Clindamycin resistance in Group A streptococcal infections: A single-centre retrospective cohort study of 186 patients

Invasive group A streptococcus infections in the intensive care unit: an unsupervised cluster analysis of a multicentric retrospective cohort

BACKGROUND

Invasive group A streptococcus (iGAS) infection incidence is rising. These infections have been studied as a whole but can be associated with critical illness in a population with a wide array of underlying conditions, sites of infection and clinical presentations. Using an unsupervised clustering approach, we aimed to identify specific clinical phenotypes regarding presentation, management and outcome.

METHODS

This was a retrospective multicentric study including all patients admitted to one of 9 ICUs of Paris University Hospitals for an iGAS infection between 01/03/2018 and 01/08/2023. iGAS infection was defined as GAS growth in any microbiological sample from a sterile site. Patients were grouped according to a clustering algorithm (k-prototypes) using a comprehensive set of clinical and biological variables available upon ICU admission. Clusters were described and clinical presentation, management and outcome were compared.

RESULTS

148 patients were included. According to the Silhouette criterion, patients were grouped in 3 clusters, and 7 patients remained unclassified. Cluster 1 (n = 73) comprised a greater proportion of less severely-ill female patients with painful skin and soft tissue infections, a quarter of whom had taken non-steroidal anti-inflammatory drugs. Cluster 2 (n = 42) was characterized by a high rate of respiratory infections with frequent viral co-infections. Cluster 3 (n = 26) included mostly socially deprived patients with high rates of chronic alcohol consumption and psychiatric illness, with severe organ dysfunction related to otherwise pauci-symptomatic skin and soft tissue infections. There was no significant difference in time to source control across clusters (0 [0-0] vs 0 [0-0] vs 0 [0-1] days, p = 0.12). Patients included in cluster 2 less frequently received antitoxin antibiotics than patients from clusters 1 and 3 (79% vs 45% vs 69%, p < 0.001) and tended to more frequently require ECMO support (3% vs 12% vs 0%, p = 0.07), while those from cluster 1 were less likely to receive invasive mechanical ventilation (48% vs 74% vs 77%, p = 0.005). There was no difference in ICU-mortality between clusters (19% vs 29% vs 31%, p = 0.32).

CONCLUSIONS

Based on simple and readily available clinical admission characteristics of critically ill patients with iGAS, unsupervised clustering analysis identified three specific patient populations that differed regarding ICU management. Whether tailoring management would affect outcome warrants further research.

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.

Severe skin infections

PURPOSE OF REVIEW

The incidence of necrotizing soft-tissue infections (NSTI) has increased during recent decades. These infections are still associated with high morbidity and mortality, underlining a need for continued education of the medical community. This review will focus on practical approaches to management of NSTI focusing on antibiotic therapies and optimizing the management of group A streptococcus (GAS)-associated NSTIs.

RECENT FINDINGS

Antibiotic therapy for NSTI patients faces several challenges as the rapid progression of NSTIs mandates broad-spectrum agents with bactericidal action. Current recommendations support using clindamycin in combination with penicillin in case of GAS-documented NSTIs. Linezolide could be an alternative in case of clindamycin resistance.

SUMMARY

Reducing the time to diagnosis and first surgical debridement, initiating early broad-spectrum antibiotics and early referral to specialized centres are the key modifiable factors that may impact the prognosis of NSTIs. Causative organisms vary widely according to the topography of the infection, underlying conditions, and geographic location. Approximately one third of NSTIs are monomicrobial, involving mainly GAS or Staphylococcus aureus . Data for antibiotic treatment specifically for necrotizing soft-tissue infections are scarce, with guidelines mainly based on expert consensus.