Environmental benchmarks based on ecotoxicological assessment with planktonic species might not adequately protect benthic assemblages in lotic systems

Freshwater ecosystems face widespread diffuse and point-source contamination. Species Sensitivity Distributions (SSDs) have been used as a tool to determine chemical concentration benchmarks that represent protective levels for most species in the environment. Here we used a SSD approach to assess on the adequacy of standard planktonic organisms to reflect the response of benthic communities, critically supporting the structure and function of lotic ecosystems. For the purpose, SSDs reflecting non-lethal responses of standard planktonic and selected benthic organisms were built based on EC50 values (collected in the literature or estimated following testing herein) regarding three model contaminants: potassium dichromate (PD), 3,5-dichlorophenol (DCP) and lead chloride (LC). The derived HC5 estimates were discriminatory between chemicals and the uncertainty associated with the estimate was remarkably low. The HC5 estimates with corresponding uncertainty were generally within the same order of magnitude for the three chemicals tested, with better discrimination between chemicals regarding their hazardous potential being achieved for benthic organisms: DCP was clearly less hazardous than PD, but LC tends to be as hazardous as PD and DCP (assuming the confidence interval ranges). Moreover, benthic communities were more sensitive to both DCP and PD, in this later case the HC5 being lower by more than one order of magnitude than that found for planktonic communities; for LC, confidence intervals overlapped, preventing a feasible assumption regarding differential sensitivity of the compared communities. Microphytobenthos was highlighted as the most sensitive group to the three tested chemicals in SSDs covering the benthic compartment, while SSDs with planktonic organisms did not consistently show trends in sensitivity ordering. Overall, our results suggest that protective benchmarks retrieved from SSDs built with the responses of standard planktonic organisms (which are the most commonly used for regulation purposes) do not adequately protect benthic communities.

Ripening and Changes in Chemical Composition of Seven Cider Apple Varieties

Changes in composition of seven Basque cider apples ( Malus x domestica Borkh.) varieties were studied for 5 weeks before harvesting, while the apples were still on the tree. The evolution of 21 parameters was measured. Special emphasis was made on the sugars, acidity and total phenolic compounds, responsible, respectively, for the sweet, acid and bitter taste of apples and their juices. The whole composition data throughout the ripening process are given. Correlation analysis was used to verify the usefulness of polyphenol index (absorbance at 280nm) for estimating the total phenolic content in apple juices. A high correlation was found between this index and the total phenolic content, either for each apple variety or for all the varieties together, demonstrating the usefulness of polyphenol index to carry out the estimation in these samples. Cluster analysis was used to find patterns of clustering between the apple varieties studied. The apple samples were classified into seven groups, coincident with the seven varieties studied. This proved that the ripening state did not affect this classification, in spite of the changes produced in the composition of apples. Principal component analysis was used to summarise the information of the data matrix in a more reduced way. Acidity (PC1) and phenolic compounds (PC2) were the most relevant parameters for discrimination of apple varieties.

Determination of serum aluminum, platelet aggregation and lipid peroxidation in hemodialyzed patients

Aluminum (Al3+) overload is frequently associated with lipid peroxidation and neurological disorders. Aluminum accumulation is also reported to be related to renal impairment, anemia and other clinical complications in hemodialysis patients. The aim of the present study was to determine the degree of lipid peroxidation, platelet aggregation and serum aluminum in patients receiving regular hemodialytic treatment. The level of plasma lipid peroxidation was evaluated on the basis of thiobarbituric acid reactive substances (TBARS). Mean platelet peroxidation in patients undergoing hemodialysis was significantly higher than in normal controls (2.7 +/- 0.03 vs. 1.8 +/- 0.06 nmol/l, P<0.05). Platelet aggregation and serum aluminum levels were determined by a turbidimetric method and atomic absorption spectrophotometry, respectively. Serum aluminum was significantly higher in patients than in normal controls (44.5 +/- 29 vs. 10.8 +/- 2.5 microg/l, P<0.05). Human blood platelets were stimulated with collagen (2.2 microg/ml), adenosine diphosphate (6 microM) and epinephrine (6 microM) and showed reduced function with the three agonists utilized. No correlation between aluminum levels and platelet aggregation or between aluminum and peroxidation was observed in hemodialyzed patients.

Multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae causing an outbreak of nosocomial bloodstream infection

This article describes an outbreak of bloodstream infection due to clonal dissemination of multiresistant Klebsiella pneumoniae in a neonatal area, during August 1999, in Mexico City General Hospital. The intestinal tract was the likely reservoir, and intensification of Contact Precaution measures contained the outbreak.

