Antimicrobial resistance patterns of Haemophilus influenzae isolated from patients with meningitis in São Paulo, Brazil

Abstract

From 1989 to 1995, a total of 391 Haemophilus influenzae isolates were recovered from the cerebrospinal fluid (CSF) of hospitalized patients in São Paulo, Brazil. The majority of strains were isolated from infants aged less than 5 years. Strains belonging to biotype I (64.7%), biotype II (34.5%) and biotype IV (0.76%) were detected. Ninety-nine percent of these strains were serotype b. Minimal inhibitory concentration (MIC) was determined for ampicillin, chloramphenicol and ceftriaxone. The ß-lactamase assay was performed for all strains. The rate of ß-lactamase producer strains ranged from 10 to 21.4% during a period of 7 years, with an overall rate of 13.8%. Of the 391 strains analyzed, none was ß-lactamase negative ampicillin resistant (BLNAR). A total of 9.7% of strains showed resistance to both ampicillin and chloramphenicol; however, 4% of them were resistant to ampicillin only and 2% to chloramphenicol. All strains were susceptible to ceftriaxone and the MIC 90 was 0.007 µg/ml, suggesting that ceftriaxone could be an option for the treatment of bacterial meningitis in pediatric patients who have not been screened for drug sensitivity.

Nasopharyngeal colonization by Haemophilus influenzae in children attending day-care centers, in Ribeirão Preto, State of São Paulo, Brazil

“…Studies at DCCs in France, reported a high rate of β-lactamase positive strains (44.5-60.0%) (9,35) compared with those of the general population (15). In the present study, the rate of β-lactamase positive strains detected at DCCs (13.9%) was not different from those reported for the population (6,8).…”

“…In Latin America (10) and in Brazil (6,8), the prevalence of β-lactamase production is almost the same as that found in Europe, around 9.0-14.5%, and BLNAR strains have not been detected.…”

Antimicrobial resistance among invasive Haemophilus influenzae strains: results of a Brazilian study carried out from 1996 through 2000

“…Lower frequencies of ß-lactamase-mediated ampicillin resistance were observed in Santa Catarina (6.7%), Pernambuco (10.5%) and Bahia (7.7%), the last two belonging to the same geographic region, unlike Santa Catarina which is located 3000 km to the South, with climatic conditions of a sub- (28), the overall frequency of ß-lactamase production was 18.9% and the frequency during the period from 1989 to 1995 was 13.8% (19). The high resistance frequency in these states may perhaps be due to the fact that they comprise population strata with greater acquisitive power that may permit the purchase of antimicrobial agents, even though most of the samples were from public hospitals whose clients usually represent a low income population.…”

“…In São Paulo municipality, Brazil, the prevalence of ampicillin resistance and ß-lactamase-producing strains has already been reported, with a mean frequency of 13.8% (18,19).…”

Impact of the Haemophilus influenzae type b vaccination program on HIB meningitis in Brazil

“…Furthermore, prospects for drug treatment of HIB infections are limited by the development of antimicrobial resistance 15,16 and the fact that HIB chemoprophylaxis is not very effective. In this sense, vaccination is important for control- ling invasive diseases caused by HIB, particularly considering that HIB is the second most frequent cause of bacterial meningitis in Brazil.…”