Prevalence and Serotype Distribution of Encapsulated Haemophilus influenzae Isolates from Patients with Lower Respiratory Tract Infections in Poland

Abstract

Among 1,272 H. influenzae isolates obtained from patients with lower respiratory tract infections, 5.6% were found to be encapsulated. The most common were serotypes b (40.3%) and e (38.9%) followed by serotypes f (16.7%) and d (4.1%). All encapsulated isolates within a particular serotype showed high genetic homogeneity and did not produce ␤-lactamases.Haemophilus influenzae is responsible for respiratory tract infections as well as severe invasive infections such as meningitis, bacteremia-sepsis, epiglottitis, and septic arthritis. Although the overwhelming majority of invasive Haemophilus sp. infections are caused by H. influenzae serotype b, other serotypes as well as nontypeable isolates (NTI) have also been associated with invasive diseases (2,3,6,12,13,17,18,24). The aim of this study was to investigate the prevalence and serotype distribution of encapsulated H. influenzae isolated from patients with lower respiratory tract infections (LRTIs).From 1996 through 2001, 1,272 H. influenzae isolates, representing the whole country, were collected during a surveillance study in 25 centers in Poland. The study included outpatients and hospitalized patients (sampled within 48 h of admission) with clinically proven community-acquired LRTIs (exacerbations of chronic obstructive pulmonary disease or pneumonia) from whom samples of bronchoalveolar lavage, blood, or sputum (evaluated with respect to the numbers of white blood cells and epithelial cells and the presence of the mucus threads) were taken (1). Although in local laboratories all isolates were identified by standard procedures, 4.07% of isolates were misidentified. PCRs were run to confirm species identification and to detect capsule-and serotype-specific genes. Supernatants obtained from boiled colonies of H. influenzae were used for duplex PCR for species identification and capsule gene detection (4, 5). For isolates for which the specific products for capsule genes were obtained, the PCRs for serotypes a to f determination were run with primers a1-a2, b1-b2, c1-c2, d1-d2, e1-e2, f1-f2, respectively (4). Quality control strains of H. influenzae of serotypes a to f used for PCR were provided by Oxford Public Health Laboratory (John Radcliffe Hospital). The H. parainfluenzae strain used as the negative control (strain no. 2259/96) was derived from our collection.The production of ␤-lactamases was determined by a nitrocefin assay according to the instructions of the manufacturer (bio Merieux, Marcy l'Etoile, France). The relatedness among encapsulated isolates was evaluated by restriction fragment length polymorphism of SmaI-digested chromosomal DNA analysis, using pulsed-field gel electrophoresis (PFGE), and interpreted as previously described (21,22).A total of 72 (5.6%) H. influenzae isolates were found to be encapsulated. The most common were H. influenzae serotypes b (40.3%; n ϭ 29) and e (38.9%; n ϭ 28) followed by serotypes f (16.7%; n ϭ 12) and d (4.1%; n ϭ 3). The results of comparisons of the frequencies of recovery of different serotypes and NTI s...

Characteristics of Haemophilus influenzae Type b Responsible for Meningitis in Poland from 1997 to 2004

“…Additionally, the most common PFGE type, A, characterized more than 95% of the Hib isolates, and the most common PFGE subtype, A1, was also the most prevalent among isolates responsible for invasive disease in Italy and the Czech Republic and among isolates causing lower respiratory tract infections in Poland (28,32). Thus, the results of this study support the evidence that the genetic structure of encapsulated H. influenzae is clonal.…”

“…Many countries, such as the United States before the vaccination era and presently Cuba, Bangladesh, and Paraguay, reported a high percentage of ␤-lactamase-producing isolates: 32%, 46.5%, 32.5%, and 30%, respectively (2,26,31,34). In the light of the above data, the percentage of ␤-lactamase producers among Polish meningitis isolates is not very high, although it is three times higher than found among H. influenzae isolates responsible for lower respiratory tract infections in Poland (28). The observation that antibiotic resistance is more prevalent in encapsulated isolates, responsible for the majority of meningitis cases, than in nontypeable H. influenzae was also revealed by other authors (4,10,32).…”

“…They constituted from 26.7% (in 1998) to 61.0% (in 2003) of notified cases, with an average of 40.1% (22). For comparison, the study also included representatives of Hib isolates of the most prevalent pulsed-field gel electrophoresis (PFGE) types responsible for invasive disease in Italy and the Czech Republic (28,32). All isolates were identified to the species level based on standard procedures (14).…”

Genomic Sequence of an Otitis Media Isolate of Nontypeable Haemophilus influenzae : Comparative Study with H. influenzae Serotype d, Strain KW20

“…Strain Rd, however, is a derivative of a serotype d strain. Serotype d strains are rarely associated with disease (23,44,94,102).Because one of the most useful sets of data in the study of an organism's biology is its genomic sequence, a number of investigations have identified and characterized genes found in H. influenzae type b strains, H. influenzae biogroup Aegyptius strains or in nontypeable strains that are not present in strain Rd (13,17,30,60,64,82,106). Previously we carried out partial analyses and comparisons of the genomes of two NTHi strains, 1885MEE and 86-028NP, that were isolated from the middle ear and nasopharynx, respectively, of children with chronic otitis media (72).…”

“…Strain Rd, however, is a derivative of a serotype d strain. Serotype d strains are rarely associated with disease (23,44,94,102).…”