Outbreak of nosocomial sepsis and pneumonia in a newborn intensive care unit by multiresistant extended-spectrum beta-lactamase-producing Klebsiella pneumoniae: high impact on mortality

We describe a case-control study of a small outbreak of nosocomial sepsis and pneumonia with high mortality due to clonal dissemination of a multiresistant Klebsiella pneumoniae in the neonatal intensive care unit of a Mexican institution. Our study helped to change nosocomial infection control policy in this hospital.

Genomic variability of Haemophilus influenzae isolated from Mexican children determined by using enterobacterial repetitive intergenic consensus sequences and PCR

Genomic fingerprints from 92 capsulated and noncapsulated strains of Haemophilus influenzae from Mexican children with different diseases and healthy carriers were generated by PCR using the enterobacterial repetitive intergenic consensus (ERIC) sequences. A cluster analysis by the unweighted pair-group method with arithmetic averages based on the overall similarity as estimated from the characteristics of the genomic fingerprints, was conducted to group the strains. A total of 69 fingerprint patterns were detected in the H. influenzae strains. Isolates from patients with different diseases were represented by a variety of patterns, which clustered into two major groups. Of the 37 strains isolated from cases of meningitis, 24 shared patterns and were clustered into five groups within a similarity level of 1.0. One fragment of 1.25 kb was common to all meningitis strains. H. influenzae strains from healthy carriers presented fingerprint patterns different from those found in strains from sick children. Isolates from healthy individuals were more variable and were distributed differently from those from patients. The results show that ERIC-PCR provides a powerful tool for the determination of the distinctive pathogenicity potentials of H. influenzae strains and encourage its use for molecular epidemiology investigations.

State of immunization in the Americas

Countries in the Americas have led the world in conquering infectious diseases preventable through vaccination. In 1971, the Western hemisphere achieved smallpox eradication. In 1991, the Americas were free of indigenous transmission of wild poliovirus. In 1998, overall regional vaccination coverage was 86% for diphtheria-pertussis-tetanus, 89% for oral poliovirus vaccine 3, 98% for bacille Calmette-Guérin vaccine, and 85% for measles. These figures confirm that most of the children in the Americas are protected against these diseases. The breakthroughs obtained in immunization have stimulated countries to promote new initiatives aimed at the control and eradication of other vaccine-preventable diseases and to introduce new vaccines into routine schedules. In the 21st century, vaccines will remain the most cost-effective means of preventing diseases and avoiding expensive treatment costs.

Klebsiella pneumoniae 35 and 36 kDa porins are common antigens in different serotypes and induce opsonizing antibodies

BACKGROUND

Klebsiella pneumoniae is a major cause of neonatal sepsis and nosocomial infections in Mexico. Antibiotic therapy is the first choice for treatment but the increase in multiple resistance strains has forced scientists to look for alternative treatments, such as immunotherapy. In this work, we propose that porins could be a common antigen among four different capsular serotypes of Klebsiella pneumoniae for the production of immune sera with opsonizing capacity.

METHODS

The 35 and 36 kDa porins from four different serotypes of the bacteria were isolated by the Nikaido method followed by purification in Sephacryl column chromatography. The 36 kDa of serotype K8 was further purified by electroelution. The 35 and 36 kDa porins were used to obtain rabbit polyclonal antibodies (PolyAb) to the four serotypes and the 36 kDa from K8 for the production of monoclonal antibodies (MoAb). Antigenic reactivity of PolyAb and MoAb were analyzed by ELISA and WB and their opsonizing capacity for human PMN was measured by chemiluminescence (CL) using capsulated and non-capsulated bacteria.

RESULTS

Porins from the four strains showe electrophoretic homology and cross reaction by ELISA and WB. CL assays indicated that PolyAb opsonized heterologous strains and that MoAb perform this in the absence of capsule.

CONCLUSIONS

K.pneumoniae 35 and 36 kDa porins are common antigens for the four serotypes studied and induce opsonizing antibodies.

Hepatitis B seroprevalence in Latin America

The seroprevalence of hepatitis B was investigated in over 12,000 subjects in six countries of Latin America: Argentina, Brazil, Chile, the Dominican Republic, Mexico, and Venezuela. Each study population was stratified according to age, gender, and socioeconomic status. Antibodies against hepatitis B core antigen (anti-HBc) were measured in order to determine hepatitis B infection. The highest overall seroprevalence was found in the Dominican Republic (21.4%), followed by Brazil (7.9%), Venezuela (3.2%), Argentina (2.1%), Mexico (1.4%), and Chile (0.6%). In all the countries an increase in seroprevalence was found among persons 16 years old and older, suggesting sexual transmission as the major route of infection. In addition, comparatively high seroprevalence levels were seen at an early age in the Dominican Republic and Brazil, implicating a vertical route of transmission.

