Use of antibacterial agents in an intensive care unit in a hospital in Brazil

It is essential to monitor the utilisation of antibacterial drugs in order to establish appropriate measures for their control. The pattern of usage of antibacterial drugs, and its association with indicators of hospital infection, has been investigated in a non-specialized adult intensive care unit (ICU) located in Santa Luzia Hospital (Brasília, DF, Brazil). The study was conducted between January 2001 and June 2004. Data concerning the utilisation of systemic antibacterial drugs, classified according to the Anatomical Therapeutic Chemical/Defined Daily Dose (ATC/DDD) system, and indicators of hospital infection, defined according to the National Nosocomial Infections Surveillance (NNIS) system, were obtained from appropriate hospital archives. During the study period, the average utilisation of antibacterial drugs was 1918.5 DDD units per 1000 patient-day (DDD(1000)). The three most used drugs were penicillins/beta-lactamase inhibitors (535.3 DDD(1000)), third generation cephalosporins (239.1 DDD(1000)) and quinolones (212.5 DDD(1000)). The total utilisation of antibacterial drugs was correlated significantly with the incidence of hospital infection (R = 0.62; p < 0.01) and the index of invasive procedures (R = 0.41; p < 0.01). Furthermore, the latter two indicators were significantly and positively correlated with the use of recently commercialized, broad spectrum antibacterial drugs (except for carbapenems). It is concluded that improved infection control procedures, together with more rigorous criteria regarding the use of invasive procedures, should be implemented by the ICU studied in order to diminish the utilisation of antibacterial drugs.

Effect of Thymoglobulin in Graft Survival and Function 1 Year After Kidney Transplantation Using Deceased Donors

This study evaluated 1-year graft function and survival among kidney transplantations from deceased donors using thymoglobulin (Thymo) as an induction strategy.

PATIENTS AND METHODS

Fifty-seven percent of patients were men and overall mean age was 42 +/- 15 years. Cold ischemia time was 20.1 +/- 4.8 hours. The primary outcome was defined as survival not censored for death after 1 year. The secondary outcome was defined as a comparison of function and survival among patients who received more or less then six doses of Thymo.

RESULTS

Four patients experienced acute rejection episodes and the other three died during follow-up. One-year graft survival was 91% with a mean serum creatinine of 1.28 +/- 0.43 mg/dL. Cytomegalovirus infection occurred in 56%. Forty-two (64%) patients displayed acute tubular necrosis of mean duration of 6.89 +/- 7.48 days. Patients who received lower doses showed better serum creatinine values 3 months (1.45 vs 1.86 mg/dL, P = .013) and 12 months (1.05 vs 1.50 mg/dL, P = .04). The difference was probably due to acute tubular necrosis that produced a RR of 1.7 (P = .02; CI 1.04-2.97) when compared with patients with Scr values above 1.30 mg/dL. When censored for death, graft survival was not different between the two groups (< or =6 doses 93% vs >6 doses 97%, P = .43).

CONCLUSION

Immunologic induction with Thymo produced excellent graft survival after 1 year with preservation of graft function. Delayed graft function was the most important determinant of graft function after 1 year.

Differential activity of a lectin from Solieria filiformis against human pathogenic bacteria

A lectin isolated from the red alga Solieria filiformis was evaluated for its effect on the growth of 8 gram-negative and 3 gram-positive bacteria cultivated in liquid medium (three independent experiments/bacterium). The lectin (500 microg/mL) stimulated the growth of the gram-positive species Bacillus cereus and inhibited the growth of the gram-negative species Serratia marcescens, Salmonella typhi, Klebsiella pneumoniae, Enterobacter aerogenes, Proteus sp, and Pseudomonas aeruginosa at 1000 microg/mL but the lectin (10-1000 microg/mL) had no effect on the growth of the gram-positive bacteria Staphylococcus aureus and B. subtilis, or on the gram-negative bacteria Escherichia coli and Salmonella typhimurium. The purified lectin significantly reduced the cell density of gram-negative bacteria, although no changes in growth phases (log, exponential and of decline) were observed. It is possible that the interaction of S. filiformis lectin with the cell surface receptors of gram-negative bacteria promotes alterations in the flow of nutrients, which would explain the bacteriostatic effect. Growth stimulation of the gram-positive bacterium B. cereus was more marked in the presence of the lectin at a concentration of 1000 microg/mL. The stimulation of the growth of B. cereus was not observed when the lectin was previously incubated with mannan (125 microg/mL), its hapten. Thus, we suggest the involvement of the binding site of the lectin in this effect. The present study reports the first data on the inhibition and stimulation of pathogenic bacterial cells by marine alga lectins.

