Ecology of the collapse of Rapa Nui society

Collapses of food producer societies are recurrent events in prehistory and have triggered a growing concern for identifying the underlying causes of convergences/divergences across cultures around the world. One of the most studied and used as a paradigmatic case is the population collapse of the Rapa Nui society. Here, we test different hypotheses about it by developing explicit population dynamic models that integrate feedbacks between climatic, demographic and ecological factors that underpinned the socio-cultural trajectory of these people. We evaluate our model outputs against a reconstruction of past population size based on archaeological radiocarbon dates from the island. The resulting estimated demographic declines of the Rapa Nui people are linked to the long-term effects of climate change on the island's carrying capacity and, in turn, on the ‘per-capita food supply’.

Dialysis outcomes in Colombia (DOC) study: a comparison of patient survival on peritoneal dialysis vs hemodialysis in Colombia

The goal of the Dialysis Outcomes in Colombia (DOC) study was to compare the survival of patients on hemodialysis (HD) vs peritoneal dialysis (PD) in a network of renal units in Colombia. The DOC study examined a historical cohort of incident patients starting dialysis therapy between 1 January 2001 and 1 December 2003 and followed until 1 December 2005, measuring demographic, socioeconomic, and clinical variables. Only patients older than 18 years were included. As-treated and intention-to-treat statistical analyses were performed using the Kaplan-Meier method and Cox proportional hazard model. There were 1094 eligible patients in total and 923 were actually enrolled: 47.3% started HD therapy and 52.7% started PD therapy. Of the patients studied, 751 (81.3%) remained in their initial therapy until the end of the follow-up period, death, or censorship. Age, sex, weight, height, body mass index, creatinine, calcium, and Subjective Global Assessment (SGA) variables did not show statistically significant differences between the two treatment groups. Diabetes, socioeconomic level, educational level, phosphorus, Charlson Co-morbidity Index, and cardiovascular history did show a difference, and were less favorable for patients on PD. Residual renal function was greater for PD patients. Also, there were differences in the median survival time between groups: 27.2 months for PD vs 23.1 months for HD (P=0.001) by the intention-to-treat approach; and 24.5 months for PD vs 16.7 months for HD (P<0.001) by the as-treated approach. When performing univariate Cox analyses using the intention-to-treat approach, associations were with age > or =65 years (hazard ratio (HR)=2.21; confidence interval (CI) 95% (1.77-2.755); P<0.001); history of cardiovascular disease (HR=1.96; CI 95% (1.58-2.90); P<0.001); diabetes (HR=2.34; CI 95% (1.88-2.90); P<0.001); and SGA (mild or moderate-severe malnutrition) (HR=1.47; CI 95% (1.17-1.79); P=0.001); but no association was found with gender (HR=1.03, CI 95% 0.83-1.27; P=0.786). Similar results were found with the as-treated approach, with additional associations found with Charlson Index (0-2) (HR=0.29; Cl 95% (0.22-0.38); P<0.001); Charlson Index (3-4) (HR=0.61; Cl 95% (0.48-0.79); P<0.001); and SGA (mild-severe malnutrition) (HR=1.43; Cl 95% (1.15-1.77); P<0.001). Similarly, the multivariate Cox model was run with the variables that had shown association in previous analyses, and it was found that the variables explaining the survival of patients with end-stage renal disease in our study were age, SGA, Charlson Comorbidity Index 5 and above, diabetes, healthcare regimes I and II, and socioeconomic level 2. The results of Cox proportional risk model in both the as-treated and intention-to-treat analyses showed that there were no statistically significant differences in survival of PD and HD patients: intention-to-treat HD/PD (HR 1.127; CI 95%: 0.855-1.484) and as-treated HD/PD (HR 1.231; CI 95%: 0.976-1.553). In this historical cohort of incident patients, there was a trend, although not statistically significant, for a higher (12.7%) adjusted mortality risk associated with HD when compared to PD, even though the PD patients were poorer, were more likely to be diabetic, and had higher co-morbidity scores than the HD patients. The variables that most influenced survival were age, diabetes, comorbidity, healthcare regime, socioeconomic level, nutrition, and education.

Characterisation of invasive pneumococcal isolates in Catalan children up to 5 years of age, 1989–2000

Ninety-six Streptococcus pneumoniae strains isolated between January 1989 and December 2000 from usually sterile sites of children aged < 5 years of age were included in the study. Resistance to penicillin (38.6% intermediate, 10.4% high-level), cefotaxime (20.8%), tetracycline (41.7%), chloramphenicol (33.3%) and erythromycin (27.1%), as well as serogroup/type, were related to age and pathology. Strains from children aged < 2 years showed the highest penicillin resistance rate. Resistance to penicillin, tetracycline, chloramphenicol and erythromycin was the most common pattern (18.8% of strains). Most isolates (80.2%) belonged to serogroups/types included in the heptavalent conjugate vaccine.

