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Changes in the catchment population – changes in the rate of penicillin-resistant Streptococcus pneumoniae strains?

Abstract number: 1733_238

Hajdu E., Matuz M., Benko R., Ordas A., Nagy E.

Objectives: The catchment population of our laboratory has changed during the years. We analysed whether this change had any impact on penicillin resistance rates of S. pneumoniae strains.

Methods: We included in our analysis the S. pneumoniae isolates if the symptoms or the source of the isolate proved of its clinical relevance. According to the changes in the catchment population (between 1998 and 2001 we provided our service exclusively for the in- and outpatient departments of the university hospital while from the year 2002 increasing number of general practitioners sent samples to our laboratory) we set up two time periods: Period I (1998–2001) and Period II (2002–2005). Isolation and identification were carried out by conventional methods.

All resistance data were collected from our laboratory database system. The same methodology was used to detect penicillin resistance throughout the study. The susceptibility of isolates was determined by using the breakpoints recommended in the NCCLS/CLSI guidelines. MIC determination was carried out by using the E test. Repeat isolates from individual patients were excluded. Differences in the distribution of resistance patterns between the two time periods were analysed by chi-square test and Fisher's exact test, using the SPSS programme package (version 13.0). A P value <0.05 was considered to be statistically significant.

Results: Our results are summarised in the table.

Age groupS. pneumoniae isolatesP value
Total numberNumber of penicillin-resistant isolates
Period IPeriod II HR*LR**
Period IPeriod IIPeriod IPeriod II    
In-patients
0–215833532 (20)13 (4)58 (37)180 (54)<0.001
3–1419329726 (13)7 (2)68 (35)129 (43)<0.001
15–65851037 (8)3 (3)22 (26)28 (27)0.270
>6541554 (10)1 (2)12 (29)11 (20)0.097
All47779069 (14)24 (3)160 (34)348 (44)<0.001
Outpatients
0–211537324 (21)9 (2)36 (31)208 (56)<0.001
3–1418154512 (7)9 (2)55 (30)297 (53)0.001
15–6584921 (1)1 (1)16 (19)25 (27)0.444
>65490 (0)0 (0)0 (0)2 (0)0.304
All384101937 (10)19 (2)107 (28)522 (51)<0.001
*HR: high level of resistance; **LR: low level of resistance including resistant (R) and intermediate resistant (IR) strains.

Conclusion: Contradictory publications exist about the rate of penicillin resistance among S. pneumoniae isolates in Hungary [1,2]. In our study the rate of penicillin resistance was found to be low and further decreasing was observed with the change of the catchment population. The importance of taking into account the used methodology for detecting resistance and the origin of the isolates (inpatient vs. outpatient) is highlighted by our study.

Reference(s)

[1] Marton A. Epidemiology of resistant pneumococci in Hungary. Microb Drug Resist 1: 127–130, 1995.

[2] Dobay O et al. Antimicrobial susceptibility and serotypes of Streptococcus pneumoniae isolates from Hungary J Antimicrob Chemother 51: 887–893, 2003.

Session Details

Date: 31/03/2007
Time: 00:00-00:00
Session name: European Society of Clinical Microbiology and Infectious Diseases
Subject:
Location: ICC, Munich, Germany
Presentation type:
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