Hepatitis A in Latin America: a changing epidemiologic pattern

In a multicenter study, hepatitis A virus (HAV) seroprevalence was surveyed in six countries in Latin America in which in 12,000 subjects were stratified for age. The highest rates of seroprevalence were recorded in the Dominican Republic (89.0%) and Mexico (81.0%), with lower rates in Brazil (64.7%), Chile (58.1%), Venezuela (55.7%), and Argentina (55.0%). The seroprevalence of HAV in children between 1 and 5 years of age was less than 50%, except in the Dominican Republic. In the 5-10-year-old age group, seroprevalence rates have also decreased compared with previous reports. This suggests that the epidemiology is shifting from high to intermediate endemicity, with the population susceptible to HAV infection shifting from children to adolescents and adults. Furthermore, data from Brazil, Argentina, and Mexico show that HAV seroprevalence is significantly lower in people living in medium and high socioeconomic conditions. This study suggests the need for appropriate vaccination programs to be implemented targeting children, adolescents, and adults, particularly in higher socioeconomic groups.

Outer membrane protein profiles of paired nasopharyngeal and middle ear isolates of nontypable Haemophilus influenzae from Mexican children with acute otitis media

We studied nontypable Haemophilus influenzae (NTHi) isolates from simultaneous cultures of nasopharyngeal exudates (NEs) and middle ear fluids (MEFs) obtained by tympanocentesis from 57 children with acute otitis media (AOM). Preparations of outer membrane proteins (OMPs) from 14 pairs of NTHi strains recovered from NEs and MEFs from 10 children with unilateral AOM and four with bilateral AOM were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis. The NTHi subtypes were determined by comparing the OMP profiles of the isolated strains with those of eight reference NTHi subtypes. Of the 14 pairs, 10 (71%) were identical, and one (8%) was different; three strains isolated from NEs (21%) did not correspond to any of the reference subtypes (nonsubtypable). Subtypes 4, 6, 5, 3, and 8 were isolated in the present study, thereby showing that their distribution is similar to that of subtypes isolated from children with AOM in the United States and suggesting that common otogenic strains are widely distributed in North America.

Possible role of calmodulin in excystation of Giardia lamblia

The protozoan Giardia lamblia initiates infection when trophozoites emerge from a cyst in the hosts by the excystation process. Although this process is crucial to the initiation of infection by G. lamblia, little is known about its regulation. To study the possible involvement of calmodulin (CaM) in excystation we tested the effect of several CaM antagonists (TFP, W-7, and W-5) on this cellular function. Except for W-5 the rest of these compounds inhibited excystation. The protein kinase C inhibitor H-7 had no effect on excystation, suggesting that CaM antagonists acted by selectively inhibiting CaM. Furthermore, CaM was redistributed after the induction of excystation and there was an increase in its fluorescence and activity. These results suggest that a CaM-dependent process is involved in G. lamblia excystation.

The Bjornstad syndrome (sensorineural hearing loss and pili torti) disease gene maps to chromosome 2q34-36

We report that the Bjornstad syndrome gene maps to chromosome 2q34-36. The clinical association of sensorineural hearing loss with pili torti (broken, twisted hairs) was described >30 years ago by Bjornstad; subsequently, several small families have been studied. We evaluated a large kindred with Bjornstad syndrome in which eight members inherited pili torti and prelingual sensorineural hearing loss as autosomal recessive traits. A genomewide search using polymorphic loci demonstrated linkage between the disease gene segregating in this kindred and D2S434 (maximum two-point LOD score = 4.98 at theta = 0). Haplotype analysis of recombination events located the disease gene in a 3-cM region between loci D2S1371 and D2S163. We speculate that intermediate filament and intermediate filament-associated proteins are good candidate genes for causing Bjornstad syndrome.

Educational Outcomes of an Otitis Media Workshop for Primary Care Providers in Latin America

Otitis media is a prevalent condition that can be diagnosed and treated by primary care providers skilled in otoscopy. Previous analysis demonstrated that brief, intensive instruction at one site in rural Mexico improved the test scores of health care providers and changed long-term practices (Eavey R, et al. Otolaryngol Head Neck Surg 1993;109:895-8). We wanted to confirm these test score findings at other sites. A didactic course on otitis media with a practical otoscopy workshop was conducted at six Mexican locations and in one Venezuelan city by an interdisciplinary group of physicians. The same coded test was given immediately before and after the course. The Wilcoxon test for significance of intra-subject performance before and after intervention was used as a nonparametric assessment. At all seven sites ( n = 190 subjects), test scores demonstrated statistically significant improvement (range = p < 0.001 to p < 0.0001). We conclude that this educational method consistently improved short-term knowledge of otitis media and that further teaching efforts and a longer term practice-impact study are warranted.

