Reversal of heavy metal-induced antibiotic resistance by dandelion root extracts and taraxasterol.

Introduction. Metal exposure is an important factor for inducing antibiotic resistance in bacteria. Dandelion extracts have been used for centuries in traditional Chinese and Native American medicine.Aim. We assessed the effects of dandelion water extracts and taraxasterol on heavy metal-induced antibiotic resistance in Escherichia coli as well as the underlying mechanisms.Methodology. Dandelion extracts were obtained through 4 h of boiling in distilled water. Bacterial growth was monitored with a spectrophotometer. Biochemical assays were performed to assess the activities and gene transcriptions of ß-lactamase and acetyltransferase. Oxidative stress was determined using an oxidation-sensitive probe, H2DCFDA.Results. The present study demonstrated that higher concentrations of nickel (>5 µg ml-1), cadmium (>0.1 µg ml-1), arsenic (>0.1 µg ml-1) and copper (>5 µg ml-1) significantly inhibited the growth of E. coli. Lower concentrations of nickel (0.5 µg ml-1), cadmium (0.05 µg ml-1) and arsenic (0.05 µg ml-1) had no effect on bacterial growth, but helped the bacteria become resistant to two antibiotics, kanamycin and ampicillin. The addition of dandelion root extracts and taraxasterol significantly reversed the antibiotic resistance induced by these heavy metals. The supplements of antibiotics and cadmium generated synergistic effects on the activities of ß-lactamase and acetyltransferase (two antibiotic resistance-related proteins), which were significantly blocked by either dandelion root extract or taraxasterol. In contrast, oxidative stress was not involved in the preventative roles of dandelion root extracts and taraxasterol in heavy metal-induced antibiotic resistance.Conclusion. This study suggests that heavy metals induce bacterial antibiotic resistance and dandelion root extracts and taraxasterol could be used to help reverse bacterial resistance to antibiotics.

The effects of amoxicillin treatment of newborn piglets on the prevalence of hernias and abscesses, growth and ampicillin resistance of intestinal coliform bacteria in weaned pigs.

This study investigated the effects of a single amoxicillin treatment of newborn piglets on the prevalence of hernias and abscesses until the age of nine weeks. We also studied whether the treatment was associated with growth and mortality, the need for treatment of other diseases, the proportions of ampicillin resistant coliforms and antimicrobial resistance patterns of intestinal Escherichia coli (E. coli). A total of 7156 piglets, from approximately 480 litters, were divided into two treatment groups: ANT (N = 3661) and CON (N = 3495), where piglets were treated with or without a single intramuscular injection of 75 mg amoxicillin one day after birth, respectively. The umbilical and inguinal areas of weaned pigs were palpated at four and nine weeks of age. At the same time, altogether 124 pigs with hernias or abscesses and 820 non-defective pigs from three pens per batch were weighed individually. Mortality and the need to treat piglets for other diseases were recorded. Piglet faecal samples were collected from three areas of the floors of each pen at four weeks of age. The prevalence of umbilical hernias or abscesses did not differ between the groups at four weeks of age, but it was higher in the CON group than in the ANT group at nine weeks of age (2.3% vs. 0.7%, P < 0.05). Numbers of inguinal hernias and abscesses did not differ between the groups at four or nine weeks of age. The ANT group, when it compared with the CON group, increased the weight gain between four and nine weeks of age (LS means ± SE; 497.5 g/d ± 5.0 vs. 475.3 g/d ± 4.9, P < 0.01), and decreased piglet mortality (19.5% ± 1.0 vs. 6.9% ± 1.0, P < 0.05) and the need to treat the piglets for leg problems (3.4% ± 0.3 vs. 1.9% ± 0.3%, P < 0.01) but not for other diseases by the age of four weeks. The proportion of ampicillin resistant intestinal coliform bacteria and the resistance patterns of the E. coli isolates were not different between the ANT and CON groups. In conclusion, our results showed that the amoxicillin treatment of new-born piglets produced statistically significant effect in some of the parameters studied. However, as these effects were only minor, we did not find grounds to recommend preventive antibiotic treatment. Further, continuous antimicrobial treatment of newborn piglets could negatively influence the development of the normal microbiota of the piglet and promote selection of antimicrobial resistance genes in herds. Therefore we suggest rejection of the use of routine administration of antimicrobial agents at birth.

Evaluation of Haemophilus influenzae type b carrier status among children 10 years after the introduction of Hib vaccine in Brazil.

