1. at George Washington University Medical Center, Washington, DC
Abstract # Poster #187
Recent Trends in Streptococcus pneumoniae Antibiotic Susceptibility
at George Washington University Medical Center, Washington, DC
Agnes Kresch, M.D, Niharika Tipirneni, M.D, John Keiser, M.D, Marc Siegel, M.D
The George Washington University, Washington, DC
No conflicts of interest to report
Contact information:
Agnes Kresch
GWUMC, Division of Infectious Diseases
2150 Pennsylvania Ave, NW Suite 5411
Washington, DC 20037
(202)
Discussion
Streptococcus pneumoniae is the most common cause of community-acquired pneumonia requiring hospitalization and is responsible for 7,000 cases of bacteremia and 1,700 cases of meningitis each year [5]. Over the past twelve years, S. pneumoniae isolates exhibited resistance to antibiotics of various classes, but especially with the more frequently used β-lactams and macrolides, leading to an increased rate of clinical failures and morbidity.
We compared our results with large national databases, including the SENTRY Antibiocrobial Surveillance program, which looked at 14,939 pneumococcal isolates from 1998 to 2009 in the USA [6], as well as the Active Bacterial Core Surveillance (ABCs) Report from the CDC, analyzing isolates yearly from nine regions countrywide [7]. Penicillin susceptibility from1998 to 2000 fell in both surveys (96.8% to 95.7% in SENTRY and 75.6% to 72.6%) in ABCs. At GWUH during the same time period penicillin susceptibility fell 84% to 68%. In 2000, the PCV 7 vaccine was introduced [6]. By , the number of penicillin-susceptible isolates had risen to 94.7%, 78.6%, and 86% for SENTRY, ABCs, and GWUH respectively. All studies showed a subsequent decline in susceptibility by 2008, perhaps accounted for by non-vaccine serotype replacement.
All three studies showed an overall decline in cephalosporin susceptibilities, with SENTRY data showing decreases from 95.0% to 84.1% for ceftriaxone , and GWUH showing a decrease from 99 to 92% for ceftriaxone (P=0.0004) and 80% to 76% for cefuroxime during the study period .
All studies revealed significant decreases in erythromycin susceptibility, with decreases from 74.3% to 60.8% in SENTRY, 78.4% to 73.8% in ABCs, and 79% to 67% (P=0.013) at GWUH.
Clindamycin also decreased both nationwide 92.3% to 79.1% and at GWUH from 92 to 77% (P=0.0004). Susceptibilities for respiratory fluoroquinolones were consistently greater than 99% both nationally and at GWUH. Vancomycin was 100% susceptible throughout, thus supporting continued empiric use in cases of possible pneumococcal meningitis.
Results
% Resistant
Abstract
Background:
Decreasing susceptibility of Streptococcus pneumoniae isolates to commonly used antibiotics has been an ongoing healthcare concern. We wanted to investigate the change in antibiotic sensitivity of the S. pneumoniae isolates at our institution.
Methods:
We investigated trends in antimicrobial susceptibility over a 12 year period at the George Washington University Hospital (GWUH) analyzed in blocks spanning 2000 through 2003 (block A), 2004 through 2007 (block B), and 2008 through 2011 (block C). We compared our results to national data from the SENTRY Antimicrobial Surveillance Program and the Active Bacterial Core Surveillance (ABCs) Report from the CDC.
Results:
The sensitivity profile of 486 S. pneumoniae isolates collected over the 12 year study period from non-sterile and sterile sites, including cerebrospinal fluid were reviewed. Erythromycin susceptibility decreased from 79% in block A to 67% in block C (P=0.013), ceftriaxone decreased from 99% to 92% (P=0.0006), clindamycin decreased from 92% to 77% (P=0.0004). The proportion of isolates exhibiting multi-drug resistance (≥3 antibiotic classes) increased from 5.1% in block A to 6.9% in block B, and 9.3% in block C.
Conclusion:
There has been a statistically significant decrease in susceptibility among S. pneumoniae isolates to erythromycin, ceftriaxone and clindamycin over the last 12 years and there has been an alarming increase in multi-drug resistant isolates at our institution . .
% Intermediate
% Susceptible
Background
Streptococcus pneumoniae is the leading cause of community-acquired pneumonia (CAP). It is estimated to cause 500,000 cases of CAP each year of which 20% are associated with bacteremia. Mortality for bacteremic pneumococcal pneumonia ranges from 10 to 30% in adults [1].
The first clinical isolate of penicillin-resistant S. pneumoniae was described in 1967 [2]. This was followed by an epidemic outbreak of pneumococcal disease caused by multidrug-resistant strains in South African hospitals in 1977 [3]. In the 1990s, the incidence of intermediate and highly penicillin resistant S. pneumoniae isolates reached 40% but has waned since the widespread introduction of the 7-valent pneumococcal conjugate vaccine [4].
We carried out a retrospective review of the antibiotic sensitivity profiles of all of the S. pneumoniae isolates obtained from patients seen at George Washington University Hospital (GWUH) during a 12 year period from January 2000 through December We compared this data with previous antibiotic sensitivity data from January 1998 through December 2000 and to national data from the SENTRY Antimicrobial Surveillance Program 2008 and the ABCs Report from the CDC.
Conclusions
There has been a statistically significant decrease in susceptibility among S. pneumoniae isolates to erythromycin, ceftriaxone and clindamycin over the last 12 years at our institution. Compared to national surveillance data, overall S. pneumoniae susceptibility at GWUH was better for ceftriaxone, cefuroxime and erythromycin but worse for penicillin G. All isolates have remained susceptible to vancomycin, and nearly all isolates to respiratory quinolones. However there has also been an alarming increase in multi-drug resistant isolates. Since most initial antibiotic choices for presumed pneumococcal disease are empiric, awareness of geographic and temporal trends in antibiotic susceptibility are essential to minimizing treatment failures .
Figure 1. Susceptibility rates for penicillin, ceftriaxone, erythromycin, and clindamycin among Streptococcus pneumoniae isolates at GWUH from 2000 through 2011.
References
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Methods
Antibacterial minimum inhibitory concentrations were determined using the E-test® procedure, according to the Clinical and Laboratory Standards Institute (CLSI) 2011 Performance Standards for Antimicrobial Susceptibility Testing. CLSI interpretive standards for non-meningitis and meningitis breakpoints were used as applicable.
Susceptibility patterns to nine antibiotics were analyzed in blocks spanning 2000 through 2003 (block A), 2004 through 2007 (block B), and 2008 through 2011 (block C).
Figure 2. A. 486 S. pneumoniae isolates were collected from blood, sputum, cerebrospinal fluid and other sterile and non-sterile sites, as above, during the twelve year study period
Figure 3. Percentage of S. pneumoniae isolates with multi-drug resistantceto three or more classes of antibiotics, with linear averaging observed over the study period.