Changes in the proportion of penicillin-non-susceptible Streptococcus pneumoniae (PNSP) isolates during an intervention programme were evaluated by phenotypic analysis of all initial isolates with penicillin MIC > or =0.5 microg/ml (n=1248) collected 1995-2004. During the study period, the proportion of such isolates was fairly constant (12-19%), and there was no statistically significant variation in the proportion of total PNSP cases (MIC > or =0.12 microg/ml) or PNSP with MIC > or =0.5 microg/ml, with the exception of an increase in 2004. Analysis restricted to clinical cases revealed no statistically significant changes. 23 different serogroups were found, and serogroup 9 isolates accounted for almost half of the PNSP cases. Only minor changes in phenotypic characteristics occurred in the other serogroups, which indicates that the increase in PNSP in 2004 was not due to import of a new resistant clone. Antibiotic consumption is considered to be an important risk factor for penicillin resistance in S. pneumoniae. After initiation of the intervention programme in Malmö, overall prescribing of antibiotics decreased 28%, and the reduction was even greater among children (52%). In conclusion, the proportion of PNSP isolates in Malmö has remained stable, despite the intervention programme and decreased consumption of antibiotics.
To review the definition and prevalence of antibiotic-resistant Streptococcus pneumoniae, its links with antibiotic prescribing, data on antibiotic prescribing and prescribing appropriateness, and evidence-based treatment guidelines for common respiratory tract syndromes.
Primary studies consist of cross-sectional surveys and case-control studies. Treatment guidelines are based on clinical trials, meta-analyses, and cohort studies. Study designs were appropriate for the specific study questions.
The increasing prevalence of penicillin-resistant S pneumoniae is concurrent with increasing antibiotic prescribing. Individual patients show a twofold to ninefold increase in nasopharyngeal carriage of resistant bacteria or invasion with resistant bacteria (among those who have received antibiotics in the preceding 3 months). Cross-sectional data as well as data from medicaid and drug databases attest to overprescribing of antibiotics for respiratory tract infections. Physician surveys and focus groups blame this on parental pressure for antibiotic prescriptions. However, parents in focus groups and surveys deny they pressure their physicians and indicate their main purpose for office visits is to obtain a diagnosis and to seek reassurance that their children are not seriously ill. Evidence-based guidelines suggest treatment strategies that would reduce antibiotic prescribing.
The few antibiotics that can be used with resistant organisms are expensive and are increasingly being needed. To control the rise of antibiotic resistance, it is important to limit antibiotic overprescribing.
The majority of antibiotics consumed in developed countries are prescribed in primary care. However, little is known about resistance levels in the primary care population.
Nasopharyngeal cultures were obtained from children, 0-10 years of age, seeking care at their Primary Health Care Centre with symptoms of respiratory tract infection. Parental questionnaires were used to retrieve information about the child's previous antibiotic consumption.
Cultures from 340 children were gathered. The level of resistant Haemophilus influenzae was low and the prevalence of penicillin non-susceptible pneumococci (PNSP MIC = 0.125 mg/L) was 6% compared to 10% (p = 0.31) in corresponding cultures from children diagnosed at the local clinical microbiology laboratory. Antibiotic treatment within the previous 4 weeks predisposed for resistant bacteria in the nasopharynx, OR: 3.08, CI 95% (1.13-8.42).
Low prevalence of PNSP supports the use of phenoxymethylpenicillin as empirical treatment for childhood upper respiratory tract infections attending primary care in our setting. It is important that studies on resistance are performed in primary care populations to evaluate data from microbiological laboratories. Recent antibiotic treatment increases risk of bacterial resistance in children and continuous work to reduce unnecessary antibiotic prescribing should be prioritised.
Cites: Clin Infect Dis. 2002 May 15;34(10 ):1301-911981724
Outbreaks of invasive pneumococcal disease (IPD) typically occur within institutions. Beginning in 2005, we detected an increase in serotype (ST) 5 and ST8 IPD cases, predominantly in homeless persons living in an open community.
CASPER (Calgary Area S. pneumoniae Epidemiology Research) surveillance study of all IPD (sterile site isolates) in our region (pop ~1,100,000). Interviews and chart reviews of all cases and all isolates phenotypically analyzed and selected isolated tested by multi-locus sequence typing (MLST).
During 2005-2007, 162 cases of ST5 IPD and 45 cases of ST8 IPD were identified. The isolates demonstrated phenotypic and genotypic clonality. The ST5 isolates were sequence type (ST) 289 and demonstrated intermediate susceptibility to TMP-SMX. The ST8 isolates were predominantly ST1268, with a susceptible antimicrobial susceptibility profile. Individuals with ST5 IPD were more likely to be middle aged (OR 2.6), homeless (OR 4.4), using illicit drugs(OR 4.8), and asthmatic(OR 2.6). Those with ST8 were more likely to be male (OR 4.4), homeless (OR 2.6), aboriginal (OR7.3), and a current smoker (OR 2.5). Overlapping outbreaks of ST5 and ST8 IPD occurred in an open community in Calgary, Canada and homelessness was a predominant risk factor. Homelessness represents a unique community in which pneumococcal outbreaks can occur.
