Seroprevalence of Chlamydia pneumoniae in Chile

We used microimmunofluorescence to survey the prevalence of antibodies to Chlamydia pneumoniae in 403 serum samples from asymptomatic subjects aged 6 months to 89 y in Santiago, Chile. The results suggest that Chlamydia pneumoniae infection is endemic in Chile, with a seroprevalence of 60% which does not differ by gender.

Effects of UV-B radiation on growth, photosynthesis, UV-B-absorbing compounds and NADP-malic enzyme in bean (Phaseolus vulgaris L.) grown under different nitrogen conditions

The effects of UV-B radiation on growth, photosynthesis, UV-B-absorbing compounds and NADP-malic enzyme have been examined in different cultivars of Phaseolous vulgaris L. grown under 1 and 12 mM nitrogen. Low nitrogen nutrition reduces chlorophyll and soluble protein contents in the leaves and thus the photosynthesis rate and dry-matter accumulation. Chlorophyll, soluble protein and Rubisco contents and photosynthesis rate are not significantly altered by ambient levels of UV-B radiation (17 microW m-2, 290-320 nm, 4 h/day for one week). Comparative studies show that under high nitrogen, UV-B radiation slightly enhances leaf expansion and dry-matter accumulation in cultivar Pinto, but inhibits these parameters in Vilmorin. These results suggest that the UV-B effect on growth is mediated through leaf expansion, which is particularly sensitive to UV-B, and that Pinto is more tolerant than Vilmorin. The effect of UV-B radiation on UV-B-absorbing compounds and on NADP-malic enzyme (NADP-ME) activity is also examined. Both UV-B radiation and low-nitrogen nutrition enhance the content of UV-B-absorbing compounds, and among the three cultivars used, Pinto exhibits the highest increases and Arroz the lowest. The same trend is observed for the specific activity and content of NADP-ME. On a leaf-area basis, the amount of UV-B-absorbing compounds is highly correlated with the enzyme activity (r2 = 0.83), suggesting that NADP-ME plays a key role in biosynthesis of these compounds. Furthermore, the higher sensitivity of Vilmorin than Pinto to UV-B radiation appears to be related to the activity of NADP-ME and the capacity of the plants to accumulate UV-B-absorbing compounds.

Adherence of Acinetobacter baumannii to rat bladder tissue

Acinetobacter baumannii, an important nosocomial pathogen, causes severe infections in patients of intensive care units, but its pathogenic attributes are unknown. Previously, the adherence of A. baumannii to cell lines has been negative in the authors' laboratory. In this work, the adherence of strains of A. baumannii of various biotypes to small pieces of rat bladder tissue was investigated. Tissue pieces were submerged into cultures of A. baumannii and sessile cells were counted after removing planktonic bacteria. Fimbriae and sessile cells were examined by transmission and scanning electron microscopy, respectively. In contrast to a uropathogenic strain of Escherichia coli, all cultures exhibited a mannose- and galactose-resistant agglutination of human group O red blood cells as well as mannose- and galactose-resistant adherence to the bladder tissue. Inhibition of exopolysaccharide synthesis did not modify adherence. Indeed, adherence, apparently unrelated to these fimbriae or to the exopolysaccharide, may be a factor contributing to the pathogenicity of A. baumannii in the urinary tract or in other tissues.

[Adherence of Acinetobacter baumannii to rat tracheal tissue]

BACKGROUND

Acinetobacter baumannii is an important nosocomial pathogen whose virulence factors have not been fully elucidated.

AIM

To study the adherence and hemagglutinating capacity of several biotypes of Acinetobacter baumannii.

MATERIAL AND METHODS

Thirty nine strains of Acinetobacter baumannii isolated from hospitalized patients were studied. The adherence of these strains to small pieces of rat tracheal tissue was studied. Additionally, their ability to hemagglutinate human erythrocytes and the effect of D-mannose and D-galactose on the adherence and hemagglutinating capacity was assessed. Transmission electron microscopy of strains was performed looking for the presence of fimbriae.

