Effective concentration of intravenous immunoglobulin for neutralizing Panton-Valentine leukocidin in human blood

Catastrophic complications of PVL-MRSA necrotizing pneumonia presenting as respiratory failure and rhabdomyolysis, case report and review of the literature

Panton-Valentine leucocidin toxin-producing methicillin-resistant staphylococcus aureus is an important uncommon cause of community-acquired pneumonia; we describe a case of necrotizing pneumonia presenting as respiratory failure necessitating early initiation of extracorporeal membrane oxygenation, acute kidney injury and rhabdomyolysis, awareness, prompt recognition and appropriate management are crucial due to possible significant pathology.

Neutralization of the Staphylococcus aureus Panton-Valentine leukocidin by African and Caucasian sera

Background

The prevalence of Staphylococcus aureus isolates carrying the Panton-Valentine leukocidin (PVL) gene is higher in Africa (≈50%) compared to Europe (< 5%). The study aimed to measure anti-PVL-antibodies in Africans and Germans in a multi-center study and to test whether detected antibodies can neutralize the cytotoxic effect of PVL on polymorphonuclear leukocytes (PMNs).

Methods

Sera from asymptomatic Africans (n = 22, Nigeria, Gabon) and Caucasians (n = 22, Germany) were used to quantify antibody titers against PVL and α-hemolysin (in arbitrary units [AU]) by ELISA. PMNs from one African and German donor were exposed to 5 nM recombinant PVL to measure the neutralizing effect of serial dilutions of pooled sera from African and Caucasian participants, or donor sera at 0.625 and 2.5% (v/v).

Results

Anti-PVL-antibodies were significantly higher in Africans than in Germans (1.9 vs. 0.7 AU, p < 0.0001). The pooled sera from the study participants neutralized the cytotoxic effect of PVL on African and German PMNs in a dose dependent manner. Also, neutralization of PVL on PMNs from the African and German donors had a stronger effect with African sera (half-maximal inhibitory concentration (IC50) = 0.27 and 0.47%, respectively) compared to Caucasian sera (IC50 = 3.51 and 3.59% respectively).

Conclusion

Africans have higher levels of neutralizing anti-PVL-antibodies. It remains unclear if or at what level these antibodies protect against PVL-related diseases.

Choosing antibiotic therapy for severe community-acquired pneumonia

PURPOSE OF REVIEW

Community-acquired pneumonia (CAP) is known as a major worldwide health concern considering it has been shown to account for 78% of infection-related deaths in the USA. It is a common cause for hospitalization with a continued incidence rise in the elderly, high mortality rate and long-term sequelae in critically ill patients. Severe CAP (sCAP) is an accepted terminology used to describe ICU admitted patients with CAP. The aim of this review is to further report on the major advances in treatment for patients with sCAP including new antibiotic treatments despite macrolide resistance as seen in the ICU, and multifaceted antibiotic stewardship interventions that may lead to the reduction broad-spectrum antibiotic use in CAP.

RECENT FINDINGS

We aim to examine the most recent findings in order to determine appropriate empirical antibiotic choices, timing regimens and evidence for clinical effectiveness. This will be addressed by focusing on the use combination therapies, the usefulness of severity scores and the difficulty to treat multidrug-resistant pathogens, including gram negatives such as Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus. Relevant reports referenced within included randomized controlled trials, meta-analyses, observational studies, systematic reviews and international guidelines where applicable.

SUMMARY

New antibiotics have been recently launched with direct agent-specific properties that have been shown to avoid the overuse of previous broad-spectrum antibiotics when treating patients sCAP. Although narrow-spectrum antibiotics are now recommended and imperative in improving a patients' prognosis, there are also some considerations when prescribing antibiotics that are beyond the spectrum. There is a need to implement effective policies of de-escalation to avoid antibiotic resistance and the risk for developing subsequent infections by combining informed clinical judgement and the application of biomarkers. Reaching clinical stability and avoidance of treatment failure are the most important pillars in treatment success.

Prevalence, clinical expression, invasiveness and outcome of Staphylococcus aureus containing Panton-Valentine leukocidin in children treated in a university hospital of Lithuania

Background: There is a high prevalence of Staphylococcus aureus virulence factor Panton-Valentine leukocidin (PVL) in North-East parts of Europe. The aim was to evaluate data regarding the PVL occurrences in Lithuania, determine the relationship with Methicillin resistant Staphylococcus aureus (MRSA), association with demographic and clinical conditions, invasiveness and severity of the disease in children treated in hospital Kauno klinikos (KK).Methods: We performed a prospective case-cohort single-center study on paediatric patients hospitalized from 2012 to 2015 to KK. We compared characteristics in PVL positive [SA-PVL(+)] and PVL negative [SA-PVL(-)] groups among non-invasive and invasive infections. Logistic regression was performed to detect PVL predicting factors and Cox regression was presented to define factors associated with admission to intensive care unit (ICU).Results: PVL was detected in 51.5%, MRSA in 7.0% and MRSA-PVL(+) in 4.8% of cases. In general, PVL was associated with older age comparing with SA-PVL(-) (median 8.5 vs. 4.0 years, p < .001). Skin and soft tissue infections were presented in 87.9% of all SA-PVL(+) cases. Invasive infections (44.7% vs. 12.1%, p < .001) and co-morbidities (20.5% vs. 2.9%, p < .001) were associated with SA-PVL(-) infections compared to SA-PVL(+), but ICU admission number was higher in invasive SA-PVL(+) cases comparing to invasive SA-PVL(-) cases (41.2% vs. 10.2%, p = .007).Conclusions: There was a high prevalence of pvl gene in patients treated in KK. SA-PVL(+) infections were associated with SSTI and were not common in invasive infections, but the invasive infections caused by SA-PVL(+) were related to severe disease progression and admission to ICU.