Evaluación de la resistencia a los antibióticos de cepas de Escherichia coli aisladas en carne de cerdo comercializada en los mercados municipales de la ciudad de Guatemala / Evaluation of antibiotics resistance of Escherichia coli strains isolated in pork sold in municipal markets of Guatemala City

La resistencia a los antimicrobianos es un problema de salud pública a nivel mundial que va en aumento y se ve reflejada en la falta de eficacia de los tratamientos de infecciones bacterianas con antibióticos en humanos y en animales. El presente estudio tuvo como objetivo evaluar la resistencia a los antibióticos de cepas de Escherichia coli aisladas en carne de cerdo expendida en los mercados municipales de la ciudad de Guatemala. Se identificaron los antibióticos que presentaron mayor resistencia y mayor sensibilidad in vitro frente a las cepas de E. coli aisladas a partir de 76 muestras de carne de cerdo. Se realizó un muestreo aleatorio simple con afijación proporcional por mercado. Para la identificación de las cepas de E. coli se utilizó la prueba de IMViC y para evaluar la resistencia a los antimicrobianos se utilizó la prueba de Kirby Bauer empleando 9 antibióticos. Se aisló E. coli en el 55% (42/76) de las muestras. La resistencia en las 42 cepas aisladas fue: tetraciclina (83%) neomicina (50%) y sulfametoxasole + trimetoprim (50%). 83% de las cepas (35/42) fueron resistentes a 2 antibióticos y 50% (21/42) a 3 antibióticos o más. Se obtuvo mayor sensibilidad con ceftriaxona (91%), amikacina (83%), gentamicina (65%) y ácido nalidíxico (65%). Se concluye que existe resistencia a los antibióticos evaluados, lo que constituye un riesgo para la salud pública ya que se encuentra en cepas aisladas en un alimento para consumo humano.

Antimicrobial resistance is a global public health threat that is increasing and is reflected in the lack of efficacy of bacterial infection treatments with antibiotics in humans and animals. The objective of this study was to evaluate the resistance to antibiotics of Escherichia coli strains isolated from pork in the municipal markets of Guatemala City. Antibiotics with the highest resistance and those with the highest sensitivity in vitro against the strains of E. coli were evaluated. A simple random sampling was carried out with proportional allocation by market, and 76 samples were collected. IMViC test was used to identify the E. coli strains, and antibiotics resistance was evaluated using the Kirby Bauer with nine different antibiotics. E. coli was isolated in 55% (42/76) of the samples. Resistance was evaluated in the 42 isolates. Antibiotic resistance was detected to tetracycline (83%), neomycin (50%), and sulfamethoxazole + trimethoprim (50%). All isolates presented resistance to at least one antibiotic; it was determined that 83% (35/42) showed resistance to two antibiotics and 50% (21/42) showed resistance to three antibiotics or more. The sensitivity obtained was higher for ceftriaxone (91%), amikacin (83%), gentamicin (65%), and nalidixic acid (65%). In conclusion, antibiotic resistance was detected, which constitutes a risk to public health since it is found in isolated strains in food for human consumption.

Evaluation of Reverse Hybridization Assay for Detecting Fluoroquinolone and Kanamycin Resistance in Multidrug-Resistance Mycobacterium tuberculosis Clinical Isolates / 결핵및호흡기질환

BACKGROUND: Multidrug-resistant tuberculosis (MDR-TB) is an increasing public health problem and poses a serious threat to global TB control. Fluoroquinolone (FQ) and aminoglycoside (AG) are essential anti-TB drugs for MDR-TB treatment. REBA MTB-FQ(R) and REBA MTB-KM(R) (M&D, Wonju, Korea) were evaluated for rapid detection of FQ and kanamycin (KM) resistance in MDR-TB clinical isolates. METHODS: M. tuberculosis (n=67) were isolated and cultured from the sputum samples of MDR-TB patients for extracting DNA of the bacilli. Mutations in genes, gyrA and rrs, that have been known to be associated with resistance to FQ and KM were analyzed using both REBA MTB-FQ(R) and REBA MTB-KM(R), respectively. The isolates were also utilized for a conventional phenotypic drug susceptibility test (DST) as the gold standard of FQ and KM resistance. The molecular and phenotypic DST results were compared. RESULTS: Sensitivity and specificity of REBA MTB-FQ(R) were 77 and 100%, respectively. Positive predictive value and negative predictive value of the assay were 100 and 95%, respectively, for FQ resistance. Sensitivity, specificity, positive predictive value and negative predictive value of REBA MTB-KM(R) for detecting KM resistance were 66%, 94%, 70%, and 95%, respectively. CONCLUSION: REBA MTB-FQ(R) and REBA MTB-KM(R) evaluated in this study showed excellent specificities as 100 and 94%, respectively. However, sensitivities of the assays were low. It is essential to increase sensitivity of the rapid drug resistance assays for appropriate MDR-TB treatment, suggesting further investigation to detect new or other mutation sites of the associated genes in M. tuberculosis is required.

