Multifocal community-acquired necrotizing fasciitis caused by a Panton-Valentine leukocidin-producing methicillin-sensitive Staphylococcus aureus

The Effect of Ascorbic Acid and Nicotinamide on Panton-Valentine Leukocidin Cytotoxicity: An Ex Vivo Study

Background: Panton−Valentine Leukocidin sustains a strong cytotoxic activity, targeting immune cells and, consequently, perforating the plasma membrane and inducing cell death. The present study is aimed to examine the individual effect of ascorbic acid and nicotinamide on PVL cytotoxicity ex vivo, as well as their effect on granulocytes viability when treated with PVL. Materials and Methods: The PVL cytotoxicity assay was performed in triplicates using the commercial Cytotoxicity Detection Kit PLUS (LDH). LDH release was measured to determine cell damage and cell viability was measured via flow cytometry. Results and discussion: A clear reduction in PVL cytotoxicity was demonstrated (p < 0.001). Treatment with ascorbic acid at 5 mg/mL has shown a 3-fold reduction in PVL cytotoxicity; likewise, nicotinamide illustrated a 4-fold reduction in PVL cytotoxicity. Moreover, granulocytes’ viability after PVL treatment was maintained when incubated with 5 mg/mL of ascorbic acid and nicotinamide. Conclusions: our findings illustrated that ascorbic acid and nicotinamide exhibit an inhibitory effect on PVL cytotoxicity and promote cell viability, as the cytotoxic effect of the toxin is postulated to be neutralized by antioxidant incubation. Further investigations are needed to assess whether these antioxidants may be viable options in PVL cytotoxicity attenuation in PVL-associated diseases.

Towards Understanding COVID-19: Molecular Insights, Co-infections, Associated Disorders, and Aging

BACKGROUND

COVID-19 can be related to any diseases caused by microbial infection(s) because 1) co-infection with COVID-19-related virus and other microorganism(s) and 2) because metabolites produced by microorganisms such as bacteria, fungi, and protozoan can be involved in necrotizing pneumonia and other necrotizing medical conditions observed in COVID-19.

OBJECTIVE

By way of illustration, the microbial metabolite of aromatic amino acid tryptophan, a biogenic amine tryptamine inducing neurodegeneration in cell and animal models, also induces necrosis.

METHODS

This report includes analysis of COVID-19 positivity by zip codes in Florida and relation of the positivity to population density, possible effect of ecological and social factors on spread of COVID-19, autopsy analysis of COVID-19 cases from around the world, serum metabolomics analysis, and evaluation of autoantigenome related to COVID-19.

RESULTS

In the present estimations, COVID-19 positivity percent per zip code population varied in Florida from 4.65% to 44.3% (February 2021 data). COVID-19 analysis is partially included in my book Microbial Metabolism and Disease (2021). The autoantigenome related to COVID-19 is characterized by alterations in protein biosynthesis proteins including aminoacyl-tRNA synthetases. Protein biosynthesis alteration is a feature of Alzheimer's disease. Serum metabolomics of COVID-19 positive patients show alteration in shikimate pathway metabolism, which is associated with the presence of Alzheimer's disease-associated human gut bacteria.

CONCLUSION

Such alterations in microbial metabolism and protein biosynthesis can lead to toxicity and neurodegeneration as described earlier in my book Protein Biosynthesis Interference in Disease (2020).

A systematic review of necrotising fasciitis in children from its first description in 1930 to 2018

BACKGROUND

Necrotising fasciitis is a rapidly progressing soft-tissue infection with a low incidence that carries a relevant risk of morbidity and mortality. Although necrotising fasciitis is often fatal in adults, its case fatality rate seems to be lower in children. A highly variable clinical presentation makes the diagnosis challenging, which often results in misdiagnosis and time-delay to therapy.

METHODS

We conducted a protocol-based systematic review to identify specific features of necrotising fasciitis in children aged one month to 17 years. We searched 'PubMed', 'Web of Science' and 'SCOPUS' for relevant literature. Primary outcomes were incidence and case fatality rates in population-based studies, and skin symptoms on presentation. We also assessed signs of systemic illness, causative organisms, predisposing factors, and reconstructive procedures as secondary outcomes.