Mortality associated with systemic candidiasis in children

The purpose of this study was to determine factors associated with an increased risk of mortality due to systemic Candida infections in children hospitalized at our tertiary care facility. A total of 71 cases of Candida bloodstream infections were identified over a 2-year period. The attack rate was 47 cases of candidemia per 10,000 discharges and the case fatality rate was 46.5%. Sixty-one cases occurred in infants under 2 years; 27 were newborns (38%). Using logistic regression analysis, we evaluated the independent effects of potential risk factors for death due to candidemia. Three factors were associated with the subsequent risk for death due to systemic candida infection: malnutrition (OR = 4.3; 95% CI 1.2-14.8), prior surgery (OR = 3.8; 95% CI 1.2-13.2), and the number of days between the first positive candida blood culture and the onset of antifungal treatment (OR = 1.12; 95% CI 1.06-1.25). Newborns showed an almost three times greater risk of death due to candidemia as compared to other age groups, but this association was only marginally significant (OR = 2.8; 95% CI 0.9-9.3). There was no difference in the rate of candidemia between the 2 years of the study; however, the observed mortality declined significantly from 65% in year one to 20% in year two (p = 0.02). The major finding of this study was to observe that for every day treatment was delayed the risk of death increased significantly. Thus, this study provides support for empirical antifungal therapy early in the course of suspected systemic candidiasis in order to improve survival among children.

Increased frequency of HLA-DR3 and complotype SCO1 in Mexican mestizo children with amoebic abscess of the liver

The increase of HLA-DR3 and complotype SCO1 previously found in Mexican mestizo adults with E. histolytica amoebic abscess of the liver, was also found in Mexican mestizo children of either sex with the same disease, when compared to the healthy control population (adults and/or children) of the same ethnic and socioeconomic background. This HLA and complotype pattern was not found in Mexican Mestizo patients with amoebic rectocolitis. No linkage disequilibrium was found between these and the other MHC determinants tested in this survey. Thus, HLA-DR3 and SCO1 may constitute primary, independent risk factors, not for any kind of amoebic tissue invasion (i.e. amoebic rectocolitis), but specifically for amoebic liver abscess, irrespective of age or sex. The possibility of linkage disequilibrium with other factors (i.e. the TNF family) within or close to the MHC that were not tested in this study, is discussed. Children with amoebic liver abscess revealed a significant increase in HLA-DR5, and the absence of HLA-DR6 when compared to adults with amoebic liver abscess, suggesting that at least in this ethnic group these class II HLA traits may contribute to some of the peculiarities of pediatric amoebic liver abscess as opposed to the adult version of this disease. HLA-DR3, SCO1, but also HLA-DR5 and HLA-DR6 have all been associated with certain forms of immune-dysfunction, and may thus contribute to some of the clinical and immunological features of this parasitic disease.

Nutrition, infection, and immunocompetence

The nutritional status of an individual has a profound effect on both host susceptibility to specific infectious diseases and on their outcome. Available data suggest that specific and aggregate nutritional deficiencies can alter a host's immune response and increase susceptibility to infection. From a nutritional point of view, the process of nutrient loss and redistribution has the potential for being exploited to the benefit of the infected malnourished host. The proposal to use nutritional support to bolster the host response to infection in severely ill malnourished patients gains support from the fact that this reiterative cycle of malnutrition and infection is the main cause of morbidity and mortality in children in underdeveloped countries.

An education model for otitis media care field-tested in Latin America

The World Health Organization has designated the teaching of otitis media management skills a "priority" status. Effective treatment of ear disease requires that the physician be both informationally educated as well as physically trained to use otoscopy. Little is known about how well this education can be provided in a short time and in a foreign country. To more objectively assess teaching effect, results of an education session for rural Mexican pediatric primary-care providers who were given an intensive otitis media lecture and otoscopy skills workshop in 1990 were evaluated. To test immediate cognitive impact, an anonymous written examination was given both before and after the teaching session. Average test scores after the educational sessions improved 24% (p < 0.001) over baseline scores before the sessions. To evaluate long-term impact on clinical practice, a follow-up telephone survey 2 years later was conducted. The use of an otoscope to diagnose otitis media had increased from 40% to 93% of respondents. We conclude that pediatric primary-care providers in rural Mexico possess a baseline level of knowledge about otitis media that can be significantly enhanced with one educational session. Further, this teaching effort produces an impact on practice pattern that lasts at least 2 years.