Behavioral modulation by mutilation pictures in women

Previous studies have shown that women are more emotionally expressive than men. It is unclear, however, if women are also more susceptible to the emotional modulation of behavior imposed by an affective stimulus. To investigate this issue, we devised a task in which female subjects performed six sequential trials of visual target detection following the presentation of emotional (mutilation and erotic) or neutral pictures (domestic utensils and objects) and compared the data obtained in the present study with those described in a previous study with male subjects. The experiment consisted of three blocks of 24 pictures and each block had an approximate duration of 4 min. Our sample consisted of 36 subjects (age range: 18 to 26 years) and each subject performed all blocks. Trials following the presentation of mutilation pictures (283 ms) had significantly slower reaction times than those following neutral (270 ms) pictures. None of the trials in the "pleasant block" (271 ms) was significantly different from those in the "neutral block". The increase in reaction time observed in the unpleasant block may be related in part to the activation of motivational systems leading to an avoidance behavior. The interference effect observed in this study was similar to the pattern previously described for men. Thus, although women may be more emotionally expressive, they were not more reactive to aversive stimuli than men, as measured by emotional interference in a simple reaction time task.

Fluctuation analysis of stellar x-ray binary systems

We study time series of x-ray sources of 129 stellar binary systems present in the public data collected by the instrument All Sky Monitor on board of the satellite Rossi X-Ray Timing Explorer. The light time series was analyzed by applying detrended fluctuation analysis to estimate the long-range power-law correlation exponents alpha. The scaling exponent was calculated for all systems and its value indicated a signature of each kind of system, i.e., whether flare takes place (with alpha=1.22) or not (with alpha=0.64). As a consequence, our results may identify the stability of the systems from the scaling exponent alpha value, for instance, if alpha approximately 0.5 (white noise) the system is stable and unstable when alpha not equal to 0.5 (long-range power-law correlation).

Assessment of water systems for contaminants from domestic and industrial sewages

The State of Minas Gerais represents one of Brazil's most outstanding mining resources. The contamination of river water from kaolin processing activities may be harmful to people in the way of slow but chronic poisoning. On the other hand, the discharge of untreated or inadequately treated domestic sewage into aquatic environments can also cause deleterious effects to the health. However, no reliable figures are available for pollutant occurrences in river water. This draws attention to the very precarious situation that exists with respect to pollution by organic and inorganic toxic wastes, especially with respect to humans and fauna in all its expressions. Thus, with the purpose of establishing a preliminary report to trace out industrialisation outcomes, samples of river water, vegetation and fish were collected and analysed to detect pollutant inputs. The concentration of metals was determined in suspended particle, vegetation and fish, while those of nitrite, nitrate, phosphate and chloride were determined in river water samples. The concentration of dissolved oxygen (DO) was measured in river water at the time of collection. Chemical oxygen demand (COD) and biochemical oxygen demand (BOD) were also determined. Metal inputs in the samples analysed appeared to be related to effluent discharges into the rivers. The suspended particles showed high concentrations (in mg kg(-1)) of zinc (62 600) and aluminium (559 000), while vegetation samples collected near rivers were heavily contaminated with iron (7680). The fishes examined were contaminated with chromium (1.5 mg kg(-1)). In general, the concentrations of nitrite, nitrate, chloride, phosphate and BOD in river water were lower than the maximum values established by the Brazilian Environmental Standards.

