Incidence of antibiotic and metal resistance and plasmid Carriage in Aeromonas isolated from brown bullhead (latalurus nebulosus)

G.W. PETTIBONE, J.P. MEAR AND B.M. SAMPSELL. 1996. Seventy-four strains of Aeromonas were isolated from skin, intestine, kidney and liver of 16 brown bullhead ( Ictalurus nebulosus ). All strains demonstrated multiple antibiotic resistance (MAR) with most strains resistant to rifampin (97%), novobiocin (96%) and vancomycin (85%). The minimum inhibitory concentration of eight metals to selected strains of Aeromonas revealed an apparent toxicity of chromium > copper > cadmium > nickel > mercury > zinc > cobalt > lead, based on the percentage of isolates sensitive to each concentration of metal. Plasmid DNA was found in 36% (27) of the isolates and most plasmid-containing strains had multiple plasmids less than 12 kilobase pairs (kbp) in size. No relationship between plasmid content and antibiotic or metal resistance was found. Plasmid incidence in bacteria isolated from five fish indicated that plasmids were more likely to occur in strains isolated from kidney and liver than in strains isolated from skin and intestine.     

Microbiologic analysis of results from blood cultures

The aim of our investigations was the microbiological analysis together with the evaluation of sensitivity of bacteria frequently isolated from blood cultures. Blood samples were taken from patients with symptoms suggesting bacteremia in Rydygier's Hospital in Cracow. A total of 11,170 blood samples taken from 1997 to 2000 were tested. Automatic VITAL system (bioMerieux) was applied to culture and detect microorganisms. Bacteria were identified by ATB system (bioMerieux). Susceptibility was detected by ATB and disc diffusion method. Percentage of positive results relating to detection of microorganisms of clinical significance was 16.9% (1891 cultures). Staphylococcus spp. (Staph. epidermidis in range 22.8% to 21.9%), Enterococcus spp. and Streptococcus spp. were most frequently isolated species among aerobic Gram-positive bacteria. In 2000, compared to 1997 the number of isolates of MRSA increased considerably (from 1.8% to 6.8%). In blood infections the increase of frequency of E. coli bacteria was also noted: 6.1% and 11.4% in 1997 and 2000, respectively. Among non-fermentant bacilli the percentage of occurrence of P. aeruginosa in the period of 4 years was comparable in the range 7.3% in 1997 to 7.2% in 2000. The increase in the frequency of blood infections of A. baumanii was also noticed (respectively from 4.8% to 9.9%). Susceptibility of P. aeruginosa strains to selected beta-lactame antibiotics and aminoglycosydes increased in 2000 in comparison to 1999. A. baumanii strains were 100% sensitive only to imipenem.     

Occurrence of bacteria in the mouth from genera of Micrococcus,Kocuria, Nesterenkonia,Kytococcus and Dermacoccus

The aim of the study was to assess the prevalence of different bacteria in the oral cavity. The bacteria were present in the oral cavities of 73 (48.7%) of 150 individuals. Nesterenkonia halobia, the most frequently isolated species, was found in 20 (27%) individuals, Micrococcus luteus in 16 (22%), Kocuria kristinae in 12 (16%), Kocuria varians in 10 (14%), Dermacoccus sedentarius in 9 (12%), Micrococcus lylae in 8 (11%), and Kytococcus nishinomiyaensis in 3 (4%). Mean counts of these microorganisms were relatively low and amounted in log10 CFU/ml saliva for M. luteus 1.87 +/- 0.52, for M. lylae 2.03 +/- 0.39, for N. halobia 2.14 +/- 0.56, for K. kristinae 2.20 +/- 0.69, for K. varians 2.19 +/- 0.67, for K. nishinomiyaensis 1.72 +/- 0.39, and for D. sedentarius 2.27 +/- 0.55. The factor limiting the population sizes of these microorganisms was most probably the antagonistic activity of the bacteria living in oral cavity.     

Screening for restriction endonucleases in methane-oxidizing bacteria.

