Comparison of in Vitro Activity of Doripenem versus Old Carbapenems against Pseudomonas Aeruginosa Clinical Isolates from both CF and Burn Patients.

PURPOSE: The antimicrobial activity of doripenem in comparison of imipenem, meropenem and ertapenem among Pseudomonas aeruginosa isolated from burn and Cystic Fibrosis (CF) patients were determined. METHODS: Metallo-ß-lactamase (MBL) genes in imipenem non susceptible P. aeruginosa isolates were detected using PCR method. The in vitro susceptibilities of doripenem, imipenem, meropenem and ertapenem were determined by Etests. MIC50 and MIC90 for corresponding antibiotics were determined individually in burn and CF isolates. RESULTS: Among isolates which were resistant to imipenem, 16 isolates were positive for the bla IMP gene. All isolates had no bla VIM gene. All MBL producing isolates were excluded. MIC50/MIC90 of doripenem in CF and burn isolates were 0.75/>32 and >32/>32 mg/L respectively. The corresponding values for imipenem in CF and burn isolates were 2/>32 and >32/>32 mg/L, respectively. CONCLUSION: The susceptibility rate of doripenem is higher than that of imipenem and meropenem among P.aeruginosa isolated from CF patients, whereas, there is no difference between the efficiency of doripenem and old carbapenems in non MBL producing P.aeruginosa isolates in burn patients.

Study of the carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii: comparison of burn and non-burn strains.

We examined the prevalence of various carbapenem resistance mechanisms in clinical isolates of Acinetobacter baumannii collected from hospitalized burn and non-burn patients. Antimicrobial susceptibility testing was performed for 43 burn and 32 non-burn isolates. Carbapenem resistance genes were identified and repetitive extragenic palindromic PCR (REP-PCR) was used to define clonal relatedness. CarO disruption was investigated by PCR and its expression analyzed by real time reverse transcription-PCR. Of the sixty-four (85%) carbapenem resistant A. baumannii isolates, 42 (66%) and 22 (34%) strains were recovered from burn and non-burn patients, respectively. Isolates were categorized into 6 major REP-PCR patterns; with the highest prevalence of non-burn and burn isolates in pattern A (63%) and B (35%), respectively. Prevalence of blaOXA-23 was 68% and isolates harbored this element belonged to all REP clusters. The blaOXA-40-like was detected in 49% of isolates, with higher prevalence among burn isolates. Three of the four isolates lacked carO gene were cultured from burn patients and level of the carO expression was decreased in carbapenem resistant isolates. These findings show that blaOXA-23 is widely distributed in carbapenem resistant A. baumannii isolates and other resistance mechanisms such as blaOXA-40-like and loss or decreased carO expression could be added in burn strains.

Detection of metallo-ß-lactamase-encoding genes among clinical isolates of Pseudomonas aeruginosa in northwest of Iran.

The prevalence of metallo-ß-lactamase (MBL) production among 104 clinical isolates of Pseudomonas aeruginosa from northwest of Iran was investigated by phenotypic and polymerase chain reaction (PCR) methods. Thirty-nine (37.50%) of isolates were MBL positive by double-disk synergy test. Results of PCR revealed that 18 (17.31%) and 6 (5.77%) imipenem nonsusceptible isolates of P. aeruginosa carried bla(VIM) and bla(IMP) genes respectively, while 92.4% (62/67) of isolates contained class 1 integron gene. This is the first report of MBL-producing P. aeruginosa from northwest of Iran.

Infection with Mycoplasma pneumoniae is not related to asthma control, asthma severity, and location of airway obstruction.

BACKGROUND: Mycoplasma pneumoniae is an organism that reportedly has a strong relationship to asthma. However, asthma severity and location of airway obstruction have not been compared between asthmatic patients with and without evidence for remote mycoplasma infection. OBJECTIVES: The aim of this research was to study the relationship between previous M. pneumoniae infections in asthmatic patients and presence of any predilection for the involvement of central or peripheral airways, the severity of the disease, and asthma control. METHODS: Sixty-two patients with asthma were assessed by a validated asthma control test (ACT). All patients underwent spirometry and lung volume studies by body plethysmography. The forced expiratory volume in 1 second (FEV(1)), forced vital capacity (FVC), total lung capacity (TLC), residual volume (RV), and functional residual capacity (FRC) were measured. An oropharyngeal swab was obtained for polymerase chain reaction analysis to detect the mycoplasma antigen. Moreover, blood samples were obtained to measure the titration of antimycoplasma immunoglobulin M (IgM) and IgG antibodies. The asthmatic patients with a positive IgG for mycoplasma and negative PCR and negative IgM antibody were considered to have remote history of mycoplasma infection. The relationship between the asthma control using ACT score and pulmonary function variables were compared in patients with and without evidence for remote mycoplasma infection. RESULTS: The incidence of postnasal drip was higher among the patients with asthma who had no evidence for remote mycoplasma infection (61.3% vs 32%, P = 0.035). The median ACT score was 16.5 (11-22) and 20 (13.75-24) in patients with and without remote M. pneumoniae infection, respectively (P > 0.05). In addition, the medians of the predicted values of the pulmonary function test parameters (FEV(1), FEV(1)/FVC, FRC, FRC/TLC, RV/TLC, maximal mean expiratory flow 25%-75%, forced expiratory flow [FEF] 50%, and FEF 75%) and actual values of 5 Hz and 20 Hz resistance were not different between asthmatic patients with and without evidence of mycoplasma infection (P > 0.05). CONCLUSIONS: The present study revealed that the asthma control status and parameters of lung function tests did not differ between asthmatic patients with and without evidence of chronic M. pneumoniae infection. The latter indicates the similar location of airway obstruction and comparable severity of asthma between the two groups.