Epidemiology and antibiotic susceptibility of bacteria causing skin and soft tissue infections in the USA and Europe: a guide to appropriate antimicrobial therapy
Introduction
Bacterial infections of the skin and underlying soft tissues are one of the most common presentations in patients visiting emergency room clinics in both hospitals and office based practices [1], [2], [3]. The most common community acquired skin and soft tissue infections (SSTI) include cellulitis, folliculitis, furunculosis and trauma related wound infections, many of which can be treated empirically with oral agents such as cephalosporins, β-lactamase stable penicillins or macrolides. Some infections particularly in patients with co-morbidities (e.g diabetes mellitus, ischaemic ulceration, chronic lymphoedema) or that have developed bacteraemia, can be classified as complicated and often require hospitalisation [4], [5], [6], [7], [8]. In many cases patients can suffer more serious fulminant infection such as necrotising fasciitis associated with high mortality rates [4], [5], [6]. For these cases upon diagnosis immediate therapy is required, normally with intravenous antibiotics. For SSTI Staphylococcus aureus and Streptococcus spp., especially Streptococcus pyogenes, are the predominant pathogens, although for skin infections Corynebacterium spp., Pasteurella spp. and Enterobacteriaceae are also frequently involved. Anaerobes, often as mixed infections, are relatively common in traumatic wounds, ischaemia or diabetes mellitus. Recently the increase in invasive medical techniques and in particular the number of immuno-compromised patients through immunosuppresive drugs, cancer, transplant surgery and HIV/AIDS have dramatically increased the incidence of serious SSTI [6]. Additionally, in the hospital setting, surgical wound site infections represent a significant source of SSTI. These and other nosocomial SSTI are often due to S. aureus, with the number of MRSA varying considerably by region [9], [10], [11].
Changes in patient populations and risk profile together with an apparent resurgence of the incidence of streptococcal disease [12] and the increasing threat of antimicrobial resistance has created renewed interest in these infections [9], [10]. To derive a current picture of the incidence and antimicrobial susceptibility of pathogens associated with SSTI in hospitals, we reviewed data from The Surveillance Network (TSN) databases in the USA and EU with the aim of informing the clinician of the most appropriate therapy for a particular region based on microbiological grounds.
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TSN Database in USA and EU countries
TSN is a queriable real-time database that electronically assimilates daily antimicrobial susceptibility testing and patient demographic data from a network of laboratories in the United States (283 hospital sites), France (63 hospital sites), Germany (169 hospital sites), Italy (48 hospital sites) and Spain (21 hospital sites) [13].
Laboratories in TSN include those servicing university, community and private hospitals with bed sizes ranging from 100 to >1000 beds. In each country, laboratories
Origin of isolates
During 2001, S. aureus, Enterococcus spp., and CNS and E. coli and P. aeruginosa were the most common organisms isolated and susceptibility tested from SSTI irrespective of geographical region (Table 1). Together these five groups made up 66.4% (11 412 strains; Germany), 69.3% (8148 strains; Spain), 71.8% (16 543 strains; France), 77.2% (20 248 strains; USA) and 80.4% (5531 strains; Italy) of all isolates reported. S. aureus the most significant pathogen from this group, comprised between 17.0%
Discussion
SSTI represent an important area of infectious disease covering a large range of pathologies of varying severity and complexity. The majority of uncomplicated SSTIs are treated in the community and respond well to oral therapies, invariably with agents targeted against susceptible Gram-positive agents such as a first generation cephalosporin, a macrolide, or a penicillinase-stable penicillin such as flucloxacillin [1], [4], [5], [6], [18], [19]. It is likely that data from these infections
Acknowledgements
We thank F. Hoffmann-La Roche Ltd., Basel, Switzerland for financial support of this study. Additionally we thank the many clinical microbiology laboratories around the world, that contribute data to TSN Databases and without whom such studies would not be possible.
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