51 methane-oxidizing bacteria strains such as Methylomonas methanica, M. rubra, Methylococcus capsulatus, M. thermophilus, M. luteus, M. ucrainicus, M. whittenburyi, Methylosinus trichosporium, M. sporium, Methylocystis parvus isolated from various ecological niches and geographical regions of the Ukraine and also the strains received from R. Whittenbury and Y. Heyer were screened for restriction endonucleases. Type II restriction endonucleases were detected in IMV B-3112 (= 12 b), IMV B-3027 (= 26), IMV B-3019 (= 9 c), IMV B-3017 (= 17 c), IMV B-3226 (= 26 v), IMV B-3033 (= Y), IMV B-3100 (= 100) and IMV B-3494 (= 1E494). The results obtained were indicative of relatively high frequency of restriction enzymes occurrence in methane-oxidizing bacteria. There were Kpn I (Asp 7181) restriction endonuclease isoschizomers in crude extracts of IMV B-3112, B-3017, B-3019, B-3027 isolated from fresh-water silt as well as in IMV B-3226 strain isolated from waste-water silt. Although these isolates had bee previously considered as untypical strains of M. ucrainicus, more detailed study of their properties allowed placing them with Methylovarius luteus (= Methylococcus luteus). IMV B-3494 strain was identified as Methylococcus capsulatus. Strain IMV B-3033 had earlier been allocated to Methylovarius whittenburyi (= Methylococcus whittenburyi). Specificity of restriction endonucleases of this strain was not tested. Therefore, for the first time restriction endonucleases were detected in methane-oxidizing bacteria. 8 strains (3 species) among 51 strains (13 species) were found to produce restriction endonucleases displaying three different types of specificity in the least. Producers of restriction endonucleases having Kpn I (Asp 7181) specificity were isolated from different water and silt samples of the Dnieper flood-land more than 20 years ago.     

Infectivity and resistance to antibiotics of bacterial strains isolated from patients hospitalised in intensive care units

The aim of this study was to evaluate the frequency of isolation and antimicrobial resistance testing of bacterial strains isolated from clinical specimens from patients hospitalized in three Intensive Care Units in Wroc?aw. The susceptibility of bacteria (107 strains) to selected antibiotics was determined. The results clearly show that non-fermentative rods were identified as the main agents causing pneumonia (58% of isolates). The second commonest pathogens were Gram-positive cocci (29%). The P. aeruginosa and E. cloacae strains were resistant to ampicillin, amoxicillin/clavulanate, cefuroxime and cefotaxime. All isolates of A. baumanii were susceptible only to imipenem. The rods of K. pneumoniae and E. coli were resistant to ampicillin, about 55% strains of both bacteria were sensitive to other antibiotics, except piperacillin/tazobactam, imipenem and ciprofloxacin. About 90% of methicillin resistant S. epidermidis strains were resistant to all antibiotics, except vancomycin (100% isolates were sensitive). ESBL were detected among E. cloace, K. pneumoniae and E. coli. We found P. aeruginosa rods producing MBL.     

Phylogenetic analysis of antimicrobial lactic acid bacteria from farmed seabass Dicentrarchus labrax

The use of lactic acid bacteria (LAB) in the prevention or reduction of fish diseases is receiving increasing attention. In the present study, 47 LAB strains were isolated from farmed seabass ( Dicentrarchus labrax ) and were phenotypically and phylogenetically analysed by 16S rDNA and randomly amplified polymorphic DNA - polymerase chain reaction (RAPD-PCR). Their antimicrobial effect was tested in vitro against a wide variety of pathogenic and spoilage bacteria. Most of the strains isolated were enterococci belonging to the following species: Enterococcus faecium (59%), Enterococcus faecalis (21%), Enterococcus sanguinicola (4 strains), Enterococcus mundtii (1 strain), Enterococcus pseudoavium (1 strain), and Lactococcus lactis (1 strain). An Aerococcus viridans strain was also isolated. The survey of their antimicrobial susceptibility showed that all isolates were sensitive to vancomycin and exhibited resistance to between 4 and 10 other antibiotics relevant for therapy in human and animal medicine. Different patterns of resistance were noted for skin and intestines isolates. More than 69% (32 strains) of the isolates inhibited the growth of the majority of pathogenic and spoilage bacteria tested, including Listeria monocytogenes, Staphylococcus aureus, Aeromonas hydrophila, Aeromonas salmonicida, Vibrio anguillarum, and Carnobacterium sp. To our knowledge, this is the first report of bioactive enterococcal species isolated from seabass that could potentially inhibit the undesirable bacteria found in food systems.     