[Evaluation of dipstick for diagnosis of urinary tract infection in children and adults]

BACKGROUND

Dipstick is used as a first test for screening urinary tract infection.

MATERIAL AND METHOD

1087 urine samples from paediatric and adult patients were processed with dipstick and direct microscopic observation of pellet as well as of a Gram stain. A culture was also performed in all of them and was considered as the reference method in order to evaluate all other tests.

RESULTS

Sensitivity of dipstick and of Gram stain was higher in urines from adults than in those from children, but direct examination of pellet was better in paediatrics. Specificity of the three screening tests previous to culture presented few variations in both groups. Predictive positive value of dipstick and direct pellet was slightly better in children's urines; on the contrary, Gram stain was better in adults. Negative predictive value was similar for the three parameters.

CONCLUSIONS

The dipstick here evaluated is a good method for screening of urinary tract infection, though its positivity obliges to a bacteriologic follow up in order to get a certainty diagnosis. Nevertheless, in children less than 2 year old we recommend universal urine culture.

[Helicobacter pylori infections: antigen detection in stool samples]

BACKGROUND

The aim of this study is to evaluate a new diagnostic test to detect Helicobacter pylori antigen in stool samples (HpSA), and compare the results with those obtained by standard techniques (rapid urease test,culture, histological examination of gastric biopsy specimens,13C-urea breath test and serology), in a paediatric population with gastrointestinal symptomatology.

PATIENTS AND METHODS

Sixty patients with dyspeptic symptoms (37 females and 23 males;mean age 10.9 years) attending the Gastroenterology Service were included in the study. Exclusion criterium was previous treatment with proton pump inhibitors, bismuth compounds or antibiotics. Rapid urease test, culture and histologic study of gastric biopsies,13C-urea breath test and serology, as well as HpSA, were performed to all patients.

RESULTS

Forty seven patients were considered infected by H.pylori on the basis of bacterium isolation and 13C-urea breath test positivity. HpSAwas detected in 45 of the 47 H.pylori positive patients(95.7%). There were no HpSA false positive.

CONCLUSION

Our results show that this new test is highly sensitive (95%) and specific(100%) for detection of H. pylori infection. It has some advantages over other non invasive techniques: it is easy to perform,requires no blood samples and its cost is lower than that of 13C-urea breath test.

A 22,000-Year Record of Monsoonal Precipitation from Northern Chile's Atacama Desert

Fossil rodent middens and wetland deposits from the central Atacama Desert (22 degrees to 24 degrees S) indicate increasing summer precipitation, grass cover, and groundwater levels from 16.2 to 10.5 calendar kiloyears before present (ky B.P.). Higher elevation shrubs and summer-flowering grasses expanded downslope across what is now the edge of Absolute Desert, a broad expanse now largely devoid of rainfall and vegetation. Paradoxically, this pluvial period coincided with the summer insolation minimum and reduced adiabatic heating over the central Andes. Summer precipitation over the central Andes and central Atacama may depend on remote teleconnections between seasonal insolation forcing in both hemispheres, the Asian monsoon, and Pacific sea surface temperature gradients. A less pronounced episode of higher groundwater levels in the central Atacama from 8 to 3 ky B.P. conflicts with an extreme lowstand of Lake Titicaca, indicating either different climatic forcing or different response times and sensitivities to climatic change.

Neisseria meningitidis: evolution of penicillin resistance and phenotype in a children's hospital in Barcelona, Spain

Neisseria meningitidis is the most prevalent micro-organism involved in paediatric bacterial meningitis in the Barcelona area in children over 3 mo of age and it is an important cause of morbidity and mortality in Spain. A total of 498 strains of N. meningitidis, obtained between the years 1986 and 1997 from children with sepsis and/or meningitis, were characterized according to their serogroup and penicillin resistance; their distribution in serotypes and subtypes was studied from 1990. A decreasing tendency in the number of annual isolates was observed in this period. Most isolates belonged to serogroups B (403 strains) and C (77 strains). Serogroup C accounted for 1.8% of the strains in 1986 and 57.1% in 1997. The most prevalent phenotype between 1990 and 1996 was B:4:P1.15. but C:2b:P1.2,5 was the most prevalent in 1997. Overall penicillin-resistance rates ranged from 9.1% in 1986 (when a non-susceptible strain was isolated for the first time in the Hospital Sant Joan de Déu, Barcelona, Spain) to 71.4% in 1997, and it was more common among strains belonging to serogroup C (52% of resistant strains) than to serogroup B (22.1 % of resistant strains). The penicillin-resistance level was low, MIC always < or = 0.5 microg/ml. The present increase in N. meningitidis group C isolates, mainly C:2b:P1.2,5, and the availability of preventive measures for this highly pathological and resistant phenotype, argues strongly for the establishment of an epidemiological monitoring system. Detection of penicillin resistance should be standardized worldwide in order to unify data from all laboratories.