[Phases of treatment for alcoholic patients]

Alcoholism remains a controversial area, concerning both theoretical definitions and modalities of clinical intervention. In spite of this, and perhaps as a consequence, it stands as a huge public health problem, consuming a large amount of resources (and mental health services resources in particular). Some clinical issues in this area are reviewed, according to the authors' personal experience. Data related to clinical work in an alcohology centre (South Regional Alcohology Centre-CRAS) are presented. Based in a previous model of Sequential Combined Treatment of Heroin Addicted Patients with Naltrexone and Family Therapy, the authors outline some basic principles of a similar intervention designed for alcoholic patients and their families, which includes, when possible, a family integrated with an individual approach, an emphasis on normativity, on firmness and on self help groups. They revise, on the light of these concepts, the chain of medical care to these kind of patients, outpatient and inpatient, and the role of the medical doctor, which must not be confounded with the family system.

Association of herd composition, stocking rate, and duration of calving season with fecal shedding of Cryptosporidium parvum oocysts in beef herds

OBJECTIVE

To evaluate the association of herd demographics, parturition variables, stocking rate, and rotational grazing practices with the probability of fecal shedding of Cryptosporidium parvum from beef cow-calf herds in California.

DESIGN

Cross-sectional study.

SAMPLE POPULATION

38 beef cow-calf operations.

PROCEDURE

Fecal specimens were collected and examined for C parvum oocysts, using immunofluorescent microscopy. Association between various demographic and management factors and the probability of shedding C parvum were statistically evaluated.

RESULTS

Adjusted for age and month of collection of a fecal sample, cattle from herds with a high number of young calves (< or = 2 months old) on the day of sample collection, a high stocking rate (No. of cattle/acre/mo), or a longer calving season were more likely to shed C parvum oocysts, compared with cattle from herds with fewer young calves, a lower stocking rate, or a shorter calving season. Cattle from herds with a higher number of older calves (> 2 months old) on the day of sample collection were less likely to shed C parvum oocysts, compared with cattle from herds with fewer older calves. Using our multivariate model, rotational grazing systems or season of onset of calving were not associated with shedding status for C parvum oocysts.

CONCLUSIONS AND CLINICAL RELEVANCE

Reproductive management that would result in a shorter calving season and use of a lower stocking rate for cattle may be associated with reduced risk of C parvum shedding. Intensive rotational grazing systems and time of year for onset of calving season apparently have little effect on reducing prevalence of oocyst shedding.

The Orbital Period of the Accreting Pulsar GX 1+4

We report strong evidence for a approximately 304 day periodicity in the spin history of the accretion-powered pulsar GX 1+4 that is most probably associated with the orbital period of the system. We have used data from the Burst and Transient Source Experiment on the Compton Gamma-Ray Observatory to show a clear periodic modulation of the pulsar frequency from 1991 to date, in excellent agreement with the ephemeris proposed by Cutler, Dennis, & Dolan in 1986. Our results indicate that the orbital period of GX 1+4 is 303.8+/-1.1 days, making it the widest known low-mass X-ray binary system by more than 1 order of magnitude and putting this long-standing question to rest. A likely scenario for this system is an elliptical orbit in which the neutron star decreases its spin-down rate (or even exhibits a momentary spin-up behavior) at periastron passages due to the higher torque exerted by the accretion disk onto the magnetosphere of the neutron star. These results are not inconsistent with either the X-ray pulsed flux light curve measured by BATSE during the same epoch or the X-ray flux history from the All-Sky Monitor on board the Rossi X-Ray Timing Explorer.

[The repercussions of mental disease in the family. A study of the family members of psychotic patients]

Caregiving and related concepts such as family or caregiver burden have been widely discussed in recent literature. A descriptive, cross-sectional study was conducted in a sample (n = 80) of primary caregivers to severe mental patients (diagnosed schizophrenia, chronic psychosis or affective disorder).

OBJECTIVES

To describe the caregivers' and corresponding patients' sample, as well as the nature of existing relationships. Levels of caregiver burden and psychological distress were evaluated and a preliminary analysis conducted on objective and subjective burden correlation.

METHODS

Involvement Evaluation Questionnaire (IEQ), General Health Questionnaire (GHQ) and a semi-structured interview designed for this purpose.

RESULTS

The extent of burden was found significant in this sample, being unevenly distributed in its components (e.g. tension, worrying or financial burden). Forty-one percent of caregivers experienced minor psychiatric morbidity. Measures of objective and subjective burden were moderately correlated. The same applied to magnitude of associations between each of them and distress parameters. Higher levels of burden were found in groups of caregivers to more severely ill or disabled patients, while diagnosis was not important for this purpose.

