[Show abstract][Hide abstract] ABSTRACT: Staphylococcus epidermidis and S. aureus have been identified as the most common bacteria responsible for sub-clinical and overt breast implant infections and their ability to form biofilm on the implant as been reported as the essential factor in the development of this type of infections. Biofilm formation is a complex process with the participation of several distinct molecules, whose relative importance in different clinical settings has not yet been fully elucidated. To our knowledge this is the first study aimed at characterizing isolates causing breast peri-implant infections.
Thirteen S. aureus and seven S. epidermidis causing breast peri-implant infections were studied. Using the broth microdilution method and the E-test, the majority of the strains were susceptible to all antibiotics tested. Methicillin resistance was detected in two S. epidermidis. All strains had different RAPD profiles and were able to produce biofilms in microtitre plate assays but, while all S. aureus carried and were able to express icaA and icaD genes, this was only true for one S. epidermidis. Biofilm development was glucose- and NaCl-induced (5 S. aureus and 1 S. epidermidis) or glucose-induced (the remaining strains). Proteinase K and sodium metaperiodate treatment had different effects on biofilms dispersion revealing that the strains studied were able to produce chemically different types of extracellular matrix mediating biofilm formation. All S. aureus strains harboured and expressed the atlA, clfA, FnA, eno and cna genes and the majority also carried and expressed the sasG (10/13), ebpS (10/13) genes. All S. epidermidis strains harboured and expressed the atlE, aae, embp genes, and the majority (six strains) also carried and expressed the fbe, aap genes. Genes for S. aureus capsular types 5 and 8 were almost equally distributed. The only leukotoxin genes detected were lukE/lukD (6/13).
S. aureus and S. epidermidis breast peri-implant infections are caused by heterogeneous strains with different biofilm development mechanisms. Since the collagen adhesin (cna) gene is not ubiquitously distributed among S. aureus, this protein could have an important role in the cause of breast peri-implant infections.
[Show abstract][Hide abstract] ABSTRACT: Implant infections represent a relevant problem after immediate breast cancer reconstruction. In addition to difficulties in distinguishing early infections from other post-surgical complications (such as hematoma, seroma, and liponecrosis) late breast implant infections still represent a grey area of our knowledge with regards to heir definition and management. To address this issue, we prospectively monitored breast cancer patients at their center.
Between February 1, 2009, and May 31, 2013, we enrolled all patients undergoing breast implant reconstruction or expander-to-prosthesis substitution. Patients without at least 6 mo of post-operative observation were excluded. We collected data from patient records including age, days from surgery (DFS), chemotherapy/radiotherapy, infecting microorganism, type of implant, antibiotic management and eventual implant removal. Sixty days from surgery were defined as the clinical threshold between early and late infection. Infections were further classified according to a graded scale into possible, probable and microbiologically proved.
Seventy-eight infections were recorded out of 766 surgical procedures (10.2%). Fifty-three (67%) cases occurred early ≤60 DFS, and 25 (33%) occurred late (i.e., beyond 60 d). By defining infection types as possible, probable or proved, the majority of late infections were classified as proved (84%) compared with 56% of early infections (p=0.0014). Microbiological isolate distribution was similar in proved early infections compared with proved late infections. Among late infections, a delayed occurrence was observed after prosthesis placement compared with expander insertion. Late infections were fraught with lower treatment success rates (12% vs. 41%, p=0.009).
Late infection represents a consistent proportion of infections after immediate breast implant reconstruction or prosthesis placement and bear lower chance of salvage after treatment. An increased attention is warranted to improve prevention and treatment strategies.