[Detection of TEM-beta-lactamase in strains of Haemophilus influenzae resistant to ampicillin using the polymerase chain reaction (PCR)]

With the purpose of determining the type of beta-lactamases that mediate ampicillin resistance to in Haemophilus influenzae strains in the Hospital Infantil de México "Federico Gómez", we determined the minimum inhibitory concentration of 180 strains, isolated from different sources, to ampicillin, amoxicillin-clavulanic acid and ampicillin-sulbactam. All ampicillin resistant strains (29) were beta-lactamase positive as determined by nitrocephin hydrolysis. Using PCR with the primers from pBR322, we detected the presence of the gene for the TEM-beta-lactamase in 100% of the ampicillin resistant strains.

Effects of oral soy phosphatidylcholine on phagocytosis, arachidonate concentrations, and killing by human polymorphonuclear leukocytes

A dietary supplement of linoleic acid (LA) as soy phosphatidylcholine (PC) or as triglyceride on polymorphonuclear leukocyte (PMNL) functions, arachidonate (AA) concentrations, AA release, and leukotriene B4 (LTB4) generation was studied in normal adults. Study 1: Eight subjects were fed PC (27 g) or placebo for 3 d in a blinded crossover experiment with PMNL assays at baseline and 4, 7, and 14 d. Study 2: Subjects were fed equal quantities of LA as PC (18 g, n = 8), safflower (SF, n = 4), or soybean oil (SY, n = 4) with PMNL assays at baseline and 48 h. Study 1: PC increased PMNL phagocytosis and killing of Candida albicans twofold (P less than 0.001) and PMNL phospholipid AA content threefold (P less than 0.001); AA release after Candida albicans stimulation increased 5.3-fold, correlating with PMNL killing (r = 0.932) and phagocytosis (r = 0.872). Study 2: PC, but not SF or SY, produced changes similar to those of study 1. With PMNL exposure to calcium ionophore A23187 or N-formyl-methionyl-leucyl-phenylalanine, PC increased LTB4 generation. Phospholipid LA, in contrast to triglyceride LA, enhanced PMNL phospholipid AA, phagocytosis, and killing.

In vitro and in vivo effects of clindamycin on polymorphonuclear leukocyte function

The effects of clindamycin on polymorphonuclear leukocytes (PMNLs) were evaluated in vitro and in vivo in an experimental model and in immunocompromised patients with and without infection. Chemotaxis, chemiluminescence, and bactericidal capacity were evaluated using PMNLs preincubated with clindamycin in different concentrations. In the three phases of the study, clindamycin at a concentration of 2 mg/L significantly increased PMNL function. In contrast, when higher concentrations were used, PMNL function was not modified and in some cases it was decreased. Our findings suggest that clindamycin, in concentrations of 2 mg/L, positively modifies PMNL function.

Evidence of preferential female prevalence of HTLV-I associated tropical spastic paraparesis in Bahia-Brazil

In order to evaluate the prevalence of HTLV-I infection and its association with tropical spastic paraparesis (TSP) in Bahia, a Northeastern State of Brazil, CSF and sera from TSP patients and CSF and/or sera from some selected groups of individuals were studied. The results seem to indicate a higher prevalence of HTLV-I infection in women than men with TSP and among individuals of HIV risk groups. Some alterations of routine analysis of CSF can suggest HTLV-I infection in TSP patients.

[Recurrent respiratory infection in children: its clinical and laboratory evaluation]

Respiratory infections comprise the main cause of medical consultations, and one of two of the first causes of morbidity and mortality in children under five in developing countries. Epidemiological studies have shown that preschool children contract between four and six respiratory infections in the course of a year without this causing any alarm as a deviation from "normality". Yet, the general practitioner and the pediatrician are frequently faced with the dilemma of deciding whether the child who is "always ill" the use of the recurrent infections is, normal or has predisposing conditions to the infections. Among the predisposing conditions for recurrent respiratory infections in children are several host factors, such as immune defense mechanisms and non-immune mechanisms as well as the infections agent and/or the environment. This article is an overview of the clinical and laboratory evaluation findings of children with recurrent respiratory infections.

