From Medscape Medical News
Nancy A. Melville
June 20, 2011 (Milan, Italy) — Overall hospitalization rates for Staphylococcus aureus increased only moderately in the United States between 2004 and 2008; however, the rate of hospitalizations related to the USA300 strain of isolates expanded dramatically, more than tripling during the same period, according to a study presented here at the 21st European Congress of Clinical Microbiology and Infectious Diseases (ECCMID).
In combining data from the Surveillance Network (Eurofins Medinet) and the Nationwide Inpatient Sample (Healthcare Cost and Utilization Project), researchers identified 3 major groups of clonal complexes to corresponded with 89% of all isolates during the 4-year study period. Two of these groups are methicillin-resistant, and 1 is methcillin-sensitive.
The USA300 strain represented just 7.3% of all S. aureus hospitalizations in 2004, with a hospitalization rate of 1.03 ± 0.08 per 1000 discharges. However, the rate had increased as much as 3.5 times by 2008 to represent 23.9% of all S. aureus hospitalizations, with a rate of 3.62 ± 0.24 per 1000 discharges (P < .001).
Increases in the USA300 strain have been previously documented outside the hospital and among skin and soft tissue infections, but the study documents the rise among invasive disease at the hospital level, said lead author Robertino Mera MD, PhD, director of the Research Statistics Unit with GlaxoSmithKline in Collegeville, Pennsylvania.
"The strength of our study is to show [increases in] incidence rates at the national level and among invasive diseases such as pneumonia and bacteremia," Dr. Mera said.
The increase has been greater among children than adults, he noted. "The rate of USA300 increased 2.8 times among children compared with 1.95 times among adults during the study period."
The study showed that overall, S. aureus hospitalization rates per 1000 discharges significantly increased, from 14.1 ± 0.25 in 2004 to 15.1 ± 0.24 in 2008 (P < .05).
Rates of clonal complex 5 PVL-MRSA, the most common hospital genotype in 2004 (41.3% of all S aureus hospitalizations, with a hospitalization rate of 5.83 ± 0.14), declined significantly by 2008, dropping down to become the second most common group (28.3% of all S. aureus hospitalizations, with a rate of 4.28 ± 0.11 per 1000 discharges; P < .01).
No significant change was seen in the polyclonal methcillin-sensitive clonal complex over time, which accounted for 39.7% of all hospitalizations in 2004 (rate, 5.59 ± 0.19) and 38.5% of all S. aureus hospitalizations in 2008 (rate, 5.83 ± 0.19 per 1000 discharges).
"Although the overall S. aureus hospitalization rate increased moderately during the period of observation, the share of USA300 isolates dramatically increased from 1 out of 13 S. aureus hospitalizations in 2004 to one out of four in 2008," the authors concluded.
USA300 has likely been able to spread because of its resistance to antibiotics and its robust ability for transmission, Dr. Mera said.
"The key factor that explains the expansion of the clonal group USA300 is its capacity to transmit and invade, coupled with innate resistance to most penicillins and macrolide [azithromycin, clarithromycin] antibiotics," he said.
Loren G. Miller, MD, MPH, associate professor of medicine and director of the Infection Care Program at Harbor-UCLA Medical Center in Torrance, California, agreed that the USA300 strain appears to have a stronger endurance than other methicillin-resistant S. aureus (MRSA) strains.
"The USA300 strain is known to live on inanimate objects longer than other MRSA strains and be a relatively fit S. aureus strain compared with other MRSA strains in in vitro and in vivo studies, in terms of growth rates and ability to cause disease. These features may give USA300 advantages to spread to other persons and cause disease more easily than other MRSA strains," Dr. Miller said.
"This study presents further support that the USA300 strain is very successful at causing disease and may be more pathogenic and transmissible than other MRSA strains," he added.
Dr. Mera indicated that more recent data from the Centers for Disease Control and Prevention will likely show a plateau in the USA300 strain, and Dr. Miller said that has also been his observation.
"Data I have seen and my clinical experience all suggest that the rapid increase in incidence of USA300 MRSA seen in the early-mid 2000s has leveled off, and infection rates haven't significantly changed over the past few years."
Nevertheless, the strain may remain a powerful force in boosting S aureus infection rates indefinitely, Dr. Miller noted.
"The success of USA300 causing disease may mean that S. aureus infection rates may be above historical averages for many years to come," he said. "This rise could have a significant impact on patient morbidity and healthcare expenditures."
GlaxoSmithKline is currently working to develop an S. aureus vaccine, which, if successful, could play an important role in preventing widespread infection, Dr. Miller said.
"An S. aureus vaccine, if successful, could be a huge step in disease prevention and would have the potential to prevent many ambulatory infections that cause or complicate hospitalizations, and prevent deaths from serious S aureus infections," he noted.
"Even a vaccine that works against USA300...would have enormous public health implications, given [that] S. aureus infections are so common."
The study received support from GlaxoSmithKline, which is developing an S. aureus vaccine. Dr. Mera is an employee of GlaxoSmithKline. Dr. Miller's financial disclosures include that he served as an advisor or consultant for: Forest Laboratories, Inc, and received grants for clinical research from Pfizer Inc and Cubist Pharmaceuticals Inc.
21st European Congress of Clinical Microbiology and Infectious Diseases (ECCMID). Presented May 9, 2011.
miércoles, 13 de julio de 2011
Most Antibiotics Safe to Use During Pregnancy
News Author: Emma Hitt, PhD
May 31, 2011 — During the second and third trimester of pregnancy, sulfonamides and nitrofurantoins may be used as first-line agents for urinary tract and other infections, but in the first trimester, these agents may be used when no alternatives are available, according to a Committee Opinion from the American College of Obstetricians and Gynecologists (ACOG).
