Community-acquired disseminated methicillin-resistantStaphylococcus aureusinfection: case report and clinical implications

The development of thymol-isatin hybrids as broad-spectrum antibacterial agents with potent anti-MRSA activity

Bacterial resistance toward available therapeutic agents has become a nightmare for the healthcare system, causing significant mortality as well as prolonged hospitalization, thereby needing the urgent attention of research groups working on antimicrobial drug development worldwide. Molecular hybridization is a well-established tool for developing multifunctional compounds to tackle drug resistance. Inspired by the antibacterial profiles of isatin and thymol, along with the efficiency of a triazole linker in molecular hybridization, herein, we report the design, synthesis and antibacterial activity of a novel series of triazole tethered thymol-isatin hybrids. Most of the hybrids exhibited a broad-spectrum antibacterial efficacy against standard human pathogenic as well as clinically isolated multidrug-resistant bacterial strains listed in the WHO's 'priority pathogen' list and also in the ESKAPE group. Among them, hybrid compound AS8 was the most effective against methicillin-resistant Staphylococcus aureus (MIC = 1.9 μM and MBC = 3.9 μM), exhibiting biofilm inhibitory potential. AS8 exhibited dehydrosqualene synthase (CrtM) inhibitory potential in MRSA and decreased the production of virulence factor staphyloxanthin, which is one of the key mechanisms of its anti-MRSA efficacy, which was further supported by molecular docking and simulation studies. Moreover, AS8 was found to be non-toxic and showed a potent in vivo antibacterial efficacy (90% survival at 10 mg kg-1) as well as a modulated immune response in the larva-based (Galleria mellonella) model of systemic infections. Overall findings confirmed that AS8 can be a promising candidate or take the lead in the treatment and further drug development against drug-resistant infectious diseases, especially against MRSA infections.

Carvacrol Targets SarA and CrtM of Methicillin-Resistant Staphylococcus aureus to Mitigate Biofilm Formation and Staphyloxanthin Synthesis: An In Vitro and In Vivo Approach

Carvacrol is an essential oil traditionally used in culinary processes as spice due to its aromatic nature and also known for various biological activities. In the present study, the antivirulence efficacy of carvacrol against methicillin-resistant Staphylococcus aureus (MRSA) is explored. MRSA is an opportunistic pathogen capable of causing various superficial and systemic infections in humans. Biofilm formation and virulence factors of MRSA are responsible for its pathogenesis and resistance. Hence, the aim of this study was to explore the antibiofilm and antivirulence efficacy of carvacrol against MRSA. Carvacrol at 75 μg/mL inhibited MRSA biofilm by 93%, and it also decreased the biofilm formation on polystyrene and glass surfaces. Further, microscopic analyses revealed the reduction in microcolony formation and collapsed structure of biofilm upon carvacrol treatment. The growth curve analysis and the Alamar blue assay showed the nonfatal effect of carvacrol on MRSA. Further, carvacrol significantly reduced the production of MRSA biofilm-associated slime and extracellular polysaccharide. In addition, carvacrol strongly inhibited the antioxidant pigment staphyloxanthin and its intermediates' synthesis in MRSA. Inhibition of biofilm and staphyloxanthin by carvacrol enhanced the susceptibility of MRSA to oxidants and healthy human blood. Quantitative polymerase chain reaction (qPCR) analysis unveiled the downregulation of sarA-mediated biofilm gene expression and staphyloxanthin-associated crtM gene expression. The sarA-dependent antibiofilm potential of carvacrol was validated using S. aureus Newman wild-type and isogenic ΔsarA strains. In silico molecular docking analysis showed the high binding efficacy of carvacrol with staphylococcal accessory regulator A (SarA) and 4,4'-diapophytoene synthase (CrtM) when compared to positive controls. Furthermore, the in vivo efficacy of carvacrol against MRSA infection was demonstrated using the model organism Galleria mellonella. The results revealed the nontoxic nature of carvacrol to the larvae and the rescuing potential of carvacrol against MRSA infection. Finally, the current study reveals the potential of carvacrol in inhibiting the biofilm formation and staphyloxanthin synthesis of MRSA by targeting the global regulator SarA and a novel antivirulence target CrtM.

Community-Acquired MRSA Pericarditis and Mediastinitis in a Previously Healthy Infant

Invasive community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) infections disproportionately affect children, but there are few pediatric reports of pericarditis and mediastinitis caused by CA-MRSA in previously healthy children. Here we report a severe case of CA-MRSA pericarditis with extension to the mediastinum and carotid sheath in a previously healthy 8-month-old infant who was successfully treated with surgical interventions and with a combination of daptomycin and vancomycin. The relatively indolent clinical course in this patient was notable given the significant extent of infection. This case highlights the potential virulence of CA-MRSA in previously healthy children and the importance of early diagnosis, prompt drainage, and appropriate antibiotic coverage.

Disseminated Staphylococcus aureus infection following spinal anesthesia: a case report

We here presented a 65-year-old woman with disseminated Staphylococcus aureus infection following spinal anesthesia. The patient underwent spinal anesthesia for great saphenous vein stripping. Twenty days after the procedure, the patient developed hydrocephalus, pulmonary infection, and epidural abscess. Microbiological culture of the pus showed infection by S aureus. Appropriate antibiotic therapy and prompt surgical abscess drainage were associated with good outcome. Hydrocephalus is thought to be associated with arachnoiditis caused by S aureus infection, which provides new insights into the pathophysiology of arachnoiditis. Here we reported a case of disseminated S aureus infection following spinal anesthesia, implicating that appropriate interventions should not be delayed for waiting for the microbiological results.