RESULTS

All strains exhibited adherence to tissues. All strains had also D-mannose and D-galactose resistant hemagglutinating ability. Fimbriae were found in Acinetobacter baumannii and E coil cells.

CONCLUSIONS

Adherence of Acinetobacter baumannii to rat tracheal tissue, apparently not related to the presence of fimbriae, may be a virulence mechanism of this bacterium.

[Surface characteristics and antimicrobial sensitivity of clinical strains of Acinetobacter spp]

BACKGROUND

The treatment of nosocomial infections caused by Acinetobacter baumannii has been hindered by the easiness of this species to acquire antimicrobial resistance.

AIM

To study surface hydrophobicity, the presence of capsule and antimicrobial susceptibility of nosocomial Acinetobacter spp strains.

MATERIAL AND METHODS

Ninety four Acinetobacter spp strains isolated from a public hospital of Santiago, between July 1995 and April 1996, were studied.

RESULTS

Compared to Acinetobacter genospecies 3 isolates, A baumannii isolates exhibited greater antimicrobial resistance, was uniformly susceptible to imipenem and highly resistant to other antimicrobials of clinical use. Most strains of biotypes 8 and 9 were hydrophilic and encapsulated, whereas those of infrequent biotypes and of Acinetobacter genospecies 3 were, with few exceptions, hydrophobic and not encapsulated.

CONCLUSIONS

Capsule production might confer a greater virulence to Acinetobacter baumannii biotypes 8 and 9, and explain their higher prevalence in the studied hospital.

Epidemiology of invasive pneumococcal infections in infants and young children in Metropolitan Santiago, Chile, a newly industrializing country

AIM

To study the epidemiology of invasive pneumococcal infections in infants and young children in Santiago, Chile, as a representative pediatric population in a newly industrializing country where pneumococcal conjugate vaccines may be used in the future.

METHODS

A 5-year retrospective laboratory-based review (1989 to 1993) was followed by a 3-year prospective laboratory and hospital surveillance study in two of the six health administrative areas of Santiago to detect all hospitalized cases of invasive pneumococcal disease (defined as Streptococcus pneumoniae isolated from blood, cerebrospinal fluid or another normally sterile site) among infants and children (0 to 23 months of age in the retrospective and 0 to 59 months of age in the prospective study).

RESULTS

During the 5-year retrospective survey the incidence of invasive pneumococcal disease was 90.6 cases per 10(5) infants 0 to 11 months old and 18.5 cases per 10(5) toddlers 12 to 23 months old. Similar rates (60.2 per 10(5) infants and 18.1 per 10(5) toddlers) were recorded during the 3 years of prospective surveillance. Among the 110 cases in children 0 to 59 months of age detected during the 3-year prospective surveillance, 2 clinical forms, pneumonia and meningitis, accounted for 87.2% of all cases; 13 of the 49 pneumonia patients (26%) had empyema as a complication. Notably 40 of the 110 cases (36.4%) occurred before 6 months of age (63.4% of the 63 infant cases). Serotypes 1, 14, 5 and 6B were the most prevalent. Overall 76 and 69%, respectively, of S. pneumoniae isolates were antigenic types that would be covered by the 11- or 9-valent conjugate vaccines under development.

CONCLUSIONS

Invasive pneumococcal infections in Santiago, Chile, exhibit an epidemiologic pattern intermediate between that of developing and industrialized countries. The high burden of disease in early infancy dictates that an accelerated immunization schedule (beginning in the perinatal period) or maternal immunization with pneumococcal vaccines should be explored.

Microbiology of recurrent parotitis

BACKGROUND

Infantile chronic recurrent parotitis (ICRP) is characterized by episodes of recurrent swelling of the parotid gland with decreased salivary flow and purulent secretion. The etiology of this little unknown clinical condition has been attributed to multiple causes such as canalicular system malformations, ascending bacterial infection, hyposialia, parotitis sequelae, viral infections and immunologic disorders, among others.

