Patterns of antibiotic resistance in pathogens causing respiratory tract infections: results of the 2002–2003 PROTEKT Italy survey

Abstract number: 1134_03_229

Marchese A., Ardito F., Stefani S., Fadda G., Nicoletti G., Schito G.C.

Objective:  

PROTEKT Italy, an extension of PROTEKT International Survey, is an ongoing 3-year surveillance study established to assess the susceptibility of community-acquired respiratory pathogens circulating in this Country.

Methods:  

52 (year 1: 2002) and 46 (year 2: 2003) Clinical Microbiology Laboratories provided 1056 and 1086 S. pyogenes, 848 and 798 S. pneumoniae, 463 and 518 methicillin-susceptible S.aureus (MSSA), 317 and 349 H.influenzae, 207 and 196 M. catarrhalis respectively. In vitro susceptibility to 20 (year 1) and 19 (year 2) antibiotics was determined according to NCCLS-approved microdilution methods and breakpoints (2004).

Results:  

High rates of macrolide resistance (30.0%, year 1) and (34.0%, year 2) were observed in S.pyogenes. Telithromycin (92.7%–92.8% susceptibility) was active on the great majority of these macrolide-refractory strains. Total pneumococcal penicillin-resistance was stable during the study period ranging from 23.7% to 23.4%, while lack of susceptibility to macrolides increased from 40.0% to 43.4%. The most active drugs were: telithromycin (99.7–99.1%), levofloxacin (97.3–97.1%), rifampin (96.7–98.9%), amoxicillin (93.8–96.6%) and ceftriaxone (88.9–93.7%). Percentages of ampicillin-resistance in H. influenzae were 26.5% (year 1) and 20.6% (year 2). For the first time in 2003 two ampicillin-resistant beta-lactamase negative (0.6%) isolates were recovered. High rates of resistance were found for clarithromycin (36.9–25.7%) and co-trimoxazole (13.6–14.1%). The remaining drugs tested (ciprofloxacin, levofloxacin, moxifloxacin, azithromycin, telithromycin, amoxicillin-clavulanate, chloramphenicol, tetracycline, 2nd and 3rd generation cephalosporins) were highly active: 100–94.6% of susceptible strains. In M. catarrhalis the susceptibility rates ranged from 22.7–18.9% (ampicillin) and 77.3–81.1% (co-trimoxazole) to 100% (amoxicillin-clavulanate, ceftriaxone, cefixime, telithromycin, azithromycin, ciprofloxacin, levofloxacin and moxifloxacin). Against MSSA the most active drugs (100%-92% susceptibility) were teicoplanin, rifampin, co-trimoxazole, ceftriaxone, cefaclor, telithromycin and levofloxacin.

Conclusions:  

Antibiotic resistance among community-acquired respiratory pathogens circulating in Italy is on the rise in comparison to the values described in previous National Surveys (1997–2000). Globally, telithromycin, levofloxacin, amoxicillin-clavulanate and ceftriaxone are the most active drugs.