CONCLUSION

A shift between serogroups B and C is observed in Barcelona from 1986 to 1997, as well as a rapid distribution of decreased penicillin susceptibility.

Prevalence of Haemophilus influenzae pharyngeal carriers in the school population of Catalonia. Working Group on invasive disease caused by Haemophilus influenzae

The objective of this study was to determine the prevalence of healthy Haemophilus influenzae (Hi) pharyngeal carriers in a representative sample of the Catalonian school population, as well as the factors associated. A two-stage cluster sampling was carried out. Parents were given a questionnaire to collect information on sociodemographic and epidemiological variables. A pharyngeal swab was performed on children when informed consent was given by parents, and was cultured on chocolate agar with 260 microg/ml bacitracin. Of the 1212 children studied, 316 (26%) H. influenzae carriers were detected: 5 (0.4%) serotype b, 1 (0.08%) serotype c, 6 (0.5%) serotype e, 5 (0.4%) serotype f, and 299 (24.7%) non-typable. Age, gender and geographical location were the only variables associated with H. influenzae carrier status. The prevalence of non-typable H. influenzae carriers was similar to that of studies carried out in other countries, while that of serotype b carriers was similar to the remainder of H. influenzae capsulates, and lower than that described in previous studies. These data are in accordance with the low incidence of the disease observed in our context, although the possibility that the vaccine coverage may have affected the results of this study cannot be dismissed.

Prevalence of Haemophilus influenzae carriers in the Catalan preschool population. Working Group on Invasive Disease Caused by Haemophilus influenzae

This study was designed to determine the prevalence of healthy Haemophilus influenzae carriers in a random sample of the preschool population in Catalonia. Oropharyngeal swabs were collected and cultured on chocolate agar supplemented with 260 microg/ml of bacitracin. Four hundred two of the 734 (54.8%) children studied were detected as Haemophilus influenzae carriers: 7 (0.9%) carried serotype b, 14 (1.9%) serotype e, 6 (0.8%) serotype f, and 375 (51%) carried nontypable strains. The results show that, although the prevalence of Haemophilus influenzae carriers is similar to figures reported from other countries, the prevalence of Haemophillus influenzae serotype b carriers is lower and corresponds with the low incidence of invasive disease observed in the Catalan community.

[Neonatal sepsis by Malassezia furfur.]

We report one case of neonatal sepsis caused by Malassezia furfur in an infant who had been in the Intensive Care Unit for 64 days. She had received prolonged therapy with intravenous fat emulsion. We used Sabouraud's medium with an overlay of sterile olive oil for the blood culture, because we had observed yeast forms in one smear of peripheral blood. M. furfur was isolated after three days of incubation. The patient recovered following removal of the port-a-cath and antifungal treatment, and had no further evidence of fungal infection. The skin colonization by the same yeast was demonstrated.

[Prospective study of the invasive strains of Streptococcus pneumoniae isolated in 16 hospitals in Cataluna, Spain]

BACKGROUND

The increasing penicillin resistance rates of Streptococcus pneumoniae led us to review the strains isolated from usually sterile sources during 1996 in 16 hospitals of Cataluña.

METHODS

A card was designed for the prospective collection of patients' data. Susceptibility to penicillin, cefotaxime and erytromicin, as well as serotypes, were studied.

RESULTS

237 S. pneumoniae strains were isolated from patients aged from one month to 95 years (19% younger than 5 years), 9.7% of adult patients being HIV antibodies carriers. Global penicillin resistance was of 35.4% (27.4% with minimal inhibitory concentration [MIC] between 0.1 and 1 microgram/ml and and 8.0% > 1 microgram/ml), but it was only of 25% in strains causing meningeal infections, and of 34.1% in those involved in respiratory processes. Paediatric patients less than five years old had a higher resistance rate (47.7%), as well as octagenarian ones (44.7%), but HIV+ patients had a lower rate (30.4%). 12.2% of strains (10% of meningeal ones) showed some degree of cefotaxime resistance but only five of them (none from meningeal origin) reached a MIC of 2 micrograms/ml. Global erythromicin resistance was 17.7% (17.1% in strains causing respiratory infections). Prevalent serotypes were 6, 9 and 14.

CONCLUSIONS

The high percentage of strains, mainly from paediatric patients, with diminished penicillin, cefotaxime and erythromicin susceptibility among those causing meningitis and respiratory infections, alerts of possible therapeutic failures if empiric treatments are established in infections produced by this microorganism. For this reason, nowadays it is necessary the routine study of the susceptibility of all pathogen strains of pneumococci. Most strains (208 out of 216) causing invasive disease in our area belong to serotypes covered by the present 23-valent vaccine.

