptococcus pyogenes (group A streptococcus; GAS) in particular. NSTIs caused by Streptococcus dysgalactiae (SD) have also been reported. In the INFECT cohort of 409 NSTIs patients, more than a third of the cases were caused by GAS (31%) or SD (7%). Risk factors of streptococcal NSTIs compared to streptococcal cellulitis have previously been largely unknown. The INFECT study confirmed blunt trauma as an important risk factor. In addition, absence of pre-existing skin lesions and a lower BMI were associated with NSTIs. The study also confirmed that septic shock is more frequent in GAS cases than in other types of NSTIs. Septic shock was also among several predictors of mortality. The role of intravenous immunoglobulin (IVIG) in streptococcal NSTIs has been unclear. In the INFECT cohort, IVIG treatment was associated with increased survival. As in other studies, a significant microbial diversity was observed, but with predominance of a few emm types. Overall, the INFECT study gives a comprehensive and contemporary picture of the clinical characteristics and the microbes involved in streptococcal NSTIs. The reported severity of disease underscores the need for new efforts aimed at identifying novel diagnostic measures and improved treatment.

[Invasive Streptococcus pyogenes infections (2011-2018): EMM-type and clinical presentation]

INTRODUCTION

Streptococcus pyogenes (S. pyogenes) is an important human pathogen that is responsible for a broad range of infections, from uncomplicated to more severe and invasive diseases with high morbidity/mortality. The M protein (emm type) is a critical virulence factor. Several studies have shown an increased incidence of invasive S. pyogenes disease. This was associated with an increase in the prevalence of M1 and M3 types, well-recognised virulent M types. The aim of the present study was to confirm the resurgence of invasive S. pyogenes disease during 2011-2018 and to identify the relationship between specific M types with disease presentation.

MATERIAL AND METHODS

Isolates were confirmed using standard techniques: colony morphology, β-haemolysis, biochemical tests, and agglutination with specific antisera (DiaMondiaL Strep Kit, DiaMondiaL, Langenhagen, Germany). The antibiotic sensitivity was performed using microdilution (Vitek®2 Compact, bioMeriéux, Inc., Durham, NC). Molecular analysis included the determination of the emm gene and superantigen profile.

RESULTS

A total of 29 invasive isolates were collected (2011-2018) from blood (16), pleural fluid (9), synovial fluid (3), and cerebrospinal fluid (1). One strain per year was isolated between 2011 and 2013, with 2, 5, 4, 6, and 9 strains being isolated between 2014 and 2018, respectively. The most frequent clinical presentations were bacteraemia and pneumonia (10 and 9 cases). The predominant types were M1 (11 isolates) and M3 (3 isolates). A correlation was found between M1 and M3 types, and pneumonia (6/7 cases) and deep soft tissue infections (3/3 cases).

CONCLUSIONS

An increased incidence of invasive S. pyogenes disease was observed during the study period, with M1 and M3 types being those most commonly isolated and associated with pneumonia and deep soft tissue infections.

Population-based risk factors for community-onset bloodstream infections

Although a number of comorbidities have been associated with development of bloodstream infection, actual risk factors have not been well defined and quantified in nonselected populations. We sought to quantify population-based risk factors for development of community-onset bloodstream infection (COBSI). Surveillance was conducted among all residents of the Western Interior of British Columbia, Canada, during 2011-2018. Risks were expressed as incidence rate ratios (IRR) with 95% confidence intervals (CI). The annual incidence was 147.1 per 100,000 and older individuals, and males were at overall higher risk. The median Charlson score was 2 (IQR, 0-3), and this was higher among those with healthcare-associated (2; IQR, 1-4) as compared to community-associated (1; IQR, 0-2; P < 0.0001) COBSI. Risk factors for development of COBSI included (IRR; 95% CI): HIV infection (8.89; 5.17-14.27), cancer (6.80; 6.13-7.54), congestive heart failure (4.68; 4.00-5.46), dementia (3.31; 2.82-3.87), diabetes mellitus (3.10; 2.80-3.42), cerebrovascular accident (2.79; 2.34-3.31), renal dysfunction (2.75; 2.33-3.22), chronic lung disease (2.03; 1.79-2.28), peripheral vascular disease (1.68; 1.39-2.01), and rheumatic disease (1.44; 1.14-1.79). Patients with multiple comorbid illnesses were older, more likely to be male, and have healthcare-associated BSI, higher rates of antimicrobial resistance, and different clinical foci of infection. A number of demographic and comorbid conditions significantly increase the risk for development of COBSI.