CONCLUSIONS

Most relatives remain highly involved. These results suggest the need to implement specific interventions addressing psychotic patients as well as their families.

[Evaluation of the structures of agreement and disagreement in reliability studies]

The kappa coefficient has been the measurement preferred by epidemiologists for reliability studies. Various articles have demonstrated that the use of the kappa coefficient may have some undesirable features in certain contexts. Recently, methodologies using an ordinal scale for the modelling of interobserver agreement have been developed as an alternative to kappa. To show that there is a class of log-linear statistical models that when analyzed sequentially can be used to rate the patterns of agreement and disagreement. Using data on the comparability of primary and proxy respondent reports with respect to the frequency of alcoholic consumption and its correlation to coronary diseases a nested set of log-linear models was adjusted to find the "best" model. Computed odds ratios to determine the measure of agreement were also computed. The weight kappa was equal 0.685 with 95% CI (0.638-0.732) showing a good agreement. But it does not give any information about the structure of the agreement and disagreement. Among the sequence of models analyzed, the one with the best adjustment showed an agreement estimated at 0.4454 with 95% CI (0.1300-0.7608) and an association estimated at 1.3309 with 95% CI (0.9649-1.6978). The measure tau for adjacent categories was 9.2 with 95% CI (6.0-14.2). Thus, evidence shows that the observers tended to rate many phenomena similarly. Furthermore, high (or low) ratings made by primary respondents tended to be associated with high (or low) ratings made by the proxy respondents. Log-linear models can give us a more informative and more complete analysis with respect to the rating of matched pairs of observers than that given by kappa. In conclusion, the indiscriminate use of kappa as the only agreement index must be questioned. The appendix demonstrates how to use PROC GENMOD in SAS to fit these models.

Prevalence of and associated risk factors for shedding Cryptosporidium parvum oocysts and Giardia cysts within feral pig populations in California

Populations of feral pigs (Sus scrofa) may serve as an environmental reservoir of Cryptosporidium parvum oocysts and Giardia sp. cysts for source water. We conducted a cross-sectional study to determine the prevalence of and associated demographic and environmental risk factors for the shedding of C. parvum oocysts and Giardia sp. cysts. Feral pigs were either live-trapped or dispatched from 10 populations located along the coastal mountains of western California, and fecal samples were obtained for immunofluorescence detection of C. parvum oocysts and Giardia sp. cysts. We found that 12 (5.4%) and 17 (7.6%) of 221 feral pigs were shedding C. parvum oocysts and Giardia sp. cysts, respectively. The pig's sex and body condition and the presence of cattle were not associated with the probability of the shedding of C. parvum oocysts. However, younger pigs (< or = 8 months) and pigs from high-density populations (> 2.0 feral pigs/km2) were significantly more likely to shed oocysts compared to older pigs (> 8 months) and pigs from low-density populations (< or = 1.9 feral pigs/km2). In contrast, none of these demographic and environmental variables were associated with the probability of the shedding of Giardia sp. cysts among feral pigs. These results suggest that given the propensity for feral pigs to focus their activity in riparian areas, feral pigs may serve as a source of protozoal contamination for surface water.

Heat destruction of Salmonella in poultry feed: effect of time, temperature, and moisture

Salmonella enteriditis in poultry feed declines with increasing time of exposure to heat. The interactions of temperature, time, and moisture and their effect on the thermal death of S. enteriditis were established in a factorial randomized experiment. Two other serotypes were tested, and though there was some variation, the thermal death rate followed the same basic pattern. A number of samples of poultry feed were collected and dried. After drying, the water was added back to give specific percentages of moisture contents. The feed was then inoculated with salmonella and heated at specific temperatures, with samples being removed at certain time intervals. These samples were then cultured, and the surviving salmonella were counted. A linear relationship was obtained when the logarithm of survivors was plotted against the logarithm of exposure time. These results permitted the construction of a graph depicting that the rate of reduction in numbers of S. enteriditis when plotted against increasing temperatures is linear. This linear relationship is apparent for other salmonella serotypes such as S. typhimurium and S. haardt. Our results show that the thermal death rate of salmonella in poultry feed can now be predicted at varying time, temperature, and moisture contents.

