Dossier n. 210/2011 [Abstract] Surveillance of antimicrobial resistance and consumption of systemic antibiotics in Emilia-Romagna. Rapporto 2009

The surveillance system of antimicrobial resistance in Emilia-Romagna regularly provides data on this phenomenon since 2003 and reached in 2009 a 90% population coverage within the region. During the period 2003-2009, there has been a rapid increase in antimicrobial resistance that has become a relevant public health problem. The awareness of the importance of antimicrobial resistance has increased among health workers who, with growing frequency, face difficult to treat infections. These difficulties sometimes become extreme in high-risk departments like intensive care units.

Between 2005 and 2009, the incidence rates of bacteraemia have significantly raised from 146 to 211 episodes per 100,000 inhabitants/years (+45%). Bacteraemia caused by Escherichia coli and Klebsiella pneumoniae grew by 77% and 105%, in parallel with the increase of antimicrobial resistance of these microorganisms. E. coli, which is the most common etiologic agent, produced 40% of the overall increase of bacteraemia during the period 2005-2009.

The single and combined resistance of Enterobacteriaceae increased very rapidly, reaching levels unexpected until a few years ago. In 2009, 22% of K. pneumoniae isolates from blood culture is co-resistant to fluoroquinolones, third generation cephalosporins and aminoglycosides. The alert levels have been overcome for E. coli, the leading cause of bacteraemia and urinary tract infection, which is resistant to three classes of antibiotics in 10% of isolates from blood culture.

In bacteraemia caused by this microorganisms, the prevalence of resistance to third generation cephalosporins, which is largely due to extended spectrum betalactamases (ESBL), was amounting to 23% in 2009. Similar trends are also observed in other infections caused by these organisms (e.g. urinary tract infection). The combined antimicrobial resistance infections affect not only small subgroups of high risk patients, but a growing number of individuals of lesser complexity of care for whom treatment options are reduced, with the frequent need of prescribing carbapenems (imipenem, meropenem and ertapenem). These antibiotics are now used as a reference therapy in severe Gram-negative infections acquired in hospital but their effectiveness is threatened by the emergence of new resistance mechanisms such as production of carbapenemase (eg KPC, VIM and NDM-1 ). While in Italy carbapenemase-producing enterobacteria are still relatively infrequent, there is already evidence of supra-regional transmission of K. pneumoniae strains with these characteristics.

The other Gram-negative microorganisms, relevant for the high prevalence of antimicrobial resistance, are Pseudomonas aeruginosa and Acinetobacter baumannii. For the latter, in particular, an outbreak of infections caused by strains resistant to carbapenems has been detected in 2009 in Emilia-Romagna, affecting some hospital trusts.

Among the Gram positive bacteria, Staphylococcus aureus retains a leading role. Despite it remains the second leading cause of bacteraemia, the incidence rates of S. aureus bacteraemia show a less pronounced increase than other microorganisms and the proportion of methicillin resistance (MRSA) remains stable over time although at high levels (37% in 2009). Also Streptococcus pneumoniae shows stable proportion of resistance while a significant reduction in vancomycin resistance was observed in Enterococcus faecium and Enterococcus faecalis isolates from blood culture.

The use of systemic antibiotics, as assessed by regional databases, shows significant increases in recent years. The drugs with a more noticeable absolute increase in hospital and community settings are penicillins associated with betalactamase inhibitors and fluoroquinolones. The progression of use is visible in community (+19% in 2009 vs. 2003) and hospitals (+26% in 2009 vs 2004). In the hospital settings, carbapenems are the antibiotic class showing the biggest relative increase (91% versus 26% average increase), although these drugs are used in a minority of patients.

The implementation of effective measures to counteract the spread of antimicrobial resistance and to reduce the frequency of infections caused by resistant microorganisms is urgent in Emilia-Romagna. The appropriateness of use of antibiotics is therefore a priority in all areas of care. Infection control in hospital, which is based on adoption of universal precautions (e.g. hand washing), recognition and contact isolation of patients infected or colonized by multidrug-resistant organisms and on early identification and containment of epidemics, is also essential. Special attention should be paid to infections by Gram-negative enterobacteria (e.g. E. coli and K. pneumoniae) resistant to carbapenems.