No preview · Article · Jul 2015 · Surgical Infections
[Show abstract][Hide abstract] ABSTRACT: The role of DNA gyrase in F’lac plasmid conjugation was studied using Escherichia coli gyrA43 (Ts), gyrB41(Ts), and dnaA46(Ts) thermosensitive mutants as donor or recipient organisms, and a rifampicin or nalidixic acid-resistant J-53 strain in the presence or absence of nalidixic acid. Mating experiments were also performed employing Hfr derivatives of the thermosensitive strains. Conjugation was carried out in broth for 60 min using a standard method at permissive and non-permissive (32 and 43 °C) temperatures, with or without drugs. At 32 °C, nalidixic acid reduced the number of transconjugants by about 97 % in comparison to the control, while at 43 °C, the drug inhibited F’lac transfer by about 98 % from dnaA46(Ts) mutant and by about 6.5 % from gyrA43(Ts) and 15 % from gyrB41(Ts) hosts. Using the temperature-sensitive mutants as recipient strains, the transconjugants found were approximately the same under all conditions. The number of transconjugants did not change significantly when nalidixic acid-resistant strains were used as donor or recipient strains. Lastly, nalidixic acid reduced the number of transconjugants from Hfr selected in the above mutants under all experimental conditions. These findings suggest that F’lac transfer does not involve DNA gyrase activity.
No preview · Article · May 2015 · Annals of Microbiology
[Show abstract][Hide abstract] ABSTRACT: Small colony variant (SCV) Staphylococcus aureus are a subpopulation of auxotroph, slow-growing strains causing persisting and relapsing infections in cystic fibrosis (CF) patients. Twenty-eight SCV and 29 normal S. aureus strains were isolated from 42 out of 222 Italian CF patients. The isolates were characterized for: susceptibility to antibiotics, methicillin-resistance (MR), Panton Valentine leukocidin, auxotrophy, hypermutability and biofilm formation. Clonal identity of SCV and normal strains was determined by pulsed-field gel electrophoresis. We found that 27 out of 28 SCVs were thymidine-dependent. Furthermore, in contrast to normal phenotype, SCVs were characterized by antibiotic resistance. We also found that 39.3% SCV vs 20.7% normal strains were strong mutators. Moreover, SCVs showed a higher capability to form biofilm compared to normal strains (100% vs 59%). Importantly, we found evidence of clonal spread of SCV strain among CF patients. Using molecular typing, we found that five patients shared the same type A and five out of seven MR-SCV belonged to the same clone (Clone C). The particular virulence and spreading ability of MR-SCV observed highlights the importance of accurate identification and susceptibility testing of these strains. It is important to adopt the optimal approach to treat patients and to prevent cross-infection in CF centres.
No preview · Article · Apr 2015 · The New Microbiologica: official journal of the Italian Society for Medical Virology (SIVIM)
[Show abstract][Hide abstract] ABSTRACT: In traditional medicine, plants have been used since ancient times for the prevention and/or protection against infectious diseases. In recent years, the use of herbal medicines and food supplements containing botanical ingredients, as alternative therapy for infectious diseases, has been intensified due to their high content of antimicrobial agents such as polyphenols, i.e. flavonoids, tannins, and alkaloids. Plants from the genus Thymus are important medicinal herbs, which are known to contain antimicrobial agents, and are rich in different active substances such as thymol, carvacrol, p-cymene and terpinene. In this review, we summarise the available literature data about the in vitro antibacterial effects of the main plants belonging to the genus Thymus. We also provide information about cultivation, chemical composition of the essential oils obtained from these plants, and their use for medicinal purposes.
[Show abstract][Hide abstract] ABSTRACT: The spread of Klebsiella pneumoniae carbapenemase (KPC)-producing K. pneumoniae continues to increase, and the possible development of KPC-producing K. pneumoniae infections in cystic fibrosis (CF) patients is a matter of concern. Here, we describe the establishment of a chronic lung
infection due to a colistin-resistant KPC-producing K. pneumoniae isolate in an Italian CF patient.
Preview · Article · Feb 2015 · Journal of Clinical Microbiology
[Show abstract][Hide abstract] ABSTRACT: The spread of carbapenem-resistant gram negatives is a global emergency, and surveillance of new resistant clones is critical from both public health and clinical standpoints. Herein, we describe the emergence of a KPC-3-producing Escherichia coli ST69 as a cause of bloodstream infection in two Italian patients.