The aim of the present study was to assess the prevalence of Haemophilus influenzae type b (Hib) nasopharyngeal (NP) colonisation among healthy children where Hib vaccination using a 3p+0 dosing schedule has been routinely administered for 10 years with sustained coverage (> 90%). NP swabs were collected from 2,558 children who had received the Hib vaccine, of whom 1,379 were 12-< 24 months (m) old and 1,179 were 48-< 60 m old. Hi strains were identified by molecular methods. Hi carriage prevalence was 45.1% (1,153/2,558) and the prevalence in the 12-< 24 m and 48-< 60 m age groups were 37.5% (517/1,379) and 53.9% (636/1,179), respectively. Hib was identified in 0.6% (16/2,558) of all children in the study, being 0.8% (11/1,379) and 0.4% (5/1,179) among the 12-< 24 m and 48-< 60 m age groups, respectively. The nonencapsulate Hi colonisation was 43% (n = 1,099) and was significantly more frequent at 48-< 60 m of age (51.6%, n = 608) compared with that at 12-< 24 m of age (35.6%, n = 491). The overall resistance rates to ampicillin and chloramphenicol were 16.5% and 3.7%, respectively; the co-resistance was detected in 2.6%. Our findings showed that the Hib carrier rate in healthy children under five years was very low after 10 years of the introduction of the Hib vaccine.

Evaluation of Haemophilus influenzae type b carrier status among children 10 years after the introduction of Hib vaccine in Brazil

The aim of the present study was to assess the prevalence of Haemophilus influenzaetype b (Hib) nasopharyngeal (NP) colonisation among healthy children where Hib vaccination using a 3p+0 dosing schedule has been routinely administered for 10 years with sustained coverage (> 90%). NP swabs were collected from 2,558 children who had received the Hib vaccine, of whom 1,379 were 12-< 24 months (m) old and 1,179 were 48-< 60 m old. Hi strains were identified by molecular methods. Hi carriage prevalence was 45.1% (1,153/2,558) and the prevalence in the 12-< 24 m and 48-< 60 m age groups were 37.5% (517/1,379) and 53.9% (636/1,179), respectively. Hib was identified in 0.6% (16/2,558) of all children in the study, being 0.8% (11/1,379) and 0.4% (5/1,179) among the 12-< 24 m and 48-< 60 m age groups, respectively. The nonencapsulate Hi colonisation was 43% (n = 1,099) and was significantly more frequent at 48-< 60 m of age (51.6%, n = 608) compared with that at 12-< 24 m of age (35.6%, n = 491). The overall resistance rates to ampicillin and chloramphenicol were 16.5% and 3.7%, respectively; the co-resistance was detected in 2.6%. Our findings showed that the Hib carrier rate in healthy children under five years was very low after 10 years of the introduction of the Hib vaccine.

Ampicillin-resistant Haemophilus influenzae isolates in Geneva: serotype, antimicrobial susceptibility, and ß-lactam resistance mechanisms.

The purpose of this study was to analyze the molecular mechanisms of ampicillin-resistant Haemophilus influenzae isolated in Geneva, Switzerland. We investigated the association between specific patterns of amino acid substitutions in penicillin-binding protein 3 (with or without ß-lactamase production) and ß-lactam susceptibility. Another main focus for this study was to compare the accuracy of disk diffusion and Etest methods to detect resistance to ampicillin and amoxicillin/clavulanic acid. The antibiotic susceptibility to ß-lactam antibiotics of 124 H. influenzae isolates was determined by disk diffusion and Etest methods, and interpreted by European Committee on Antimicrobial Susceptibility Testing (EUCAST) and Clinical and Laboratory Standards Institute (CLSI) breakpoints. Alterations in PBP3 were investigated by sequencing the ftsI gene. Of the 124 clinical isolates analyzed, ampicillin resistance was found in 36% (45 out of 124). The rate of resistance to amoxicillin/clavulanic acid was 9% and 0.8%, using EUCAST and CLSI breakpoints respectively. For the 78 ß-lactamase negative ampicillin-susceptible (BLNAS) isolates for which the Etest method indicated a high degree of susceptibility (MIC ≤ 1 mg/L), the disk diffusion method revealed resistance to ampicillin and amoxicillin/clavulanic acid in 33 cases (42%). Most common amino acid substitutions were Asn526Lys and Val547Ile, followed by Asp569Ser, Ala502Val, Asp350Asn, Met377Ile, Ile449Val, and Arg517His. The patterns observed were classified into six groups (IIa, IIb, IIc, IId, III-like, and miscellaneous). Continued characterization of both invasive and respiratory H. influenzae isolates is necessary in order to observe changes in the microbiology and epidemiology of this pathogen that could lead to clinical failure when treated by empirical antibiotic therapy.