RESULTS

We included five studies reporting incidence and case fatality rates, two case-control studies, and 298 cases from 195 reports. Incidence rates varied between 0.022 and 0.843 per 100,000 children per year with a case-fatality rate ranging from 0% to 14.3%. The most frequent skin symptoms were erythema (58.7%; 175/298) and swelling (48%; 143/298), whereas all other symptoms occurred in less than 50% of cases. The majority of cases had fever (76.7%; 188/245), but other signs of systemic illness were present in less than half of the cohort. Group-A streptococci accounted for 44.8% (132/298) followed by Gram-negative rods in 29.8% (88/295), while polymicrobial infections occurred in 17.3% (51/295). Extremities were affected in 45.6% (136/298), of which 73.5% (100/136) occurred in the lower extremities. Skin grafts were necessary in 51.6% (84/162) of the pooled cases, while flaps were seldom used (10.5%; 17/162). The vast majority of included reports originate from developed countries.

CONCLUSIONS

Clinical suspicion remains the key to diagnose necrotising fasciitis. A combination of swelling, pain, erythema, and a systemic inflammatory response syndrome might indicate necrotising fasciitis. Incidence and case-fatality rates in children are much smaller than in adults, although there seems to be a relevant risk of morbidity indicated by the high percentage of skin grafts. Systematic multi-institutional research efforts are necessary to improve early diagnosis on necrotising fasciits.

Necrotizing Soft Tissue Infections in the Vasculopathic Patient: Review of Literature

Background:

Necrotizing soft tissue infection is a surgical emergency associated with high mortality. Its presence in patients with risk factors for peripheral arterial disease such as diabetes mellitus is consistently associated with significantly poorer outcomes. Though it has been over a century since it was initially described in the literature, mortality rates remain high and treatment regimens are not standardized.

Materials and methods:

PubMed and Cochrane databases were searched for articles pertaining to necrotizing soft tissue infections. Articles were screened for relevance with the intent to compare outcomes in prospective studies of patients with diabetes mellitus or peripheral arterial disease. Patient demographics, clinical findings, mortality, rates of amputation, and morbidity were intended to be compared.

Results:

857 articles were identified, 165 duplicates were removed, and 6 prospective trials were identified for inclusion. Due to significant paucity of data, patient heterogeneity, and lack of standardization for surgical management, a descriptive review of the literature in relation to necrotizing soft tissue infections was pursued, with a focus on high-risk patients with peripheral arterial disease or diabetes mellitus.

Conclusions:

Early aggressive surgical intervention or major amputation may reduce mortality at the cost of increased disability and poorer quality of life in the long term, and may be appropriate in vasculopaths with poorly controlled diabetes and rapidly progressive fulminant infection. However, there is a deficiency in high-level evidence supporting surgical decision-making in this setting, with no standardized protocols for amputation. Future research will be needed to clarify the patient population who would benefit from radical amputation versus intention for limb salvage.

Serious life-threatening multifocal infection in a child, caused by Panton-Valentine leucocidin-producing Staphylococcus aureus (PVL-MSSA)

Groin pain is a frequently occurring complaint in presentations to the Emergency Department. Muscular sprain is often a differential diagnosis, however serious conditions such as pyomyositis should not be ignored. This case report presents a child with atraumatic right groin pain, which was initially diagnosed as a muscular sprain. The patient later re-presented out of hours to the Emergency Department with what was found to be extensive pelvic abscesses. He was subsequently found to have bilateral pneumonia and later developed a pericardial effusion and osteomyelitis of the right iliac bone, sacroiliac joint and sacrum. With multiple surgical interventions and appropriate antibiotics, he made a full recovery and was discharged home after a total admission time of 41 days. The causative organism was found to be Panton-Valentine leucocidin-positive methicillin-susceptible Staphylococcus aureus.

