Detection of Aminoglycoside and Macrolide Resistance Mechanisms in Methicillin-Resistant Staphylococcus Aureus.

Methicillin-resistant Staphylococcus aureus can become resistant to many different classes of antibiotics. Objective: To characterize aminoglycoside and macrolide resistance mechanisms in MRSA strains in relation to antibiotic susceptibility patterns. Materials and methods: We tested 86 MRSA strains using multiplex PCR for detection of genes mecA, aac(6')-Ie/aph(2″), ant(4')-Ia, aph(3')-IIIa, ermA, ermC and msrA. Results: There was a prevalence of msrA (32.5%), ermC (30.2%) and aph(3')-IIIa (61.6%) genes, which are less frequently reported in MRSA. Most msrA genes was detected in PVL positive strains (92.8%) and was associated only with non-MDR strains, while ermC genes were associated with MDR strains. PVL producing strains were characterized by the presence of aph(3')-IIIa (93.1%) and msrA genes (93.1%), being phenotypically susceptible to clindamycin. Conclusions: Detection of aminoglycoside and macrolide resistance genes allowed us to establish the concordance between genotypic and phenotypic methods and to correlate the presence of certain resistance genes with the type of circulating strain and the production of virulence factors.

Triplex real-time pcr for detection of methicillin-resistant staphylococcus aureus and Panton-Valentine leukocidin in North-East Romania.

UNLABELLED: The aim of the present study was to investigate S. aureus isolates for the presence of methicillin-resistance and Panton-Valentine leukocidin (PVL) genes and to further characterize positive strains by means of antibiotic resistance patterns. MATERIAL AND METHODS: We used a triplex Real-Time PCR method for simultaneous detection of nuc, mecA and pvl genes in clinical isolates from 188 patients admitted to "Sf. Parascheva" Infectious Diseases Hospital lasi, during a 3 year period (2008-2010). RESULTS: The study revealed a relatively high rate of PVL-producing strains (23.93%), mainly community-associated (CA-MRSA) (51.11%). Most pvl-positive CA-MRSA isolates were resistant to erythromycin (91.3%), but none was resistant to clindamycin, fluoroquinolones, rifampicin, chloramphenicol or fusidic acid. CONCLUSIONS: Antibiotic susceptibility testing showed a high rate of multidug-resistance among strains classified as CA-MRSA (54.83%), but not among PVL-producers (4.44%). Although resistance to fusidic acid was previously proposed as a marker for PVL-producing CA-MRSA, our data suggest that we cannot rely on resistance to fusidic'acid to screen for PVL-producing CA-MRSA in our setting.

[Antimicrobial resistance of Streptococcus pneumoniae, 2003-2009]. / Rezistenta la antibiotice a Streptococcus pneumoniae, 2003-2009.

UNLABELLED: 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 Iasi "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 lasi, Romania are often resistant to beta-lactams and available non-beta-lactam agents, especially if penicillin non-susceptible.

[Use of real time PCR for testing Staphylococcus aureus isolates from the Iasi Infectious Diseases Hospital]. / Utilizarea real time PCR pentru testarea izolatelor clinice de Staphylococcus aureus din Spitalul Clinic de Boli Infectioase Iasi.

UNLABELLED: 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.

[MecA and pvl genes detection in Staphylococcus aureus strains isolated from lower respiratory tract infections]. / Detectarea genelor mecA si pvl la tulpini de Staphylococcus aureus izolate din infectii ale tractului respirator inferior.

UNLABELLED: 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]. / Dozarea gama-interferonului în sânge si în lichid cefalorahidian--metoda rapida de diagnostic a meningitei tuberculoase.

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 Iasi 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.