Identification of genomic regions affecting plant height in sorghum and maize

The objective of this study was to use restriction fragment length polymorphisms (RFLPs) to determine the genetic location and effects of genomic regions controlling plant height in sorghum. F2 plants (152) from the cross CK60 x PI229828 were used. Genomic and cDNA clones (106) identified 111 loci distributed among ten linkage groups covering 1299 cM. Interval mapping identified four regions, each in a separate linkage group. These regions may correspond to loci (dw) previously identified by alleles with qualitative effects. Also, these regions identified in sorghum may be orthologous to those previously reported for plant height in maize. Gene effects and gene action varied among genomic regions. In each region, PI229828 alleles resulted in increased plant height. Each region accounted for 9.2-28.7% of the phenotypic variation. Positive, additive effects ranged from 15 to 32cm. Tallness was dominant or overdominant and conferred by alleles from PI229828 for three quantitative trait loci (QTL). At the fourth QTL, PI229828 contributed to increased plant height, but short stature was partially dominant. One digenic interaction was significant. The presence of a PI229828 allele at one region diminished the effects of the other region. A multiple model indicated that these four regions collectively accounted for 63.4% of the total phenotypic variation. The utility of this information for germplasm conversion through backcross breeding is discussed.

[Cross infection in a high risk nursery: comparison of two epidemiologic surveillance methods]

Two methods of surveillance for nosocomial infection--routine notification and active case finding--were compared during three consecutive months at the high risk newborn unit of the Hospital de Base of the Federal District, involving 66 newborns, which represented 93% of the total patient population referred to that unit for specialized care. Our purpose was to measure the efficiency of routine notification. While this method involved infection notification forms routinely filled by the physician at discharge time, active surveillance consisted of physical examination and chart review of all the newborns, carried out, independently, twice a week: routine notification estimated a 27.3 per cent prevalence rate, versus a 30.3 per cent by active-case finding, considered by the authors a superior surveillance method. Although infection rates were similar, routine surveillance resulted in many false-positive and false-negative notifications, reaching a sensitivity of 60.0 per cent and a specificity of 86.9 per cent. The resulting positive predictive value was 66.7 per cent and negative, 83.3 per cent. The data collected by routine notification was often incomplete and inconsistent. In conclusion, the results seem to indicate that control programs based solely on routine surveillance could be producing inaccurate nosocomial infection rates and, consequently inadequate control measures.

Are smoking behaviours different in industrialized and developing countries?

Several previous studies in industrialized countries have linked both parents' smoking and low-socio-economic status with cigarette smoking in high school students. The purpose of the present study was to examine the association of parental smoking habits and family income with cigarette smoking by Brazilian students enrolled in an agricultural high school, in a developing area. As the study findings differ, additional studies are necessary to evaluate the differences in behaviour between students from developed and less developed countries.

Association between parental and student smoking behaviour in a Brazilian medical school

In a 20% random sample of University of Brasilia medical students no association was found between student and parental smoking behaviour. A low prevalence of habitual smoking (14.0%) and a low mean daily cigarette consumption (8.9 cigarettes per smoker, per day) characterized this population.

Serum albumin and gamma globulin in Trypanosoma cruzi infections

This paper examines the association between serum protein levels and infection with Trypanosoma cruzi in a region of Central Brazil. 148 people 6 to 78 years of age, were included in this study. There were no statistically significant difference in albumin levels between those with positive T. cruzi serology (2.94 +/- 0.74 g/100 ml) and those with negative serology (3.04 +/- 0.61 g/100 ml). Thus the null hypothesis of no association between infection with T. cruzi and serum albumin is accepted. Gamma-globulin levels were elevated in both groups and were significantly greater (p less than 0.05) in the group with positive T. cruzi serology (1.91 +/- 0.41 g/100 ml) than in the group with negative serology (1.75 +/- 0.41 g/100 ml). The serum albumin levels suggest that malnutrition (either associated with low protein intake or increased loss due to hookworm) is a major problem and unlikely to change if T. cruzi transmission was controlled.