[Evaluation of a simple rapid polymerase chain reaction (PCR) technique for the diagnosis of Helicobacter pylori infection in childhood]

BACKGROUND

The purpose of this study was to evaluate the use of polymerase chain reaction (PCR) applied to the diagnosis Helicobacter pylori infection in the pediatric population, by means of a rapid and simple method of extraction and posterior detection by a colorimetric hybridation of amplified H. pylori DNA.

METHODS

Fifty three gastric biopsies, obtained through upper gastrointestinal endoscopy from 53 patients with gastric pathology (45 recidivant abdominal pain and eight hematemesis), were processed from october 1995 to july 1996. Three non invasive tests were performed: detection of IgG by (Cobas) Core Anti-H. pylori EIA (Roche), breath test with 13C-urea and PCR of dental plaque, as well as four invasive ones: histologic study, culture into selective (Pylori Agar, bioMérieux) and non selective media (Columbia Agar with 5% sheep blood, bioMérieux), test of rapid urease and PCR of gastric biopsies. A 20% solution of Chelex 100 resin (DNA Extraction Reagen, Perkin Elmer) was used for DNA extraction, amplification was performed from gen ureA (Clayton, 1992) and amplified DNA was detected by colorimetric hybridation (PCR ELISA, Boehringer, Mannheim). Duration of the PCR process was: extraction 25 min, amplification two hours and detection three hours.

RESULTS

Results of culture and PCR from gastric biopsies agreed in 84.3% of cases (27 positives, 16 negatives and two not determined). Two samples were positive by culture and negative by PCR, and were considered as PCR false negatives due to positivity of three or more other tests. Six samples were negative by culture and positive by PCR, being considered as culture false negatives due to positivity of three or more other tests. Sensitivity of PCR and culture was 94.2 and 82.8%. Specificity was 100% for both tests. None of the dental plaque samples was positive.

CONCLUSIONS

When invasive techniques are to be done for microbiologic diagnose of H. pylori, PCR increases the confirmation rate of infection; the present procedure enables daily routine work due to its simplicity and its short turnaround time.

[Haemophilus influenzae type b invasive disease in Catalonia (1996)]

BACKGROUND

The purpose of this study was to find out the incidence and characteristics of H. influenzae type b invasive disease (HibID) in Catalonia, Spain.

MATERIAL AND METHODS

An active surveillance of H. influenzae isolated from normally sterile sites was carried out during 1996. Microbiology laboratories of hospitals of Catalonia were periodically contacted by telephone. The serotype of all the strains was studied.

RESULTS

The incidence of H. influenzae invasive disease (HIID) was 7.1 per 100,000 in children under 5 years and 1.0 per 100,000 in those over 5 years. The incidence of serotype b was 6.4 per 100,000 children under 5 years and 0.2 above this age. Only three strains belonged to types other than b (d, e and f).

CONCLUSIONS

The incidence of HIbID is uncommon in Catalonia, lower than that registered in the prevaccine era in other countries and regions of the same geographical area.

[Evaluation of the polymerase chain reaction technique for the diagnosis of meningitis caused by Neisseria meningitidis and Haemophilus influenzae]

BACKGROUND

Bacterial meningitis is a severe infection of the central nervous system (CNS), most frequently caused by Neisseria meningitidis in our setting. Microbiologic diagnosis of bacterial meningitis is not enough sensitive because its efficiency can be affected by the therapeutic regimen given to the patient. Polymerase chain reaction (PCR) can provide a more sensitive diagnosis and allow us to get an earlier result.

OBJECTIVES

To assess the sensitivity and specificity of a PCR technique for the diagnosis of meningitis caused by N. meningitidis and Haemophilus influenzae.

MATERIAL AND METHODS

Ninety-six patients who were attended because of suspected bacterial meningitis on the Hospital de Sant Joan de Déu, Corporació Sanitària Parc Taulí and Hospital de la Santa Creu i Sant Pau, and had negative results by conventional laboratory methods, were selected for the study. A total of 99 cerebrospinal fluid samples (CSF) were obtained and evaluated for PCR. DNA extracts of the CSF samples were amplified by universal primers. Amplification products were hybridized with specific probes for Haemophilus genus and N. meningitidis. Positive and negative controls were included to asses the reliability of PCR.

RESULTS

Eight of the 99 CSF samples (8%) were positive by PCR and subsequent hybridization with the specific probe of N. meningitidis. None of the amplicons hybridized with the probe of Haemophilus genus. Thirteen percent of the patients (8/59) with clinical suspicious of non-neonatal sepsis or meningitis were diagnosed by PCR, amongst them, 36% of the cases (4/11) with initial diagnosis of meningococcal sepsis or meningitis.

CONCLUSIONS

The sensitivity and the specificity of the PCR technique afford a complementary method to conventional ones, in special for the diagnosis of meningococcal meningitis in the group of pediatric patients.

