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In vitro antimicrobial sensitivity of 12 Hungarian isolates and the type strain ATCC 33144 of Actinobaculum suis to different antimicrobial compounds was determined both by the agar dilution and by the disc diffusion method. By agar dilution, MIC50 values in the range of 0.05-3.125µg/ml were determined for penicillin, ampicillin, ceftiofur, doxycycline, tylosin, pleuromutilins, chloramphenicol, florfenicol, enrofloxacin and lincomycin. The MIC50 value of oxytetracycline and spectinomycin was 6.25 and 12.5µg/ml, respectively. For ofloxacin, flumequine, neomycin, streptomycin, gentamicin, nalidixic acid, nitrofurantoin and sulphamethoxazole + trimethoprim MIC50 values were in the range of 25-100µg/ml. With the disc diffusion method, all strains were sensitive to penicillin, cephalosporins examined, chloramphenicol and florfenicol, tetracyclines examined, pleuromutilins, lincomycin and tylosin. Variable sensitivity was observed for fluoroquinolones (flumequine, enrofloxacin, ofloxacin), most of the strains were susceptible to marbofloxacin. Almost all strains were resistant to aminoglycosides but most of them were sensitive to spectinomycin. A strong correlation was determined for disc diffusion and MIC results (Spearman's rho 0.789, p<0001). MIC values of the type strain and MIC50 values of other tested strains did not differ significantly. Few strains showed a partially distinct resistance pattern for erythromycin, lincomycin and ampicillin in both methods.
Enterococci are opportunistic bacteria that cause severe infections in animals and humans, capable to acquire, express, and transfer antimicrobial resistance. Susceptibility to 21 antimicrobial agents was tested by the disk diffusion method in 222 Enterococcus spp. strains isolated from the fecal samples of 287 healthy domestic dogs. Vancomycin and ampicillin minimum inhibitory concentrations (MICs) and high-level aminoglycoside resistance (HLAR) tests were also performed. Isolates showed resistance mainly to streptomycin (88.7%), neomycin (80.6%), and tetracycline (69.4%). Forty-two (18.9%) isolates showed an HLAR to streptomycin and 15 (6.7%) to gentamicin. Vancomycin and ampicillin MIC values showed 1 and 18 resistant strains, respectively. One hundred and thirty-six (61.2%) strains were classified as multidrug resistant and six (2.7%) strains as possibly extensively drug-resistant bacteria. Enterococcus faecium and Enterococcus faecalis were the most prevalent antimicrobial resistant species. Companion animals, which often live in close contact with their owners and share the same environment, represent a serious source of enterococci resistant to several antibiotics; for this reason, they may be a hazard for public health by providing a conduit for the entrance of resistance genes into the community.
This study performed an epidemiological survey of Neisseria meningitidis strains isolated from patients and from asymptomatic carriers. Altogether, 74 N. meningitidis strains (46 invasive and 28 non-invasive) were isolated between February 2011 and May 2018 in different regions of the Republic of Belarus. Serogenotyping was carried out by real-time PCR. Minimum inhibitory concentrations (MICs) of antibiotics were determined by broth microdilution and results were interpreted in accordance with EUCAST. The serogroups of N. meningitidis were determined as follows: serogroup B – 65%, C – 11%, W – 9%, A – 5%, Y – 4%, and Z and NG – 3% each. The MIC50 and MIC90 for benzylpenicillin (0.032/0.064–0.125 mg/L), ampicillin (0.032/0.125 mg/L), amoxicillin (0.125/0.25 mg/L), cefotaxime (0.016/0.016 mg/L), ceftriaxone (0.002/0.016 mg/L), ciprofloxacin (0.004/0.008 mg/L), chloramphenicol (1/1 mg/L), meropenem (0.008/0.008–0.016 mg/L), tetracycline (0.25/0.5 mg/L), and rifampicin (0.016/0.25 mg/L) were established. Strains with intermediate susceptibility for benzylpenicillin (12.3%), ampicillin (6.8%), and amoxicillin (24.7%) have been identified. In this study, we report the first rifampicin-resistant N. meningitidis in Belarus.
Penicillins and cephalosporins (subclasses of β-lactam antibiotics) are widely used against Gram-positive and Gram-negative bacteria. Use of HPLC, TLC-bioautography, and thin silica gel layers precoated with fluorescent material has been reported in literature for the analysis of these compounds. This manuscript deals with a straightforward and sensitive method for rapid separation and detection of selected β-lactams. Bulk impregnation of homemade silica gel G layers and impregnation of ready made silica gel 60 layers with 0.2% ammonium chloride was carried out and various mobile phases have been established for UV detection of the compounds. Separation of penicillins (benzylpenicillin, ampicillin, and amoxicillin) and cephalosporins (cephalexin, cefoperazone, ceftriaxone, cefixime, and cefadroxil) was achieved by use of propanol-acetic acid 4:1 ( v/v ) and butanol-acetic acid-water 4:1:2 ( v/v ) respectively, as mobile phases.
