[Review of the effectiveness of an empirical antibiotic therapy in suspected ventilator-associated pneumonia]. / Ocena skutecznosci rekomendowanych scheatów antybiotykoterapii emprirycznej VAP w oparciu o analize in vitro lekowraziliwosci glównych patogenów.

BACKGROUND: Ventilator-associated pneumonia (VAP) occurs in approximately 10-20% of mechanically ventilated patients, and is associated with an extremely high mortality rate (up to 70%). The purpose of the study was to determine the susceptibility spectrum of Klebsiella, Pseudomonas and Acinetobacter strains isolated from VAP patients. METHODS: We analysed 81 strains of microorganisms isolated from bronchoalveolar lavages (BAL) of VAP patients. The minimal inhibitory concentrations (MIC) of antibiotics recommended for empirical therapy were determined using an automated VITEK 2 system, and for the MIC of doripenem - the Etest assay. Results were analysed following the guidelines of the Clinical and Laboratory Standards Institute. RESULTS: For infections caused by the group of bacteria under investigation, the most successful regimen was monotherapy with carbapenems (doripenem, meropenem and imipenem). Cephalosporins (cefepim and ceftazidim) were less effective in vitro. The worst results were obtained with the combination of piperacillin/tazobactam with aminoglycosides (amikacin or gentamicin) or fluoroquinolones (ciprofloxacin). CONCLUSIONS: Antibiotic monotherapy proved to be more effective in VAP patients than combined therapy; the best results were achieved with carbapenems. Doripenem showed strong activity in vitro against P. aeruginosa and Klebsiella sp. and should be considered for empirical VAP therapy; however, carbapenems may be less effective against Acinetobacter baumannii. The wide range of bacteria, and their broad range of susceptibility to antibiotics, suggests the need for modification of current recommendations.

Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) in Poland: further evidence for the changing epidemiology of MRSA.

This study reports the isolation of CA-MRSA strain which was found to colonize the nasal mucosa of a patient undergoing haemodialysis treatment. The MRSA was subjected to molecular analysis by Pulsed Field Gel Electrophoresis (PFGE), multiplex PCR assay for staphylococcal cassette chromosome mec (SCCmec) typing, and PCR detection of the pvl gene encoding for Panton-Valentine leukocidin. The analyzed MRSA harbored the SCCmec type IV and the pvl gene-two unique genetic markers of CA-MRSA. The PFGE pattern of the strain corresponded to the common European CA-MRSA (MLST Type ST80). Moreover, the strain was only resistant to beta-lactam agents and tetracycline. This study adds further evidence for the changing epidemiology of MRSA and indicates the ability of CA-MRSA to affect persons with established risk factors in addition to previously healthy individuals.

Characterisation of Staphylococcus aureus nasal and skin carriage among patients undergoing haemodialysis treatment.

The aim of the study was to investigate the rate of Staphylococcus aureus nasal and skin carriage in patients undergoing haemodialysis. The cultured staphylococcal isolates were subsequently characterized by molecular methods. The study group comprised 43 haemodialysed patients from whom nasal and skin swabs from the vascular access sites were collected. The identification of staphylococcal isolates and antibiotic susceptibility testing were performed on the basis of conventional diagnostic procedures. The staphylococci were further characterized using Pulsed-Field Gel Electrophoresis (PFGE). S. aureus was cultured from 12 (27.9%) patients. Only one (8.3%) patient was colonized with the microorganism both in the anterior nares and the vascular access site representing a single strain, as evidenced by PFGE analysis. Antibiotic susceptibility testing identified one (7.6%) methicillin-resistant S. aureus (MRSA) strain. PFGE typing identified several S. aureus genotypes with the lack of one specific strain responsible for colonization. However, it should be noted that among two (A and D) PFGE patterns genetically indistinguishable and closely related isolates (two isolates for each pattern) were identified. The obtained results revealed a relatively low rate of S. aureus carriage accompanied by low methicillin resistance rate and a significant genetic diversity of cultured isolates with the lack of one predominant strain responsible for colonization.

The investigation of Staphylococcus aureus and coagulase-negative staphylococci nasal carriage among patients undergoing haemodialysis.

The frequency of nasal staphylococcal colonization among haemodialysed patients was investigated. The swabs were collected in 1998 and 2004 from 28 and 43 patients, respectively. Staphylococcus aureus colonization rates were 57.1% and 27.9% in 1998 and 2004, respectively. Twenty-six coagulase-negative staphylococci (CNS) isolates were cultured: S. epidermidis (21), S. lugdunensis (2), single S. haemolyticus, S. warneri, and S. capitits isolates. One S. aureus and 10 CNS isolates were methicillin resistant. The methicillin-resistant S. aureus (MRSA) was resistant to beta-lactams, tetracycline, and harbored the pvl gene encoding the Panton-Valentine leukocidin. The decrease in S. aureus colonization at 6-year interval was observed. The presence of the pvl gene and a favorable antibiotic susceptibility pattern of the MRSA suggest that the isolate was a member of community-acquired MRSA (CA-MRSA). Concluding, screening of haemodialysed patients for staphylococcal colonization accompanied by characterization of cultured isolates is important to understand its epidemiology and to develop infection prevention measures and treatment strategies.