Ceftizoxime disposition in neonates and infants during the first six months of life

The single-dose pharmacokinetics of ceftizoxime sodium were studied in 52 neonates and infants between 0.1 and 189 days of age. Subjects received ceftizoxime 25 or 50 mg/kg iv over 15-30 minutes. The drug was administered q8-12h for five days to permit tolerance evaluation on repetitive dosing. No differences were observed in ceftizoxime pharmacokinetic parameter estimates relative to dose. However, marked differences were observed in ceftizoxime pharmacokinetic characteristics relative to infant age; ceftizoxime half-life and mean residence time decreased, whereas body clearance increased with infant age. Ceftizoxime volume of distribution remained relatively constant over infant age. No adverse effects associated with ceftizoxime administration were observed. These data suggest that ceftizoxime 50 mg/kg q12h be used for infants less than or equal to 2 weeks of age (less than or equal to 40 weeks postconceptional age) and that 50 mg/kg q8h be administered for older infants.

[Neonatal meningitis: observations on its etiology, mortality and sequelae]

A retrospective study was carried out on all cases diagnosed with neonatal meningitis at the Hospital Infantil de México Federico Gómez. A rate of 9.6 cases per 1,000 discharged patients was found as well as 6.7% association with sepsis. In 50 of the cases analyzed, an etiologic agent was identified in 23 children; the main bacteria identified were Escherichia coli (24%), Klebsiella pneumoniae (14%), Enterobacter (4%), Proteus mirabilis and Pseudomonas sp (2%), respectively. The mortality rate was 60% and sequelae were seen in 13 of the surviving 20 patients. The unfavorable prognosis of neonates with meningitis forces us to establish an early diagnosis, make every effort to identify the causing agent and try new medications as well as co-adjuvant treatments.

[Guidelines for vaccination against measles in children]

After the introduction of massive immunization campaigns in Mexico, started in 1973, the measles mortality rate has been reduced in children under five years of age from 2.8% in 1989 to a level of 1.6% in 1985. Two epidemics occurred in 1985 and 1989 with 19,460 and 20,076 reported cases respectively. In the first quarter of 1990 a total of 22,906 cases were reported. The age distribution has been: patients greater than 1 year 26.3%; 1-4 years 24.8%; 5-14 years 35.5% and greater than 15 years 18.2%. The vaccination coverage, between 1987 and 1988, ranges from 34% to 75% in outbreaks studies and in the National Health Survey. The vaccine efficacy in those outbreaks has been estimated from 63% to 89%. The epidemics have been primary related to low vaccination coverage during the last 15 years. The conglomeration of a cumulative number of non vaccinated persons could explain the distribution of cases in all age groups. The strategy based on two doses as has been recommended in the US, is useful in programs addressed to eradicate measles, but the low resources and limited access to health services in rural communities of Mexico have made these control measures in feasible. The measles control in Mexico, must be based in vaccinate each child at the first anniversary, this strategy could be enough to take off the measles epidemics.

[Complications in children with measles]

Ongoing immunization campaigns have significantly reduced the incidence of measles. To evaluate the efficacy of vaccination policies, however, it is necessary to analyze disease indicators of mortality and of morbidity such as medical complications and sequelae. We reviewed the hospital experience at Hospital Infantil de Mexico regarding children with measles who necessitated hospitalization between January 1976 and December 1989. During this 14 year period, 176 patients with measles were hospitalized; the majority of the cases corresponded to the period between 1985 and 1989. Fifty five percent of the cases corresponded to children under one year of age. Of those older than 12 months, 81% lacked an immunization history. Eighty percent were from Mexico city or from the neighboring state of Mexico. The mayor complications included: respiratory tract infections such as pneumonia (50.8%), diarrhea (18.2%), and less frequent: laringotracheitis, otitis media, myocarditis and pyodermitis. More than 70% were significantly (grade II or III) malnourished. Twenty three patients died, for a mortality of 13%. The factors more likely related to measles mortality were; age less than two years, undernutrition, and more than two medical complications associated. This report emphasizes that medical complications and mortality are more likely to occur in very young unimmunized, malnourished children.

[Nosocomial measles: a proposal for its control in hospitals]

The transmission of measles in medical settings has become increasingly recognized. Due to the lack of information on nosocomial measles in Mexico we performed a 14 year retrospective study at the Hospital Infantil de México Federico Gómez. The objectives of our study were: a) to determine the frequency of the disease in our hospital; b) to determine the association between nutritional status and risk of acquiring nosocomial measles and c) to establish the relationship between nutritional status and complications in morbidity and mortality due to nosocomial measles. Eighty nine children with nosocomial measles were identified. We observed that patients with severe malnutrition had a greater risk of acquiring nosocomial measles developing complication and dying. The most frequent complication was pneumonia.