Treatment of Staphylococcus aureus Infections

Staphylococcus aureus, although generally identified as a commensal, is also a common cause of human bacterial infections, including of the skin and other soft tissues, bones, bloodstream, and respiratory tract. The history of S. aureus treatment is marked by the development of resistance to each new class of antistaphylococcal antimicrobial drugs, including the penicillins, sulfonamides, tetracyclines, glycopeptides, and others, complicating therapy. S. aureus isolates identified in the 1960s were sometimes resistant to methicillin, a ß-lactam antimicrobial active initially against a majority S. aureus strains. These MRSA isolates, resistant to nearly all ß-lactam antimicrobials, were first largely confined to the health care environment and the patients who attended it. However, in the mid-1990s, new strains, known as community-associated (CA-) MRSA strains, emerged. CA-MRSA organisms, compared with health care-associated (HA-) MRSA strain types, are more often susceptible to multiple classes of non ß-lactam antimicrobials. While infections caused by methicillin-susceptible S. aureus (MSSA) strains are usually treated with drugs in the ß-lactam class, such as cephalosporins, oxacillin or nafcillin, MRSA infections are treated with drugs in other antimicrobial classes. The glycopeptide drug vancomycin, and in some countries teicoplanin, is the most common drug used to treat severe MRSA infections. There are now other classes of antimicrobials available to treat staphylococcal infections, including several that have been approved after 2009. The antimicrobial management of invasive and noninvasive S. aureus infections in the ambulatory and in-patient settings is the topic of this review. Also discussed are common adverse effects of antistaphylococcal antimicrobial agents, advantages of one agent over another for specific clinical syndromes, and the use of adjunctive therapies such as surgery and intravenous immunoglobulin. We have detailed considerations in the therapy of noninvasive and invasive S. aureus infections. This is followed by sections on specific clinical infectious syndromes including skin and soft tissue infections, bacteremia, endocarditis and intravascular infections, pneumonia, osteomyelitis and vertebral discitis, epidural abscess, septic arthritis, pyomyositis, mastitis, necrotizing fasciitis, orbital infections, endophthalmitis, parotitis, staphylococcal toxinoses, urogenital infections, and central nervous system infections.

Synchronous multifocal necrotizing fasciitis prognostic factors: a retrospective case series study in a single center

Purpose

No reports have been published on synchronous multifocal necrotizing fasciitis (SMNF), a multifocal presence of necrotizing fasciitis in different extremities. We evaluated the clinical characteristics and outcomes of SMNF.

Methods

Eighteen patients (14 men, 4 women; mean age: 59 years) diagnosed with SMNF of the extremities between January 2004 to December 2012 were enrolled and evaluated.

Results

Vibrio species were the most commonly (78%; n = 14) isolated; others were two cases (11%) of Aeromonas spp., one case (6%) of group A β-hemolytic streptococcus, and one case of coagulase-negative staphylococcus. SMNF was in the bilateral lower limbs (72%; n = 13), bilateral upper limbs (17%; n = 3), and one patient with one upper and one lower limb (11%). Non-surviving patients had more bilateral lower limb involvement and thrombocytopenia.

Conclusions

Most patients with SMNF were male and had bilateral lower limb and marine Gram-negative bacteria involvement. The mortality of SMNF remained extremely high in patients with involvement of bilateral lower limb and initial thrombocytopenia.

[Staphylococcus aureus broncho-pulmonary infections]

Staphylococcus aureus accounts for 2-5% of the etiologies of community-acquired pneumonia. These infections occur mainly in elderly patients with comorbidity, after a respiratory viral infection. S. aureus could also be responsible for necrotizing pneumonia, which occurs in young subjects, also after flu. Necrotizing pneumonia are associated with the production of a particular staphylococcal toxin called Panton-Valentine leukocidin, responsible for pulmonary focal necrosis, occurrence haemoptysis, leucopenia, and death. In Europe, these strains are still predominantly sensitive to anti-staphylococcal penicillin, which must be used at high dosage intravenously in combination with an antibiotic that reduces toxin production such as clindamycin, and intravenous immunoglobulin in severe cases. The mortality rate is estimated at 50%. In addition, S. aureus is one of the pathogens involved in early respiratory infections in cystic fibrosis patients, in whom methicillin resistance plays an important prognostic role. However, the involvement of S. aureus in COPD exacerbations is rare. Finally, S. aureus represents 20 to 30% of cases of hospital-acquired pneumonia, including ventilator-associated pneumonia. In these cases, methicillin-resistance is common and requires the use of glycopeptides or linezolid. The place of new anti-staphylococcal antibiotics such as new generation cephalosporins or tigecyclin remains to be defined.