Synergistic activity and mechanism of action of Stephania suberosa Forman extract and ampicillin combination against ampicillin-resistant Staphylococcus aureus.

BACKGROUND: Ampicillin-resistant S. aureus (ARSA) now poses a serious problem for hospitalized patients, and their care providers. Plant-derived antibacterial that can reverse the resistance to well-tried agents which have lost their original effectiveness are the research objectives of far reaching importance. To this aim, the present study investigated antibacterial and synergistic activities of Stephania suberosa extracts (SSE) against ARSA when used singly and in combination with ampicillin. RESULTS: The majority chemical compounds of SSE were alkaloid (526.27 ± 47.27 mg/1 g of dried extract). The Minimum inhibitory concentration (MICs) for ampicillin and SSE against all ARSA strains were >512 µg/ml and 4 mg/ml, respectively. Checkerboard assay revealed synergistic activity in the combination of ampicillin (0.15 µg/ml) and SSE (2 mg/ml) at fractional inhibitory concentration index (FICI) <0.5. The killing curve assay had confirmed that the viability of ARSA was dramatically reduced from 5 x 10(5) cfu/ml to 10(3) cfu/ml within 6 h after exposure to SSE (2 mg/ml) plus ampicillin (0.15 µg/ml) combination. Electron microscopic study clearly revealed that these ARSA cells treated with this combination caused marked morphological damage, peptidoglycan and cytoplasmic membrane damage, and average cell areas significant smaller than control. Obviously, Immunofluorescence staining and confocal microscopic images confirmed that the peptidoglycan of these cells were undoubtedly disrupted by this combination. Furthermore, the CM permeability of ARSA was also increased by this combination. Enzyme assay demonstrated that SSE had an inhibitory activity against ß-lactamase in concentrations manner. CONCLUSIONS: So, these findings provide evidence that SSE has the high potential to reverse bacterial resistance to originate traditional drug susceptibility of it and may relate to three modes of actions of SSE: (1) inhibits peptidoglycan synthesis, resulting in morphological damage, (2) inhibits ß-lactamases activity, and (3) increases CM permeability. It is widely recognized that many types of drugs are derived from alkaloids. So, this SSE offers the prominent potential to develop a novel adjunct phytopharmaceutical to ampicillin for the treatment of ARSA. Further active ingredients study, toxicity of it, and the synergistic effect on blood and tissue should be performed and confirmed in an animal test or in humans.

Reversal of ampicillin resistance in MRSA via inhibition of penicillin-binding protein 2a by Acalypha wilkesiana.

The inhibitory activity of a semipure fraction from the plant, Acalypha wilkesiana assigned as 9EA-FC-B, alone and in combination with ampicillin, was studied against methicillin-resistant Staphylococcus aureus (MRSA). In addition, effects of the combination treatment on PBP2a expression were investigated. Microdilution assay was used to determine the minimal inhibitory concentrations (MIC). Synergistic effects of 9EA-FC-B with ampicillin were determined using the fractional inhibitory concentration (FIC) index and kinetic growth curve assay. Western blot experiments were carried out to study the PBP2a expression in treated MRSA cultures. The results showed a synergistic effect between ampicillin and 9EA-FC-B treatment with the lowest FIC index of 0.19 (synergism ≤ 0.5). The presence of 9EA-FC-B reduced the MIC of ampicillin from 50 to 1.56 µg mL(-1). When ampicillin and 9EA-FC-B were combined at subinhibitory level, the kinetic growth curves were suppressed. The antibacterial effect of 9EA-FC-B and ampicillin was shown to be synergistic. The synergism is due the ability of 9EA-FC-B to suppress the activity of PBP2a, thus restoring the susceptibility of MRSA to ampicillin. Corilagin was postulated to be the constituent responsible for the synergistic activity showed by 9EA-FC-B.

Listeria and enterococcal infections in neonates 28 days of age and younger: is empiric parenteral ampicillin still indicated?