[Educational and research program on diagnosis and treatment of otitis media in Latin America]

Otitis media in Latin America is an important cause of hearing impairment and infectious complications which can be prevented without an inordinate effort or investment of resources. The Latin American Otitis Media Research and Training Program is a multidisciplinary, international project designed to improve the detection an treatment of otitis media in Latin America. Over 200 health care providers have already participated in pilot seminars presented in Brazil, Costa Rica, and Mexico. These sessions were highlighted by audiovisual presentations emphasizing pneumatic otoscopy. We conclude that this focused program of medical education can significantly contribute to improve primary health care in the region.

[Capacity of opsonic recognition of polymorphonuclear neutrophils in malnourished children]

The opsonic recognition capacity of polymorphonuclear neutrophils (PMNs) was evaluated in 19 noninfected children (13 eutrophic and 6 malnourished) and 22 infected children (10 eutrophic and 12 malnourished) by determining the rosette-formation capacity of the PMNs with sheep erythrocytes. After evaluating the percentage of rosette-forming neutrophils (RFN), we did not observe significant differences between the PMNs from eutrophic children and those from noninfected malnourished children (70.2 +/- 5% vs 67 +/- 3% respectively, P greater than 0.5). In contrast, the opsonic recognition capacity of PMNs from children with acute bacterial infections was significantly lower in the eutrophic (54.4 +/- 5.8%, P less than 0.05) and even more accentuated in the malnourished children (42.8 +/- 5%, P less than 0.01) when compared to the noninfected children. These results indicate that the opsonic recognition capacity of the PMNs decreases during bacterial infections. Due to the critical role of the PMNs as a mechanism of defense against infection, the greater decrease of the opsonic recognition capacity of the PMNs observed in infected malnourished children could be yet another explanation for the greater morbidity and mortality from the infectious processes observed in malnourished children.

In vitro and in vivo effects of subinhibitory concentrations of clindamycin on experimental Klebsiella pneumoniae sepsis

We studied the effect of subinhibitory doses of clindamycin on the course of experimental Klebsiella pneumoniae sepsis. Wistar rats were injected intraperitoneally with an inoculum containing 5 x 10(6) colony-forming units of K. pneumoniae resistant to clindamycin (minimum inhibitory concentration greater than 128 micrograms/ml) and then distributed to receive clindamycin 10 mg/kg/day or placebo for 10 days. All animals were bacteremic at 3 h. When the magnitude of bacteremia was compared, no difference was seen during the first 24 h; however, by 72 h the clindamycin-treated group had a significant decrease in the number of colony-forming units per milliliter blood (p less than 0.01). The mortality rate showed a tendency to decrease in the treated group (0%) as compared with the control group (30%). By 120 h, 3 of the 9 (33%) surviving animals from the control group were still bacteremic versus 0 of 11 (0%) in the clindamycin-treated group. These results suggest that subinhibitory clindamycin therapy can improve bacterial clearance and survival during the course of experimental K. pneumoniae sepsis.

[Impact of infections on mortality in children with cancer]

A study of the role infections play in the death of 29 children with cancer was conducted from 1983 to 1988. An infection was the main cause of death in twelve patients and was associated with hemorrhage in nine. Five of the patients were free of infection at the time of their death. The most frequently found etiological agents found in hemocultures taken while still alive were: Staphylococcus epidermidis, Staphylococcus aureus, Streptococcus viridans, Salmonella enteritidis, Escherichia coli, Enterobacter sp and Candida spp. A retrospective study on the role of infections in the death of children with cancer was conducted. The clinical and autopsy records of 29 children who died between 1983 and 1988 were reviewed. Infection was the main cause of death in twelve patients and was associated with hemorrhage in nine. Five of the patients were free of infection at the time of death. The most frequent etiologic agents found in blood cultures taken while still alive were: Staphylococcus epidermidis.

The in vitro effect of sulbactam on polymorphonuclear leukocyte function

The effects of sulbactam on polymorphonuclear leukocyte (PMN) chemotaxis, respiratory burst, and microbicidal activity against Staphylococcus aureus were evaluated in vitro. PMNs from normal adult volunteers were incubated with 0.5, 2, 5, 10, and 20 micrograms/ml of sulbactam for 30 min each. At concentrations of 5 and 10 micrograms/ml, sulbactam was found to enhance PMN bactericidal activity. No inhibitory effects on PMN function were noted at the concentrations of sulbactam that were tested. In addition, the in vitro inhibitory effect of ampicillin on PMN chemiluminescence was partially abrogated by the presence of sulbactam. These findings suggest that the microbicidal phagocytic response of human PMNs against S. aureus may be improved in vitro using concentrations of sulbactam that may be readily achieved with therapeutic doses of sulbactam/ampicillin.