Cites: Can Commun Dis Rep. 2008 Sep;34(ACS-5):1-1218856005
Penicillin-resistant and multi-resistant pneumococci have spread globally and reached high prevalence in many countries. Antimicrobial use is considered a major driving force for resistance, although the influence in the community has not been as clearly demonstrated. Other risk factors may be important, and only with a clear understanding of the risk factors can effective control measures be introduced. The main habitat of the pneumococcus is the nasopharynx of children. Carriage increases from birth and is maximal at pre-school age. Antimicrobial use in children is likely to have a significant influence on the susceptibility of pneumococci. Most studies looking for risk factors for resistance in pneumococci have identified antimicrobial use as a risk factor, especially the following aspects: ongoing, recent, repeated, frequent, and prophylactic antibiotic use. The effect of individual classes of antimicrobials has not been studied in detail but use of beta-lactam antibiotics and trimethoprim-sulpha has been associated with increased risk. Other risk factors are young age, nosocomial acquisition, prior hospitalization, and HIV infection. Day-care centers can facilitate the spread of resistant pneumococci and an Icelandic study showed that carriage of resistant pneumococci was associated with young age, domicile in an area with high antimicrobial consumption, recent antimicrobial use, frequent antimicrobial use, and use of trimethoprim-sulpha. The rapid increase of penicillin-resistant pneumococci in Iceland was met with propaganda against overuse of antimicrobials, which lead to reduction of antimicrobial use and subsequently a reduced incidence of penicillin-resistant pneumococci. This reduction may be related to reduced antimicrobial use. Reducing antimicrobial use should be considered important for programs aimed at reducing antimicrobial resistance.
Increasing resistance of Streptococcus pneumoniae to macrolides represents a challenge for clinicians. New ketolides have an enhanced activity against macrolide-resistant strains. Four hundred and seventy-four strains of S. pneumoniae were collected during the 2000-2001 season in Quebec through a surveillance network. Macrolide resistance was 20.2%, and significantly higher in non-invasive strains versus invasive ones (22.4% versus 14.8%), and in children (30%) versus adults (14.8%). For susceptible strains, MIC(90)s of ABT-773 and telithromycin were 0.008 and 0.015 mg/L. Among the 96 macrolide-resistant strains, 56 (58%) were erm(B), 35 (37%) carried the mef(A) gene, four were carrying both genes and one none. ABT-773 and telithromycin were very active against all these resistant strains irrespective of the resistance mechanism, with MIC(90)s of 0.25 and 0.5 mg/L, respectively.
In response to increasing frequencies of penicillin-nonsusceptible pneumococci (PNSP), for which the MIC of penicillin was >0.12 mg/L, in Skåne County, southern Sweden, national recommendations were initiated in 1995 to limit the spread of pneumococci with high MICs (> or =0.5 mg/L) of penicillin (PRP), especially among children of preschool age. Traditional communicable disease control measures were combined with actions against inappropriate antimicrobial drug use. During the first 6 years that these recommendations were applied in Skåne County, the average frequency of penicillin-resistant pneumococci has been stable at =2.6%, as has the average PNSP frequency (7.4%). However, PNSP have been unevenly distributed in the county, with the highest frequencies in the southwest. Simultaneously, the rate of antimicrobial drug use for children
The prevalence of isolates of Streptococcus pneumoniae (pneumococcus) that are resistant to antimicrobial agents is increasing globally. We studied the connection between antimicrobial resistance of pneumococci and regional use of antimicrobial agents in Finland. In 1997, a total of 6106 pneumococcal isolates were identified in clinical microbiology laboratories in Finland. Most of the pneumococci were isolated from respiratory tract samples, 8% were from blood culture samples, and 0.5% were from cerebrospinal fluid samples. The regional levels of resistance for pneumococci in 1997 were compared with the regional rates of use of antimicrobial agents from 1995 through 1996. We found that resistance to macrolides correlated highly significantly with macrolide use (P=.006). A significant correlation was also found between resistance to trimethoprim-sulfamethoxazole and trimethoprim-sulfamethoxazole use (P=.043). We did not find a correlation between penicillin resistance and the use of any antimicrobial agent. The positive correlation between macrolide-resistant pneumococci and the use of macrolides is worrying, because macrolides are used worldwide in the treatment of patients with respiratory tract infections, which are often caused by pneumococci.