The effect of some boron derivatives on kanamycin resistance and survival of E. coli and P. aeruginosa in lake water / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To study MIC value of 7 boron derivatives namely [Boric acid (H(3)BO(3)), Anhydrous Borax (Na(2)B(4)O(7)), Sodium Borate (NaBO(2)), Diammonium Tetraborate (NH(4))(2)B(4)O(7), Sodium Perborate (NaBO(3)), Boron Trioxide (B(2)O(3)), Potassium Tetraborate (K(2)B(4)O(7))] on E. coli and P. aeruginosa and their effects on survival of bacteria in lake water and resistance against kanamycin antibiotic.</p><p><b>METHODS</b>MIC values of Boron derivatives and antibiotic were studied by broth microdilution method. The effect of boron derivatives on survival of bacteria in lake water were also determined with plate count.</p><p><b>RESULTS</b>Sodium perborate was determined as the most effective substance among the studied substances. Effectiveness increased as temperature increased. E. coli was more affected from P. aeruginosa in 8 mg/mL sodium perborate concentration in lake water. Moreover, it was determined that MIC value of kanamycin antibiotic decreased 200 times by especially treating P. aeruginosa with sodium perborate in lake water. However, it can be stated that this change in resistance did not arise from microorganisms.</p><p><b>CONCLUSION</b>Sodium perborate solution can be used supportedly in kanamycin antibiotic applications for P. aeruginosa. Future studies are necessary to explore the relation between sodium perborate and kanamycin which is effective on P. aeruginosa in lake water.</p>

Development of a Mycobacterial Gene Knock-out System using Sequence-specific Recombinase FLP/FRT and its Application to the Construction of a Rhamnose Biosynthetic Gene rmlD Deletion Mutant

Development of a new and effecient tuberculosis vaccine is very important since the efficacy of the only available vaccine against tuberculosis, BCG, is variable among races and different ages. Attempts to develop attenuated vaccines by disrupting virulence gene(s) specifically in Mycobacterium tuberculosis are now actively being tried after the release of whole genome sequence of M. tuberculosis in 1998. However, disruption of specific genes in M. tuberculosis is still very difficult due to the lack of effective gene knock-out system(s) in mycobacteria. In this study, we developed a novel method to delete specific genes in both Escherichia coli and mycobacteria. This knock-out system is operated by a sequence-specific recombinase FLP and its recognition sequence FRT (FLP/FRT system). Two shuttle vectors (an FLP expressing vector and a gene targeting vector) between Escherichia coli and Mycobacteria were developed. The gene targeting vector contains a kanamycin resistance gene (KmR) flanked by two neighboring genes and two FRTs (FLPrecognition targets). We applied this system to knock-out the rhamnose biosynthetic gene rmlD of Escherichia coli. The upstream and downstream genes of rmlD, rmlB and rmlA, were cloned into the gene targeting vector. After and allelic exchange of E. coli chromosomal rmlB, rmlD, rmlA with vectoral rmlB, FRT-KmR-FRT, rmlA by homologous recombination, FLP-expressing plasmid was introduced to induce the excision of KmR cassette remaining one FRT sequence between rmlB and rmlA. We also demonstrated our shuttle vector could disrupt a target gene (kanamycin resistance gene) in M. smegmatis. These results suggest that our gene knock-out system can be used for the development of an attenuated tuberculosis vaccines and for the functional genomic study of mycobacteria.

Spontaneous Kanamycin-resistant Escherichia coli mutant with altered periplasmic oligopeptide permease protein (OPPA) and impermeability to aminoglycosides

A spontaneous kanamycin-resistant Escherichia coli mutant, showing cross resitance to five other aminoglycosides and absence of the OppA protein was isolated. [3H]- dihydrostreptomycin uptake is reduced in this mutant, implying that the oligopeptide transport system in involved in accumulation of aminoglucosides, although apparently not related with aminoglycoside permeability alteration due to bacterial adaptation to osmotic changes.

Phage-mediated conjugation in staphylococci as a means of transfer of drug-resistance.

Penicillin resistance plasmid was transferred from Staphylococcus aureus B4 (PcrKms, donor) to S. aureus ML351 (PcsKmr, recipient) by co-cultivation of the donor with the recipient in nutrient broth with or without the modifying effects of CaCl2 or sodium dodecyl sulfate. It was found that the transfer of drug-resistance occurred maximally between 6 and 18 hr postinoculation; however, addition of DNase (200 micrograms/ml) could totally prevent such a transfer up to 6 hr and significantly reduce it thereafter. Cell-free filtrate of the donor culture when mixed with the recipient was ineffective in bringing about the transfer of Pcr.

Susceptibility of south Indian strains of Mycobacterium tuberculosis to tuberactinomycin.