Vitamin A supplementation improves macrophage function and bacterial clearance during experimental salmonella infection

The effects of additional but nontoxic amounts of vitamin A on susceptibility to salmonella infection was studied by comparing rates of bacterial clearance and phagocytosis. Forty-eight male Lewis rats were divided into a treatment group receiving a total of 6000 units of vitamin A palmitate weekly for 5 weeks and a control group was given an equal volume of saline. After completion of the treatment regimen, one-half from each group were infected intraperitoneally with 10(5) Salmonella typhimurium; the other half received intraperitoneal injection of saline. At this time no differences in weight gain were noted and all animals were sacrificed within 2 weeks. At 72 hr after bacterial challenge, all saline-treated control animals displayed bacteremia. Cultures of liver and splenic homogenates were positive in 89 and 100% of infected control animals vs 0 and 44% for treated animals during the first week of infection. Kupffer cell, peritoneal, and splenic macrophages of the vitamin A-treated group had greater phagocytic activity than controls as assessed by the percentage of cells ingesting yeast particles and by the number of particles ingested (phagocytic index). These results suggest that vitamin A in moderate amounts may benefit the host's response to infection by enhancing phagocytic cell function.

Antimicrobial susceptibility of selected bacterial enteropathogens in Latin America and worldwide

We conducted an in vitro susceptibility study of bacterial pathogens to various antimicrobials. Strains of Shigella, Salmonella, Escherichia coli, and Klebsiella pneumoniae collected in the 1960s, 1970s, and 1980s at the Hospital Infantil de Mexico Federico Gomez were tested against ampicillin, chloramphenicol, tetracycline, trimethoprim-sulfamethoxazole, amikacin, gentamicin, and furazolidone. Over the 3-decade period, the resistance of enteropathogens to furazolidone showed the least overall increase. Klebsiella susceptibility to the aminoglycosides decreased during the same period. Worldwide reports of enteropathogenic resistance to antimicrobials are also reviewed. In comparing the results of these worldwide studies with our own, we conclude that there is a need for periodic surveillance and testing of bacterial resistance to antimicrobials.

Nutritional implications and physiologic response to pediatric diarrhea

As depicted in Figure 1 acute diarrhea causes the host to undergo a sequence of hormonal, metabolic and immunologic responses, all of which have a nutritional cost. The impact will be more significant in the debilitated or marginally nourished child. From a nutritional point of view this process of nutrient loss and redistribution has the potential for being exploited to the benefit of the host. Two treatment techniques could be used to improve the host response to infection. Nutrients which are essential for optimal immune function and which are rapidly being metabolized may be selectively replaced, while nutrients that the offending organism needs may be withdrawn or temporarily withheld. A better understanding of the physiologic response and nutritional consequences of diarrhea should permit us to further improve the outcome of this and other infectious diseases.

Newborn sepsis following antepartum group B streptococcal maternal infection in rats

Group B streptococcus is an important pathogen in man and infection due to this bacteria is responsible for significant mortality and morbidity in neonates. An animal model of neonatal infection caused by group B streptococcus that results from vertical transmission is described. Nine pregnant Sprague-Dawley rats received intraperitoneal inoculation of 10(9)-10(10) colony forming units of group B streptococcus on day 20 or 21 of gestation. Four of nine rats died following inoculation. A total of 51 pups was born to the surviving five mothers. Pups were sacrificed at 4- to 8-h intervals and cultures of blood, brain, liver, and spleen were obtained. Nineteen of 51 pups (37%) had group B streptococcus isolated from blood or tissues within the first 48 h of life. Results suggest that antepartum systemic infection in rats can result in vertical transmission of disease. This animal model can be used to further study the mechanisms of transmission of group B streptococcus and the pathogenesis and treatment of neonatal sepsis caused by this pathogen.

Assessment of the virulence factors of group B streptococci: correlation with sialic acid content

Previous studies demonstrated strain-specific differences in opsonic requirements and virulence in neonatal rats among organisms of the same serotype of group B streptococci. The present study investigated the role of sialic acid cell-surface determinants in differences in virulence. Serotype III strains resistant to opsonization by antibody-containing sera had a higher percentage of cellular sialic acid than other organisms (1.02% sialic acid for four type III resistant strains versus 0.59% for three type III sensitive strains; P less than 0.01). Neuraminidase removed up to 70% of the extractable sialic acid from serotype III strains, markedly decreased their virulence, and made them more sensitive to the effects of protective antibody. No differences in sialic acid content were detected between sensitive and resistant strains of serotype II, and neuraminidase did not significantly remove sialic acid or affect their virulence. The present studies suggest differences in the nature or mode of attachment of virulence factors between types II and III of group B streptococci.