Antimicrobial Peptides against Multidrug-Resistant Pseudomonas aeruginosa Biofilm from Cystic Fibrosis Patients.

Lung infection is the leading cause of morbidity and mortality in cystic fibrosis (CF) patients and is mainly dominated by Pseudomonas aeruginosa. Treatment of CF-associated lung infections is problematic because the drugs are vulnerable to multidrug-resistant pathogens, many of which are major biofilm producers like P. aeruginosa. Antimicrobial peptides (AMPs) are essential components in all life forms and exhibit antimicrobial activity. Here we investigated a series of AMPs (d,l-K6L9), each composed of six lysines and nine leucines but differing in their sequence composed of l- and d-amino acids. The d,l-K6L9 peptides showed antimicrobial and antibiofilm activities against P. aeruginosa from CF patients. Furthermore, the data revealed that the d,l-K6L9 peptides are stable and resistant to degradation by CF sputum proteases and maintain their activity in a CF sputum environment. Additionally, the d,l-K6L9 peptides do not induce bacterial resistance. Overall, these findings should assist in the future development of alternative treatments against resistant bacterial biofilms.

Invasive meningococcal disease epidemiology and characterization of Neisseria meningitidis serogroups, sequence types, and clones; implication for use of meningococcal vaccines.

BACKGROUND AND AIMS: Neisseria meningitidis (N. meningitidis) is a Gram-negative bacterium that can cause life-threatening invasive infections referred to as invasive meningococcal disease (IMD). In the last decade the incidence of IMD in Israel is about 1/100,000 population annually. We aimed to describe the epidemiology of IMD in Israel combining epidemiological data and characterization of N. meningitidis isolates. METHODS: Invasive infection caused by N. meningitidis is a notifiable disease in Israel. Data were collected by epidemiological investigations and control measures were employed. Laboratory work-up included serogrouping, N. meningitides molecular characterization and whole-genome sequencing. RESULTS: During 1998-2017, 1349 cases of IMD were notified in Israel (mean annual incidence rate 0.94/100,000). The peak incidence rates were observed in infants under 1 year of age (10.9/100,000). Case fatality rate was 9.7%. The majority of the N. meningitidis isolates were of serogroup B (67.9%). During 2007-2017, three clonal complexes (CC) 32, 41/44 and 23 (hyper-invasive clonal complexes) were the leading CC (61%). CC32 was the leading CC causing meningococcemia and mortality. In 2017, 35 isolates were tested for 4CMenB antigens variants; of the serogroup B isolates tested 46.7% showed a match to one or more antigens (fHbp or PorA:VR1), most were ST32 (CC32). CONCLUSIONS: Preliminary analysis based on limited number of samples suggests that the 4CMenB coverage would be about half the strains; further research is necessary. Integration of clinical, epidemiological and laboratory data is essential to support decision-making on the introduction of the novel MENB vaccines in Israel.

Delayed diagnosis of colorectal sexually transmitted diseases due to their resemblance to inflammatory bowel diseases.

OBJECTIVE: Sexually transmitted diseases (STDs), mainly lymphogranuloma venereum (LGV), induce colorectal symptoms that may be misdiagnosed as inflammatory bowel disease (IBD). This study describes patients who presented with STDs masquerading as IBD in order to improve understanding of missed diagnosis of colorectal STDs and their association with LGV in Israel. METHODS: This retrospective, descriptive study characterized the clinical, endoscopic, and pathological findings of 16 patients who were diagnosed with a colorectal STD after erroneously being diagnosed with IBD. Molecular genotyping was used to characterize some of the Chlamydia trachomatis isolates. RESULTS: All patients were men who have sex with men (MSM), mostly HIV-1-positive, and had clinical and endoscopic findings compatible with IBD. The STD was diagnosed 1-36 months after the initial diagnosis: 14 were positive for Chlamydia trachomatis, of which three were of the LGV2b (ST58) serotype and one was ST 108 serotype. Five were positive for gonorrhea and four were positive for syphilis. Several pathogens were diagnosed in six episodes. CONCLUSIONS: Colorectal STDs may resemble IBD and therefore their diagnosis may be delayed. IBD symptoms in MSM who engage in non-protected anal sex should prompt at least syphilis and anal PCR for STD testing. If C. trachomatis is diagnosed but LGV subtyping cannot be done, doxycycline 100mg twice daily for 21days should be recommended.

The synergistic effect of PDT and oxacillin on clinical isolates of Staphylococcus aureus.