METHODS

We studied the types (with counts) of microorganisms involved in ICRP. Saliva samples were obtained from 56 patients and 20 controls, inoculated onto enriched media and incubated under aerobic and anaerobic conditions. Antimicrobial susceptibility and serotyping of the isolated organisms isolated were performed.

RESULTS

Of 57 saliva samples from ICRP patients, 52 (91%) were culture-positive. The most frequently isolated microorganisms were Streptococcus pneumoniae and Haemophilus influenzae. Thirteen of twenty (65%) samples were also culture-positive, mostly for viridans streptococci. However, colony counts were lower than in clinical samples (P < 0.004). Approximately one-third of S. pneumoniae strains resistant or moderately resistant to penicillin, and all H. influenzae strains were susceptible to all of the antimicrobials tested.

CONCLUSIONS

S. pneumoniae or H. influenzae were isolated in high concentrations in IRCP cases but not in controls, suggesting that these microorganisms may have a role in the development of this clinical entity. Quantitative cultures are very important in assessment of the pathogenic role of these microorganisms in patients but not in controls.

[Identification of Enterococcus species from clinical samples and their antimicrobial susceptibility]

The genus enterococcus has 12 species of which, E faecalis and E faecium are most important in human infections. A progressive resistance to penicillin and ampicillin has been detected in these species. The aim of this work was to identify Enterococcus species isolated in a hospital and to study their antimicrobial susceptibility. We studied 209 Enterococcus species coming from patients admitted to a public hospital. Their susceptibility to penicillin, ampicillin, imipenem, vancomycin, tetracycline, chloramphenicol, ciprofloxacin, gentamicin and streptomycin was determined with the agar dilution technique. Eighty seven percent of species were E faecalis and 7.1% were E fecium, other isolated species were E hirae, E casseliflaws, E avium, E solitarius and E faecalis variant. Thirty eight percent of these species were isolated from the urinary tract, 22% from the skin and 14% from surgical wounds. All E faecalis species were susceptible to penicillin, ampicillin, imipenem and vancomycin; 27.3% were susceptible to tetracycline, 54.7% to chloramphenicol and 80% to ciprofloxacin. Seventy three percent of E faecium species were susceptible to penicillin, 80% to ampicillin and 60% to imipenem. Sixty two percent of E faecalis and 42.4% of E faecium were resistant to streptomycin. It is concluded that the correct identification of Enterococcus species has therapeutic implications.

V3 peptide binding pattern and HIV-1 transmission route in Rio de Janeiro

To characterize antibody binding to a panel of V3 loop peptides representing diverse HIV-1 neutralization epitopes, 149 HIV-1 infected individuals from Rio de Janeiro (RJ) were investigated. Results were analyzed with respect to risk factors for infection and other epidemiological and clinical data. Peptide reactivity was not associated with sex, clinical status, CD4 counts, antigenemia or beta 2-microglobulin serum level. A segregation of peptide reactivity according to route of infection was encountered. This finding suggests that more then one viral strain may be circulating in RJ, in subjects with different risk factors for HIV-1 infection. An investigation of prevalent HIV-1 genotypes, serotypes and immunotypes may be of importance for the design and selection of potential vaccines to be used in Brazil as well as for the selection of populations to be included in future vaccine efficacy trials.

Identification and biotyping of Acinetobacter spp. isolated in Chilean hospitals

Two hundred and eighty-one isolates of Acinetobacter spp. obtained from clinical specimens in hospitals from five Chilean cities were identified to species level and biotyped. Respiratory tract and wound secretions were the main sources of the isolates. Acinetobacter baumannii was the most frequent species (96.8%), followed by Acinetobacter genospecies 3 (2.8%). Twelve different biotypes of A. baumannii strains were found of which biotypes 9, 8 and 6 were the most frequent. Isolates of other biotypes were rare. These results differ from most other Latin American and European countries.

The sleeping giant. Antimicrobial resistance

Resistance to most of the antimicrobial agents in use today is present in Latin America as of this publication. Their underlying mechanisms are in place and an even more serious situation is foreseen in the years to come. Both nosocomial and common community-acquired infections have changed to require more complex ways of management. Although newer antibiotics take the place of the older ones, wiser and more restrictive usage of the currently available antibiotics is needed. This may be obtained through education and with the amplification of national and supranational networks of surveillance, which could anticipate trends in resistance.

