Methicillin-resistant Staphylococcus aureus: related infections and antibiotic resistance

Summary Staphylococcus aureus is a well adapted human pathogen, capable of living freely in the inanimate environment and spreading from person to person, existing as a colonizer or commensal, hiding in intracellular compartments and, most importantly, inducing various forms of human disease. Infections caused by S. aureus , above all by antibiotic-resistant strains, have reached epidemic proportions globally. The overall burden of staphylococcal disease caused by antibiotic-resistant S. aureus , particularly by the methicillin-resistant strains, is increasing in many countries, including Italy, in both healthcare and community settings. The widespread use of antibiotics has undoubtedly accelerated the evolution of S. aureus , which, acquiring multiple resistance genes, has become able to survive almost all antibiotic families; this evolution versus more resistant phenotypes has continued among the newer agents, including linezolid and daptomycin. The diminished clinical usefulness of vancomycin is seen as one of the most worrisome problems in many clinical settings and in many countries. In fact, the increasing spread of heteroresistant vancomycin-intermediate S. aureus (hVISA) and vancomycin intermediate (VISA) strains adds new problems, not only in terms of the treatment of severe infections sustained by these microorganisms, but also in the microbiological definition of susceptibility

A multi-society position paper on the prevention and management of nosocomial and severe infections: the Italian Society for Infectious Diseases, the Italian Multidisciplinary Society of Hospital Infections, the Italian Society of Chemotherapy, the Italian Society of Respiratory Medicine, the Italian Society of Clinical Microbiology, the Italian Society of Microbiology, and GISIG (Italian Study Group on Severe Infections)

Amulti-society position paper on the prevention and management of nosocomial and severe infections: the Italian Society for Infectious Diseases, the Italian Multidisciplinary Society of Hospital Infections, the Italian Society of Chemotherapy, the Italian Society of Respiratory Medicine, the Italian Society of Clinical Microbiology, the Italian Society of Microbiology, and GISIG (Italian Study Group on Severe Infections

Indagine nazionale sulle metodiche per emocoltura in Italia

Sepsis is an important cause of morbidity and mortality; Blood cultures are the standard for identifying the responsible pathogen, bacteria or fungi.A number of factors influence the yield of blood culture, most of them concerning the microbiolist skill and the laboratory organization. In order to collect information about the practices and procedures used for the detection of microrganisms in blood cultures in the italian laboratory, a questionnaire was sent to all the 2000 members of the Italian Association of Clinical Microbiology. Responses were received from 110 laboratories, located from all over the country (2.028.581 hospital admission).The results presented hereby concern specimen collection, culture techniques, rapid identification and susceptibility testing. In summary, most laboratories use automated systems (83.6%), the lenght of incubation was 7 days in two out of three laboratories, although it is common to extend the incubation period when brucellosis (83 lab), endocarditis (47 lab), systemic mycosis (27 lab) is suspected.A wide variety of media are employed for subcultures. All laboratories examine the bottles at least once a day, while only 32 of 95 (33.7%) laboratories processe the positive blood cultures on holiday. Communication between clinicians and microbiologist include: distribution of specimen collection guidelines by 93 (84.5%) laboratories, availability of patients’ clinical situation in 35 (32.4%) laboratories, and adding to report the suggestion of potentialy contaminated culture (i.e.“a positive results does not necessarly indicate bacteremias”) in 31 (28.4%). Only laboratories perform direct, tests 18.6% antimicrobial susceptibility test, and 9.3% perform rapid direct identification

Survey of blood cultures methods in Italy in 2010

Sepsis is a serious clinical condition, associated with high mortality despite advanced modern medical treatment. Traditionally, the detection and identification of bacteria and fungi circulating in the blood-stream is based on blood cultures. A number of factors influence the yield of blood culture, most of them concerning the microbiologist skill and the laboratory organization. In order to collect information about the practices and procedures used for the detection of microrganisms in blood cultures in the italian laboratory (lab), an e-mail with the invitation to participate in the survey was sent to 2000 members of the Italian Association of Clinical Microbiology. Responses were received from 100 lab, located from all over the country (in 18/20 italian regions). The results presented hereby concern specimen collection, culture techniques, rapid identification and susceptibility testing, laboratory organization, relationships with physicians. In summary, most lab use automated systems (96%), the bottles are incubated immediately during public holidays in 72/96 lab (75%) and in 49/97 lab at night (50.5%), the lenght of incubation was 5 or 7 days in 93% of the lab, although it is common to extend the incubation period when brucellosis (74 lab), endocarditis (49 lab), systemic mycosis (33 lab) is suspected. A wide variety of media are employed for subcultures. All lab process the positive bottles at least once a day, while only in 42 of 81 (51.9%) lab the positive blood are processed on holiday. Communication between clinicians and microbiologist include: distribution of specimen collection guidelines (96/100 lab), availability to microbiologist of patients’ clinical situation (77/96 lab, 80.2%), and adding to report the microbiologist’ suggestion (75/98 lab, 76.5%). The results, compared with those collected with a similar questionnaire in 2001, show a greater adherence to guidelines: the number of bottles examined by lab yearly is almost doubled, the length of incubation is shortened to 5 days in 42% (vs 9.2% in 2001), direct susceptibility tests seem to be performed more frequently (in 29% of lab vs18.6% in 2001, mostly in larger hospitals), more lab process positive bottles on Sunday, cooperation with clinicians is improved

Confronto dei risultati dell’esame microscopico diretto e dell’identificazione definitiva nei casi di batteriemia

Introduction. All the microbiology texts underline the importance of performing a gram stain on blood culture broth, if positive, with a double purpose: address the microbiologist in the choice of subculture media and provide the clinician with preliminary indication for the choice of the treatment. However, there are few data and literature on the concordance between gram stain and definitive result.The study aims at evaluating, in the reality of our hospital, the reliability of the gram stain performed starting from the blood culture broth. Materials and methods. The results of the gram stain on broth and of the final detection of all positive blood cultures performed from January 1st 2003 to December 31st 2004 by the Microbiology Lab based at Ospedali Riuniti Bergamo have been analysed. Results. In two years 52909 bottles have been processed; 6328 (11.96%) resulted positive, of which 5921 (11.19%) for monomicrobial flora and 407 (0.77%) for polymicrobial flora. Concerning the 6643 definitive identifications, the gram stain resulted fully correct in 6140 cases (92.43%); errors have been interpreted as “minor” in 285 cases (4.29%) for a partial or absent definition of the morphologic-dyeing features, “major” in 14 cases (0.21%) for notification of micro-organisms non grown later, “serious” in 204 (3.07%) for wrong reading of Gram (36 cases, equal to 0.54%) or no interpretation, in case of mixed cultures, of micro-organisms grown later (168 cases equal to 2.53%). Conclusions. Our study confirms the reliability of Gram stain and its role in providing in advance the definitive results of blood culture; however, it highlights the risk that Gram stain cannot detect polymicrobial aetiologies