Molecular characterization and panton-valentine leucocidin typing of community-acquired methicillin-sensitive Staphylococcus aureus clinical isolates

Limited comprehensive molecular typing data exist currently for Panton-Valentine leucocidin (PVL)-positive, methicillin-sensitive Staphylococcus aureus (PVL-MSSA) clinical isolates. Characterization of PVL-MSSA isolates by multilocus sequence typing (MLST) and spa typing in this study showed a genetic similarity to PVL-positive, methicillin-resistant S. aureus (PVL-MRSA) strains, although three novel spa types and a novel MLST (ST1518) were detected. Furthermore, the detection of PVL phages and haplotypes in PVL-MSSA identical to those previously found in PVL-MRSA isolates highlights the role these strains may play as precursors of emerging lineages of clinical significance.

Simulated antibiotic exposures in an in vitro hollow-fiber infection model influence toxin gene expression and production in community-associated methicillin-resistant Staphylococcus aureus strain MW2

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain MW2 harbors a plethora of toxins to mediate its virulence. However, toxin expression and regulation with simulated clinical antimicrobial exposures are unclear. This study evaluated these relationships using an in vitro pharmacodynamic hollow-fiber infection model. Clinical doses of clindamycin, linezolid, minocycline, trimethoprim-sulfamethoxazole (SXT), and vancomycin were simulated over 72 h against MW2 in the hollow fiber model. Expression levels of lukSF-PV and enterotoxin genes sec4, sek, seq, and sel2 were quantified by real-time PCR. Panton-Valentine leukocidin (PVL) was quantified by enzyme-linked immunosorbent assay (ELISA), and cytotoxicity was determined on polymorphonuclear cells (PMNs). Vancomycin produced the maximum MW2 killing (2.53 log(10) CFU/ml) after the first dose, but the greatest sustained killing over 72 h occurred with linezolid and clindamycin. Vancomycin and minocycline induced gene upregulation from 0 to 8 h, followed by downregulation for the remaining simulation period. Clindamycin decreased gene expression in the first 24 h, followed by moderate increases (2.5-fold) thereafter. Linezolid increased gene expression 11.4- to 200.4-fold but inhibited PVL production (0.6 ± 0.3 versus 5.9 ± 0.2 μg/ml, linezolid versus control at 72 h; P < 0.05). Similar effects on PVL production occurred with clindamycin and minocycline. SXT increased PVL production at 48 h (2.8-fold) and 72 h (4.9-fold) of treatment (P < 0.05), resulting in increased PVL cytotoxicity on PMNs. Linezolid, clindamycin, and minocycline were the most effective agents on decreasing the virulence potential in CA-MRSA, notably after 8 h of treatment. SXT had minimal effects on toxin gene regulation, but it increased production and cytotoxicity of PVL toxin in the model and may enhance virulence when it is used to treat severe infections.

Multifocal necrotising fasciitis: an overlooked entity?

OBJECTIVE

The aim of the study is to report a case of multi-focal necrotising fasciitis, review research on this subject to identify common aetiological factors and highlight suggestions to improve management.

CONTEXT

Necrotising fasciitis is a severe, life-threatening soft tissue infection that typically arises from a single area, usually secondary to a minor penetrating injury. Multi-focal necrotising fasciitis, where there is more than one non-contiguous area of necrosis, is much less commonly reported. There are no guidelines specific to the management of multi-focal necrotising fasciitis, and its under-reporting may lead to missed management opportunities.