Frequency and susceptibility patterns of non-fermenting gram-negative rods isolated from patients hospitalised in intensive care units of a tertiary care hospital

The aim of the study was to assess frequency and susceptibility to antimicrobial agents of non-fermenting gram-negative rods isolated from clinical specimens obtained from patients requiring intensive care, with emphasis on profile of the unit. Identification of cultured isolates was done using automated VITEK and API systems (bioMerieux, France). Susceptibility to antimicrobial agents was tested by a disk-diffusion method according to the NCCLS recommendations. In total the analysis comprised 425 strains of non-fermenting gram-negative rods, constituting 58.9% of all isolates of gram-negative bacteria. In blood cultures predominated strains of A. baumannii (46.8%) and P. aeruginosa (40.4%), while in cultures of other clinical specimens these bacteria comprised 42.9% and 43.9% of isolates. Major differences were observed in frequency of these species on both ICU units. Strains of non-fermenting rods isolated from blood cultures comprised a lower percentage of strains susceptible to antimicrobials (particularly cefepime and carbapenems) than isolates cultured from other specimens. Strains of A. baumannii resistant to imipenem and meropenem were detected with a frequency of 12.5% and 26.7%, respectively. Resistance of P. aeruginosa strains to carbapenems was 62.2% and 44.3%, respectively. There was a relatively high percentage of strains susceptible to cefepime (82.0%), ceftazidime (78.9%), amikacin (77.8%) and piperacillin/tazobactam (69.7%). Conclusions: 1. There was a predominance (58.9%) of strains of gram-negative non-fermenting rods. 2. Isolates from blood cultures were characterised by a much higher percentage of resistant strains in comparison to other specimens. 3. Strains of A. baumannii resistant to carbapenems were recorded. 4. There were differences in frequency and antimicrobial susceptibility among the strains of P. aeruginosa and A. baumannii depending on the type of clinical specimen and ICU profile.     

Nitrogen-deficient Medium in the Differential Isolation of Klebsiella and Enterobacter from Feces

On a nitrogen-deficient agar medium, the tribe Klebsielleae formed large, glistening, mucoid colonies which were easily distinguished from other colony types. Of 113 Klebsielleae isolates from human feces which were characterized, Klebsiella accounted for 88% of the total; 75% were K. pneumoniae; K. ozaenae (13%) was isolated from one individual only. The remaining strains (12%) were identified as Enterobacter cloacae. Counts (for the tribe) ranged from 10(2) to 10(6), with a median of 10(4); 9 of 53 stool specimens were negative. K. pneumoniae was also isolated from 6 of 41 frozen foil-pack foods. Anaerobic studies at room temperature and 37 C revealed no appreciable differences from aerobic plates. The nitrogen-deficient medium appeared better than E M B for isolation of Klebsielleae when they were present in low numbers relative to other coliforms; slime production by Klebsielleae concomitant with minimal growth of other bacteria is involved.     

