[Use of real time PCR for testing Staphylococcus aureus isolates from the Iaşi Infectious Diseases Hospital]

S. aureus is capable of producing a wide spectrum of diseases and can quickly develop resistance to antibiotics. These features require a careful monitoring of these organisms, by detection of resistance genes and virulence factors, such as Panton-Valentine leukocidin (PVL).

AIM

To determine the presence of mecA and pvl genes in S. aureus isolates by a Real Time-PCR technique (RT-PCR) in order to shorten the detection time.

MATERIALS AND METHODS

We tested 119 strains isolated from pus, using phenotypic methods for methicillin resistance characterization, according to CLSI 2008-2010 guidelines. Detection of mecA and pvl genes was done with hydrolysis probes.

RESULTS

The prevalence rate of methicilin resistant S. aureus (MRSA) was 40,33%, and pvl was detected in 52,08% of those strains. The results of the conventional methods for methicillin resistance detection were validated by those obtained by RT-PCR CONCLUSIONS: RT-PCR is useful in epidemiological surveillance of MRSA and PVL-producing strains and validation of test results for phenotypic resistance to oxacillin.

[Antimicrobial resistance of Streptococcus pneumoniae, 2003-2009]

Streptococcus pneumoniae is the most important respiratory tract pathogen in otitis, sinusitis, bronchitis, and community-acquired pneumonia.

MATERIAL AND METHODS

A total of 155 patient isolates of S. pneumoniae were collected between February 2003 and December 2009 from the Iaşi "Sf. Parascheva" Infectious Diseases Hospital. Susceptibility to antibiotics was assessed by disk diffusion method (CLSI 2003-2008); minimum inhibitory concentrations (MIC) to penicillin and cefotaxime were determined by broth dilution method or E-test method.

RESULTS

Of these isolates, 32.6% were penicillin non-susceptible (MIC > or = 0.12 microg/mL for nonmeningeal isolates before 2008 and all meningeal isolates and MIC > or =2 microg/mL for nonmeningeal isolates after 2008). The percentage of penicillin resistance increased from 0% to a maximum of 50% in 2008. Resistance rates (intermediate and resistant strains) among non-beta-lactam agents were as follows: macrolides, 30.9%; clindamycin, 9%; tetracycline, 34.3%; chloramphenicol, 2.1%; and trimethoprim-sulfamethoxazole, 57.5%. No resistance to vancomycin, linezolid and quinupristin-dalfopristin was observed. Resistance to non-beta-lactam antibiotics was higher among penicillin-resistant strains than penicillin-susceptible strains. Overall, antimicrobial resistance was higher among isolates from respiratory tract comparing with isolates from cerebrospinal fluid and blood.

CONCLUSIONS

Resistance rates with S. pneumoniae have markedly increased in Romania during the last years. Pneumococcal isolates from laşi, Romania are often resistant to beta-lactams and available non-beta-lactam agents, especially if penicillin non-susceptible.

[MecA and pvl genes detection in Staphylococcus aureus strains isolated from lower respiratory tract infections]

Although community-acquired Staphylococcus aureus pneumonia with highly virulent Panton-Valentine leukocidin (PVL)-positive strains, a severe disease with significant lethality, is rare, especially in adult and adolescent patients, recent reports highlight that these infections are on the rise. On the other hand, methicillin-resistant S. aureus (MRSA) is one of the high-risk and potential multi-drug resistant microorganisms.

OBJECTIVES

The aim of this study was to investigate the prevalence of mecA and pvl genes in S. aureus strains isolated from lower respiratory tract infections and to assess the antibiotic resistance profile of these strains.

MATERIAL AND METHOD

The antibiotic susceptibility testing was performed by the disk diffusion method according to CLSI recommendations in 32 consecutive non-repeated S. aureus strains isolated from sputum specimens and endotracheal aspirates of hospitalized patients over the period from January 2005 to December 2009. Only 20 strains (2008-2009) were tested for the presence of mecA and pvl genes by real-time PCR and detection with specific fluorescence probes.

RESULTS

Of the 32 S. aureus isolates, 68.7% were MRSA. MRSA strains showed higher resistance rates to gentamicin, tetracycline, rifampicin, fluoroquinolones comparing to the methicillin susceptible ones. Only one strain produced pvl; it was isolated from a 7 year old child with lethal sepsis with pulmonary and meningeal secondary localisations.

CONCLUSIONS

Glicopeptides and linezolid are therapeutic options indicated in the treatment of staphylococcal pneumonia produced either by MRSA strains or pvl positive S. aureus strains.

[Gamma interferon testing in blood and cerebrospinal fluid--rapid method for the diagnosis of tuberculous meningitis]

AIM

To evaluate the benefit of this early method of diagnosis of tuberculous meningitis, gamma-interferon levels comparatively in blood and cerebrospinal fluid (CSF).

MATERIAL AND METHOD

We have studied 50 patients with tuberculous meningitis admitted in the Clinic of Infectious Diseases Iaşi between 2006-2007, from the epidemiological, clinical, diagnosis and therapeutical points of view.

RESULTS

Tuberculous meningitis was more frequent in males, with a mean ration of 2.5. The age of patients varied between 2 and 78 years of age, with a mean value of 30.5 years. 35.6% of patients were children. In 32 cases the meningeal infection was secondary, disseminated from a primary site, most frequently from the lungs (68,7%). The bacteriologic confirmation was through culture in 13.3%, with an average of 23.4 days of incubation. In whole blood the sensitivity Quantiferon TB Gold assay (QTF) was 78.57%. In CSF the specificity was higher than in blood (96.1 vs. 88.4%), having a positive prediction value over 90%. Antituberculous therapy prior to QTF testing had a negative impact, 50 to 6 cases having negative QTF results.

CONCLUSION

The performance indicators of TB Gold Quantiferon Test in serum or CSF are high, being more sensitive and rapid than the direct exam of CSF or BK culture.