title: An observational study on the epidemiology of respiratory tract bacterial pathogens and their susceptibility to four injectable beta-lactam antibiotics: piperacillin, piperacillin/tazobactam, ceftazidime and ceftriaxone.
abstract: Bacterial infections of the respiratory tract account for a large proportion of total medical consultations in general practice. In recent years, antibiotic resistance has increased alarmingly in a number of bacterial species that are common causes of these infections. The aim of this observational study was to determine the antibiotic resistance of microbial agents isolated from patients with acute or acutely exacerbated respiratory infections. Subjects recruited as potential sources of bacteria were either outpatients seen in a number of specialized clinics and hospital practices, or hospitalized patients. Overall, 648 consecutive patients (67% male, mean age 48.1+/-27.0 years) with infection of the upper or lower respiratory tract were observed during a 13-month period. A total of 551 pathogenic microbial strains were isolated and tested for their in vitro susceptibility to piperacillin, piperacillin/tazobactam, ceftazidime, and ceftriaxone. Among all isolates, the four most frequent pathogens were Pseudomonas aeruginosa (132 isolates, 24%), Streptococcus pyogenes (99 isolates, 18%), Staphylococcus aureus (93 isolates, 17%), and Klebsiella pneumoniae (46 isolates, 8%). The susceptibility of gram-positive isolates ranged from 97.5% to 95.1%, and no remarkable difference was found in the antibacterial activity of tested b-lactam antibiotics. The susceptibility of gram-negative isolates to piperacillin and piperacillin/tazobactam was also similar: 96.5% and 97.1%, respectively. In contrast, differences were found between piperacillin (or piperacillin/tazobactam) and either ceftazidime (p=0.003) or ceftriaxone (p<0.0003) in gram-negative isolates. We conclude that, despite the extensive use of beta-lactam antibiotics (piperacillin, ceftazidime, and ceftriaxone) in medical practice during the past three decades, the susceptibility of the most common pathogens involved in the etiology of upper and lower respiratory tract infections to these antibiotics is still high. In particular, bacterial resistance developed by gram-positive organisms against piperacillin is negligible and not alarming.
authors.affiliation: Department of Pharmacology, University of Milan, Milano, Italy. f.fraschini@unimi.it
authors.forename: F
authors.initials: F
authors.lastname: Varotto
authors.forename: G D
authors.initials: GD
authors.lastname: Maria
authors.forename: R
authors.initials: R
authors.lastname: Azzaro
authors.forename: P
authors.initials: P
authors.lastname: Bellissima
authors.forename: R
authors.initials: R
authors.lastname: Amato
authors.forename: V
authors.initials: V
authors.lastname: Fogliani
authors.forename: G
authors.initials: G
authors.lastname: Muscianisi
authors.forename: S
authors.initials: S
authors.lastname: Vitale
authors.forename: G
authors.initials: G
authors.lastname: Girbino
authors.forename: F
authors.initials: F
authors.lastname: Andò
authors.forename: P
authors.initials: P
authors.lastname: Laganà
authors.forename: S
authors.initials: S
authors.lastname: Delia
authors.forename: C
authors.initials: C
authors.lastname: Jacoviello
authors.forename: G
authors.initials: G
authors.lastname: Maierna
authors.forename: A
authors.initials: A
authors.lastname: Pezza
authors.forename: I
authors.initials: I
authors.lastname: Covelli
authors.forename: M
authors.initials: M
authors.lastname: Magrì
authors.forename: G
authors.initials: G
authors.lastname: Napoletano
authors.forename: A
authors.initials: A
authors.lastname: Rossi
authors.forename: P
authors.initials: P
authors.lastname: Marone
authors.forename: C
authors.initials: C
authors.lastname: Sanguinetti
authors.forename: R
authors.initials: R
authors.lastname: Pela
authors.forename: D
authors.initials: D
authors.lastname: Tedeschi
authors.forename: B
authors.initials: B
authors.lastname: Viola
authors.forename: S
authors.initials: S
authors.lastname: Cicciarella
authors.forename: G
authors.initials: G
authors.lastname: Messina
authors.forename: S
authors.initials: S
authors.lastname: Rizza
authors.forename: F
authors.initials: F
authors.lastname: Fraschini
authors.forename: V
authors.initials: V
authors.lastname: Sabato
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002442:Ceftazidime / Q000494:pharmacology; D002443:Ceftriaxone / Q000494:pharmacology; D004198:Disease Susceptibility / Q000453:epidemiology; D005260:Female; D006088:Gram-Negative Aerobic Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D006094:Gram-Positive Bacteria / Q000187:drug effects* / Q000302:isolation & purification; D006801:Humans; D008297:Male; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D015337:Multicenter Studies as Topic; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D010878:Piperacillin / Q000494:pharmacology; D012141:Respiratory Tract Infections / Q000453:epidemiology* / Q000382:microbiology; D000078142:Tazobactam
chemical_list: D000900:Anti-Bacterial Agents; D002443:Ceftriaxone; D010397:Penicillanic Acid; D002442:Ceftazidime; D000078142:Tazobactam; D010878:Piperacillin