Predicting CD4 counts in HIV-infected Brazilian individuals: a model based on the World Health Organization staging system

CD4 cell counts are one of the best available surrogate markers for disease progression; they are widely used laboratory parameters in clinical trials and commonly used indicators for the introduction of primary prophylaxis and antiretroviral therapy. However, measurement is too expensive to be done in most developing countries. The objective of this study was to derive a model for prediction of CD4 counts < 200 cells/mm3 based on the proposed World Health Organization (WHO) staging system for HIV infection and widely available laboratory parameters. One hundred and six consecutive patients enrolled in a prospective cohort study who were not taking anti-HIV drugs or prophylaxis for opportunistic infections were included. Blood tests were performed within 72 h of the outpatient visit. Lymphocyte phenotyping was done by flow cytometry. Two models based on the WHO staging system, hematocrit and total lymphocyte counts, were developed. The two models had sensitivity > 90% and specificity > 83%. These results indicate that the combined use of simple clinical and laboratory parameters can predict CD4 counts < 200 cells/mm3 with high sensitivity and specificity. Similar studies should be conducted in other countries. Should our findings be confirmed, intervention strategies based on this model of potential universal applicability should be devised and validated.

[Molecular characterization of the transferable resistance to amikacin in Enterobacteriaceae strains isolated from hospital infections]

Sixty-three amikacin resistant strains of Enterobacteriaceae isolated in three hospitals from Santiago, between 1988 and 1990 were included in this study. The strains were multiresistant and harbored 1-5 plasmids. Fifty six isolates (88.9%) transferred amikacin resistance to E coli C600 receptor strain by conjugation. The transconjugants acquired a 11 kilobase-pair or a larger plasmid. The plasmids also encoded resistance to kanamycin, tobramycin, streptomycin and ampicillin. A DNA probe from the gene AAC (6')-I encoding an aminoglycoside 6'-N-acetyltransferase, AAC (6')-I hybridized in Southern blot with plasmid DNA of the 10 Enterobacteriaceae strains tested, but not with the plasmid DNA of 8 amikacin resistant clinical strains of A baumannii. The results indicate that amikacin resistance in Enterobacteriaceae is due mainly to conjugative plasmids encoding an AAC (6')-I.

[Susceptibility of Neisseria gonorrhoea strains]

The susceptibility of 45 strains of Neisseria gonorrhoea was studied measuring minimal inhibitory concentrations of five antimicrobials. Results show that 66.7% of strains are resistant to tetracycline and 11.2% to penicillin. All strains were susceptible to ciprofloxacin, ceftriaxone and cefotaxime. This results should prompt to perform surveillance in different areas of Santiago and to establish new therapeutic norms for the treatment of gonococcal infections.

[Identification and sensitivity of acinetobacter sp isolated from clinical specimens and hospital environment]

One hundred thirty two strains of acinetobacter isolated between october 1989 and march 1991 at the San Juan de Dios Hospital, Santiago de Chile were included in this study. One hundred twelve isolates were obtained from patients and 20 from the hospital environment. Among the 112 clinical isolates, 108 (96.4%) were identified according to the new classification proposed by Bouvet and Grimont in 1986 as A. baumannii, and four as acinetobacter genospecies 3. The 20 strains obtained from the hospital environment corresponded to A baumannii. No differences in the activities of the antimicrobial agents were found between clinical and environmental strains of A baumannii. Imipenem was the most active antimicrobial drug against A baumannii followed in descending order by sulbactam ampicillin and ceftazidime. The other antimicrobials tested showed poor activity against these strains as revealed for the MICs 50 and 90 in the resistance range.

[Typhoid fever in school children: by what measures is the modification of the clinical course due to oral vaccination?]