[Study of the viral etiology of lower respiratory tract infections in a neonatal unit]

OBJECTIVE

To study the possible viral etiology in 139 infants with lower respiratory tract infection who required hospitalization in the Infant Unit of our hospital, from October 1994 to June 1995.

PATIENTS AND METHODS

139 patients were admitted, aged from 13 days to 14 months, during this period. The etiological agent was detected by direct immunofluorescence from nasopharyngeal secretions. Monoclonal antibodies were used against Respiratory Syncitial Virus, Influenza A Virus, Influenza B Virus, Adenovirus and Parainfluenza 3 Virus. Antibody detection against these viruses by Complement Fixation Test was done on 29 of these patients, with paired sera (acute and convalescent phase).

RESULTS

In 82 patients (59%) we found at least one viral agents from the nasopharyngeal specimens, but in 64 of these only one was detected, in the remaining 18, there were more than one. Significant levels of antibodies were detected in only six of the 29 patients tested. Serology was negative in the remaining 23 patients.

CONCLUSIONS

Syncitial Respiratory Virus is the first virus responsible for the lower respiratory tract infection in this age group (49%). There was no correlation between serological diagnosis and antigen detection.

A case-control study of diarrhoea in children caused by Escherichia coli producing heat-stable enterotoxin (EAST-1)

Escherichia coli strains associated with diarrhoeal disease have been classified into several types according to the pathogenic mechanism. Among these, enteroaggregative E. coli strains (EAggEC) have been associated with persistent childhood diarrhoea. Some strains of EAggEC produce a heat-stable toxin (EAST-1) that differs from others described previously. The main goal of this case-control study was to determine the prevalence of EAggEC and EAST-1-producing E. coli strains as a cause of diarrhoea in children in Spain and to study their in-vitro susceptibility to 21 antimicrobial agents. In the case group (115 children) 22 (19%) isolates and four (3.5%) isolates were EAST-1-producing E. coli and EAggEC, respectively, whereas in the control group (79 children) four (5%) isolates produced EAST-1 (p = 0.005) and three (3.8%) isolates were EAggEC. The present study suggests that EAST-1-producing E. coli strains are associated with diarrhoeal diseases in Spanish children, whereas EAggEC strains are not. Moreover, EAST-1-producing E. coli strains showed a high susceptibility to all the antimicrobial agents tested except for ampicillin.

Streptococcus pneumoniae isolated from a paediatric population: changes in 10 years

Susceptibility to penicillin, cefotaxime, erythromycin and chloramphenicol, as well as serotypes of 100 Streptococcus pneumoniae strains isolated between 1984 and 1985, were compared to those of the same number of strains isolated between 1994 and 1995. The strains were obtained in Hospital Sant Joan de Déu, Barcelona, and were thought to be the cause of a variety of infectious diseases in paediatric patients attending this centre. Minimal inhibitory concentrations (MICs) of penicillin were higher in strains of the second period (51% of resistant strains during the first period vs 61% during the second one), as were those of cefotaxime (12% vs 18%) and erythromycin (6% vs 36%), while chloramphenicol MICs showed a light decrease (65% vs 46%). Serotypes 6, 19 and 23 were the most prevalent. Five new serotypes (4, 10, 18, 22 and 31) were detected in 10 penicillin-susceptible strains during the second period. Because of the increase in resistance to antibiotics commonly used in the treatment of systemic and localized infections, therapeutic alternatives must be studied and suggested in order to offer oral and percutaneous treatment for our children's infections caused by pneumococci.

Perinatal listeriosis: a population-based multicenter study in Barcelona, Spain (1990-1996)

The aim off this study was to describe the incidence, epidemiology, clinical presentation, and outcome of perinatal listeriosis for a 7-year period (1990-1996) based on data of an active population-based surveillance project implemented in the city of Barcelona, Spain. There were 30 cases (20.8%) associated with pregnancy (15 pregnant women, 13 neonates, and 2 fetal deaths). The incidence of perinatal listeriosis varied from 4.1 to 0 per 10,000 live births. The proportion of perinatal cases in relation to the total number of cases of listeriosis varied between 0 and 42%. Early-onset neonatal sepsis accounted for 12 of 13 live births. The mean age of infected pregnant women with listeriosis was 30.1+/-2.0 years. Chorioamnionitis was the predominant clinical form (86.7%). Only two mothers had primary bacteremia by L. monocytogenes in the second trimester of pregnancy. Both infants were born healthy, without signs of infection. One of these mothers was infected with the human immunodeficiency virus (HIV). Since January 1994, 12 strains were available for serotyping and phagotyping; 9 belonged to serovar 4b, 2 to serovar 1/2b, and 1 to serovar 1/2a. No outbreaks of L. monocytogenes infection occurred during the study period. The overall neonatal mortality rate was 7.7% among infected live births. All pregnant women were treated with ampicillin and none died. Early antenatal treatment with ampicillin improves neonatal outcome and can result in the birth of healthy babies.

