Variability in gene cassette patterns of class 1 and 2 integrons associated with multi drug resistance patterns in Staphylococcus aureus clinical isolates in Tehran-Iran.

BACKGROUND: To investigate antibiotic resistance, the occurrence and distribution of class 1 and 2 integrons in multidrug- resistant Staphylococcus aureus isolates from hospitals in Tehran, Iran. The isolates were examined for susceptibility to antimicrobial agents. The mecA gene, class 1 and 2 integrons were detected by PCR. Integrase positive strains were further analysed for the presence of resistance gene cassettes using specific primers and were sequenced. RESULTS: Among 139 S.aureus isolates, 109 (78.4 %) and 112 (80.5 %) strains were considered as multidrug resistant and mecA positive, respectively. Class 1 integrons and internal variable regions were found in 72.6 % (101/139) and 97 % (98/101) and class 2 integrons and variable regions also in 35.2 % (49/139) and 65.3 % (32/49) of S.aureus clinical isolates, respectively. Twelve distinct cassette arrays were found, containing genes encoding resistance to ß-lactams, aminoglycosides, streptothricin, trimethoprim, chloramphenicol,a putative glucose dehydrogenase precursor and a protein with unknown function. Gene cassette arrays aadB, aadA2 and dhfrA1-sat2-aadA1 were common in S.aureus isolates. We detected a completely new gene cassettes which contained aadB, oxa2, aacA4, orfD-aacA4-catB8, aadB-catB3, orfD-aacA4 and aadB-aadA1-cmlA6 of class 1 and dhfrA1-sat2-aadA1, dhfrA11, dhfrA1-sat2 of class 2 integrons. CONCLUSIONS: This is the first study to report carriage of class 1 and 2 integrons and associated gene cassettes among in S.aureus isolates from Iran.

Assessing clonal correlation of epidemic Vibrio cholerae isolates during 2011 in 16 provinces of Iran.

A total of 1,187 Vibrio cholerae isolates were received during 2011 cholera outbreaks from 16 provinces in different geographical location to Iranian reference Health laboratory. A random selection was performed, and 61 isolates were subjected to further investigations. Cholera cases were come up from May with nine cases and reached to its maximum rate at August (57 cases) and continued to October after which a fall occurred in September. All of the isolates were susceptible to three antimicrobial agents including ciprofloxacin, cefixime, and ampicillin. The highest rate of resistance was seen to nalidixic acid (96.7 %) and co-trimoxazole (91.8 %). Clonality of isolates was investigated through genotyping by PFGE method. A total of seven pulsotypes were obtained from 61 isolates under study. The pulsotypes were highly related with only 1-3 bands differences. Three pulsotypes (PT5, PT6, and PT7) constituted 93.4 % of total isolates. One environmentally isolated strain showed distinct pattern from clinical specimens. This strain although had no any evidence in identified cholera infections, highlighted selecting more environmental specimens in any future outbreaks as long as human samples. In conclusion, emergence and dominance of Ogawa serotypes after about 7 years in Iran are alarming due to fear of import of new V. cholerae clones from out of the country. Approximately, one third of patients in 2011 cholera outbreak in Iran were of Afghan or Pakistani nationality which makes the hypothesis of import of Ogawa serotype strains from neighboring countries more documented and signifies the need to monitor and protect the boundaries.

Efficacy of multiplex PCR procedure for Iranian Streptococcus pneumoniae isolates.

BACKGROUND: Identifying regional types and evaluating the frequency of pneumococcal strains has become increasingly important especially in vaccination. The purpose of this study was the identification and frequency determination of our regional serotype and evaluation of the performance of recent type specific multiplex PCR for the diagnosis of streptococcus pneumonia serotypes. METHODS: All isolated S. pneumonia from suspected patients in Tehran and Isfahan Hospitals from June to December of 2012 were evaluated. All specimens and their serotypes were identified through a conventional method and specific antisera. Serotype specific multiplex PCR was applied and ran in seven reactions consisting of 34 S. pneumonia primer pairs plus a primer pair as an internal control for this purpose. RESULTS: Overall, 14 genotype specific serotypes (including two subtypes for 19 and 23) were detected and had identical results with stereotyping method except for serotype 28 and one of the identified serotype 23. The serotypes 19, 6 and 23 were dominant with the frequency of 51.8%. A cross reactivity was also observed between genotypes 1 and 9A/9V. CONCLUSION: Applied multiplex PCR format can be suitable and cost effective tool for identification of S. pneumonia serotypes.