INTRODUCTION: Empiric parenteral ampicillin has traditionally been used to treat listeria and enterococcal serious bacterial infections (SBI) in neonates 28 days of age or younger. Anecdotal experience suggests that these infections are rare. Existing data suggest an increasing resistance to ampicillin. Guidelines advocating the routine use of empiric ampicillin may need to be revisited. OBJECTIVE: This study aimed to describe the epidemiology and ampicillin sensitivity of listeria and enterococcal infections in neonates 28 days of age and younger who presented to 2 pediatric emergency departments (ED) in Michigan. METHODS: We conducted a 2-center, retrospective chart review (2006-2010) of neonates 28 days of age or younger who were evaluated for SBI in the ED. We abstracted and compared relevant demographic, historical and physical details, laboratory test results, and antibiotic sensitivity patterns to ampicillin from the eligible patient records. RESULTS: We identified SBI in 6% (72/1192) of neonates 28 days of age or younger who were evaluated for SBI, of which 0.08% (1/1192) neonates had enterococcal bacteremia and 0.08% (1/1192) neonates had listeria bacteremia. A total of 1.4% (15/1192) of patients had enterococcal urinary tract infection (UTI). Urinalysis is less helpful as a screening tool for enterococcal UTI when compared with Escherichia coli UTI (P < 0.001). Seventy-three percent (11/15) of urine isolates had an increase of minimal inhibitory concentrations, which indicate gradual development of resistance to ampicillin. CONCLUSIONS: Listeria is an uncommon cause of neonatal SBI in febrile neonates who presented to the ED. Empiric use of ampicillin may need to be reconsidered if national data confirm very low listeria and enterococcal prevalence and high ampicillin resistance patterns.

Antibacterial activity against ß- lactamase producing Methicillin and Ampicillin-resistants Staphylococcus aureus: Fractional Inhibitory Concentration Index (FICI) determination.

BACKGROUND: The present study reports the antibacterial capacity of alkaloid compounds in combination with Methicillin and Ampicillin-resistants bacteria isolated from clinical samples. The resistance of different bacteria strains to the current antibacterial agents, their toxicity and the cost of the treatment have led to the development of natural products against the bacteria resistant infections when applied in combination with conventional antimicrobial drugs. METHOD: The antibacterial assays in this study were performed by using inhibition zone diameters, MIC, MBC methods, the time-kill assay and the Fractional Inhibitory Concentration Index (FICI) determination. On the whole, fifteen Gram-positive bacterial strains (MRSA/ARSA) were used. Negative control was prepared using discs impregnated with 10 % DMSO in water and commercially available Methicillin and Ampicillin from Alkom Laboratories LTD were used as positive reference standards for all bacterial strains. RESULTS: We noticed that the highest activities were founded with the combination of alkaloid compounds and conventional antibiotics against all bacteria strains. Then, results showed that after 7 h exposition there was no viable microorganism in the initial inoculums. CONCLUSION: The results of this study showed that alkaloid compounds in combination with conventional antibiotics (Methicillin, Ampicillin) exhibited antimicrobial effects against microorganisms tested. These results validate the ethno-botanical use of Cienfuegosia digitata Cav. (Malvaceae) in Burkina Faso. Moreover, this study demonstrates the potential of this herbaceous as a source of antibacterial agent that could be effectively used for future health care purposes.

Distribution of oral streptococci highly resistant to amoxicillin in dental plaque specimens from Japanese children and adolescents.

Oral streptococci are major pathogens of infective endocarditis. Prophylactic antibiotics are commonly given to subjects with certain kinds of heart disorders when invasive dental treatments are performed, with amoxicillin (AMPC) being widely used for this purpose. However, there is little information regarding AMPC-resistant oral streptococci. Here, a total of 344 dental plaque specimens collected from 253 healthy Japanese children, adolescents and young adults (aged 2-22 years) were diluted and streaked onto culture medium containing high-dose AMPC. The MICs for the isolated strains were evaluated using a macrodilution broth method described by the Clinical and Laboratory Standards Institute. Bacterial DNA was extracted from each strain and the entire sequences of the 16S rRNA gene were compared with those in GenBank to identify the species. The results showed that strains with AMPC MICs >16 µg ml(-1) were isolated from 18 specimens from 14 patients. Analyses of the 16S rRNA gene sequences of these strains identified them as major oral streptococcal species, including Streptococcus oralis and Streptococcus mitis. These findings indicate that oral streptococci with elevated MICs for AMPC exist in certain small populations of healthy children, and highlight the need for further studies to determine risk factors that lead to the appearance of such strains.