[Antibiotic sensitivity of Streptococcus pyogenes in pediatrics]

BACKGROUND

The purpose of this study was to set up the current level of Streptococcus pyogenes sensitivity, in pediatric patients in our community, to penicillin, clindamycin, clarithromycin, erythromycin and azithromycin.

MATERIAL AND METHODS

100 strains were collected between October 1996 to July 1997. 79 were pharyngeal and 21 were non-pharyngeal strains. The MICs were obtained by the E-test method, and furthermore the results were compared by the Kirby-Bauer method.

RESULTS

All strains were sensitive to penicillin and except one (inducible resistance) to clindamycin. 19% were resistant to macrolide, without differences among clarithromycin, erythromycin and azithromycin. From 13 strains (16.5%) of pharyngeal and 6 (28.5%) from non-pharyngeal samples, 4 of these from cutaneous samples, showed resistance. 18 of the resistance strains belonged to novel resistance fenotip and one to 10 inducible fenotip. Only minor discrepancies about erythromycin and clindamycin were observed between E-test and Kirby-Bauer methods.

CONCLUSIONS

This study confirms a remarkable level of resistance to macrolides in pediatric patients, mainly in the cutaneous samples. Due to the reduced prevalence of macrolide-susceptible strains, in vitro susceptibility testing appears necessary in case of macrolide chemotherapy.

[Recurrent infection by Streptococcus agalactiae]

BACKGROUND

To study the factors implicated in the infectious process (host, microorganism and antibiotic) of a newborn early sepsis by S. agalactiae that suffered a reactivation at day five from discharge.

METHODS

Description of two episodes of newborn sepsis by S. agalactiae corresponding to the same patient and microbiologic study of the isolated strain: typing by "genomic macrorestriction" and antibiotic tolerance by "timed killing curves".

RESULTS

It was demonstrated that both strains of S. agalactiae type la/c belonged to the same clone as well as the tolerance to ampicillin of the strain.

DISCUSSION

This sort of infections processes in the newborn are very serious and there is possibility of relapse. Thus, it is important to study the ethiologic agent and its relationship with antibiotics, in order to stablish the best treatment regimes, avoiding the possibility of relapses as the case we have described.

[Diagnosis of tuberculosis in children. Evaluation of the PCR technique]

OBJECTIVE

The purpose of this study was to evaluate the usefulness of the technique of polymerase chain reaction (PCR) for the diagnosis of tuberculosis in the pediatric population.

PATIENTS AND METHODS

All patients seen at the University Hospital Sant Joan de Déu in Barcelona during the year of 1995 in which there was a clinical suspicion of or an interest in discarding tuberculosis were studied. Two types of diagnoses were considered: 1) Diagnosis from clinical evidence without microbiological confirmation, 2) A certain diagnosis including microbiological confirmation. All samples received at the microbiology laboratory were processed by baciloscopy, culture and PCR, Amplicor PCR M. tuberculosis was used as the PCR method.

RESULTS

Sixty-four samples (most of them gastric juices) from 41 children were processed during the study period. Fourteen patients, between 8 months and 17 years of age, were diagnosed of tuberculosis, Microbiological confirmation by culture and/or PCR was obtained in four patients (31%). PCR was the only positive technique in one child (staining and culture negative) with clinical evidence of tuberculosis. All samples from the other three patients that had positive cultures also had positive PCR results. False positives were not detected.

CONCLUSIONS

PCR improves the diagnosis of pediatric tuberculosis. It stands out because of its quickness (possibility of a 9 hour turn-around time), sensitivity (slightly higher than cultures in our series) and specificity.

Serogroup-specific epidemiology of Streptococcus pneumoniae: associations with age, sex, and geography in 7,000 episodes of invasive disease

A study sample of 7,010 episodes of invasive Streptococcus pneumoniae disease was obtained by combining 13 existing datasets. Disease episodes due to each of 12 pneumococcal serogroups (1, 3-9, 14, 18, 19, and 23) were then compared with episodes in a constant internal control group to describe serogroup-specific variations in disease frequency by age, sex, and geographic origin. The results are presented as odds ratios (with 95% confidence intervals) derived by logistic regression, with adjustment for the major confounders, including dataset of origin. Variation in the male:female ratios between serogroups is small, suggesting that capsular characteristics are an unlikely explanation for the male preference of S. pneumoniae. Serogroups associated with higher nasopharyngeal prevalence (e.g., 19 and 24) are relatively more common in Europe and North American, while the invasive serotypes 1 and 5 are much more common in South America. The custom of reporting serogroup frequencies in two age groups, children and adults, conceals much of the variation in the age distributions across the whole span of life. The reduction of risk associated with serogroups 6, 14, 18, 19, and 23 beyond childhood follows different gradients, being most abrupt in serogroups 14 and most gradual in serogroup 18. The relative risk of disease with serotype 1 declines steadily throughout life, while with serotypes 3 and 8 it increases over middle age. Serogroups 7 and 23 are found unusually frequently in the third decade of life. Because of the wide differences in the epidemiology of individual serogroups of S. pneumoniae, it is questionable whether pneumococcal infection should continue to be classified as a single disease entity.

