Real-time PCR detection of Helicobacter pylori and virulence-associated cagA in nasal polyps and laryngeal disorders

OBJECTIVE

To identify Helicobacter pylori and major virulence factor, cagA, in patients with laryngeal diseases and nasal polyps.

STUDY DESIGN

Cross-sectional study with planned data collection.

SETTING

The study was performed on fresh tissue samples from patients with 32 nasal polyps, 29 normal nasal mucosa, and 27 laryngeal diseases presenting to the Otolaryngology-Head and Neck Surgery department of a major military hospital in Istanbul, Turkey.

SUBJECTS AND METHODS

Tissue specimens were evaluated by in-house polymerase chain reaction (PCR) and real-time PCR for bacterial DNA and by real-time PCR for cagA. The impact of commercial and in-house DNA extraction methods was also evaluated.

RESULTS

H pylori DNA was detected only by real-time PCR in 59.4 percent of nasal polyps, 70.4 percent of nasal mucosa samples, and 58.6 percent of larynx samples. cagA was identified in 78.9, 89.5, and 82.4 percent of positive polyp, nasal mucosa, and larynx samples, respectively. No statistically significant differences were observed between groups. DNA purification methods were equally effective.

CONCLUSION

H pylori DNA is present in nasal polyp and larynx tissues as well as normal nasal mucosa, as detected by a sensitive real-time PCR assay. cagA-positive strains dominate in all groups.

Molecular epidemiology of Blastocystis infections in Turkey

Blastocystis is a very common unicellular intestinal parasite of ubiquitous occurrence. In order to describe the molecular epidemiology of Blastocystis infections in Turkey, 87 isolates from 69 symptomatic and 18 asymptomatic individuals were sequenced. Sequence data were phylogenetically analyzed and statistically tested against unmodifiable risk factors such as gender and age. Blastocystis-positive males were complaining mainly of gastroenteritis, whereas dyspepsia was the chief complaint among Blastocystis-positive females. Blastocystis sp. subtypes detected in the study included subtypes 1, 2, 3 and 4, subtype 3 being the most predominant (75.9%). No association was detected between Blastocystis sp. subtype and symptoms (p>0.365), or between infection intensity and symptoms (p>0.441). There was a tendency of subtype 2 isolates being more common among older study individuals, and subtype 2 isolates were significantly associated with higher parasite abundance (p=0.017). Compared to data from similar studies, the distribution of Blastocystis sp. isolates in Turkey was found to more or less reflect the one seen in other countries, and it was deduced that subtype 3 is generally by far the most common subtype infecting humans, followed by subtypes 1, 2 and 4.

Investigation of aminoglycoside modifying enzyme genes in methicillin-resistant staphylococci

Methicillin-resistant staphylococci may also be resistant to some other antibiotics as well as beta-lactams. In this study, co-existence of resistance to methicillin and aminoglycosides was genetically investigated in staphylococci. A total of 50 staphylococci from in-patients, 17 Staphylococcus aureus and 33 coagulase negative staphylococci (CNS) that contained mecA (gene encoding PBP 2a, an altered penicillin-binding protein) determined by polymerase chain reaction (PCR) were included in the study. Aminoglycoside modifying enzyme (AME) genes were investigated using multiplex-PCR. Aminocyclitol-6'-acetyltransferase-aminocyclitol-2''-phosphotransferase [aac(6')/aph(2'')] gene (encoding bifunctional acetyltransferases/phosphotransferases) was determined in 66% of the isolates, aminocyclitol-4'-adenylytransferase (ant(4')-Ia) gene (encoding phosphotransferases) in 24%, and aminocyclitol-3'-phosphotransferase (aph(3')-IIIa) gene (encoding nucleotidyltransferases) in 8%. Two isolates contained all these three genes. Thirty-six (72%) isolates had at least one of these genes. Three CNS and one S. aureus isolates sensitive to oxacillin had the mecA gene. In conclusion, a high rate of aminoglycoside resistance was determined in methicillin-resistant staphylococci. The aac(6')/aph(2'') was the most frequently detected.

Investigation of erythromycin and tetracycline resistance genes in methicillin-resistant staphylococci

In this study, erythromycin [erm(A) and erm(C)] and tetracycline [tet(K) and tet(M)] resistance genes were investigated by multiplex polymerase chain reaction (PCR) in a total of 56 methicillin-resistant (mecA+) staphylococcal hospital isolates, 28 of which were determined to be Staphylococcus aureus (MRSA) and the other 28 were coagulase-negative staphylococci (MRCNS). Internal control primers amplifying a specific fragment of 16S rDNA of staphylococci were included in the multiplex PCR protocol to ensure the efficacy of amplification and to determine any PCR inhibition. No resistance genes were detected in 5 of 56 (8.9%) isolates in the study. In the study, tet(K) genes were detected widely (42.9%) in MRCNS, whilst tet(M) genes were detected in MRSA (50.0%). Regarding the erythromycin resistance genes, whilst erm(A) genes were detected in most (71.4%) MRSA isolates, detection rates of erm(C) genes were the same (64.3%) both in MRCNS and MRSA. The resistance rates for tetracycline and erythromycin were 57.1% and 78.6%, respectively, in MRSA isolates. In conclusion, in this study, the multiplex PCR technique including an internal control is shown to be a fast, sensitive, reliable, practical, reproducible and economic technique for the detection of erythromycin and tetracycline resistance in staphylococcal isolates.