Engineered Liposomes Protect Immortalized Immune Cells from Cytolysins Secreted by Group A and Group G Streptococci

The increasing antibiotic resistance of bacterial pathogens fosters the development of alternative, non-antibiotic treatments. Antivirulence therapy, which is neither bacteriostatic nor bactericidal, acts by depriving bacterial pathogens of their virulence factors. To establish a successful infection, many bacterial pathogens secrete exotoxins/cytolysins that perforate the host cell plasma membrane. Recently developed liposomal nanotraps, mimicking the outer layer of the targeted cell membranes, serve as decoys for exotoxins, thus diverting them from attacking host cells. In this study, we develop a liposomal nanotrap formulation that is capable of protecting immortalized immune cells from the whole palette of cytolysins secreted by Streptococcus pyogenes and Streptococcus dysgalactiae subsp. equisimilis—important human pathogens that can cause life-threatening bacteremia. We show that the mixture of cholesterol-containing liposomes with liposomes composed exclusively of phospholipids is protective against the combined action of all streptococcal exotoxins. Our findings pave the way for further development of liposomal antivirulence therapy in order to provide more efficient treatment of bacterial infections, including those caused by antibiotic resistant pathogens.

Acute posteromedial papillary muscle rupture secondary to aortic valve endocarditis: a case report

Background Acute papillary muscle rupture due to infective involvement has been recognized as a complication of infective endocarditis. However, there is very limited literature describing the rupture of the posteromedial papillary muscle in primary aortic valve endocarditis without aortic root abscess. This report highlights the etiology of the papillary muscle rupture in the setting of primary aortic valve endocarditis and the importance of a multidisciplinary approach. Case summary An 81-year-old man without any heart failure symptoms presented with fever and loss of vision in his left eye. Initial echocardiography revealed moderate aortic valve regurgitation due to a perforated right coronary cusp without aortic root abscess, and his blood cultures were positive for Group G Streptococci. During adequate antibiotic therapy, he developed acute severe mitral regurgitation secondary to posteromedial papillary muscle rupture. Following emergent aortic and mitral valve replacement using bioprosthetic valves, he made excellent progress on a 6-week course of intravenous antibiotics. Discussion The echocardiography and the histological findings suggested that the main cause of papillary muscle rupture was most likely a metastatic focus of infection from the aortic valve via a regurgitant jet. Successful treatment of this fatal complication includes early diagnosis and prompt surgical intervention by a multidisciplinary approach.

Determination of Group Distributions and Antibiotic Resistance Profiles of Beta- Hemolytic Streptococci Isolated from Throat Cultures of Patients with Tonsillopharyngitis in Canakkale Province

Objective: Group A, C and G beta- hemolytic streptococci (BHS) are bacterial agents of tonsillopharyngitis, and cause various diseases and increase morbidity and mortality. In this study, we aimed to determine the percentage of group distribution and the rate of antibiotic resistance of BHS identified from the throat cultures of patients with acute tonsillopharyngitis. Method: The throat swabs were collected from 200 patients with tonsillopharyngitis aged 1-80 years between October 2017 and May 2018. Bacterial isolates were identified by conventional methods such as Gram staining, bacitracin-trimethoprim sulfamethoxazole, catalase, and L-pyrrolidonyl β-naphthylamide. Latex agglutination test was used for serogrouping BHS. The antibiotic susceptibility profiles of BHS were determined by Kirby Bauer disc diffusion method. Streptococcus pyogenes ATCC 19615 strain was used as a control. Inhibition zone diameters were evaluated according to the Clinical Laboratory Standards Institute (CLSI) criteria. Results: Thirty-four (17%) BHS were isolated from 200 throat swap specimens.Distribution percentages of BHS group were determined as 44.1% (15) for A, 29.4% (10) C, 23.5% (8) G and 2.9% (1) F. All isolates were 100 % susceptible to penicillin, vancomycin and levofloxacin. The highest resistance (29.4%) was found against ampicillin followed by clindamycin (26.5%), erythromycin (23.5%), amoxycillin-clavulanic acid and tetracycline (14.7%), cefotaxime and ceftriaxone (11.8%), clarithromycin (8.8%) and chloramphenicol (2.9%). Conclusion: This study revealed that Group C, and Group G Streptococci had lower resistance to some antibiotics than Group A Streptococci. Based on the findings, the BHS group distributions and antibiotic resistance profiles should be repeated at certain intervals and precautions should be taken with public health surveillance studies

Erysipelas or cellulitis with a prosthetic joint in situ

We describe a case of a 60-year old male who developed an acute prosthetic joint infection (PJI) of the knee, secondary to erysipelas of the lower leg due to beta-hemolytic Group G streptococci. As it is unknown how often this phenomenon occurs in patients with prosthetic implants and which patients are most prone to develop this complication, we analyzed: i) the incidence of the development of a PJI in these patients and ii) the clinical characteristics of streptococcal PJI during an episode of erysipelas/cellulitis. Based on a retrospective analysis of patients with a prosthetic implant in situ presenting at the emergency department with erysipelas/cellulitis, 1 out of 10 patients developed a PJI. An additional analysis within a multicenter cohort on streptococcal PJI demonstrated in 22 patients that a secondary PJI due to erysipelas/cellulitis mostly develops in young implants (<5 years old). In 20 cases (91%), the skin infection was in the same limb as the joint prosthesis suggesting contiguous spread of bacteria. These data emphasizes the importance of preventive measures to reduce the occurrence of skin infections in patients with prosthetic implants, and if an erysipelas or cellulitis does occur, to monitor patients carefully.