[Microbiological study of the respiratory tract in children with cystic fibrosis]

PURPOSE

Pulmonary infections is a main cause of morbimortality in patients suffering from cystic fibrosis. The objective of this study was to know the flora implicated in respiratory pathology of all mucoviscidotic children attending Hospital Sant Joan de Déu of Barcelona.

METHODS

Quantitative cultures from respiratory samples (most of them: sputum) of 26 patients were performed from January 91 to June 93. There were 13 girls and 13 boys, aged 1 to 13 years (mean: 7 years).

RESULTS

282 microorganisms were isolated from 203 positive samples. Cultures of 88.4% of patients yielded in some moment Haemophilus influenzae, 82.6% of them Haemophilus parainfluenzae, 65.3% Pseudomonas aeruginosa, 50% Streptococcus pneumoniae, 38.4% Staphylococcus aureus. The most prevalent microorganism was P. aeruginosa (66%) followed by H. influenzae (29%) and S. aureus (26.6%). 59% of P. aeruginosa strains showed a mucoid phenotype.

CONCLUSIONS

Haemophilus sp. causes short term infections that affect children of all ages, whereas infections due to P. aeruginosa persist in spite of correct antimicrobial therapy.

[Evaluation of the E test method in the antimicrobial sensitivity of Neisseria meningitidis to penicillin]

BACKGROUND

The E test (AB Biodisk, Solna, Sweden) is a rather new method for performing antimicrobial susceptibility test--their results are generated directly as MICs. Due to its simplicity, is available in nearly all laboratories. The present study evaluates the effectiveness of the E test for susceptibility studies of Neisseria meningitidis to penicilline.

METHODS

The MICs of penicilline of 55 strains of Neisseria meningitidis, studied by E test and by microdilution method, were compared to those obtained by agar dilution using both Mueller-Hinton (MH) and Mueller-Hinton with a 5% of sheep blood (MH+S) as test culture bases.

RESULTS

The concordance rate (+/- 1 log2 of dilutions) was 100% in all cases, except for the E test on MH+S which yielded a 98.2% value. The Pearson's correlation coefficients were 0.95 and 0.84 for the E test and 0.88 and 0.85 for microdilution, using MH and MH+S. Roughly 70% of strains were considered susceptible to penicillin using MH for the in vitro tests, whereas only 40% of them were so considered using MH+S.

CONCLUSIONS

The E test can be considered a good alternative to agar dilution method when testing susceptibility of N. meningitidis to penicilline, and MH is the best culture base for these assays.

[Osteoarticular infections in children]

We presented a retrospective review of osteoarticular infections diagnosed at Sant Joan de Deu Hospital from Barcelona, in the last 10 years (1981-1990). A total of 127 arthritis and 113 osteomyelitis were recorded in children aged from a few days to 15 years. This represents a 3.5% of all infectious diseases patients during the study period. The most common microorganism was S. aureus (52.3%) followed by Brucella (8.2%) and Salmonella as well as Streptococcus agalactiae (7.3% each). The most common involved joint were hip and knee in arthritis cases, but long bones (tibia and humerus) in osteomyelitis cases.

Antigenic variation of penicillin-binding proteins from penicillin-resistant clinical strains of Streptococcus pneumoniae

Penicillin-resistant strains of Streptococcus pneumoniae that are isolated with increasing frequency worldwide contain low-affinity penicillin-binding proteins (PBPs). The relatedness of PBPs from 55 resistant strains isolated on three continents was investigated by testing the reactivity of antibodies specific for PBP 1a or 2b and by comparing the PBP patterns. Seventeen patterns of antibody reactivity could be distinguished, 12 of which were specific to one isolate. Most strains, including all German and South African strains, had a unique PBP profile. A few groups of Spanish and Finnish isolates were identified where the strains within each group shared the same PBP profile, the same antigenic variants of PBPs 1a and 2b, and the same serogroup, suggesting that they represent different clones of S. pneumoniae. The results demonstrated highly variable pathways of resistance development and confirmed that resistant strains have emerged independently in different locations.