Evaluation of the antibacterial and anticancer activities of some South African medicinal plants.

BACKGROUND: Several herbs are traditionally used in the treatment of a variety of ailments particularly in the rural areas of South Africa where herbal medicine is mainly the source of health care system. Many of these herbs have not been assessed for safety or toxicity to tissue or organs of the mammalian recipients. METHODS: This study evaluated the cytotoxicity of some medicinal plants used, inter alia, in the treatment of diarrhoea, and stomach disorders. Six selected medicinal plants were assessed for their antibacterial activities against ampicillin-resistant and kanamycin-resistant strains of Escherichia coli by the broth micro-dilution methods. The cytotoxicities of methanol extracts and fractions of the six selected plants were determined using a modified tetrazolium-based colorimetric assay (3-(4, 5-dimethylthiazol)-2, 5-diphenyl tetrazolium bromide (MTT) assay). RESULTS: The average minimum inhibitory concentration (MIC) values of the plants extracts ranged from 0.027 mg/mℓ to 2.5 mg/mℓ after 24 h of incubation. Eucomis autumnalis and Cyathula uncinulata had the most significant biological activity with the least MIC values. The in vitro cytotoxicity assay on human hepatocarcinoma cell line (Huh-7) revealed that the methanol extract of E. autumnalis had the strongest cytotoxicity with IC(50) of 7.8 µg/mℓ. Ethyl acetate and butanol fractions of C. uncinulata, Hypoxis latifolia, E. autumnalis and Lantana camara had lower cytotoxic effects on the cancer cell lines tested with IC(50) values ranging from 24.8 to 44.1 µg/mℓ; while all the fractions of Aloe arborescens and A. striatula had insignificant or no cytotoxic effects after 72 h of treatment. CONCLUSIONS: Our results indicate that the methanol fraction of E. autumnalis had a profound cytotoxic effect even though it possessed very significant antibacterial activity. This puts a query on its safety and hence a call for caution in its usage, thus a product being natural is not tantamount to being entirely safe. However, the antibacterial activities and non-cytotoxic effects of A. arborescens and A. striatula validates their continuous usage in ethnomedicine.

Longitudinal characterization of resistant Escherichia coli in fecal deposits from cattle fed subtherapeutic levels of antimicrobials.

Model fecal deposits from cattle fed or not fed antimicrobial growth promoters were examined over 175 days in the field for growth and persistence of total Escherichia coli and numbers and proportions of ampicillin-resistant (Amp(r)) and tetracycline-resistant (Tet(r)) E. coli. In addition, genotypic diversity and the frequency of genetic determinants encoded by Amp(r) and Tet(r) E. coli were investigated. Cattle were fed diets containing chlortetracycline (44 ppm; A44 treatment group), chlortetracycline plus sulfamethazine (both at 44 ppm; AS700 treatment group), or no antibiotics (control). Fecal deposits were sampled 12 times over 175 days. Numbers of Tet(r) E. coli in A44 and AS700 deposits were higher (P < 0.001) than those of controls and represented up to 35.6% and 20.2% of total E. coli, respectively. A time-by-treatment interaction (P < 0.001) was observed for the numbers of Tet(r) and Amp(r) E. coli. Except for Amp(r) E. coli in control deposits, all E. coli numbers increased (P < 0.001) in deposits up to day 56. Even after 175 days, high Tet(r) E. coli numbers were detected in A44 and AS700 deposits [5.9 log(10) CFU (g dry matter)(-1) and 5.4 log(10) CFU (g dry matter)(-1), respectively]. E. coli genotypes, as determined by pulsed-field gel electrophoresis, were diverse and were influenced by the antimicrobial growth promoter and the sampling time. Of the determinants screened, bla(TEM1), tetA, tetB, tetC, sul1, and sul2 were frequently detected. Occurrence of determinants was influenced by the feeding of antimicrobials. Fecal deposits remain a source of resistant E. coli even after a considerable period of environmental exposure.

Evaluation of cefotaxime and desacetylcefotaxime concentrations in cord blood after intrapartum prophylaxis with cefotaxime.