DESIGN

A systematic literature review in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol.

DATA SOURCES

A search of MEDLINE, OLD MEDLINE and the Cochrane Collaboration was performed from 1966 to March 2011 using 16 search terms.

DATA EXTRACTION

All articles were screened for genuine non-contiguous multi-focal necrotising fasciitis. Of the papers that met this criterion, data on patient demographics, likely inciting injury, presentation time-line, microbial agents, sites affected, objective assessment scores, treatment and outcome were extracted.

DATA SYNTHESIS

A total of 31 studies met our inclusion criteria and 33 individual cases of multi-focal necrotising fasciitis were included in the quantitative analysis. About half (52%) of cases were type II necrotising fasciitis; 42% of cases had identifiable inciting injuries; 21% of cases developed multi-focal lesions non-synchronously, of which 86% were type II. Nearly all (94%) of cases had incomplete objective assessment scores. One case identified inflammatory imaging findings prior to clinical necrosis.

CONCLUSIONS

Multifocality in necrotising fasciitis is likely to be associated with type II disease. We postulate that validated objective tools will aid necrotising fasciitis management pathways that will identify high-risk groups for multifocality and advise early pre-emptive imaging. We recommend the adoption of regional multi-focal necrotising fasciitis registers.

Pragmatic management of Panton-Valentine leukocidin-associated staphylococcal diseases

Panton-Valentine leukocidin (PVL)-producing Staphylococcus aureus is associated with a broad spectrum of diseases, ranging from common uncomplicated soft tissue infections to severe diseases such as complicated soft tissue infections, extensive bone and joint infections, and necrotising pneumonia. Specialised management of infection based on the presence of PVL may not be required for mild infections, whereas it could be lifesaving in other settings. Moreover, most severe PVL diseases are recently identified entities and a 'gold standard' treatment from comparatives studies of different therapeutic options is lacking. Thus, recommendations are based on expert opinions, which are elaborated based on theory, in vitro data and analogies with other toxin-mediated diseases. In this review, we consider the potential need for specialised PVL-based management and, if required, which tools should be used to achieve optimal management.

Factors associated with the outcome of life-threatening necrotizing pneumonia due to community-acquired Staphylococcus aureus in adult and adolescent patients

BACKGROUND

Although community-acquired Staphylococcus aureus pneumonia with highly virulent Panton-Valentine leukocidin (PVL)-positive strains, a severe disease with significant lethality, is rare, especially in adult and adolescent patients, recent reports highlight that these infections are on the rise.

OBJECTIVES

To describe the demographic and clinical features of reported cases of life-threatening community-acquired S. aureus pneumonia with usually PVL-positive strains in adult and adolescent patients, to evaluate the variables related to death, and to select a more appropriate antimicrobial treatment for this potentially deadly disease.

METHODS

We summarized all of the 92 reported cases and our case. The effect of 5 variables on mortality was measured using logistic regression.

RESULTS

S. aureus community-acquired pneumonia (CAP) with usually PVL-positive strains is a severe disease with significant lethality, i.e. 42.9%; a short duration of the time from the onset of symptoms to death, i.e. 5.5 ± 10.1 days, and prolonged hospital admissions, i.e. 33.2 ± 29.5 days. Seventy-three cases have been tested for the gene for PVL, and 71 strains have been found to carry the PVL gene. Logistic regression analysis showed that leucopenia (p = 0.002), influenza-like symptoms or laboratory-confirmed influenza (p = 0.011), and hemoptysis (p = 0.024) were the factors associated with death. Antibiotic therapies inhibiting toxin production were associated with an improved outcome in these cases (p = 0.007).

CONCLUSIONS

Physicians should pay special attention to those patients who acquired severe CAP during influenza season and have flu-like symptoms, hemoptysis, and leucopenia, and they should consider S. aureus more frequently among the possible pathogens of severe CAP. Empiric therapy for severe CAP with this distinct clinical picture should include coverage for S. aureus. Targeted treatment with antimicrobials inhibiting toxin production appears to be a more appropriate selection.