The clinical course of infection by Salmonellae was compared between patients who had been vaccinated against typhoid fever using the Ty21a vaccine and those who had not. Of 2566 bacteriological confirmed cases 84% were infected with S typhi, 14% with S paratyphi B and 2% with S paratyphi A. Among patients with typhoid fever, 34% were treated in hospital, 3.5% had relapses, 5.4% developed complications and 1 patient died (0.05%). Among patients with paratyphoid fever, 18% were treated in hospital, 0.6% had relapses, 1.4% developed complications and there were no deaths. These figures were similar among vaccinated and non-vaccinated cases. A slightly greater proportion of vaccinated cases were treated in hospital (38 vs 30%). Thus, use of oral vaccination against typhoid fever does not alter the clinical course of infection with Salmonellae.

In vitro antibacterial activity of trospectomycin (U-63,366F) against anaerobic bacteria and aerobic gram-positive cocci in Chile

The in vitro activity of trospectomycin sulfate was compared with those of several antimicrobials, against 301 anaerobic bacteria and 613 aerobic Gram-positive cocci. Trospectomycin was about 4- to 32-fold more active than was spectinomycin. Trospectomycin exhibited consistently good activity against all Bacteroides fragilis group isolates, except Bacteroides vulgatus, and against all other anaerobes comparable or higher to that of clindamycin. The trospectomycin's activity was most similar to that of vancomycin, even against methicillin-resistant Staphylococcus aureus and methicillin-resistant Staphylococcus epidermidis.

[Bacterial isolation in infants hospitalized for acute diarrhea]

Bacteria were investigated in stools of 156 children under two years of age admitted to the pediatric wards of a general hospital at the western metropolitan area of Santiago, Chile, because of acute diarrhea with only one stool sample. A known pathogenic agent was isolated from 115 cases (73.7%), this being a bacteria in 87/115 (75.6%). Most prevalent microorganisms were Enteropathogenic Escherichia coli (EPEC). (65.5%), specially serogroups 0111, 0119 and 055, Enterotoxigenic Escherichia coli (ETEC) (18.4%), Campylobacter yeyuni (13.8%), Salmonellae (9.2%) and Shigellae (6.9%). Invasive Escherichia coli (EIEC) and Aeromonas hydrophila were observed in only one case. Yersinia enterocolitica was not isolated. Age was under one year in 92% of patients and 83% were normally or slightly under nourished. Fecal leucocytes were abnormally increased (greater than 5 per high power field) in 41.4% of positive bacterial isolates, in 83% of children with Shigellae, in 50% of those with EPEC and Salmonellae and in 25% of the Campylobacter yeyuni group.

[Infection in severe neutropenia: analysis of 140 episodes]

We analyzed infections complicating 140 episodes of severe neutropenia in 86 patients. The underlying diagnosis was acute leukemia in 64, lymphoma in 12 and isolated cases of bone marrow aplasia, agranulocytosis, dysmyelopoiesis and solid tumors. No fever developed in 35 (25%) episodes. No cause for the fever was identified in 40% of the remaining episodes. Clinical evidence of an infection was present in 20%, with positive bacteriologic findings in 27%. Respiratory infection (16%), pneumonia (11%) and sepsis (10%) were the most common infectious processes. Infectious agents isolated were gram negative bacilli (72%), gram positive cocci (19%) and fungi (9%). The association of amikacin and carbenicillin or cephalosporins proved to be superior to gentamycin-penicillin (p less than 0.01). 16 patients died for an overall mortality of 11%. Pneumonia and infection by K pneumoniae or C albicans were associated to a poorer prognosis.

[Identification of group B beta hemolytic Streptococcus in infections of adults and children]

The frequency of isolation of group B beta-hemolytic streptococcus was investigated in samples from the skin, genitourinary tract and respiratory tract in adults and children, in 2 periods, 1977-79 and 1984-86. Hydrolysis of sodium hippurate or bile and sensitivity to bacitracin were used to identify the germ. Serologic group was confirmed by coagglutination. The incidence of isolation increased from 6.1% (n = 18) to 28.7% (n = 119) from the first to the second period, ranking second among all S groups. Isolation from blood and from spinal fluid in newborns was observed only in the second period.