Antimicrobial Susceptibility of Respiratory Isolates of Enterobacteriaceae and Staphylococcus aureus in Italy: Incidence and Trends Over the Period 1997–1999

Abstract

The antibiotic susceptibility of members of the family Enterobacteriaceae and of Staphylococcus aureus strains isolated from the respiratory tract was assessed over the period 1997-1999 as part of the Italian Epidemiological Observatory survey sponsored by the Smith-Kline Foundation. A standardised method was used to determine the MICs of 22 antibiotics against isolates of Klebsiella pneumoniae (n=870), Escherichia coli (n=684), Enterobacter cloacae (n=342), Enterobacter aerogenes (n=187) and Serratia marcescens (n=135) as well as the MICs of 11 antibiotics against isolates of Staphylococcus aureus (n=1,606). Overall, the susceptibility rate of Enterobacteriaceae isolates was > or = 90% to 5 agents (meropenem, imipenem, amikacin, cefepime and gentamicin); 89-80% to 2 agents (ciprofloxacin and tobramycin); and <80% to 11 agents (cefotaxime, piperacillin-tazobactam, trimethoprim-sulfamethoxazole, cefetamet, ceftriaxone, ceftazidime, aztreonam, ticarcillin-clavulanate, tetracycline, piperacillin, cefuroxime, chloramphenicol, ticarcillin, amoxicillin-clavulanate and amoxicillin). During the 3-year monitoring period, antibiotic susceptibility increased in Klebsiella pneumoniae against amoxicillin-clavulanate, in Escherichia coli against third-generation cephalosporins and aztreonam, in Enterobacter aerogenes against amoxicillin and piperacillin-tazobactam and in Serratia marcescens against most of the antibiotics. In contrast, Enterobacter cloacae showed a tendency to develop resistance to cefetamet, amikacin and ciprofloxacin. Of the total number of Staphylococcus aureus strains, 38% were methicillin resistant. Nearly 80% of the methicillin-resistant strains displayed a multiresistance pattern (additional resistance to 2 or more non-beta-lactam antibiotics). Rates of susceptibility of particular species (Klebsiella pneumoniae, Escherichia coli, Staphylococcus aureus) were compared using strains from different geographical areas of Italy (northern, central and southern) and from different nosocomial areas (outpatients, intensive care unit [ICU] inpatients, non-ICU inpatients). Susceptibility of Klebsiella pneumoniae to several antibiotics was lower in southern Italy, whereas the incidence of methicillin-resistant strains was higher in northern and central Italy. The susceptibility of Escherichia coli was similar in all three areas. No significant differences in susceptibility of Klebsiella pneumoniae or Escherichia coli were found between strains from inpatients and outpatients or from inpatients admitted to ICU and non-ICU units. The incidence of methicillin-resistant Staphylococcus aureus was higher in ICU inpatients (52%) than in non-ICU inpatients (38%) and lower in outpatients (19%) than in inpatients.

Novel Tetracycline Resistance Determinant Isolated from an Environmental Strain of Serratia marcescens

“…We first showed by biochemical assays and by 16S rRNA gene sequencing that the environmental organism was S. marcescens. Tetracycline resistance is reportedly abundant in S. marcescens (6,12,15,38), although with the exception of the tet(B) allele found on the broad-host-range conjugative plasmid R478 (13), the resistance determinants have not been characterized. In addition to tet(B), S. marcescens also contains tet(A), tet(C), and tet(E) alleles (7), including tet(E) found in S. marcescens isolated from a polluted aquatic environment (4).…”

“…S. marcescens is ubiquitous in nature and can be found in water, soil, plants, insects, and animals (1). While tetracycline resistance is reportedly widespread in S. marcescens (6,12,15,38), the only characterized S. marcescens tetracycline resistance determinant is the Tet(B) protein expressed by the conjugative plasmid R478 (13).…”

Serratia Infections: from Military Experiments to Current Practice

“…In a study from Beirut, Lebanon, from 1994, Araj and others reported that 56% of Serratia species recovered from a variety of clinical sites were resistant to trimethoprim-sulfamethoxazole, compared to 12 to 48% resistance in Saudi Arabia, 50% resistance in Kuwait, and no resistance in the United States (13). From 1997 to 1999, S. marcescens isolates recovered from respiratory sites were 64 to 75% sensitive to trimethoprim-sulfamethoxazole in Italy (134). National antimicrobial resistance surveillance in Taiwan from the year 2000 indicated that 62% of S. marcescens isolates were resistant to trimethoprim-sulfamethoxazole (232).…”

Antimicrobial Resistance of Gram-Negative Bacteria Isolated from Lower Respiratory Tract Specimens of Hospitalized Patients

“…Alt solunum yolu infeksiyonları, hastanede yatarak tedavi gören hastalarda önemli morbidite ve mortalite nedenidir (1,2).…”

“…Pseudomonas aeruginosa ve Acinetobacter baumannii başta olmak üzere Gram-negatif bakteriyel patojenler nozokomiyal alt solunum yolu infeksiyonlarının önemli bölümünden sorumludurlar (1)(2)(3).…”