Hydrolytic and haemolytic activity of Klebsiella pneumoniae and Klebsiella oxytoca

Hydrolytic enzymes and haemolysins are important extracellular substances produced by many bacteria. We investigated 57 K. pneumoniae strains and 40 K. oxytoca strains isolated from clinical materials. We estimated the ability to produce: proteases hydrolyzing milk powder, caseinase, gelatinase, elastase, lecithinase, lipases, DNase and haemolysins on human, sheep and horse erythrocytes on TSA medium with or without 5% Egg Yolk. We detected that K. oxytoca strains produced proteases hydrolyzing milk powder (37.5%), caseinase (15.0%) and gelatinase (17.5%) more frequently than K. pneumoniae strains (respectively 21.0%, 5.3%, 8.9%). None of the analysed Klebsiella spp. strains produced elastase. Only K. pneumoniae strains produced lecithinase (5.3%). Lipases hydrolyzing Tween were produced from 3.5% (for Tween 60 and 80) to 7.0% (for Tween 20). Among K. oxytoca strains only one (2.5%) hydrolyzing Tween 20. DNase was produced by 38.6% of K. pneumoniae strains and by 27.5% K. oxytoca strains. Haemolytic properties on human erythrocytes were detected in 5.3% K. pneumoniae strains on TSA medium and 29,8% on medium with Egg Yolk. In K. oxytoca strains haemolytic properties on human erythrocytes were detected only on medium with Egg Yolk (12.5%). Haemolytic properties on sheep erythrocytes were detected respectively in 21.0% and 22.8% K. pneumoniae strains and in 7.5% K. oxytoca strains on each medium. Haemolytic properties on horse erythrocytes were detected respectively in 33.4% and 52.6% K. pneumoniae strains and in 15.0% and 20.0% K. oxytoca strains.     

Aminoglycoside resistance rates, phenotypes, and mechanisms of Gram-negative bacteria from infected patients in upper Egypt

With the re-emergence of older antibiotics as valuable choices for treatment of serious infections, we studied the aminoglycoside resistance of Gram-negative bacteria isolated from patients with ear, urinary tract, skin, and gastrointestinal tract infections at Minia university hospital in Egypt. Escherichia coli (mainly from urinary tract and gastrointestinal tract infections) was the most prevalent isolate (28.57%), followed by Pseudomonas aeruginosa (25.7%) (mainly from ear discharge and skin infections). Isolates exhibited maximal resistance against streptomycin (83.4%), and minimal resistance against amikacin (17.7%) and intermediate degrees of resistance against neomycin, kanamycin, gentamicin, and tobramycin. Resistance to older aminoglycosides was higher than newer aminoglycosides. The most common aminoglycoside resistance phenotype was that of streptomycin resistance, present as a single phenotype or in combination, followed by kanamycin-neomycin as determined by interpretative reading. The resistant Pseudomonas aeruginosa strains were capable of producing aminoglycoside-modifying enzymes and using efflux as mechanisms of resistance. Using checkerboard titration method, the most frequently-observed outcome in combinations of aminoglycosides with β-lactams or quinolones was synergism. The most effective combination was amikacin with ciprofloxacin (100% Synergism), whereas the least effective combination was gentamicin with amoxicillin (53.3% Synergistic, 26.7% additive, and 20% indifferent FIC indices). Whereas the studied combinations were additive and indifferent against few of the tested strains, antagonism was never observed. The high resistance rates to aminoglycosides exhibited by Gram-negative bacteria in this study could be attributed to the selective pressure of aminoglycoside usage which could be controlled by successful implementation of infection control measures.     

Isolation of a novel carotenoid, OH-chlorobactene glucoside hexadecanoate, and related rare carotenoids from Rhodococcus sp. CIP and their antioxidative activities

In the course of screening for antioxidative carotenoids from bacteria, we isolated and identified a novel carotenoid, OH-chlorobactene glucoside hexadecanoate (4), and rare carotenoids, OH-chlorobactene glucoside (1), OH-γ-carotene glucoside (2) and OH-4-keto-γ-carotene glucoside hexadecanoate (3) from Rhodococcus sp. CIP. The singlet oxygen ((1)O(2)) quenching model of these carotenoids showed potent antioxidative activities IC(50) 14.6 μM for OH-chlorobactene glucoside hexadecanoate (4), 6.5 μM for OH-chlorobactene glucoside (1), 9.9 μM for OH-γ-carotene glucoside (2) and 7.3 μM for OH-4-keto-γ-carotene glucoside hexadecanoate (3).     