No preview · Article · Dec 2014 · Microbial drug resistance (Larchmont, N.Y.)
[Show abstract][Hide abstract] ABSTRACT: The antistaphylococcal activity as well as the metabolic profiling and polyphenols content of green tea (Camellia sinensis) before and after in vitro simulated gastric, duodenal and gastroduodenal digestion were investigated. Gastric and duodenal digested samples showed antistaphylococcal activity, whereas gastroduodenal digested samples did not show any antibacterial activity. Metabolite analysis, carried out using an explorative untargeted NMR-based approach and a RP-HPLC-PAD-ESI-MSn method, showed that green tea polyphenols are stable under gastric conditions. Duodenal digested sample maintained the antibacterial activity, even if some polyphenols are widely degraded. Epicatechin 3-gallate, under duodenal digestive conditions, is hydrolyzed to produce epicatechin, whereas epigallocatechin 3-gallate reacts with digestive enzymes and a galloyl- high molecular weight derivative is produced. Gastroduodenal digestion results in degradation of polyphenols, especially gallocatechins, considered the main responsible for the antibacterial activity. These results explains the loss of activity of gastroduodenal digested samples and why in vivo green tea has neither protective nor therapeutic effects against intestinal and systemic bacterial infections.
Full-text · Article · Sep 2014 · Food Research International
[Show abstract][Hide abstract] ABSTRACT: Polyphenols are a widely distributed group of natural products found in fruits, vegetables, nuts, seeds, stems and flowers. Such compounds, especially dietary flavonoids and tannins, have been shown to exert antioxidant, antiinflammatory, anti-cancer and antibacterial effects and may have beneficial effects on human health. The antimicrobial activity of polyphenols has been widely studied and hundreds of publications reporting the antimicrobial activity of polyphenols have been recently published. In an era of increasing antibiotic resistance, the development of new strategies to fight bacteria is welcome. Further studies are needed to evaluate the therapeutic potential of polyphenols alone or in combination with currently available antibiotics.
No preview · Article · Aug 2014 · Current Pharmaceutical Biotechnology
[Show abstract][Hide abstract] ABSTRACT: Background
During June-July 2012, six imipenem-resistant Escherichia coli isolates were isolated from two patients hospitalized in a ward of one large tertiary-care hospital in Genoa, Italy. Genetic features associated with blaNDM-4 gene were investigated.
The isolates exhibited the same PFGE profile and a multidrug-resistant (MDR) phenotype to aminoglycosides, fluoroquinolones, and β-lactams. The strains produced the NDM-4 carbapenemase and the blaNDM-4 gene was part of the variable region of a class 1 integron. MLST analysis revealed that all isolates belonged to sequence type 405 (ST405).
This is the first report on the emergence of an MDR strain of E.coli producing the NDM-4 MBL in Italy.
[Show abstract][Hide abstract] ABSTRACT: The production of Klebsiella pneumoniae (Kp) carbapenemases (KPCs) by Enterobacteriaceae has become a significant problem in recent years.To identify factors that could predict isolation of KPC-Kp in clinical samples from hospitalized patients, we conducted a retrospective, matched (1:2) case-control studies in five large Italian hospitals. The case cohort consisted of adult inpatients whose hospital stay included at least one documented isolation of a KPC-Kp strain from a clinical specimen. For each case enrolled, we randomly selected two matched controls with no KPC-Kp-positive cultures of any type during their hospitalization. Matching involved hospital, ward, and month/year of admission, as well as time at risk for KPC-Kp isolation. A subgroup analysis was also carried out to identify risk factors specifically associated with true KPC-Kp infection.During the study period, KPC-Kp was isolated from clinical samples of 657 patients; 426 of these cases appeared to be true infections. Independent predictors of KPC-Kp isolation were recent admission to ICU, indwelling urinary catheter, central venous catheter (CVC), and/or surgical drain, ≥ 2 recent hospitalizations, hematological cancer, and recent fluoroquinolone and/or carbapenem therapy. Charlson Index ≥3, indwelling CVC, recent surgery, neutropenia, ≥2 recent hospitalizations, and recent fluoroquinolone and/or carbapenem therapy were independent risk factors for KPC-Kp infection. Models developed to predict KPC-Kp isolation and KPC Kp infection displayed good predictive power with the areas under the receiver-operating characteristic curves of 0.82 (95% CI, 0.80-0.84) and 0.82 (95% CI, 0.80-0.85), respectively.This study provides novel information, which might be useful for the clinical management of patients harboring KPC Kp and for controlling the spread of these organisms.
