title: Antibiotic susceptibility of Legionella pneumophila strains isolated from hospital water systems in Southern Italy.
abstract: OBJECTIVE
  The purpose of this study was to describe the susceptibility of environmental strains of Legionella spp. to 10 antimicrobials commonly used for legionellosis therapy. A study of environmental strains could be useful to timely predict the onset of antibiotic resistance in the environment before it is evidenced in clinical specimens.
  
  
  METHODS
  The minimum inhibitory concentrations (MICs) of 100 environmental Legionella pneumophila (Lpn) strains belonging to serogroups (sgs) 1, 6, 8, and 10 were tested using the E-test methodology on buffered charcoal yeast extract agar supplemented with α-ketoglutarate. The most frequent sgs were selected from those obtained during microbiological surveillance conducted in 2014 in a hospital in Southern Italy. The MICs were read after 2 days of incubation at 35 °C in a humidified atmosphere without CO2.
  
  
  RESULTS
  All isolates were inhibited by low concentrations of fluoroquinolones and macrolides. Rifampicin was the most active drug against the isolates in vitro. All Lpn isolates were inhibited by the following drugs (in decreasing order of their MICs): doxycycline>tigecycline>cefotaxime. The MICs of azithromycin, ciprofloxacin, levofloxacin, moxifloxacin, and tigecycline were significantly lower for Lpn non-sg 1 than Lpn sg 1 isolates.
  
  
  CONCLUSIONS
  Susceptibility testing of Legionella strains to appropriate antibiotics should be performed often to evaluate the possible emergence of resistance, to improve the outcomes of patients, and to reduce the direct costs associated with hospitalization.
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.
authors: Osvalda
authors: O
authors: De Giglio
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.
authors: Christian
authors: C
authors: Napoli
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.
authors: Grazia
authors: G
authors: Lovero
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.
authors: Giusy
authors: G
authors: Diella
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.
authors: Serafina
authors: S
authors: Rutigliano
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy.
authors: Giuseppina
authors: G
authors: Caggiano
authors: Department of Biomedical Science and Human Oncology, Hygiene Section, University of Bari "Aldo Moro", Piazza Giulio Cesare 11, 70124 Bari, Italy. Electronic address: mariateresa.montagna@uniba.it.
authors: Maria Teresa
authors: MT
authors: Montagna
mesh_terms: D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D006761:Hospitals; D007558:Italy; D016952:Legionella pneumophila / Q000187:drug effects*; D008826:Microbial Sensitivity Tests; D014871:Water Microbiology; D014881:Water Supply
chemical_list: D000900:Anti-Bacterial Agents
keywords: E-test; Fluoroquinolones.; Legionella; MIC; Macrolides