Emergency department diagnosis of a quadriceps intramuscular loculated abscess/pyomyositis using dynamic compression bedside ultrasonography

Introduction

A 73-year-old man with a past medical history of myelodysplastic syndrome and recent chemotherapy presented to the emergency department with a 1-week history of progressively increasing left thigh pain and swelling. His physical examination revealed left anterolateral diffuse thigh swelling with no erythema or warmth to palpation. The anterolateral quadriceps was markedly tender to palpation. Emergency department bedside dynamic compression ultrasonography that was performed on the left anterolateral thigh revealed a quadriceps intramuscular abscess with loculated yet movable pus.

Conclusion

Bedside dynamic compression ultrasonography can assist the emergency or critical care physician in the diagnosis of quadriceps intramuscular abscess or pyomyositis.

Panton-Valentine leukocidin in the pathogenesis of community-associated methicillin-resistant Staphylococcus aureus infection

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that causes serious infectious diseases and was endemic in hospitals by the late 1960s. Beginning with its first report in the late 1990s, the rapid emergence of community-associated MRSA (CA-MRSA) worldwide responsible for a wide spectrum of diseases ranging from minor skin infections to fatal necrotizing pneumonia has been found in previously healthy individuals without established risk factors for MRSA acquisition. Recently, various virulence determinants unique to CA-MRSA have been uncovered, which explain how the pathogen spreads easily and causes severe CA-MRSA infections among humans. However, the role of Panton-Valentine leukocidin (PVL) in the pathogenesis of CA-MRSA infection is currently a matter of much debate because of conflicting data from epidemiologic studies of CA-MRSA infections and various murine disease models. Identifying specialized pathogenic traits of CA-MRSA and the concerted regulation of these factors remains a challenge that will foster development of vaccines and therapies designed to control CA-MRSA infections. This review focuses on the current status of molecular epidemiology associated with CA-MRSA in Taiwan and progresses toward understanding the enhanced virulence properties of CA-MRSA, with an emphasis on the role of Panton-Valentine leukocidin.

Community acquired methicillin-resistant Staphylococcus aureus preseptal cellulitis complicated by zygomatic osteomylitis, cavernous sinus thrombosis and meningitis in a healthy child

We report a case of community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) preseptal cellulitis complicated by zygomatic osteomyelitis, cavernous sinus thrombosis, meningitis, and necroziting pneumonia in a previously healthy two and half month old girl. This case exemplifies an aggressive and disseminated CA-MRSA infection with deep venous thrombosis in an infant without predisposing risk factors. The literature is reviewed and recommendations for management are provided.

Community-associated methicillin-resistant Staphylococcus aureus: epidemiology and clinical consequences of an emerging epidemic

Staphylococcus aureus is an important cause of skin and soft-tissue infections (SSTIs), endovascular infections, pneumonia, septic arthritis, endocarditis, osteomyelitis, foreign-body infections, and sepsis. Methicillin-resistant S. aureus (MRSA) isolates were once confined largely to hospitals, other health care environments, and patients frequenting these facilities. Since the mid-1990s, however, there has been an explosion in the number of MRSA infections reported in populations lacking risk factors for exposure to the health care system. This increase in the incidence of MRSA infection has been associated with the recognition of new MRSA clones known as community-associated MRSA (CA-MRSA). CA-MRSA strains differ from the older, health care-associated MRSA strains; they infect a different group of patients, they cause different clinical syndromes, they differ in antimicrobial susceptibility patterns, they spread rapidly among healthy people in the community, and they frequently cause infections in health care environments as well. This review details what is known about the epidemiology of CA-MRSA strains and the clinical spectrum of infectious syndromes associated with them that ranges from a commensal state to severe, overwhelming infection. It also addresses the therapy of these infections and strategies for their prevention.

Life-threatening infection due to community-acquired methicillin-resistant Staphylococcus aureus: case report and review

We report an unusual case of serious, multifocal, invasive infection due to community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in a 10-year-old girl with favorable outcome. The child manifested femoral osteomyelitis, pyomyositis, deep femoral vein thrombosis, pneumonia, encephalopathy, and disturbances of almost all organs. She remained in a critical condition for a week. Fever persisted for 6 weeks and acute phase reactants remained increased for 6 months, necessitating a 7-month antistaphylococcal therapy with a glycopeptide and clindamycin. This led to resolution of infection-associated problems during the subsequent 36 months of follow-up. CA-MRSA strain isolated from the patient harbored both staphylococcal chromosomal cassette type IV (SCCmec type IV) and Panton-Valentine leukocidin genes. A literature review of serious CA-MRSA infections indicated that only a small minority of published cases had favorable outcome.

Central nervous system invasion by community-acquired meticillin-resistant Staphylococcus aureus

We report a case of community-acquired meticillin-resistant Staphylococcus aureus (CA-MRSA) bacteraemia with cavernous sinus thrombosis, meningitis and brain abscess in a previously healthy American, who was employed in Belgium. We consecutively reviewed all published cases of CA-MRSA with central nervous system (CNS) involvement. A total of 12 similar cases were found, of which 11 were published in the last 4 years. Predominantly, young previously healthy subjects were affected (median age 28 years). The cases involved brain abscesses (5/12), disseminated disease (4/12), cavernous sinus thrombosis (2/12) and other (1/12). Infection origins were superficial skin infections (5/12), mostly of the face, sinusitis (1/12), otitis media (1/12), other or unknown (5/12). Although, in our review of the literature patients treated with linezolid had a better outcome compared to patients treated with vancomycin, the latter is still the mainstay of therapy for CNS infections associated with MRSA.