A series of 2-[4-(4-substitutedbenzamido/phenylacetamido/butanamido)phenyl]-5-ethylsulphonyl-benzoxazole derivatives were synthesized and biologically evaluated as possible antimicrobial agents and inhibitors of tyrosinase, acetylcholinesterase (AChE), and butyrylcholinesterase (BChE). The results demonstrated that the synthesized compounds exhibited a broad spectrum of activity with minimum inhibitory concentration (MIC) values of 128-16 μg/ml against some Gram-positive, Gram-negative bacteria as well as Candida albicans and C. krusei. The compound 10 displayed higher activity in this series against methicilline resistant Staphylococcus aureus (MRSA) with a MIC value of 16 μg/ml than the compared control drugs ampicillin and ceftriaxone. Compound 14 showed moderate tyrosinase inhibition, however, none of the compounds showed effect as inhibitor of AChE and BChE.
In this study, two bacilli strains, namely TN51 and TN69, previously isolated from Thua Nao, a Thai traditional fermented soybean, were studied in terms of their phenotypic and biochemical properties. Initially, both strains were subjected to morphological determination and a series of biochemical tests. Both were Gram-positive, endosporeforming bacilli. Based on 16S rRNA gene sequence analysis, the identities of strains TN51 and TN69 were confirmed as Bacillus subtilis and B. cereus, respectively. In addition, these two strains were also assessed for their antibiogram profiles. It was found that both strains were susceptible to chloramphenicol, erythromycin, kanamycin, tetracycline, and vancomycin and resistant to ampicillin and intermediately susceptible to bacitracin.
An imipenem-resistant Bacteroides fragilis strain was isolated from the blood of a 72-year-old male patient with a urinary bladder tumor in Osijek, Croatia. This strain was also resistant to ampicillin, piperacillin/tazobactam, cefoxitin, clindamycin, tetracycline, and harbored cfiA, ermF, and tetQ genes where the high-level expression of the cfiA carbapenem-resistant gene was driven by an IS1187 element. Interestingly, despite the carbapenem-resistant feature of the B. fragilis from blood, the patient relatively easily recovered from the bacteremia. It was the first characterized imipenem-resistant B. fragilis isolate with its case report from Croatia, which confirmed the appearance of carbapenem-resistant B. fragilis strains, that continues worldwide with low incidence and the molecular characteristics vary temporally and geographically.
In this study antibiotic combinations for multidrug-resistant Klebsiella pneumoniae strains were investigated. The study included a colistin-susceptible and a colistin-resistant KPC-2 producing K. pneumoniae ST258 strains isolated in 2008 and 2009 during an outbreak in Hungary. Antibiotic combinations were analyzed by checkerboard technique and fractional inhibitory concentration indices were calculated. The following antibiotics were tested: ceftazidime, cefotaxime, ceftriaxone, ampicillin, imipenem, ertapenem, amikacin, tobramycin, ciprofloxacin, levofloxacin, moxifloxacin, rifampicin, polymyxin B and colistin. Combinations including 0.25 μg/ml colistin plus 1 μg/ml rifampicin, 0.25 μg/ml polymyxin B plus 1 μg/ml rifampicin, 1 μg/ml imipenem plus 2 μg/ml tobramycin, were found synergistic.These in vitro synergistic combinations suggest potential therapeutical options against infections caused by KPC-2 producing, multidrug-resistant K. pneumoniae ST258.
Two male harbour seals (Phoca vitulina; 33 and 35 years old, respectively), housed since 2002 at a zoo for exhibition purposes, developed severe, multifocal and diffuse skin lesions. Skin scrapings and microscopy for parasites as well as pure cultures for bacteria and dermatophytes were carried out to identify the aetiological agent. Skin scrapings showed that lesions appearing on the seals were caused by an infestation of Demodex mites, which is uncommon in marine mammals, and were not due to other causative agents (parasites, bacteria or dermatophytes). Treatment with amitraz (0.01%) once a week for three weeks and with ampicillin (10 mg/kg SID per os) for six days eliminated the mites and resolved the clinical signs of demodectic mange in the harbour seals. The purpose of this report is to describe the successful treatment of naturally acquired demodectic mange with amitraz in harbour seals.
The integron content of 52 DT104/U302 phage type strains and 53 non-DT104/U302 strains of Salmonella enterica serotype Typhimurium (S. Typhimurium) was studied in PCR experiments using a 5'-CS/3'-CS primer pair (Lévesque et al., 1995). Forty-three out of 44 streptomycin- and/or ampicillin-resistant DT104 and related phage type strains were found to carry a 1 kb and/or 1.2 kb long integron. The other resistance markers did not affect the number and size of integrons; no integron-free multidrug-resistant (MDR) DT104 strains were found. The two large groups of DT104 strains (Felix-Callow's phage types 2 and 2c) proved to be identical in respect of integron patterns (IPs), supporting the views of those authors who consider DT104 a single clone. Strains of human and animal origin did not differ from each other in their IPs. Within the non-DT104 phage types, ampicillin- and/or streptomycin-resistant, integron-free MDR strains were also found. Based on amplicons varying between 290 and 3500 bp an IP system was suggested. The commonest amplicon sizes in non-DT104 strains were 1450 and 2050 bp. The IPs of DT104 strains and of non-DT104 strains containing an integron of 1 and 1.2 kb size were stable. In contrast, the IPs of other non-DT104 strains showed a varying degree of instability. Integron loss was frequently associated with spontaneous plasmid elimination and changes of R-type among the descendants of a given strain.
