Objectives:

S. maltophilia is an important nosocomial pathogen. The number of S. maltophilia infections has dramatically increased in recent years. Long-term hospitalisation, antimicrobial pressure and presence of induelling catheters are serious predisposing factors for the disease. Also most of these strains are inherently and highly resistant to antibiotics. We conducted a 4-year review of episodes of colonisation or infection due to S. maltophilia in order to study the epidemiology and resistance profile of the microorganism.

Methods:

During a 4-year period (2000–2003) S. maltophilia was isolated from 82 clinical specimens from 70 patients in our hospital. All isolates were identified by API or VITEK-II system (Biomerieux, France). Susceptibility testing was performed by disc-diffusion method according to NCCLS guidelines. Nineteen antibiotics of all groups were tested. Also in some cases medical records of patients were reviewed.

Results:

Clinical samples were various and mostly of the respiratory tract. In descending order other samples were blood, wounds, catheters, urine, drainage fluids. Thirty-eight of 82 (31.1%) specimens, 32 patients, were from the ICU and concerned mostly elderly and intubated patients. Most of these isolates were from the respiratory tract and from a polymicrobial culture. The rest 44 of 82 (36%) specimens, 38 patients, were from different wards (36 of 38) and outpatients (two of 38). As to the susceptibility results to antimicrobial agents, all isolates were resistant to several antibiotics, thus multiresistant. The most active antibiotics against S. maltophilia were the newer fluoroquinolones ciprofloxacin and pefloxacin (71.5%). The combination of Ticarcillin–clavulanic acid was the second most active antibiotic tested (62.3%) followed by Trimethoprim–sulphomethoxazol (42.9%). Another important finding was that susceptibility to ceftazidime showed to decrease through the study period. In 2000 it was 34.6% and in 2003 decreased to 14.3%. All other isolates showed no or poor sensitivity. Also of importance was that one recently isolated clinical strain from an ICU patient was found to be resistant to all 19 antibiotics tested.

Conclusions:

We demonstrated that fluoroquinolones are most active against clinical strains of S. maltophilia followed by Ticarcillin–clavulanic acid that showed good sensitivity. Also the emergence of a strain resistant to all antibiotics tested is a worrying event and has to be taken under concern.