Non-invasive erythromycin-resistant pneumococcal isolates are more often non-susceptible to more antimicrobial agents than invasive isolates

National Neisseria and Streptococcus Reference Center, Department for Bacteriology, Mycology and Parasitology, Statens Serum Institut, Artillerivej 5, DK-2300 Copenhagen S, Denmark.
International journal of antimicrobial agents (Impact Factor: 4.3). 11/2009; 35(1):72-5. DOI: 10.1016/j.ijantimicag.2009.09.006
Source: PubMed


Multiresistant Streptococcus pneumoniae infections are of great concern as treatment failures may occur with commonly used treatment regimens using beta-lactams and macrolides. The proportion of non-susceptible S. pneumoniae differs from country to country. In Denmark, the proportion of invasive penicillin- or erythromycin-non-susceptible isolates is still low. The aim of this study was to characterise and compare invasive and non-invasive penicillin-non-susceptible and erythromycin-resistant pneumococcal isolates from the same geographic area and the same time period with respect to serotype and antibiotic susceptibility profile. We aimed to identify which serotypes were multiresistant among Danish isolates and to confirm or reject whether there was a difference in serotype distribution and resistance profiles between invasive and non-invasive isolates. We observed that non-invasive penicillin-non-susceptible pneumococci had higher serotype diversity than invasive isolates. This was not the case for erythromycin-resistant pneumococci. The dominant serotypes among non-susceptible invasive isolates were serotypes 9V and 14, whereas the dominant serotypes among non-susceptible non-invasive isolates were serotypes 19F, 14, 9V, 6B and non-typeable (NT). Non-invasive isolates were also more likely to be resistant to three or more antimicrobial agents than invasive isolates, however isolates being multiresistant were often co-resistant to the same antimicrobial agents.

Download full-text


Available from: Anette M Hammerum
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Antibiotic resistance in Streptococcus pneumoniae has increased worldwide but varies within geographical regions. We conducted a retrospective analysis of resistance in S. pneumoniae over a 12-year period to assess local and temporal trends in antibacterial resistance. From 1997 to 2008, a total of 1814 non-duplicate S. pneumoniae isolates were identified at the Institute of Hygiene, Microbiology and Environmental Medicine, Medical University of Graz, Austria. Antibiotic resistance was determined by the Clinical and Laboratory Standards Institute (CLSI) disk diffusion test. For penicillin, the minimum inhibitory concentration was determined by Etest. Susceptibility was defined according to CLSI interpretive criteria. For penicillin, resistance rates were consistently low at 0.2% over the 12-year study period. An increase in resistance was remarkable for erythromycin (3.5% in 1997; 14.7% in 2008), clindamycin (1.8% in 1997; 10.6% in 2008) and tetracycline (1.8% in 2000; 11.0% in 2008). For trimethoprim/sulfamethoxazole, resistance increased slightly to 9.2% in 2008. Quinolones showed a low resistance rate of 0.2% that persisted over the whole study period. In contrast to previously published national data, resistance to penicillin was observed to remain at a remarkably low and constant level. Although international surveillance programmes have set up sustainable and interlinked data networks, our results suggest that regional surveillance may still be needed as decision support for appropriate empirical antibiotic therapy in the local health setting.
    Full-text · Article · Jul 2010 · International journal of antimicrobial agents
  • [Show abstract] [Hide abstract]
    ABSTRACT: Over the last decade, erythromycin resistance has been increasing in frequency in Streptococcus pneumoniae in Denmark. In the present study, 49 non-related erythromycin-resistant S. pneumoniae isolates from invasive sites and 20 isolates from non-invasive sites were collected; antimicrobial susceptibility was tested, and they were genotyped and serotyped. Gene transfer was studied for selected isolates. The frequency of erm(B) was significantly higher in non-invasive isolates compared to invasive isolates (p = 0.001). For the first time, mef(I) was detected in 1 isolate in Denmark. All tested mef(E) isolates had an identical mef(E) sequence, apart from 1 gene with a point mutation, and mef(E) was correlated to 7 different sero-types. The tested erm(B) sequences were 99.3% similar with 5 point mutations at different positions distributed among different serotypes, which did not cause a detectable influence on the protein. Transformation was detectable in 5 out of 13 isolates and transfer of erm(B), mef(I) and mef(E) was detected. To our knowledge, this is the first time mef(I) has been proved transformable. Gene transfer by conjugation was not detectable. Erythromycin resistance in pneumococcal isolates is likely to be caused primarily by horizontal spread of mef(E) and erm(B), as well as clonal spread of a serotype 14 strain carrying mef(A) primarily detected in invasive isolates.
    No preview · Article · Aug 2010 · Scandinavian Journal of Infectious Diseases
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In the elderly, Streptococcus pneumoniae is the most common cause of pneumonia and one of the most frequently isolated pathogens in cases of acute exacerbation of chronic obstructive pulmonary disease (AECOPD). This study was conducted to compare the pneumococcal isolates obtained during episodes of AECOPD and pneumonia in patients of ≥65 years old and to analyze whether in patients with AECOPD and pneumonia within a short interval, the same isolate caused both episodes. This laboratory-based study was performed between 2005 and 2008. Pneumococcal isolates from episodes of pneumonia (n = 401) and AECOPD (n = 398), matched one-to-one by date of isolation, were characterized. The serotypes and genotypes of other pneumococcal isolates causing pneumonia and AECOPD in the same patient were compared. In patients with pneumonia, COPD as an underlying disease was not associated with more-drug-resistant pneumococci. In contrast, isolates causing AECOPD showed higher rates of resistance than those causing pneumonia. Serotypes 1, 3, and 7F were more frequent in pneumonia. The same pneumococcus was involved in 25.7% (9/35 patients) of patients with two consecutive AECOPD episodes but in only 6.3% (2/32 patients) of COPD patients with pneumonia and exacerbation (Fisher's exact test; P = 0.047). Less invasive serotypes were isolated more often in AECOPD and were more resistant to antimicrobials. The presence of a specific pneumococcal serotype in AECOPD does not predict the etiology of subsequent pneumonia.
    Full-text · Article · Mar 2011 · Antimicrobial Agents and Chemotherapy
Show more