Evaluation of frxA and rdxA gene mutations in clinical metronidazole resistance Helicobacter pylori isolates.

Metronidazole resistance is an important factor related to failure in the treatment of Helicobacter pylori. The mutation in the rdxA and frxA genes is the most important cause of resistance to metronidazole. Since the resistance rate of metronidazole is high in our region, we decided to assess the frequency of these mutations among H. pylori clinical isolates. Antral gastric biopsy specimens were cultured and minimal inhibitory concentrations (MICs) of metronidazole were determined by the E-test method. The rdxA and frxA genes were amplified in all isolates through the use of PCR with the specific primers. PCR products were purified for sequencing. The resultant sequences were compared with the wild type reference sequences to find any possible mutations. According to our findings, the rate of metronidazole resistance was 77%, with the MICs ranging from 0.25-1 µg/ml for metronidazolesensitive group and from 16-256 µg/ml for resistance group. H. pylori isolates containing a single mutation in rdxA or frxA genes demonstrated a low MIC (8-16 µg/ml), while those containing mutations in both genes showed a higher MIC (32-256 µg/ml). In this study, all resistant H. pylori isolates contained single or multiple nucleotide substitutions in the mentioned genes. Nevertheless, no nucleotide substitutions were found in the sensitive clinical isolates. The results of our study showed that the mutations in rdxA are mostly related to metronidazole resistance, and mutations in frxA are able to enhance H. pylori resistance.

Molecular screening of virulence genes in high-level gentamicin-resistant Enterococcus faecalis and Enterococcus faecium isolated from clinical specimens in Northwest Iran.

PURPOSE: The present study screened clinical isolates of Enterococcus faecalis and Enterococcus faecium to determine the prevalence of high-level gentamicin-resistant enterococci and the potential virulence genes among them. MATERIALS AND METHODS: Clinical enterococcal isolates were obtained from three university teaching hospitals in Northwest Iran. Isolated enterococci were identified phenotypically followed by antibiotic susceptibility testing. Multiplex PCR was performed for the detection of genus, species-specific targets, gentamicin resistance, and potential virulence genes. RESULTS: Of 220 enterococcal isolates, 133 (60.45%) isolates were identified as high-level gentamicin-resistant. Of these isolates, 79 (59.4%) and 54 (40.6%) were E. faecalis and E. faecium, respectively. All high-level gentamicin-resistant strains carried aac(6')Ie-aph(2″)Ia. Of 220 isolates, 65.9% were positive for gelE, and 55%, 53.6%, 51.8%, and 49.5% of isolates were positive for cpd, asa1, ace, and esp, respectively. Phenotypically detected ß-haemolytic strains (19.54%) were found to possess cylL ls MAB. CONCLUSION: The study revealed that high-level gentamicin-resistance was related to the presence of aac(6')Ie-aph(2″)Ia. Isolated enterococci harboured potential virulence determinants, which were more common among E. faecalis than among E. faecium strains.

Infection and systemic inflammation, not ammonia, are associated with Grade 3/4 hepatic encephalopathy, but not mortality in cirrhosis.

BACKGROUND & AIMS: Patients with cirrhosis are prone to infection which is a frequent precipitant of hepatic encephalopathy (HE). Clinical studies have examined the importance of inflammation and infection in modulating the manifestation of symptoms of HE in acute liver failure and patients with cirrhosis and minimal/low grade HE. It would be logical to presume that this relationship persists in patients who develop severe HE in cirrhosis although this has not been examined to date. METHODS: We report the findings of a prospective audit of 100 consecutive patients with cirrhosis admitted between Jan 2000 and March 2008 to a liver Intensive Care Unit (ICU) where HE was the primary indication for admission (59% Grade 3; 41% Grade 4). Haematological and microbiological data were collected at ICU admission, and organ scores and outcomes were recorded. RESULTS: 46% of patients had positive cultures taken within ± 48h from admission to ICU [25% blood] and a further 22% were culture negative but had evidence of systemic inflammation (SIRS). SIRS score (p=0.03) and SOFA score (p=0.006) were significantly higher in those patients with Grade 4 HE, who were also less likely to survive (p<0.001). HE grade/coma score did not correlate with ammonia, biochemistry or MELD score. Fifty-two percent of patients survived their ICU stay while the remainder developed progressive multiorgan failure and died; 38% survived to discharge, and 16% were transplanted. CONCLUSIONS: These data support an association between infection/SIRS and not ammonia, in patients with cirrhosis that develop severe HE. The presence or absence of infection/SIRS did not determine survival.

Class 1 integron and Imipenem Resistance in Clinical Isolates of Pseudomonas aeruginosa: Prevalence and Antibiotic Susceptibility.

BACKGROUND AND OBJECTIVES: Pseudomonas aeruginosa is one of the most important causative agents of nosocomial infections especially in ICU and burn units. P. aeruginosa infections are normally difficult to eradicate due to acquired resistance to many antibiotics. Recent appearance of carbapenem resistant P. aeruginosa isolates is considered a major healthcare problem. The present study was conducted to detect class 1 integron and antibiotic susceptibility profiles of imipenem-sensitive and resistant clinical isolates of P. aeruginosa. MATERIALS AND METHODS: Antibiotic susceptibility profiles and minimum inhibitory concentration against imipenem was studied in 160 clinical isolates of P. aeruginosa by disk agar diffusion method and Etest, respectively. Detection of class 1 integron was performed by the PCR method. Demographic and microbiological data were compared between imipenem susceptible and non-susceptible isolates by the SPSS software. RESULTS: PCR results showed that 90 (56.3%) of P. aeruginosa isolates carried class 1 integron. Antibiotic susceptibility results revealed that 93 (58.1%) were susceptible and 67 (41.9%) were non-susceptible to imipenem. Comparison of antibiotic susceptibility patterns showed high level of drug resistance among imipenem non-susceptible isolates. We found that MDR phenotype, presence of class 1 integron and hospitalization in ICU and burn units were significantly associated with imipenem non-susceptible isolates. CONCLUSION: The high frequency of imipenem resistance was seen among our P. aeruginosa isolates. Since carbapenems are considered as the last drugs used for treatment of P. aeruginosa infections, it is crucial to screen imipenem non-susceptible isolates in infection control and optimal therapy.