Preterm premature rupture of the membranes is associated with a high risk of neonatal sepsis. An increase in the incidence of early-onset neonatal sepsis due to ampicillin-resistant Escherichia coli in premature infants has been observed in the past few years. Intrapartum prophylaxis with ampicillin has proven to be efficient for the prevention of early neonatal sepsis due to group B streptococci. To date, there is no strategy for the prevention of early neonatal sepsis due to ampicillin-resistant E. coli. Our aim was to investigate whether a standardized dosage regimen of intrapartum cefotaxime could provide concentrations in the cord blood greater than the cefotaxime MIC(90) for E. coli. Seven pregnant women hospitalized with preterm premature rupture of the membranes and colonized with ampicillin-resistant isolates of the family Enterobacteriaceae were included. Cefotaxime was given intravenously during delivery, as follows: 2 g at the onset of labor and then 1 g every 4 h until delivery. Blood specimens were collected from the mother 30 min after the first injection and just before the second injection, and at birth, blood specimens were simultaneously collected from the mother and the umbilical cord. The concentrations of cefotaxime in the cord blood ranged from 0.5 to 8.5 mg/liter. The MIC(90) of cefotaxime for E. coli strains (0.125 mg/liter) was achieved in all cases. This preliminary study supports the use of cefotaxime for intrapartum prophylaxis in women colonized with ampicillin-resistant isolates of Enterobacteriaceae. The effectiveness of this regimen for the prevention of neonatal sepsis needs to be evaluated with a larger population.

Efficacy of teicoplanin, administered in two different regimens, in the treatment of experimental endocarditis due to Enterococcus faecalis.

Using a rabbit model of endocarditis, we studied the efficacy of teicoplanin against a strain of Enterococcus faecalis resistant to ampicillin. Rabbits were randomly assigned to receive no antibiotics, teicoplanin 12 or 18 mg/kg of body weight every 12h, for 9 days. The effect of treatment on bacterial counts of vegetations and survival of the animals was evaluated at the end of treatment and 10 days thereafter. The two treatment regimens of teicoplanin produced peak serum levels 18.51+/-1.84 and 34.66+/-4.19 microg/ml, and trough levels above 10 x MIC of teicoplanin for the infecting organism. Both regimens resulted in significant bacterial reduction in the vegetations as compared to the control group (p<0.001). The drug prevented relapse of the infection 10 days after discontinuation of treatment. By increasing the teicoplanin dosage no additional therapeutic benefit was observed in terms of bacterial killing, sterilization of the vegetations, and survival of the animals, although the higher doses gave numerically superior results. These findings may have meaning for the optimum use of teicoplanin in the treatment of enterococcal endocarditis.

Perfil etiológico de las infecciones urinarias y patrón de sensibilidad de los uropatógenos / Etiological profile of urinary tract infections and antimicrobial susceptibility of urinary pathogens

Se presenta una revisión sobre el perfil etiológico de las infecciones urinarias en la infancia y el patrón de sensibilidad de los uropatógenos en nuestro país. Escherichia coli sigue siendo el principal agente etiológico de infección urinaria en la infancia, por lo que su patrón de sensibilidad va a determinar habitualmente la elección terapéutica empírica. El predominio de E. coli se ve reducido en ciertas circunstancias, en las que otros microorganismos incrementan su presencia. No obstante, la información clínica disponible al diagnóstico no permite predecir con seguridad la etiología; tan sólo la tinción y el examen microscópico de la orina pueden ayudar a seleccionar el tratamiento. E. coli presenta en España un alto porcentaje de resistencia a ampicilina y cotrimoxazol, mientras que mantienen una elevada sensibilidad las cefalosporinas de segunda y tercera generación, fosfomicina, aminoglucósidos y amoxicilina-ácido clavulánico. En algunas áreas, amoxicilina-ácido clavulánico y las cefalosporinas de primera generación presentan elevada resistencia, lo que puede comprometer su uso empírico

A review on the etiological profile of urinary tract infections in childhood and the sensitivity pattern of urinary pathogens in Spain is presented. Escherichia coli continues to be the main etiological agent of urinary tract infection in childhood. Consequently, its sensitivity pattern will usually determine the choice of empirical therapy. The predominance of E. coli is reduced in certain circumstances, in which the presence of other microorganisms is increased. However, the clinical information available at diagnosis does not allow accurate identification of the etiology; only staining and microscopic urine examination can help in treatment selection. In Spain, E. coli presents a high percentage of resistance to ampicillin and cotrimoxazole, whereas second- and third-generation cephalosporins, fosfomycin, aminoglycosides and amoxicillin-clavulanate maintain high sensitivity. In some areas, amoxicillin-clavulanate and first-generation cephalosporins show high levels of resistance, which can limit their empirical use

Evaluation of ceftobiprole medocaril against Enterococcus faecalis in a mouse peritonitis model.

