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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.
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.
Serratia ficaria was first described in 1979 as a Gram-negative facultative anaerobic rod. S. ficaria was found in figs, but also isolated from human specimens in a few cases. We now report an isolate of S. ficaria from sputum specimen.A 46-year-old man was suffering from a chronic renal failure of five years, four months of peritoneal dialysis and one week of fever due to respiratory tract infection, accompanied by cough. Sputum culture yielded a Gram-negative rod. It was identified as S. ficaria and the antibiotic susceptibility test was performed by automated Vitek II (bioMerieux). The tested S. ficaria strain was susceptible to amikacin, gentamicin, cefepime, trimethoprim-sulfamethoxazole, imipenem, meropenem, tigecycline and ciprofloxacin. This strain was resistant to ampicillin, amoxicillin-clavulanic acid, cephalothin, cefoxitine, cefuroxime and ceftriaxone. The patient was treated successfully (80 mg trimethoprim/400 mg sulfamethoxazole twice daily for 7 days)S. ficaria is an opportunistic pathogen responsible for intestinal colonization or serious infections such as septicaemia, gall bladder empyema in immunocompromised patients. The fig tree and fig play an important role in human colonization. It should be remembered that S. ficaria infections may be encountered frequently especially in fig tree culture zones.
The antimicrobial susceptibility of 19 Bordetella avium and 36 Ornithobacterium rhinotracheale strains was tested by the Kirby-Bauer disk diffusion method, and the minimal inhibitory concentrations (MIC) of amoxicillin, doxycycline and erythromycin were also determined. Most O. rhinotracheale strains were resistant to nalidixic acid, sulphamethoxazole–trimethoprim and gentamicin, and were susceptible to ampicillin, chloramphenicol, spectinomycin and tilmicosin. All B. avium strains were resistant to ceftiofur and lincomycin and susceptible to doxycycline, gentamicin, polymyxin B, spectinomycin and sulphonamides. The MICs ranged widely for all three antibiotics tested against O. rhinotracheale strains, from 0.12 μg/ml to 32 μg/ml for amoxicillin and erythromycin, and from 0.6 μg/ml to 32 μg/ml for doxycycline. For B. avium isolates, the MIC values ranged from ≤ 0.03 μg/ml to 1 μg/ml for amoxicillin, from ≤ 0.03 μg/ml to 0.12 μg/ml for doxycycline and from 8 μg/ml to 16 μg/ml for erythromycin. These findings support the idea that the use of antibiotics in a region or a farm may affect antimicrobial resistance and underline the need for prudent application of antibiotic therapy based on proper antimicrobial susceptibility testing.
Trueperella (T.) pyogenes is an opportunistic pathogen that causes suppurative diseases in domestic animals. In this work, the properties, pathogenesis and phenotypic diversity of T. pyogenes isolates from bovine mastitis were studied. Both pyolysin (plo) and collagen-binding protein (cbp) virulence factor genes were detected by PCR in all T. pyogenes isolates (n = 50). Using the tissue culture plate method, 90% of T. pyogenes isolates were able to form biofilms. The minimum inhibitory concentrations (MICs) of 13 antimicrobials against T. pyogenes isolates were determined. High susceptibility was observed to rifampin (96%), ampicillin (94%), ciprofloxacin (94%), and penicillin (92%), while low susceptibility was found to trimethoprim-sulphamethoxazole (10%) and bacitracin (2%). The intracellular assay revealed that T. pyogenes isolates had different cytopathogenic effects on cells. The high percentage (28.6%) of T. pyogenes isolates suggests that this bacterium is an important contributor to mastitis. Moreover, the high occurrence of multidrug resistance, biofilm production, intracellular survival, and the temporal dynamics of T. pyogenes interactions are key factors for a better understanding of how immunity acts on infections with these bacteria and how they evade immune surveillance, thus highlighting the need for the prudent use of antimicrobial agents in veterinary medicine.
The objective of this study was to survey the incidence of Flavobacterium columnare in wild and cultured freshwater fish species in Hungary. This bacterium usually causes disease in waters of more than 25 °C temperature. However, with the introduction of intensive fish farming systems, infected fish exposed to stress develop disease signs also at lower temperatures; in addition, the temperature of natural waters rises to the critical level due to global warming. Twenty-five isolates from wild and cultured freshwater fishes were identified as F. columnare by specific PCR, although both the fragment lengths and the results of PCRRFLP genotyping with BsuRI (HaeIII) and RsaI restriction enzymes raised doubts regarding this species classification. Sequencing of the 16S ribosomal RNA gene revealed that 23 isolates belonged to the species F. johnsoniae and two represented Chryseobacterium spp. The isolates were found to have high-level multidrug resistance: all were resistant to ampicillin and polymyxin B, the 23 F. johnsoniae strains to cotrimoxazole, 88% of them to gentamicin, and 72% to chloramphenicol. The majority of the 25 isolates were sensitive to erythromycin (88%), furazolidone (76%), and florfenicol (68%).
