Antibiotic resistance and clinical significance of Haemophilus influenzae type f.
OBJECTIVE
Little is known about the antibiotic susceptibility and clinical significance of non-type b capsulated Haemophilus influenzae. We studied the antibiotic resistance patterns, plasmid carriage and clinical features of H. influenzae type f infections in Spain during 1996-2002.


METHODS
Forty-nine H. influenzae type f recovered from Spanish hospitals were analysed at a central laboratory where full microbiological and molecular epidemiological studies were carried out. Antimicrobial susceptibility testing was performed in accordance with NCCLS guidelines.


RESULTS
Twelve strains (24.5%) were resistant to ampicillin and 22 (44.9%) to co-trimoxazole. Decreased susceptibility to clarithromycin, tetracycline, chloramphenicol and rifampicin was found in 16.3%, 12.2%, 14.3% and 2% of strains, respectively. Multidrug resistance was present in nine (18.4%) of the 49 isolates. The most prevalent resistance phenotype was ampicillin/tetracycline/co-trimoxazole/chloramphenicol, which was detected in five isolates. All six strains that were simultaneously resistant to ampicillin, tetracycline and chloramphenicol had conjugative plasmids. The main clinical diagnoses were pneumonia (32.6%), sepsis (18.4%) and meningitis (16.3%). Thirty-two patients (65.3%) had previous underlying predisposing conditions, principally respiratory diseases (20.4%). Twenty-one patients (42.8%) had impaired immunity. Thirty-seven (75.5%) patients were >14 years old, 12 (24.5%) were < or =14 years, and seven were < or =5 years. Most isolates were clonally related.


CONCLUSIONS
A high prevalence of antibiotic resistance, including multiresistance, was detected in Spanish H. influenzae type f isolates. Carriage of large conjugative plasmids was strongly associated with antibiotic resistance. H. influenzae type f is mainly an opportunistic pathogen, although it may cause primary severe infections, such as meningitis in children.
Campos
José
J
Centro Nacional de Microbiología, Instituto de Salud Carlos III, Ministry of Health, 28220 Majadahonda, Madrid, Spain. jcampos@isciii.es
Román
Federico
F
Pérez-Vázquez
María
M
Aracil
Belén
B
Oteo
Jesús
J
Cercenado
Emilia
E
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D003227:Conjugation, Genetic; D024881:Drug Resistance, Bacterial; D024901:Drug Resistance, Multiple, Bacterial; D016521:Electrophoresis, Gel, Pulsed-Field; D005260:Female; D006192:Haemophilus Infections / Q000453:epidemiology / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics; D006801:Humans; D007223:Infant; D008297:Male; D032541:Mass Vaccination; D008826:Microbial Sensitivity Tests; D008875:Middle Aged; D017720:Molecular Epidemiology; D010957:Plasmids / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013030:Spain / Q000453:epidemiology; D037521:Virulence Factors / Q000235:genetics; D001618:beta-Lactamases / Q000378:metabolism
D037521:Virulence Factors; D001618:beta-Lactamases