OBJECTIVES: Ceftobiprole is a novel broad-spectrum cephalosporin with good in vitro activity against methicillin-resistant Staphylococcus aureus and Enterococcus faecalis. The objective of this study was to assess the in vivo activity of ceftobiprole against four strains of E. faecalis, including beta-lactamase- producing (Bla+) and vancomycin-resistant strains. METHODS: Mice were infected intraperitoneally with strains of E. faecalis: (i) the Bla+ strain HH22; (ii) two vancomycin-resistant strains (TX2484 and V583); and (iii) OG1RF (a laboratory strain), using 10 x the LD50 for each strain. Ceftobiprole doses of 25, 12.5 and 6.25 mg/kg (single doses) and ampicillin 50, 25, 12.5 and 6.25 mg/kg (single and double doses) were administered subcutaneously immediately after bacterial challenge and mice were monitored for 96 h. RESULTS: All four E. faecalis had ceftobiprole MICs 100 mg/kg, whereas ceftobiprole was protective (PD50 of 2 mg/kg). Ceftobiprole PD50s for vancomycin-resistant isolates TX2484 and V583 were 7.7 and 5.2 mg/kg, respectively, similar to those of single dose ampicillin (12.5 and 16.4 mg/kg, respectively). For OG1RF, both ampicillin and ceftobiprole protected all mice at doses of 25 and 12.5 mg/kg, respectively, with a PD50 of 4.2 and 8 mg/kg for ceftobiprole and ampicillin, respectively. CONCLUSIONS: Ceftobiprole had comparable in vivo activity to that of ampicillin against vancomycin-resistant and ampicillin-susceptible strains of E. faecalis in the mouse peritonitis model. Ceftobiprole was superior in vivo to ampicillin against the Bla+ strain HH22. Our data support the further study of ceftobiprole as a therapeutic agent in humans infected with E. faecalis.

Penicillin resistance is not extrapolable to amoxicillin resistance in Streptococcus pneumoniae isolated from middle ear fluid in children with acute otitis media.

OBJECTIVES: We evaluated the in vitro antibacterial activity of amoxicillin against penicillin-susceptible and -nonsusceptible Streptococcus pneumoniae strains isolated from children with acute otitis media (AOM). METHODS: Children more than 3 months of age with AOM who were seen in the Dr Sótero del Rio and Luis Calvo Mackenna Hospitals in Santiago, Chile, between July 1998 and December 2002 were subjected to tympanic puncture for middle ear fluid culture. The penicillin and amoxicillin susceptibilities of the S pneumoniae isolates were determined by epsilometer test (E test). RESULTS: A bacterial pathogen was isolated in 432 of 543 children (80%) as follows: S pneumoniae, 40%; Haemophilus influenzae, 29%; Moraxella catarrhalis, 7%; and Streptococcus pyogenes, 4%. Penicillin-susceptible S pneumoniae strains were less common than amoxicillin-susceptible strains (60% versus 95%; odds ratio [OR], 0.08; 95% confidence interval [CI], 0.04 to 0.18). Both intermediate- and high-resistance strains were more common for penicillin (22% versus 4.5%; OR, 5.6; 95% CI, 2.5 to 12.7) than for amoxicillin (18% versus 0.5%; OR, 41.3; 95% CI, 6.0 to 821). CONCLUSIONS: Penicillin resistance is not extrapolable to amoxicillin among S pneumoniae strains isolated from middle ear fluid of children with AOM. Our results support the recommendation to evaluate the minimal inhibitory concentrations of penicillin-nonsusceptible S pneumoniae for amoxicillin and to continue use of this antimicrobial as a first-line antimicrobial choice for children with AOM.

[Cholera in Rio Grande do Norte State--Brazil: sorology and sensitivity of Vibrio cholerae to different antimicrobials]. / A cólera no Estado do Rio Grande do Norte--Brasil--perfil sorológico e de sensibilidade do Vibrio cholerae a diferentes antimicrobianos.