Variability of penicillin-binding proteins from penicillin-sensitive Streptococcus pneumoniae

Penicillin-binding proteins (PBPs) from penicillin-susceptible strains of Streptococcus pneumoniae are believed to be fairly similar in contrast to PBPs occurring in resistant isolates. The antigenic variation of PBPs 1a and 2b in 65 penicillin-susceptible strains from different geographic areas and a wide variety of isolation sites was analyzed using a set of specific antisera and monoclonal antibodies. Three strains contained different antigenic variants of PBP 1a, and 50 strains contained one of three antigenic variants found in PBP 2b. Seven patterns of antibody reactivity could be defined; all but one were distinct from those found recently in resistant strains. In addition, electrophoretic mobilities of all six PBPs, compared after conventional SDS-PAGE and fluorography, revealed an unexpected variation of PBP-profiles even for strains of one sero-group. Few strains appeared identical to each other or to the laboratory reference strain R6.

Novel plasmids in clinical strains of Streptococcus pneumoniae

Small plasmids were found in two clinical isolates of Streptococcus pneumoniae from Spain (strains 671 and 678) and in one strain (SpR) isolated in Germany. All three strains contained one plasmid (2.75 to 3.1 kb) which is related to the only previously described pneumococcal plasmid, pDP1. Strains 678 and SpR carried a second plasmid of 2.6 kb and 2.7 kb, respectively. These two plasmids hybridized neither with each other, nor with pDP1, demonstrating that they represent new types of plasmids not having been found in pneumococci before.

Neisseria meningitidis strains with decreased susceptibility to penicillin

Neisseria meningitidis strains relatively resistant to penicillin were recovered from blood or cerebrospinal fluid cultures of four children treated in Barcelona, Spain, and surrounding areas. The four strains had distinct serogrouping and serotyping patterns. The minimal inhibitory concentrations of penicillin were 0.25 microgram/ml for three strains and 0.5 microgram/ml for the fourth strain. These are the first relatively penicillin-resistant meningococcal strains identified in Spain.

Isolation and characterization of nitrogenase-derepressed mutant strains of cyanobacterium Anabaena variabilis

A positive selection method for isolation of nitrogenase-derepressed mutant strains of a filamentous cyanobacterium, Anabaena variabilis, is described. Mutant strains that are resistant to a glutamate analog, L-methionine-D,L-sulfoximine, were screened for their ability to produce and excrete NH4+ into medium. Mutant strains capable of producing nitrogenase in the presence of NH4+ were selected from a population of NH4+-excreting mutants. One of the mutant strains (SA-1) studied in detail was found to be a conditional glutamine auxotroph requiring glutamine for growth in media containing N2, NO3-, or low concentrations of NH4+ (less than 0.5 mM). This glutamine requirement is a consequence of a block in the assimilation of NH4+ produced by an enzyme system like nitrogenase. Glutamate and aspartate failed to substitute for glutamine because of a defect in the transport and utilization of these amino acids. Strain SA-1 assimilated NH4+ when the concentration in the medium reached about 0.5 mM, and under these conditions the growth rate was similar to that of the parent. Mutant strain SA-1 produced L-methionine-D,L-sulfoximine-resistant glutamine synthetase activity. Kinetic properties of the enzyme from the parent and mutant were similar. Mutant strain SA-1 can potentially serve as a source of fertilizer nitrogen to support growth of crop plants, since the NH4+ produced by nitrogenase, utilizing sunlight and water as sources of energy and reductant, respectively, is excreted into the environment.

Antibiotic resistance and serotypes of 100 Streptococcus pneumoniae strains isolated in a children's hospital in Barcelona, Spain

A total of 100 Streptococcus pneumoniae strains with various penicillin G susceptibilities, isolated in Barcelona, Spain, from different pediatric sources during 1983 and the first 4 months of 1984, were tested for susceptibility to tetracycline, chloramphenicol, erythromycin, clindamycin, vancomycin, and rifampin. The isolates were distributed in nine patterns of antibiotic resistance, and 15 different serotypes were encountered. The high incidence of resistance to multiple antibiotics clearly indicates the need to perform antibiotic susceptibility testing of all pneumococcal isolates with proved pathologic significance to avoid therapeutic failure.

Prevalence of Neisseria meningitidis in family members of patients with meningococcal infection

The aim of the study was first, to determine the prevalence of Neisseria meningitidis among the family members living with patients suffering from meningococcal infections, and second, to ascertain the distribution among these family members of strains epidemiologically related to those isolated from patients. Forty-two family groups were studied and 135 nasopharyngeal samples were taken from family members living with patients. Twenty family groups were found to contain meningococcal carriers, and of these 20, 13 contained a carrier of the strain that caused the infection (65%). Among the family members who were carriers, the mother and father most frequently yielded the strain which caused the illness. The serotypes most frequently encountered both in patients and carriers were 2 and 8, as well as nontypable strains. The polyacrylamide gel electrophoretic patterns (PAGE) most frequently found were II and IV. A notable feature of the study is the high resistance of the strains to sulphadiazine, since more than 90% of the strains found in patients and more than 75% of those from carriers possessed a minimum inhibitory concentration greater than or equal to 10 micrograms/ml.