青海湖嗜盐微生物系统发育与种群多样性

青海湖是我国境内最大的内陆咸水湖泊,水体中嗜盐微生物的生存现状尚不明确。本研究利用OSM培养基(Oesterhelt-Stoeckenius medium),从湖域生境水样中富集和分离获得嗜盐微生物35株,以中度嗜盐菌为主,约占62.9%(22株);轻度嗜盐菌次之,约占22.9%(8株);耐盐菌与非嗜盐菌分别占11.4%(4株)和2.9%(1株)。根据16SrDNA序列的系统发育分析表明,γ-变形菌纲(γ-Proteobacteria)菌株最多,约占68.6%(24株);芽孢杆菌纲次之,约占17.1%(6株);放线菌纲、α-变形菌纲(α-Proteobacteria,1株)和散囊菌亚纲(Eurotiomycetidae,1株)的类群相对较少。这些嗜盐菌属于14个属,其中以海洋螺菌目盐单胞菌属(Halomonas)为优势种群,共计10株;其次为海单胞菌属(Marinomonas),共4株。中度嗜盐菌盐单胞菌属应为青海湖嗜盐菌的优势种群,可能因为相对偏低的盐度环境,为其长期进化和适应性生存提供了必要条件。     

医院获得性肺炎病原菌分布及其耐药性分析

目的了解医院获得性肺炎(HAP)患者病原菌分布及其耐药性分析。方法236例被诊断为医院获得性肺炎(HAP)患者的痰及下呼吸道分泌物进行常规细菌培养鉴定,用NCCIS推荐的K-B法测定病原菌的耐药性。结果236例HAP患者检出病原菌276株,病原菌中革兰阴性杆菌占56.52%,以铜绿假单胞菌和肺炎克雷伯杆菌为主,构成比为24.64%和10.14%,最敏感的药物是碳青霉烯类药物亚胺培南,耐药率均在13.3%以下。革兰阳性球菌占30.44%,以金黄色葡萄球菌为主,构成比为21.02%,在药敏感试验方面除对万古霉素100%敏感外,对其他药物都表现出不同程度的耐药。真菌的检出率为13.04%,以白色念珠菌为主,构成比为9.42%。结论医院获得性肺炎患者应及时送检病原标本做细菌培养,按药敏结果合理选用抗生素。     

Digestion of Herring by Indigenous Bacteria in the Minke Whale Forestomach

Northeastern Atlantic minke whales (Balaenoptera acutorostrata) have a multichambered stomach system which includes a nonglandular forestomach resembling that of ruminants. Bacteria from the forestomachs of herring-eating whales were enumerated and isolated in an anaerobic rumen-like culture medium (M8W medium). The total viable population of anaerobic bacteria ranged from 73 × 10⁷ to 145 × 10⁸/ml of forestomach fluid (n = 4). Lactobacillus spp. (19.7%), Streptococcus spp. (35.9%), and Ruminococcus spp. (12.8%) were the most common of the bacterial strains (n = 117) isolated by use of M8W medium from the forestomach fluid population of two minke whales. Most of the isolates stained gram positive (93.2%), 62.4% were cocci, and all strains were strictly anaerobic. The population of lipolytic bacteria in one animal, enumerated by use of a selective lipid medium, constituted 89.7% of the viable population. The total viable population of anaerobic bacteria in freshly caught and homogenized herring (Clupea harengus) ranged from 56.7 to 95.0 cells per gram of homogenized prey (n = 3) when M8W medium was used. Pediococcus spp. (30.6%) and Aerococcus spp. (25.0%) were most common of the bacterial strains (n = 72) isolated from the homogenized herring. Most of the bacterial strains were gram positive (80.6%), and 70.8% were cocci. Unlike the forestomach bacterial population, as many as 61.1% of the strains from the herring were facultatively anaerobic. All bacterial strains isolated from the prey had phenotypic patterns different from those of strains isolated from the dominant bacterial population in the forestomach, indicating that the forestomach microbiota is indigenous. Scanning electron microscopic examinations revealed large numbers of bacteria, surrounded by a glycocalyx, attached to partly digested food particles in the forestomach. These data support the hypothesis that symbiotic microbial digestion occurs in the forestomach and that the bacteria are indigenous to minke whales.     

