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- Author or Editor: Emaneini Mohammad x
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The synergy between gentamicin and vancomycin, teicoplanin, ampicillin and linezolid was studied by time-kill method. Two clinical vancomycin resistant enterococci (VRE) and two vancomycin susceptible enterococci (VSE) isolates were used. Different concentrations of antibiotics were combined. Two VSE strains and the control strain exhibited synergism with the combination of gentamicin, vancomycin, teicoplanin, ampicillin and linezolid. Two VRE strains exhibited synergism with the combination of gentamicin and ampicillin. Synergy between gentamicin and vancomycin, teicoplanin and linezolid was not observed against these isolates. The VRE isolates were positive for vanA, aac (6′)-Ie aph (2“) and aph (3′)-IIIa genes and their vancomycin, teicoplanin and gentamicin MICs were 512 μg/ml, 512 μg/ml and >4000 μg/ml, respectively. In order to treat serious enterococcal infections, further clinical evaluation is needed to examine the in vitro combined effects of gentamicin and vancomycin, teicoplanin and linezolid.
Staphylococcus aureus is considered one of the most important food borne pathogens.A total of 111 isolates of S. aureus were cultured from raw milk samples during January 2009 to June 2009 from Tehran and Mashhad. The coagulase gene polymorphism and the prevalence of classical enterotoxin genes of S. aureus strains were determined by PCR-RFLP (restriction fragment length polymorphism) and Multiplex-PCR. Disk diffusion method was used to determine the susceptibility of isolates to antimicrobial agents as instructed by Clinical and Laboratory Standards Institute.Sixty-seven % of the isolates harboured one or more enterotoxin genes. The most prevalent gene was sec, found in 59 % of the isolates. Approximately 8% of the isolates were positive for sea, seb and sed genes. Only one isolate had see gene. The rate of coexistence of enterotoxin genes was 14%. All S. aureus isolates were susceptible to ciprofloxacin, gentamicin, imipenem, minocycline, oxacillin and vancomycin. They were resistant to ampicillin (64%), penicillin (56%), clindamycin (22%), tetracycline (22%), doxycycline (19%), teicoplanin (13%), rifampin (2%) and trimethoprim-sulfamethoxazole (2%). On the basis of coagulase gene analysis of 111 S. aureus isolates, the PCR products of 56 isolates were digested with Alu I that produced three distinct patterns.These data indicate the high prevalence of enterotoxigenic S. aureus in raw bovine milk in Tehran and Mashhad, and highlight the importance of proper quality control of dairy products for public health.
Forty-one Streptococcus agalactiae isolates collected from pregnant women at 35–37 weeks of gestation were analysed for their capsular types, antimicrobial resistance determinants, distribution of virulence factors and genetic relatedness using PCR and multiplex PCR. Capsular type III was predominant (65.8%), followed by capsular type II (14.6%), Ib (7.3%), and V(4.9%). All isolates were susceptible to penicillin, vancomycin, linezolid and quinupristin-dalfopristin. Resistance to tetracycline, erythromycin and clindamycin were found in 97.6%, 24.4%, and 14.6% of isolates, respectively. The most common antimicrobial resistance gene was tetM found in 97.6% of the isolates followed by ermTR and ermB found in 12% and 7.3% of isolates, respectively. The most common virulence gene was hly (100%), followed by scpB (97.6%), bca (97.6%), rib (53.65%) and bac (4.9%). The insertion sequence IS1548 was found in 63.4% of isolates. By multi locus variable number of tandem repeat analysis (MLVA) typing, 30 different allelic profiles or MLVA types (MTs) were identified. The most frequent was the MT1 (5/41, 12.2%) and followed by MT2 (4/41, 9.75%). Our data revealed that population structure of these isolates is highly diverse and indicates different MLVA types.
Methicillin-resistant Staphylococcus aureus (MRSA), particularly the multidrug-resistant clones, is an increasing worldwide problem. The average incidence rate of MRSA in Tehran was found to be over 40%. A total of 140 MRSA isolates obtained from patients attending a teaching hospital in Tehran, from May 2009 to December 2009, were included in this study. The antimicrobial susceptibility profile of MRSA isolates was determined by the agar disk diffusion method. Molecular analysis of MRSA strains was accomplished by Pulsed-Field Gel Electrophoresis (PFGE) and Multi-locus sequence typing (MLST). Detection of mecA gene was used to confirm resistance to methicillin among the MRSA isolates. All the MRSA isolates were susceptible to chloramphenicol, teicoplanin, tigecycline and vancomycin. All MRSAisolates were resistant to oxacillin, whilst 139 strains showed resistance against ciprofloxacin, erythromycin, gentamicin, tetracycline and trimethoprim-sulfamethoxazole. PFGE analysis of all the 140 MRSA isolates produced five distinct pulsotypes designated as pulsotypes A-E. Most of the isolates (n=132) were clustered into pulsotype A. The most prevalent sequence type (ST) was ST 239 (pulsotype A) found in 82% (37/45) of the tested isolates. The second most prevalent type was ST 1238 (pulsotypes B, C and D) found in 15% (7/45) of the isolates. The remaining type, ST 8 (pulsotype E) was found in a single isolate. The results of this study indicated that the MRSA clone ST 239 was a major clone in the selected university hospital of Tehran and that it was widely spread among the different wards as well as all the age groups of patients.
