High frequency of methicillin-susceptible and methicillin-resistant Staphylococcus aureus in children under 1 year old with skin and soft tissue infections

Etiology, clinical features, management, and outcomes of skin and soft tissue infections in hospitalized children: A 10-year review

PURPOSE

This study aimed to describe the etiology, clinical features, hospital course, and outcomes of hospitalized children with skin and soft tissue infections (SSTIs) and to test if clinical and laboratory variables at admission could differentiate between community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) and community-acquired methicillin-sensitive S. aureus (CA-MSSA).

METHODS

We reviewed the clinical, laboratory, treatment, and outcome data for children hospitalized with SSTIs, aged 0-18 years at MacKay Children's Hospital between 2010 and 2019. Multivariable logistic regression was used to identify independent predictors of CA-MRSA and CA-MSSA SSTIs.

RESULTS

A total of 1631 patients were enrolled. Erysipelas/cellulitis (73.8%) was the most common pediatric SSTI type, followed by acute lymphadenitis (13.6%) and abscess/furuncle/carbuncle (8.6%). Among the 639 culture-positive isolates (purulent SSTIs), 142 (22.2%) were CA-MSSA and 363 (56.8%) were CA-MRSA. The age group 0-1 month (OR, 6.52; 95% CI 1.09-38.92; P = 0.04) and local lymph node reaction (OR, 2.47; 95% CI 1.004-6.08; P = 0.049) were independent factors for differentiating children with CA-MSSA from those with CA-MRSA SSTIs. MRSA isolates in our cohort were highly susceptible to glycopeptides (100%), linezolid (100%), daptomycin (100%), and sulfamethoxazole/trimethoprim (98.6%) but were significantly less susceptible to clindamycin compared with MSSA (34.2% vs. 78.2%, P < 0.001).

CONCLUSION

S. aureus is the leading pathogen of culture-proven SSTIs in hospitalized children with MRSA accounting for more than half. Determining the optimal empirical antibiotics in CA-SSTIs may rely on the patient's age, disease severity, and local epidemiologic data.

Clonal Distribution and Antibiotic Susceptibility of Staphylococcus aureus from Pediatric Patients: 8-Year Trends in a Children's Hospital in Colombia

Emergence of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strains in healthcare settings has changed the hospital epidemiology of MRSA in the last few years. Despite a global increase in MRSA frequency, infections caused by methicillin-susceptible S. aureus (MSSA) have persisted in healthcare settings and the community. Staphylococcus aureus isolates were collected between 2009 and 2017 at the Children's Hospital of a Caribbean city in South America. Methicillin-resistant isolates were subjected to SCCmec typing. Representative isolates were analyzed by multilocus sequence typing (MLST) and spa typing. Antibiotic susceptibility was assessed by agar dilution method. D-zone test was performed in erythromycin-resistant isolates to determine macrolide/lincosamide/streptogramin resistance. Spa typing revealed 10 different spa types. The main epidemic clones circulating during the study period were: ST8-MRSA-IVc, ST923-MRSA-IVa and ST8-MRSA-IVa. The study found high frequencies of PVL genes and resistance to erythromycin and clindamycin in the isolates. This study provides the first description of the population structure of MRSA and MSSA causing infections attended in the participating Children's Hospital. ST8-MRSA-IVc, ST923-MRSA-IVa and ST8-MRSA-IVa were the most prevalent in the isolate population.

Phenotypic and Molecular Characteristics of Community-Associated Staphylococcus aureus Infection in Neonates

Background

Staphylococcus aureus is an important human pathogen causing a wide variety of diseases ranging from mild skin infections to life-threatening bacteremia. This study aimed to provide insight into the phenotype-genotype characteristics of S. aureus isolated from neonates.

Methods

A hospital-based retrospective study was conducted to recruit neonatal patients with community-associated S. aureus infection. All 92 S. aureus clinical isolates were tested for antimicrobial susceptibility, resistance genes, virulence genes, and multilocus sequence typing.

Results

A total of 92 S. aureus isolates were included in this study, including 29 (31.5%) MRSA isolates. Most S. aureus isolates were susceptible to gentamicin, and most methicillin-resistant S. aureus (MRSA) isolates were susceptible to vancomycin and linezolid. The predominant S. aureus genotypes were CC188 (ST188), CC59 (ST338), CC5 (ST5), CC88 (ST8), and CC6 (ST6), with CC59 (ST338) as the most prevalent MRSA. We observed a significantly corresponding relationship between clonal complexes and resistance patterns (such as CC45/CC59/CC121/CC630 associated with multidrug resistance) or the number of virulence genes (such as CC1/CC5/CC45/CC59/CC88 associated with harboring 5-7 virulence genes, and CC22/CC25/CC121 associated with carrying 8-13 genes). Moreover, both univariate and multivariate analyses indicated that invasive S. aureus isolates were significantly associated with resistance to several classes of antibiotics and carrying specific virulence factors.

Conclusion

Our findings provide insight into phenotype-genotype characteristics for S. aureus isolates so as to provide new ideas for differentiating potential genetic backgrounds and monitoring new epidemiologic trends.