皮肤软组织感染病原菌分布及耐药性分析

目的 调查皮肤软组织感染病原菌的种类及耐药性,为临床合理使用抗菌药物提供科学依据.方法 利用WHONET 5.6对2009年1月至2011年12月皮肤软组织感染患者脓液或分泌物细菌培养及药敏试验结果进行回顾性分析.结果 共分离菌株444株,金黄色葡萄球菌(SAU)分离率居第1位,171株占38.5％;表皮葡萄球菌居第2位,54株占12.2％;铜绿假单胞菌第3位,43株占9.7％;头孢哌酮/舒巴坦、哌拉西林/他唑巴坦、阿米卡星、亚胺培南和美罗培南对革兰阴性杆菌有较好的抗菌活性(耐药率≤3.3％);金黄色葡萄球菌对青霉素和红霉素的耐药率为93.6％和65.0％,对呋喃妥因、利奈唑胺、利福平、莫西沙星和左旋氧氟沙星耐药率为0％、0％、1.4％、2.2％和9.3％,未检出万古霉素耐药株;耐甲氧西林金黄色葡萄球菌(MRSA)检出率25.7％ (44/171);MRSA和甲氧西林敏感金黄色葡萄球菌(MSSA)对氨苄西林/舒巴坦、利福平、莫西沙星三种药物的敏感性差异有统计学意义.结论 引起皮肤软组织感染病原菌以阳性球菌尤其是金黄色葡萄球菌为主,临床上应尽量根据药敏试验结果选用抗生素,合理用药.     

Evidence for natural horizontal transfer of the pcpB gene in the evolution of polychlorophenol-degrading sphingomonads

The chlorophenol degradation pathway in Sphingobium chlorophenolicum is initiated by the pcpB gene product, pentachlorophenol-4-monooxygenase. The distribution of the gene was studied in a phylogenetically diverse group of polychlorophenol-degrading bacteria isolated from contaminated groundwater in K?rk?l?, Finland. All the sphingomonads isolated were shown to share pcpB gene homologs with 98.9 to 100% sequence identity. The gene product was expressed when the strains were induced by 2,3,4,6-tetrachlorophenol. A comparative analysis of the 16S rDNA and pcpB gene trees suggested that a recent horizontal transfer of the pcpB gene was involved in the evolution of the catabolic pathway in the K?rk?l? sphingomonads. The full-length K?rk?l? pcpB gene allele had approximately 70% identity with the three pcpB genes previously sequenced from sphingomonads. It was very closely related to the environmental clones obtained from chlorophenol-enriched soil samples (M. Beaulieu, V. Becaert, L. Deschenes, and R. Villemur, Microbiol. Ecol. 40:345-355, 2000). The gene was not present in polychlorophenol-degrading nonsphingomonads isolated from the K?rk?l? source.     

Clinical relevance and virulence factors of pigmented Serratia marcescens

Pigmented Serratia marcescens isolated in a Brazilian hospital were studied with respect to frequency of isolation, serotyping, antibiotic resistance and virulence factors. The serotype most frequent was O6:K14 (53%) and all isolates were resistant to ampicillin, cephalothin and tetracycline. The majority of the isolates (92%) were resistant to the action of human serum and all produced cytotoxins on Vero, CHO, HEp-2 and HeLa cells. These isolates were virulent for mice (LD(50)=10(7) bacteria ml(-1)) and showed virulence factors, but were isolated with low frequency (3. 4%) and caused infection in only 31% of cases. Analysis of serotyping, phage typing and chromosomal DNA revealed at least 13 unrelated strains among pigmented S. marcescens. In conclusion, this work describes a low frequency of isolation of pigmented S. marcescens from clinical specimens, indicating that non-pigmented strains are clinically more significant.     