In this study, Staphylococcus aureus strains (n = 110) isolated from seven ewe flocks in Sanliurfa, Turkey were screened for antibiotic resistance and biofilmforming ability as well as for genes associated with antibiotic resistance and biofilm-forming ability. All isolates were found to be susceptible to oxacillin, gentamicin, clindamycin, cefoxitin, tetracycline, vancomycin, amoxicillin-clavulanic acid, ciprofloxacin and sulphamethoxazole-trimethoprim. The percent proportions of strains resistant to penicillin G, ampicillin and erythromycin were 27.2% (n = 30), 25.4% (n = 28) and 6.3% (n = 7), respectively. Regarding the antibiotic resistance genes, 32 (29%) isolates carried the blaZ and 8 (7.2%) the ermC gene. Other resistance genes were not detected in the isolates. All isolates showed biofilm-forming ability on Congo red agar (CRA), while 108 (98.18%) and 101 (91.81%) of them were identified as biofilm producers by the use of standard tube (ST) and microplate (MP) methods, respectively. All isolates carried the icaA and icaD genes but none of them harboured the bap gene. The results demonstrated that S. aureus isolates from gangrenous mastitis were mainly resistant to penicillins (which are susceptible to the staphylococcal beta-lactamase enzyme), and less frequently to erythromycin. Furthermore, all of the S. aureus isolates produced biofilm which was considered a potential virulence factor in the pathogenesis of staphylococcal mastitis.
In this study, the presence of genes responsible for the pathogenicity and antibiotic resistance profile of enterococci isolated from various foodstuffs of animal origin was investigated. The percentage prevalence of enterococci was 54.1% (203/375) and the average count was found to be 3.81 log cfu/ml-g. Species-specific primers revealed Enterococcus faecalis as the predominant species carrying one or more virulence-associated traits of efa, gelE, ace, esp and agg genetic markers. Only one E. faecium isolate (from milk) was positive for the esp gene. Regarding antibiotic resistance, the highest frequency of resistance was observed for tetracycline (21.7%), followed by quinupristin/dalfopristin (13.3%), ciprofloxacin (2.0%), penicillin (2.0%), linezolid (1.0%), ampicillin (1.0%), streptomycin (1.0%), and gentamicin (0.5%). Enterococcus faecalis showed a higher prevalence of antibiotic resistance than other enterococci. The percentage of multidrug resistance among the isolates was 3.4%. Twenty-nine E. faecalis isolates (26.6%) carrying one of the virulence-associated traits were at the same time resistant to at least one antibiotic. Our results show that foods of animal origin, including ready-to-eat products, may be reservoirs of antibiotic-resistant and potentially virulent enterococci.
Abstract
The occurrence of tetracycline resistance determinants in 203 Escherichia coli isolates recovered from clinical samples at three different hospitals in Nigeria between June 2009 and May 2010 was investigated. The isolates were subjected to standard procedures. Antibiotic susceptibility to a panel of eight antibiotics was also performed, and resistance genes were detected with the polymerase chain reaction (PCR) technique. One hundred and six E. coli isolates (52.2%) were obtained at LAUTECH Teaching Hospital Osogbo, 85 (41.9%) from OAUTHC Ile Ife and 12 (5.9%) from Osun State Hospital Asubiaro Osogbo. Result of the disk diffusion antibiotic susceptibility test showed 96.1% isolates to be resistant to ampicillin, 77.8% to tetracycline, 37.9% to cotrimoxazole, 38.4% to nalidixic acid, 20.7% to ofloxacin, 17.7% to ceftriaxone, 11.8% to gentamycin, and 2% to nitrofurantoin. One hundred and sixty two (79.9%) isolates had minimum inhibitory concentration (MIC) of tetracycline ≥ 128 μg/ml. The polymerase chain reaction (PCR) detected tetA gene in 89 (43.8%) isolates, tetB gene in 65 (32.0%), and both tetA and tetB genes in 9 (4.4%) isolates. The study demonstrated a relatively high level of gene mediated antibiotic resistance to tetracycline and other antibiotics in E. coli clinical isolates in Southwest region of Nigeria.
Bacterial antimicrobial resistance mediated by the production of extended-spectrum β-lactamases (ESBLs) is considered a major threat for treatment of Salmonella and Shigella infections. This study aimed to investigate antibiotic resistance patterns of Salmonella and Shigella spp. and presence of CTX-M from three teaching hospitals in Iran. In the present study, 58 clinical Shigella and 91 Salmonella isolates were recovered between 2009 and 2013 from 3 teaching hospitals in Iran. After culture and antimicrobial susceptibility testing, ESBL-positive isolates were subjected to further investigations. These included polymerase chain reaction (PCR) amplification and DNA sequencing of bla CTX-M-15 encoding plasmid. In both genera, high sensitivity to gentamicin and amikacin, but high resistance to ampicillin, tetracycline, and trimethoprim—sulfamethoxazole, was found. Molecular investigation showed that 31.8% isolates of Salmonella spp. and 34.48% isolates of Shigella spp. were CTX-M positive and all of them were also positive for ISEcpI. Protein translation, comparing with reference sequences, showed that all CTX-M isolates belong to CTX-M-15. The present study suggests that the resistance of ESBLs-producing Salmonella and Shigella spp. in Iran hospitals is very serious. Therefore, strategies to minimize the spread of ESBL-producing isolates should be implemented.
