The increasing incidence of drug-resistant pathogens has drawn the attention of the pharmaceutical and scientific communities towards studies on the potential antimicrobial activity of plant-derived substances, an untapped source of antimicrobial chemotypes, which are used in traditional medicine in different countries. The aim of this review is to provide recent insights regarding the possibilities of the most important natural antimicrobial compounds derived from plant sources containing a wide variety of secondary metabolites, which are useful as alternative strategies to control infectious diseases. This review will focus on natural plant products as a useful source of antimicrobial molecules, active in particular, on bacteria and fungi. When considering that many of these compounds, which have been used for centuries, are a source of new drugs and that there are ever-increasing technical breakthroughs, it can be envisaged that in the next years some different molecules discovered by ingenious screening programs and obtained from different plant oils and extracts will become useful therapeutic tools.

Leishmaniasis is a neglected vector-borne tropical infection considered to be a disease of the poor. Concentrated in poverty-stricken countries within Southeast Asia, East Africa, and Latin America, it is also endemic in several Mediterranean countries. The management of the heterogeneous syndromes determined by parasites belonging to the genus Leishmania is particularly difficult in developed, non-endemic countries owing to the unfamiliarity of physicians with clinical symptoms, diagnostic possibilities, and available treatment options. Therefore, travelers and other people who may be exposed to sand flies in endemic areas should receive counseling regarding leishmaniasis and appropriate protective measures. Serological diagnosis is rarely used for cutaneous and mucocutaneous diseases, but it is the most commonly used technique for visceral leishmaniasis. The drugs used to treat this last disease are expensive and sometimes have toxic side effects. This review highlights the diagnostic, chemotherapeutic, and immunizing strategies to control leishmaniasis, though no human vaccine is commercially available currently owing to the complexity of the cellular immune response to this parasite.

Propolis, a multifunctional substance used by bees to maintain the safety of their hives, is popular for its therapeutic potential against some micro‐organisms. Ethanolic extracts of two propolis specimens, collected from different areas within a region in the north‐west of Italy, were examined to evaluate their antimicrobial activity against 46 Streptococcus pyogenes strains. By both agar dilution and agar diffusion methods, the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) were ≤ 234 µg ml−1, corresponding to a one in 512 dilution of the 12% (w/v) extracts. One of the two propolis samples was more active and this extract was shown to be richer in the flavonoids pinocembrin and galangin using HPLC. Therefore, with a simple microbiological assay technique, in particular the agar dilution method, it was possible to standardize the analysis of propolis samples to identify the quality parameters of this natural product before use for medical treatment.

Achromobacter xylosoxidans is a ubiquitous Gram‐negative non‐fermenting rod, recently characterized as an emerging pathogen in cystic fibrosis (CF) patients. Its pathogenic potential and prevalent transmission routes are still unclear. This study investigated the PFGE genetic pattern and antimicrobial resistance profile of 42 A. xylosoxidans isolates obtained over 4 years from the respiratory tract of 22 CF patients. By genotypic analysis, 31 isolates were attributed to 8 distinct PFGE patterns (A–H), whereas 11 isolates were not typable because their DNA was not restricted by XbaI and DraI restriction enzymes. The majority of the isolates showed multidrug resistance; imipenem and piperacillin were the most active drugs. During the course of A. xylosoxidans chronic infection forced expiratory volume and body mass index values were not significantly lowered. The demonstration of widespread antibiotic resistance underscores the importance of antibiogram‐directed therapy. Our data suggest that in some cases the infection may have been acquired from other patients or from a common contaminated source. Further epidemiological studies may be important for the design and implementation of prophylactic measures in CF centers.

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