Hair zinc levels and nutritional status in urban children from Ilheus, Bahia, Brazil

The mean +/-s.d. hair zinc levels of 45 pre-school and 70 school children, age 1-12 years, were 123 +/- 74 and 103 +/- 74 micrograms/g hair, respectively. The prevalence of zinc levels less than 70 micrograms/g 15 per cent (9 and 19 per cent for pre-school and school children, respectively). Anthropometric measurements showed that 25 per cent suffered from chronic malnutrition. The form of malnutrition manifested was exclusively stunting, ie, low height-for-age in the presence of adequate weight-for-height. No association was found between low hair zinc levels and nutritional status.

[Diet survey based on family food consumption: the case of Ilheus, Bahia, in 1979]

A simplified method was used to analyze the diets of 31 poor families in the city of Ilhéus, Bahia, Brazil. The results are presented in terms of frequency of foods consumed, nutritional density and theoretical adequacy of the diet. Intrafamilial distribution of food intake was not considered in the analysis. Results show that the home diet was very limited in variety; only eight of the 46 items in the dietary frequency were consumed by 50% or more of the sample. Nutrient density was low for calcium, riboflavin, vitamin A and zinc. Energy density, as measured by the ratio of fat calories to protein calories (G/P) was 1.0, value considered nutritionally inadequate. Protein provided 16% of the energy and, of all nine nutrients analyzed, presented the highest levels of intake compared to recommended amounts. Theoretically, the groups at greater nutritional risk were women and children.

[Evaluation of the correct filling out of death certificates: Brasilia, DF (Brazil), 1977-78]

O preenchimento dos itens existentes nos atestados de óbitos foi avaliado neste trabalho, quantificando-se o número de informações em branco ou ignoradas no período de 2 anos. Encontrou-se pequena omissão de dados sobre a identificação do falecido. A omissão é maior com respeito a antecedentes sociais e obstétricos, assistência médica e na parte do atestado referente a casos de óbitos violentos. Uma atuação junto a médicos e funcionários de hospitais pode concorrer para melhorar o nível de preenchimento dos atestados de óbitos no Distrito Federal.

[Morbidity in a child day care center of Brasilia. Longitudinal study of the incidence of diseases in 1977]

Foi feito estudo longitudinal de morbidade em creche de Brasília (Brasil) freqüentada por crianças com bom estado nutricional. Foram admitidas na creche durante o ano de 1977 o total de 67 crianças (34 do sexo masculino e 33 do sexo feminino), com idade entre 3 e 21 meses. Infecções de vias aéreas superiores (25,4%), diarréia (23,6%) e febre não esclarecida (18,4%) representaram dois terços dos diagnósticos. A seguir, em ordem de freqüência, apareceram conjuntivite (15,5%), viroses da infância (7,9%), doenças de pele (3,8%), pequenos acidentes (2,6%), hepatite (2,6%) e meningococcemia (0,3%). Houve um total de 343 episódios agudos, dando uma taxa de incidência de 14 enfermidades por criança por ano, independente de sexo e idade.

[Health priorities. Analysis based on mortality statistics of Brasilia, Federal District (Brazil), 1977-1978]

Foi observado, em Brasília (Brasil), no período de 1977-1978, grande número de óbitos em crianças, maior mortalidade no sexo masculino e predominância de mortes, cujas principais causas foram: a) perinatais e infecciosas em crianças pré-escolares, b) acidentes nos escolares, adolescentes e adultos jovens e c) doenças cardiovasculares e tumores após os 45 anos de idade. Esses resultados são valiosos para orientar a aplicação de recursos por parte dos serviços oficiais de saúde.

[Serological survey of syphilis in adults: Planaltina, Brazil, 1977]

Foram feitas reações sorológicas para lues - VDRL qualitativo e quantitativo - em 1502 trabalhadores de ambos os sexos, com idade compreendida entre 15 e 54 anos, moradores de Planaltina, cidade satélite do Distrito Federal, e que procuraram o hospital local, durante o ano de 1977, para exame de saúde. No setor residencial, a prevalência de soros reagentes nesse período foi de 2,3%, com taxas mais elevadas no sexo feminino, em pessoas idosas e em pessoas casadas. Na zona boêmia, de cada três prostitutas, uma apresentou sorologia positiva. Este achado reveste-se de gravidade por ser Brasília local de intenso movimento populacional.