PURPOSE: The emergence of multiple resistance to antimicrobials in Vibrio cholerae isolated in the state of Ceará, Brazil, alerted researchers in this area to the sensitivity to antimicrobials of strains isolated in Rio Grande do Norte (RN), Brazil. METHODS: One hundred and four strains of V. cholerae of human origin, isolated by Laboratório Central de Saúde Pública Dr. Almino Fernandes, were serologically typified and evaluated for in vitro sensitivity to eight antibiotics belonging to different groups (polymyxine, tetracycline, chloramphenicol, nitrofurantoin, sulphazotrin, pefloxacine, erythromycine, ampicillin). The strains were collected from patients suspected of contracting choleric diarrhea in the year 1999, in Natal/RN/Brazil. RESULTS: From the sample total, 100 were identified as V. cholerae, serogroup O:1, biotype El Tor, with 99 (95.3%) belonging to serovar Ogawa and only 1 (0.9%) to serovar Inaba. The 4 remaining were characterized as non O:1 V. cholerae, with 3 (2.9%) biochemically identified as Heiberg type I and 1 (0.9%) as type II. All the V. cholerae serogroup O:1 strains were sensitive to tetracycline, chloramphenicol, sulphazotrin, pefloxacine, erythromycine and resistant to polymyxine. In relation to nitrofurantoin, only 1 was sensitive. Only 1 was resistant to ampicillin. The non O:1 V. cholerae strains were resistant to polymyxine. CONCLUSIONS: The results showed sensitivity in 100% of the V. cholerae serogroup O:1 strains to tetracycline, an elective drug in the treatment of cholera, and an absence of multiple resistant strains in our environment. An interesting finding was the frequency of serovar Ogawa in 1999, considering the greater incidence of serovar Inaba in other years of cholera outbreaks in RN.

A cólera no Estado do Rio Grande do Norte--Brasil--perfil sorológico e de sensibilidade do Vibrio cholerae a diferentes antimicrobianos / Cholera in Rio Grande do Norte State--Brazil: sorology and sensitivity of Vibrio cholerae to different antimicrobials

PURPOSE: The emergence of multiple resistance to antimicrobials in Vibrio cholerae isolated in the state of Ceará, Brazil, alerted researchers in this area to the sensitivity to antimicrobials of strains isolated in Rio Grande do Norte (RN), Brazil. METHODS: One hundred and four strains of V. cholerae of human origin, isolated by Laboratório Central de Saúde Pública Dr. Almino Fernandes, were serologically typified and evaluated for in vitro sensitivity to eight antibiotics belonging to different groups (polymyxine, tetracycline, chloramphenicol, nitrofurantoin, sulphazotrin, pefloxacine, erythromycine, ampicillin). The strains were collected from patients suspected of contracting choleric diarrhea in the year 1999, in Natal/RN/Brazil. RESULTS: From the sample total, 100 were identified as V. cholerae, serogroup O:1, biotype El Tor, with 99 (95.3%) belonging to serovar Ogawa and only 1 (0.9%) to serovar Inaba. The 4 remaining were characterized as non O:1 V. cholerae, with 3 (2.9%) biochemically identified as Heiberg type I and 1 (0.9%) as type II. All the V. cholerae serogroup O:1 strains were sensitive to tetracycline, chloramphenicol, sulphazotrin, pefloxacine, erythromycine and resistant to polymyxine. In relation to nitrofurantoin, only 1 was sensitive. Only 1 was resistant to ampicillin. The non O:1 V. cholerae strains were resistant to polymyxine. CONCLUSIONS: The results showed sensitivity in 100% of the V. cholerae serogroup O:1 strains to tetracycline, an elective drug in the treatment of cholera, and an absence of multiple resistant strains in our environment. An interesting finding was the frequency of serovar Ogawa in 1999, considering the greater incidence of serovar Inaba in other years of cholera outbreaks in RN.

Generation of an Escherichia coli lysA targeted deletion mutant by double cross-over recombination for potential use in a bacterial growth-based lysine assay.

AIMS: To generate a stable Escherichia coli lysine auxotroph for the lysine bioavailability assay. METHODS AND RESULTS: An E. coli lysine auxotrophic strain was constructed by deleting the entire lysA gene and replacing it with a gene that confers resistance to ampicillin (bla). The linear DNA contained 50 bp homologous sequence of upstream of lysA in one end and 50 bp of downstream of lysA in the other end. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: The deltalysA::bla strain exhibited a linear response to lysine supplementation and can be used for quantifying lysine.