[Show abstract][Hide abstract] ABSTRACT: This study was conducted to evaluate the association between pneumococcal DNA load and parapneumonic pleural effusion (PPE) in children with community-acquired pneumonia. Bacterial load was quantified and related to the presence of PPE with or without empyema in 72 otherwise healthy children aged ≤5 years who were hospitalised because of radiographically confirmed CAP and showed a real-time polymerase chain reaction that was positive for Streptococcus pneumoniae. The proportion of children with a high bacterial load (i.e. ≥265 DNA copies/mL) was larger among the subjects with PPE than those without it. Multivariate analysis showed that a high bacterial load was significantly associated with PPE (OR 8.65; 95 % CI 1.10-67.8 vs a bacterial load of <125 copies/mL). Children with infection due to pneumococcal serotype 19A were at highest risk of developing PPE (OR 7.44; 95 % CI 1.10-50.4 vs all other typeable serotypes). The patients with CAP due to pneumococcal serotypes that are not included in the 13-valent conjugate vaccine (PCV13) were more frequently affected by PPE than those with infections associated with serotypes included in the vaccine, except for serotype 19A. Bacterial loads of ≥265 DNA copies/mL are significantly associated with PPE, and serotype 19A is significantly associated with a high bacterial load and the development of PPE. The mean bacterial load of the patients with empyema was higher than that of patients with simple PPE. Although further studies are required, it seems that serotypes not included in PCV13 can play a major role in causing a higher bacterial load and PPE.
No preview · Article · Jan 2013 · European Journal of Clinical Microbiology
[Show abstract][Hide abstract] ABSTRACT: In several European Countries, by the end of 2012, CLSI guidelines will be replaced by EUCAST. We compared antimicrobial susceptibility results of a large number of respiratory pathogens using both EUCAST and previously adopted CLSI criteria to evaluate the impact on susceptibility patterns and the possible consequences that could occur in clinical practice due to this replacement.For S. pyogenes and S. aureus, the interpretation of susceptibility data using the EUCAST criteria did not produce relevant changes in comparison to CLSI.Against S. pneumoniae, more restrictive EUCAST breakpoints could lead to increased benzylpenicillin and/or amoxicillin-clavulanate resistance rates, which in turn could translate in increased dosages of these antibiotics or usage of alternative agents for respiratory tract infections.Against S. pneumoniae, M. catarrhalis and H. influenzae, cefuroxime-axetil and cefaclor produced the most divergent results depending on the breakpoints adopted and these striking differences could lead to the revision of those guidelines suggesting these two cephalosporins as alternatives in the management of upper respiratory tract infections.
Many differences exist between CLSI and EUCAST breakpoints. However, only in a few cases do these differences translate in major interpretive category discrepancies. In countries adopting more restrictive EUCAST breakpoints, clinicians should be aware of these discrepancies and that they could be faced with antibiotic-resistant respiratory pathogens more frequently than before.
The interpretive discrepancies between EUCAST and CLSI suggest that the discussion on the management of community-acquired respiratory tract infections is still open and further studies are desirable to better define the role of some antibiotics.
Full-text · Article · Aug 2012 · BMC Infectious Diseases