Behavior of a hybrid F' ts114 lac+, his+ factor (F42-400) in Klebsiella pneumoniae M5a1

Episome F' ts114 lac+, his+ (F42-400) was transferred from Salmonella typhimurium to Klebsiella pneumoniae. From the progeny, a strain of K. pneumoniae able to retransfer the episome was obtained. The His+ phenotype in this strain is temperature sensitive. Escherichia coli female-specific phages phiII, W31, and T3 were shown to plate on K. pneumoniae. From phiII we obtained two derivatives; phiIIK, which plates only on K. pneumoniae, and phiIIE, which plates only on E. coli. Growth of phages T3 and phiIIK was inhibited by F42-400 in K. pneumoniae. Growth in presence of acridine orange in a defined medium at 40 C resulted in a high level of curing. The frequency of His+ cells after growth in acridine orange at 40 C was 0.001%. An extensive search to detect chromosome mobilization by F42-400 in K. pneumoniae, under different experimental conditions, was negative. We cannot exclude the possibility that the low transfer efficiencies prevented our detection of chromosome mobilization. A search among temperature-resistant, acridine orange-curing-resistant, or galactose-resistant derivatives of the K. pneumoniae donor strain failed to reveal any chromosome transfer. Our failure to detect Hfr's may be a result of: (i) the peculiarity of episome F42-400, (ii) the peculiarity of K. pneumoniae chromosome, or (iii) low transfer efficiency. K. pneumoniae-modified F42-400 and phage 424 were restricted by E. Coli K-12. E. coli K-12-modified episome F42-400 and phage 424 were restricted by K. pneumoniae. E. coli C failed to restrict F42-400 modified with K. pneumoniae specificity. The ability of K. pneumoniae to accept F42-400 is less, by about a factor of 50, than that of E. coli C. As an explanation for the differences in the behavior of E. coli C and K. pneumoniae in ability to receive F42-400 it was suggested that recipient bacteria have specific sites for interaction with the F-pilus tip; these are present in E. Coli C, leading to high transfer efficiency, whereas they may not be present (or if present, are not accessible) in K. pneumoniae, leading to low transfer efficiency.

Isolation of a hybrid F' factor-carrying Escherichia coli lactose region and Salmonella typhimurium histidine region, F42-400 (F' ts114 lac+, his+): its partial characterization and behavior in Salmonella typhimurium

Episome F' ts114 lac+ (F42-114) was transferred into Salmonella typhimurium carrying an F'his+ (FS400) episome, and fused episome F' ts114 lac+, his+ (F42-400) was obtained. Episome F42-400 could be transferred to S. typhimurium, Escherichia coli and Klebsiella pneumoniae. Identification of the episome was based on: (i) temperature sensitivity of the Lac+ and His+ phenotypes; (ii) the fact that F- segregants, obtained after temperature curing or acridine orange curing, were simultaneously Lac- and His-; and (iii) linkage of lac+ with his+ in episomal transfers to E. coli and S. typhimurium. The frequency of episome transfer was influenced by the genotype of the donor. Plasmid LT2, prevalent in S. typhimurium LT2 strains, was suggested to be responsible for the low fertility of S. typhimurium donors. Episome F42-400 was capable of chromosome mobilization, and the extent of chromosome mobilization was not influenced by the presence or absence of the histidine region on the donor chromosome. Growth in a defined medium with acridine orange was able to cure F42-400. The frequency of curing was increased (the frequency of His+ cells was 0.0001%) if the cells were grown at 40 C in the presence of acridine orange. Selection for temperature-resistant Lac+, His+ derivatives in a strain without histidine deletion yielded Hfr strains. However, similar and stronger selections in strains without the chromosomal histidine region failed to yield Hfr strains. Our inability to obtain Hfr's in strains without the chromosomal histidine region was explained by assuming that the episome F42-400 has lost the F sites involved in integration into the S. typhimurium chromosome.