Toxin profiles, and cell-surface properties of Salmonella strains isolated from Swedish travelers.

Toxin production, cell-surface hydrophobicity and fibronectin-binding properties of 21 Salmonella strains of different species, isolated from Swedish travelers to different parts of the world, were studied. Cell sonicate supernatants from blood agar grown cultures of 80% of the strains induced rabbit skin permeability reaction in the form of induration and/or blueing while 33% of the strains also produced cell necrotizing factor on rabbit skin. Four strains were negative in the rabbit skin permeability test, while only two were negative when tested on CHO cells. When cultured on blood agar, a majority of the strains (17/21) showed low cell-surface hydrophobicity, showing no aggregation even at 1.5 M ammonium sulfate concentration in salt aggregation test (SAT), while only four strains showed high cell-surface hydrophobicity. Furthermore, these strains could be classified as low fibronectin binders due to their poor interaction with fibronectin or its 29 kDa N-terminal fragment.     

Trends in the Epidemiology of Pandemic and Non-pandemic Strains of Vibrio parahaemolyticus Isolated from Diarrheal Patients in Kolkata,India

A total of 178 strains of V. parahaemolyticus isolated from 13,607 acute diarrheal patients admitted in the Infectious Diseases Hospital, Kolkata has been examined for serovar prevalence, antimicrobial susceptibility and genetic traits with reference to virulence, and clonal lineages. Clinical symptoms and stool characteristics of V. parahaemolyticus infected patients were analyzed for their specific traits. The frequency of pandemic strains was 68%, as confirmed by group-specific PCR (GS-PCR). However, the prevalence of non-pandemic strains was comparatively low (32%). Serovars O3:K6 (19.7%), O1:K25 (18.5%), O1:KUT (11.2%) were more commonly found and other serovars such as O3:KUT (6.7%), O4:K8 (6.7%), and O2:K3 (4.5%) were newly detected in this region. The virulence gene tdh was most frequently detected in GS-PCR positive strains. There was no association between strain features and stool characteristics or clinical outcomes with reference to serovar, pandemic/non-pandemic or virulence profiles. Ampicillin and streptomycin resistance was constant throughout the study period and the MIC of ampicillin among selected strains ranged from 24 to >256 µg/ml. Susceptibility of these strains to ampicillin increased several fold in the presence of carbonyl cyanide-m-chlorophenyldrazone. The newly reported ESBL encoding gene from VPA0477 was found in all the strains, including the susceptible ones for ampicillin. However, none of the strains exhibited the β-lactamase as a phenotypic marker. In the analysis of pulsed-field gel electrophoresis (PFGE), the pandemic strains formed two different clades, with one containing the newly emerged pandemic strains in this region.     

Distribution and antibacterial drug resistance ofAeromonas spp. from fresh and brackish waters in Southern Turkey

The frequency of antibiotic resistance was compared inAeromonas spp. isolated from fresh and brackish water in Southern Turkey. A total of 97Aeromonas spp. strains were isolated from four zones (three from fresh and one from brackish water). Most of the strains isolated from all samples wereAeromonas hydrophila (79.4%), while the amount ofAeromonas sobria andAeromons caviae, were rather lower in the samples examined (17.5% and 3.1% respectively). A high proportion of isolates from all water sources showed resistance to cephalotin (86.6%) and trimethoprim-sulphamethoxazole (69%). On the other hand, a low proportion of bacteria showed resistance to tetracycline (14.4%), chloramphenicol (11.3%), gentamicin (7.2%) and nitrofurantoin (6.8%). Only one strain showing resistance to amikacin was found. Multiple Antibiotic Resistance Index (MARI) to at least two antibiotics was highest in brackish water (zone 4), followed by fresh water (zone 3). MARI values ranging from 0.2 to 0.8 for the bacteria isolated from brackish water. This study suggest that, multiple antibiotic resistantAeromonas spp., especiallyA. hydrophila, can be easily recovered from fresh and brackish water sources in Turkey and these sources may play as a reservoirs responsible for disease pathogen aeromonads.