BACKGROUND: Staphylococcus aureus is a major pathogen in clinical microbiology. It is known to cause infections at various body sites and can be life-threatening. The development of resistance to many well-established antibiotic treatments and the prevalence of methicillin-resistant S. aureus (MRAS) among hospital patients and the general community pose challenges in treating the pathogen. The antimicrobial effect of photodynamic therapy (PDT) has been a subject of study for a long time and can offer new strategies for dealing with resistant strains. OBJECTIVE: In our study, we searched for a positive synergistic relationship between PDT and the standard antibiotics used to treat S. aureus and MRSA infections. MATERIALS AND METHODS: The phototoxic profile of deuteroporphyrin (DP) in both resistant and susceptible clinical strains of S. aureus was determined by plating of treated and untreated broth cultures. Electron microscopy imaging was done to explore possible sites of damage and free-radical accumulation in the cells during DP-PDT. Minimal inhibitory concentration (MIC) of oxacillin, gentamicin, vancomycin, rifampin, and fusidic acid was determined using the broth dilution method, and the checkerboard method was used to detect and evaluate the synergistic potential of DP-PDT and antibiotic combinations. A synergistic combination was further characterized using broth cultures and plating. RESULTS: DP-PDT using a light dose of 15 J/cm2 showed a bactericidal effect even with a small concentration of 17 µM DP. Transmission electron microscopy indicated profound damage in the cell wall and cell membrane, and the appearance of mesosome-like structures. Free radicals tend to localize in the cell membrane and inside the mesosome. No synergistic effect was detected by combining PDT with gentamicin, vancomycin, rifampin, and fusidic acid treatments. A positive synergistic effect was observed only in DP-PDT-oxacillin combined treatment using the checkerboard method. The effect was observed in clinical antibiotic-resistant isolates after DP-PDT using a light dose of 46 J/cm2 and small concentrations of DP. Oxacillin MIC decreased below 2 µg/ml in resistant strains under such conditions. Cultures which did not undergo new cycles of DP-PDT recovered their original oxacillin resistance after a few generations. CONCLUSIONS: PDT with porphyrins shows possible new therapeutic options in treating drug-resistant S. aureus at body sites suitable for irradiation. The synergistic effect of DP-PDT with oxacillin on clinical strains illustrates the potential of PDT to augment traditional antibiotic treatment based on cell wall inhibitors. Lasers Surg. Med. 50:535-551, 2018. © 2018 Wiley Periodicals, Inc.

Do isolation rooms reduce the rate of nosocomial infections in the pediatric intensive care unit?

PURPOSE: To determine the effect of isolation rooms on the direct spread of nosocomial infections (NIs) owing to cross-colonization in a pediatric intensive care unit (PICU). MATERIALS AND METHODS: This 6-month comparative clinical study used retrospective data from 1992 (an open single-space unit) and prospective surveillance from 1995 (individual rooms) to assess the effectiveness of the latter design on the control of NIs in critically ill pediatric patients. Patients admitted to the PICU for at least 48 hours underwent a microbiologic survey. RESULTS: The average number of NIs per patient was higher in 1992 (3.62 +/- 0.7, 78 patients) compared with 1995 (1.87 +/- 0.2, 115 patients). Bacterial NIs were caused by gram-positive cocci (33.3%) and aerobic gram-negative bacilli (66.6%). Fungemia in all cases was caused by Candida albicans. Similarly, length of stay was significantly higher in 1992 compared with 1995 (25 +/- 6 and 11 +/- 6 days, respectively; P <.05). There was a significant reduction of respiratory and urinary tract episodes of NI as well as catheter-related infections in the separate room arrangement. CONCLUSIONS: Our preliminary analysis suggests a possible beneficial effect of single isolation rooms in reducing NI rate in the PICU. Hence, the influence of room isolation on NIs in pediatric intensive care warrants further investigation.

Plasma soluble L-selectin following cardiopulmonary bypass (CPB) in children: is it a marker of the postoperative course?

BACKGROUND: There is increasing evidence that cytokine-inducible leukocyte-endothelial adhesion molecules are instrumental in the postoperative inflammatory response following cardiopulmonary bypass (CPB). L-selectin was shown to be one of those neutrophil-endothelial cell adhesion molecules. This study aimed to investigate the relationship of the soluble adhesion molecule, sL-selectin, and the postoperative course in children undergoing CPB. MATERIAL/METHODS: To determine the time course of sL-selectin after CPB, serial blood samples of 9 children undergoing CPB were collected from the arterial line or from the bypass circuits preoperatively, on initiation of CPB and 1, 6, 12, 18, 24, and 48 hours postoperatively. Plasma was recovered immediately, aliquoted and frozen at -70 degrees C until use. Circulating sL-selectin molecules were measured with a sandwich enzyme-linked immunoabsorbent assay (ELISA) technique. There were significant changes in plasma levels of sL-selectin in patients following CPB, and these levels were associated with patient characteristics, operative variables and postoperative course. Low values of sL-selectin significantly correlated with inotropic support, low PRISM score, postoperative hypotension and fever. There was a significant association between the development of postoperative sepsis and low sL-selectin levels. No correlation was found between sL-selectin values and lactate concentration or neutrophil count. CONCLUSIONS: Our results suggest a relation between CPB-induced mediators and both early and late clinical effects. Although the mechanism for the changes of sL-selectin remains undetermined, the down-regulation of sL-selectin indicates neutrophil activation and supports the possibility that anti-adhesion therapies might participate in the prevention and treatment of the inflammatory response associated with CPB.