The aim of the present study was to investigate, for the first time, the diversity of the genes encoding aminoglycoside-modifying enzymes (AME) and their association with class 1 integrons in Iranian Acinetobacter baumannii strains.A total of 100 multidrug resistant A. baumannii, isolated from eight distinct hospitals in Tehran, were enrolled in this study. Susceptibility of these isolates to antimicrobial agents including gentamicin and amikacin was determined by E-test. Aminoglycoside resistant isolates were then tested by PCR for AME genes, including aphA6, aacC1, aacC2, aacA4, aadB, aadA1, classes 1 integron, 5′-CS-3′ and typed by RAPD PCR.The rate of resistance to imipenem, meropenem, gentamicin and amikacin were 39%, 39%, 38% and 32%, respectively. Intermediate resistance phenotype to gentamicin and amikacin was observed in 2% and 5% of all the isolates, respectively. After aph6 with 90% (n = 36/40), aadA1, aacC1 and aadB with 82.5% (n = 33/40), 65% (n = 26/40) and 20% (n = 8/40) were the most prevalent AME genes among aminoglycosides resistant A. baumannii isolates. A combination of two to four different resistance genes was observed in 39 of 40 strains (97.5%), with a total of 7 different combinations. PCR of integrase genes revealed that AME gene was associated with 67% of class 1 integrons. RAPD analysis showed three predominant genotypes A (n = 20), B (n = 10) and 10 unrelated genotypes.The occurrence of identical resistance genes, gene combinations and class 1 integrons associated with these genes in clonally distinct strains indicates that horizontal gene transfer plays a major role in the dissemination of aminoglycoside resistance in A. baumannii.
Hepatitis B virus (HBV) transmission via blood and other body fluids from infected individuals to healthy people has been largely demonstrated. However, in the current literature, there is little information available on the potential role of cerumen in HBV transmission.Cerumen and blood were collected from 70 patients infected with HBV and 70 volunteer healthy people were selected as the control group, and the samples were evaluated by ELISA and Real-time PCR.All the patients proved positive for HBsAg and anti HBc total. Sixty-one of the 70 cerumen samples of cases (82.1%) and 5 (7%) of controls were positive for HBV DNA with ranges from 1.53 × 102 to 2.9 × 108 and 1.3 × 102–2.6 × 105/ml, respectively. In three patients, the level of HBV DNA in cerumen was higher than that in the serums. The patients who were positive for HBeAg showed a higher rate of HBVDNA in the serum and cerumen.The results of this study showed the level of HBV DNA as a probably indicator of high risk transmission factor, which was present in the cerumen of chronic hepatitis B patients in west of Iran.
There are documents that confirm the cycle of bacterial transmission between patients, staff, and the inanimate environment. The environment may have more effect on intensive care units (ICUs), because the patients who require intensive care have unstable clinical conditions and are more sensitive to infections. The aim of this study was to determine the prevalence of bacteria in air and inanimate surface in the ICUs and to compare the microbial levels to standard levels.Air and inanimate surface in the four ICUs of a teaching hospital underwent weekly surveillance by means of air sampler and swabs for a period of six-month. Total bacterial counts were evaluated onto trypticase soy agar and mannitol salt agar (MSA).A total of 725 samples [air (168) and inanimate surfaces (557)] were collected. The total mean ± SD CFU/m3 of airborne bacteria in all of the ICUs were 115.93 ± 48.04. The most common bacteria in air of the ICUs were Gram-positive cocci (84.2%). The total mean ± SD airborne of Staphylococcus aureus was 12.10±8.11 CFU/m3. The highest levels of S. aureus contamination were found in ventilators and bed ledges. More suitable disinfection of hospital environments and monthly rotation in utilization of the various disinfectant agents are needed for the prevention of airborne and inanimate transmission of S. aureus.
The rapid identification of relevant bacterial pathogens is of utmost importance in clinical settings. The aim of this study was to test a rapid identification technique for A. baumannii strains from Tehran Hospitals and to determine the antibiotic resistance profiles of the isolates. A hundred strains of Acinetobacter spp. grown from clinical specimens were identified as A. baumannii by conventional methods. Using PCR a bla OXA-51 -like gene was detected in all A. baumannii isolates but not in other species of acinetobacter. More than half of the isolates proved resistant to a variety of antibiotics by the disk diffusion technique. The rate of resistance to gentamicin, imipenem, ampicillin-sulbactam and amikacin was determined to be 45%, 53%, 62% and 62%, respectively. Moreover, most isolates (more than 90%) showed resistance to cephalosporins. This study shows that the demonstration of the bla OXA-51-like gene is a reliable and rapid way for the presumptive identification of A. baumannii and reveals that the rate of antibiotic resistance is high in Iranian A. baumannii isolates to a variety of antibiotics.