Genetic analysis of methicillin‐susceptible Staphylococcus aureus clinical isolates: High prevalence of multidrug‐resistant ST239 with strong biofilm‐production ability

Background

The distributions of methicillin‐susceptible Staphylococcus aureus (MSSA) are divers geographically with different genetic backgrounds. Data related to molecular characteristics of MSSA compare to methicillin‐resistant Staphylococcus aureus (MRSA) is sparse.

Methods

In this cross‐sectional study, antimicrobial susceptibility testing, virulence genes analysis, biofilm formation, accessory gene regulator (agr) typing, and multilocus sequence typing (MLST) characterized on 75 MSSA isolates.

Results

Multidrug‐resistance MSSA was found to be 84%. Forty‐eight (64%) isolates were toxinogenic with 34 and 14 isolates carrying pvl and tst representing 45.3% and 18.7%. The most common SE genes were sed (20%), sec (16%), and sea (16%). Fifty‐five (73.3%) isolates were confirmed as biofilm producer with a markedly high prevalence of fnbA (93.3%), fnbB (86.7%), icaA (65.3%), icaD (53.3%), can (24%), ebp (10.7%), and bap (1.3%). A total of 3 agr types (I, 73.3%; III, 16%; II, 10.7%) and 4 clonal complexes (CCs) and sequence types (STs), namely CC8/ST293 (45.3%), CC/ST22 (28%), CC/ST30 (16%), and CC/ST5 (10.7%) were detected in this study. All the high and low‐level mupirocin resistance strains belonged to ST239 and ST22 strains, respectively. All the fusidic acid‐resistant isolates carried fusC and belonged to ST30.

Conclusions

These findings indicated that ST239 with strong biofilm production ability is the most common type in MSSA strains isolated from patients. It seems that the antimicrobial resistance profiles, toxin, and biofilm formation were closely associated with specific STs. Further studies are required to identify and control of these clonal lineages in our area.

Genotype distribution of methicillin-susceptible Staphylococcus aureus clinical isolates in Iran: high multiresistant clonal complex 8

Objective

Compared to methicillin-resistant Staphylococcus aureus (MRSA), there have been few studies focused on the molecular characterization of methicillin-susceptible Staphylococcus aureus (MSSA). In this cross-sectional study, 85 MSSA isolates were characterized by antimicrobial susceptibility testing, virulence genes analysis, accessory gene regulator (agr) typing, and S. aureus protein A locus (spa) typing.

Results

In present study, 9 different clonal complexes namely CC8-MSSA-t037 (22.4%), CC8-MSSA-t008 (11.8%), CC7-MSSA-t091 and CC30-MSSA-t021 (each 9.4%), CC8-MSSA-t037 (8.3%), CC398-MSSA-t034 (7.1%), CC22-MSSA-t005 (5.9%), CC5-MSSA-t002 and CC15-MSSA-t084 (each 4.7%), CC22-MSSA-t790 and CC59-MSSA-t437 (each 3.5%), CC22-MSSA-t1869, CC5-MSSA-t045, and CC45-MSSA-t015 (each 2.3%), CC30-MSSA-t318 and CC15-MSSA-t491 (each 1.2%) were found. agr types detected in tested strains were mainly type I (76.5%), II (12.9%), and III (10.6%). Of 85 MSSA examined isolates, 48 (56.5%) isolates were toxinogenic with 27 producing pvl (31.8%) and 21 tst (24.7%). The findings of the study show a high genetic diversity in MSSA strains warranting continued surveillance to provide critical insights into control and treatment of MSSA infections.

Acetylcysteine-decorated Prussian blue nanoparticles for strong photothermal sterilization and focal infection treatment

The major challenge in bacterial infection in clinical settings is the development of antimicrobial materials in the treatment of drug-resistant bacteria. Herein, we report a new strategy for efficient near-infrared radiation (NIR) photothermal sterilization and focal infection treatment by acetylcysteine-modified Prussian blue nanoparticles (AC-PB). Specifically, AC-PB is fabricated as a multifunctional therapeutic agent via a co-precipitation approach, where PB acts as an effective photothermal agent and AC could prevent the formation of bacteria cluster in biofilms and the bacterial adhesion on tissues to reduce the secretion of mucus and improve the efficacy. AC-PB shows strong synergistic photothermal sterilization ability in a concentration-dependent manner by using 980 nm NIR laser. 50 μg/mL of AC-PB can eliminate up to 74% of Gram-positive Staphylococcus aureus and up to 75% of Gram-negative Escherichia coli, while irradiation of 980 nm is minimally cytotoxic to mammalian cells. The NIR radiation can be efficiently converted into local heat by subcutaneous injection of AC-PB to kill bacteria effectively in vivo to treat a focal infection. The antibacterial mechanism suggests that AC can destroy bacteria-based biofilms, while the photothermal effect driven by NIR may break the lipids on cellular membrane. Thus, this work may provide a promising strategy for highly effective eradication of bacteria in clinics.