A total of 114 strains of Mycobacterium tuberculosis isolated from sputum samples of 114 patients of pulmonary tuberculosis in south India, were coded and tested for their in vitro susceptibility to tuberactinomycin (Tum) incorporated in Lowenstein-Jensen (LJ) medium. Of these strains, 95 (83.3%) and 15 (13.2%) were susceptible to Tum at 25 and 50 mg/l respectively. Only 4 (3.5%) strains were inhibited at 100 mg/l or more. Of the 37 drug sensitive strains, 2 (5.4%) were not susceptible to Tum at 25 mg/l compared to 17 (22.1%) of 77 strains-resistant to one or more of antituberculosis drugs (P less than 0.02). The drug susceptibility pattern of the strains revealed that there was no significant association of resistance between Tum and streptomycin or rifampicin or ethambutol or ethionamide or isoniazid. However, 15 (53.6%) of 28 kanamycin (K) resistant strains were not susceptible to Tum at 25 mg/l. This cross resistance between Tum and K was further studied in 24 and 15 K sensitive and resistant strains respectively, by correlating their proportion resistance at 16 mg/l and it was found to have a significant positive correlation (r = 0.55; P less than 0.01).

Transformation and regeneration of mung bean (Vigna radiata).

The procedure relied on a protocol in which shoot organogenesis was induced on cotyledons of mung bean genotypes selected for susceptibility to agrobacterium seems to work reproducibly if not efficiently. Approximately 4-5% of the shoots produced on the kanamycin selected cotyledons are transgenic based on assays on kanamycin resistance and GUS activity. This demonstrated that transformation and regeneration in mung bean are possible. However, raising the transformed plants in field condition is yet to be perfected.

Escherichia coli colicinogênicas isoladas de material clínico humano: estudo de multirresistência a antimicrobianos / Colicinogenic Escherichia coli isolated from human clinical material: a study of multiresistance to antimicrobial agents

Foram estudadas 183 amostras de Escherichia coli com respeito à produçäo de colicina e à resistência das amostras a antimicrobianos. Trinta e duas amostras (17,5%) eram colicinogênicas, sendo predominantes os colicinótipos E1 e E3. Dos resultados obtidos, verificou-se que as amostras colicinogênicas E1 apresentaram multirresistência à KN - CO - TT - STX em maior incidência que as amostras colicinótipos E3. A multirresistência esteve mais presente em amostras isoladas de secreçöes diversas

In vitro comparative activity of kanamycin, gentamicin and sisomicin--a new aminoglycoside, against clinical isolates.

540 strains of bacteria isolated from various clinical materials comprising 440 strains of Gram negative bacilli and 100 strains of Gram positive cocci were tested for their susceptibility in vitro to Kanamycin, Gentamicin and a new aminoglycoside antibiotic Sisomicin (Ensamycin). The sensitivity pattern revealed that 68.88% of the strains were sensitive to Kanamycin, 82.9% to Gentamicin and 89.0% to Sisomicin. The effectiveness of Sisomicin is comparatively greater (6.1%) than the other two aminoglycosides. In particular a considerable number of Gentamicin resistant Pseudomonas aeruginosa (12.3%) were found to be sensitive to Sisomicin which is a highly desirable property. Existence of about 11% Sisomium resistant strains even before the wide usage of this antibiotic is note worthy.

Acción sobre haemophilus influenzae de su ácido desoxirribonucléico transformante irradiado in vitro con luz ultravioleta a -70- / Action on haemophilus influenzae of its transforming deoxyribonucleic acid irradited in vitro with ultraviolet light at -70-C

La irradiación con luz ultravioleta a - 70-C de DNA transformante desnaturalizado, el cual fue posteriormente sonicado y renaturalizado con DNA no irradiado, así como el DNA no irradiado y sometido a los otros tratamientos, provocaron un fuerte efecto letal sobre H. influenzae, el cual fue detecto al efectuarse la cuenta viable de las mezclas de transformación, encontrándose la disminución de la viabilidad de las células de un 98% para el caso del DNA irradiado y de un 97.2% para el DNA sin irradiar. Pensamos que la letalidad pueda deberse, tanto a la integración al genóforo de la célula receptora de los marcadores letales provados por la luz UV, como a la activación de un fago defectuoso causada por la penetración del DNA transformante irradiado o no con luz UV. La irradiación con luz UV del DNA transformante desnaturalizado, el cual fue renaturalizado consifo mismo, hizo aumentar ligeramente el número de mutantes resistentes a Kanamicina en células competentes de H. influenzae. Al someterse a lisis sónica del DNA irradiado, antes de renaturalizarse con DNA no irradiado, el resultaod obtenido fue aproximadamente el mismo que en el caso anterior. Sin embargo, cuando el número de mutantes resistentes a novobiocina se corrigió por la cuenta viable de la mezcla de transformación y el efecto mutagenético se cuantificó con relación a las frecuencias de mutación, encontramos un aumento de dichas frecuencias de 74 veces respecto a los testigos de células no tratadas con DNA. Este efecto puede, en principio, deberse a la integración en el genoma receptor de las lesiones mutagenéticas causadas por la irradiación con luz UV a - 70-C del DNA transformante, mas la afirmación concluyente de esto, requerirá la demostración de que dicha integración se lleva a cabo. Proponemos que estas lesiones mutagenéticas pudieran ser del tipo 5-timinil-5, 6-dihidrotimina. Fue interesante que del SNA no irradiado con luz UV, provocara también un aumento aunque menor al producido por el DNA irradiado, de las frecuencias de mutación. La explicación de este hecho, necesitará de un análisis experimental detallado posterior, utilizando mutantes rec y uvr de H. influenzae