Non-capsulated and capsulated Haemophilus influenzae in children with acute otitis media in Venezuela: a prospective epidemiological study.

BACKGROUND: Non-typeable Haemophilus influenzae (NTHi) and Streptococcus pneumoniae are major causes of bacterial acute otitis media (AOM). Data regarding AOM are limited in Latin America. This is the first active surveillance in a private setting in Venezuela to characterize the bacterial etiology of AOM in children < 5 years of age. METHODS: Between December 2008 and December 2009, 91 AOM episodes (including sporadic, recurrent and treatment failures) were studied in 87 children enrolled into a medical center in Caracas, Venezuela. Middle ear fluid samples were collected either by tympanocentesis or spontaneous otorrhea swab sampling method. Standard laboratory and microbiological techniques were used to identify bacteria and test for antimicrobial resistance. The results were interpreted according to Clinical Laboratory Standards Institute (CLSI) 2009 for non-meningitis isolates. All statistical analyses were performed using SAS 9.1 and Microsoft Excel (for graphical purposes). RESULTS: Overall, bacteria were cultured from 69.2% (63 of the 91 episodes); at least one pathogen (S. pneumoniae, H. influenzae, S. pyogenes or M. catarrhalis) was cultured from 65.9% (60/91) of episodes. H. influenzae (55.5%; 35/63 episodes) and S. pneumoniae (34.9%; 22/63 episodes) were the most frequently reported bacteria. Among H. influenzae isolates, 62.9% (22/35 episodes) were non-capsulated (NTHi) and 31.4% (11/35 episodes) were capsulated including types d, a, c and f, across all age groups. Low antibiotic resistance for H. influenzae was observed to amoxicillin/ampicillin (5.7%; 2/35 samples). NTHi was isolated in four of the six H. influenzae positive samples (66.7%) from recurrent episodes. CONCLUSIONS: We found H. influenzae and S. pneumoniae to be the main pathogens causing AOM in Venezuela. Pneumococcal conjugate vaccines with efficacy against these bacterial pathogens may have the potential to maximize protection against AOM.

Global and local variations in antimicrobial susceptibilities and resistance development in the major respiratory pathogens.

Acute respiratory tract infections, such as bacterial pneumonia and acute exacerbations of chronic bronchitis, have been identified by the World Health Organisation as the leading global infectious cause of death. An increasing prevalence of antibiotic resistance has been identified worldwide in the three major bacterial respiratory pathogens -Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae. The selection and spread of resistance is to some degree inevitable and the importance of monitoring its progress has led to the instigation of numerous international, regional and national surveillance programmes. The results from surveillance studies show wide variations in susceptibility rates, both geographically and over time, highlighting the need for local resistance prevalence data in order to guide empirical prescribing and to identify areas in which medical need for new agents is greatest.

[Prevalence of potentially pathogenic bacteria in nasopharynx of healthy children attending a day care center in Havana City]. / Prevalencia de bacterias potencialmente patógenas en la nasofaringe de niñios sanos de un círculo infantil de Ciudad de La Habana.

During the first six-month period of 2001, a descriptive cross-sectional study of carriage in healthy children attending a day-care center in Havana City was performed. The objective was to find out the prevalence of potentially pathogenic bacteria and its association with possible risk factors. The design took into account the international and domestic regulatory bioethical requirements. Swabs of posterior nasopharynx of 160 children were directly cultured in brain heart agar plus sheep blood and in brain heart agar plus NAD, hemine and bacitracin and incubated for 18-24 h. Resulting isolates were identified using conventional techniques and the API NH system. Male children aged 3-4 years were predominant. A high percentage of nasopharyngeal carriage was detected; Haemophilus was isolated in 92.50% of cases, being Haemophilus influenzae present in 54.72% of children. Other pathogens were Streptococcus pneumoniae, beta-hemolythic Streptococcus, Staphylococcus aureus and Moraxella catarrhalis. A statistically significant difference was observed when comparing S. pneumoniae carriage and non-carriage in less than 2 years-old children. The colonizing patterns of potentially pathogenic bacteria were disclosed in children attending a day care center in Havana City.

Nasopharyngeal colonization by Moraxella catarrhalis and study of antimicrobial susceptibility in healthy children from Cuban day-care centers.

The prevalence of nasopharyngeal carriage of Moraxella catarrhalis was determined for the first time in Cuba. One-hundred fifty healthy children attending three day-care centers in the municipality of Marianao, Havana City were studied. The percentage of recovering bacteria in nasal and pharyngeal swabs was compared. Antimicrobial susceptibilities to ampicillin, trimethoprim-sulfamethoxazole, tetracycline, cefotaxime, ceftriaxone, chloramphenicol, erythromycin, azithromycin, amoxicillin/clavulanate, and norfloxacin were determined by the disk diffusion method according to recommendations of the National Committee for Clinical Laboratory Standards. Sixty-five percent of the children studied carried Moraxella catarrhalis. The nasal cavity was the main isolation site for this organism (81% of positive cultures). Most strains were highly susceptible to the antimicrobial agents tested, except to ampicillin (53.6% resistance). This study provides evidence of the need for continued surveillance of antimicrobial susceptibility of Moraxella catarrhali, in order to determine optimal empiric therapy for community-acquired respiratory tract infections produced by this pathogen.

Molecular diversity of Moraxella bovis isolated from Brazil, Argentina and Uruguay over a period of three decades.

The molecular profile of 30 Moraxella bovis strains, recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina, Brazil and Uruguay between 1974 and 2001, was determined through randomly applied polymorphic DNA (RAPD) analysis. Molecular profiles of nine strains recovered after 1990 varied from those recovered before 1990. The profiles of 13 strains (48%) differed from those of three vaccinal strains extensively used since 1984 in Argentina and Uruguay. Eight Argentinean strains, one from Brazil and two from Uruguay had identical RAPD profiles. Strains belonging to different serogroups had identical RAPD profiles, demonstrating that this technique was not able to discriminate among strains with low cross-reactivity indices. RAPD may be helpful in the primary characterization of M. bovis strains, but it does not replace serological characterization.

Antigenic relationships of Moraxella bovis isolates recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina, Brazil, and Uruguay between 1983 and 2000.

Cross-reactivity indices (CRIs) of 28 isolates of Moraxella bovis recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina (A, 11 isolates), Brazil (B, 7), and Uruguay (U, 10) between 1983 and 2000 were estimated. Hyperimmune sera were produced in rabbits and antibody titres determined with each isolate. Isolates showing CRIs3 70 were placed in the same group. Group I had 13 isolates (A, 1; B, 6; U, 6); group II had 6 isolates (A, 4; U, 2); groups III, IV, and V had 2 isolates each, recovered in Argentina; group VI had 2 isolates, from Uruguay; and group VII had 1 isolate, from Brazil. The CRIs3 70 between vaccine strains and isolates recovered before and after 1990 were 58% and 42%, 50% and 50%, and 33% and 67% with vaccine strains 2419, 2358, and 2439, respectively. Isolate 273, from Uruguay, showed CRIs > 70 with 78% of the isolates and is recommended as the vaccine strain.