The opinion is published in the June issue of Obstetrics & Gynecology. According to the study authors, a 2009 case-control study of data from the National Birth Defects Prevention Study found that nitrofurans and sulfonamides were significantly associated with multiple birth defects, whereas penicillins, erythromycin, cephalosporins, and the quinolones were not.
However, the authors acknowledge several limitations of the 2009 study. In addition, they note that "other studies have not found such risks among other populations or when using different epidemiologic methods."
According to the authors, antibiotics "should be prescribed for pregnant women only for appropriate indications and for the shortest effective duration."
They add that many urine cultures show bacterial contaminants that do not represent true infection. However, when selecting an antibiotic for a true infection during the first trimester, "health care providers should consider and discuss with patients the benefits as well as the potential unknown risks of teratogenesis and maternal adverse reactions."
They suggest that prescribing sulfonamides or nitrofurantoins in the first trimester is still considered appropriate when no other suitable alternative antibiotics are available.
"During the second and third trimesters, sulfonamides and nitrofurantoins may continue to be used as first-line agents for the treatment and prevention of urinary tract infections and other infections caused by susceptible organisms," they write.
They also caution that "pregnant women should not be denied appropriate treatment for infections because untreated infections can commonly lead to serious maternal and fetal complications."
Obstet Gynecol. 2011;117:1484-1485.
Related Link
The National Women’s Health Information Center, a service of the US Department of Health and Human Service’s Office on Women’s Health, provides a comprehensive Web site, useful for patient education, on the subject of Pregnancy and Medicines.
Clinical Context
Antibiotics are often prescribed in pregnancy, resulting in considerable pharmacoepidemiologic evidence regarding the association of prenatal antibiotic exposure and birth defects. Teratogenesis caused by drugs or other agents is most likely to occur during the first trimester, when organs and nervous systems are forming. A National Birth Defects Prevention Study report published in 2009 suggested that nitrofurans and sulfonamides, which are 2 antibiotic classes often prescribed for urinary tract infections, may increase the risk for birth defects when taken during the first trimester.
Therefore, ACOG reviewed available evidence on maternal use of nitrofurans, sulfonamides, and other specific antibiotics during pregnancy and subsequent development of birth defects in the offspring. ACOG noted several methodologic limitations in research linking nitrofuran and sulfonamide use to birth defects, and it also found data supporting the safety of various other antibiotics used appropriately in pregnant women. The goals of this ACOG Committee Opinion were to summarize the current evidence linking prenatal antibiotic exposure with birth defects and to issue evidence-based recommendations for use of antibiotics during pregnancy.
Study Highlights
•This ACOG Committee Opinion summarized current evidence linking prenatal antibiotic exposure with birth defects and offered evidence-based guidelines for antibiotic use during pregnancy.
•A population-based case-control study, published in 2009, of the association between antibiotics and birth defects used data from the National Birth Defects Prevention Study.
•This study showed that nitrofuran derivatives and sulfonamides were significantly associated with multiple categories of birth defects.
•Limitations of this study include recall bias, lack of confirmation of antibiotic prescription by the medical record, inability of roughly one third of patients to recall the specific product name, and observational design with confounding.
•Some other studies of the association between prenatal exposure to these antibiotics and birth defects showed potential fetal risks, whereas still other studies did not show these risks in other populations or when using different epidemiologic methods.
•In the 2009 study, penicillins, erythromycin, cephalosporins, and quinolones were not associated with an increased risk for birth defects.
•Many other studies corroborate these findings, with no increased risk for birth defects associated with prenatal exposure to penicillin, ampicillin, amoxicillin/clavulanate, pivampicillin, cephalosporins, gentamicin, oxacillin, erythromycin, metronidazole, and quinolones.
•For pregnant women, as for all patients, antibiotics should be prescribed only for appropriate indications and for the shortest effective duration.
•Bacterial contaminants of urine cultures are common in pregnancy and do not reflect the actual infection.
•Organisms in urine cultures that may be presumed to be contaminants and therefore not treated are mixed gram-positive bacteria, lactobacilli, and Staphylococcus species other than S saprophyticus.
•For true infections occurring in the first trimester of pregnancy, clinicians should consider the benefits and potential unknown risks for teratogenesis and maternal adverse reactions, and they should discuss these with patients.
•In the first trimester, prescribing sulfonamides or nitrofurantoins is still considered appropriate when there are no other suitable alternative antibiotics.
•Sulfonamides and nitrofurantoins may continue to be used during the second and third trimesters as first-line agents to treat and prevent urinary tract and other infections caused by susceptible organisms.
•Untreated infections may cause serious maternal and fetal complications, and pregnant women therefore should not be denied appropriate treatment.
Clinical Implications
•The evidence linking prenatal exposure to nitrofurans and sulfonamides with birth defects is mixed. Penicillins, erythromycin, cephalosporins, and other commonly used antibiotics have not been found to be associated with an increased risk for birth defects.
•During the second and third trimesters, sulfonamides and nitrofurantoins may continue to be used as first-line agents to treat and prevent urinary tract and other infections caused by susceptible organisms. Even in the first trimester, prescribing sulfonamides or nitrofurantoins is still considered appropriate when no other suitable alternative antibiotics are available.
May 31, 2011 — During the second and third trimester of pregnancy, sulfonamides and nitrofurantoins may be used as first-line agents for urinary tract and other infections, but in the first trimester, these agents may be used when no alternatives are available, according to a Committee Opinion from the American College of Obstetricians and Gynecologists (ACOG).
The opinion is published in the June issue of Obstetrics & Gynecology. According to the study authors, a 2009 case-control study of data from the National Birth Defects Prevention Study found that nitrofurans and sulfonamides were significantly associated with multiple birth defects, whereas penicillins, erythromycin, cephalosporins, and the quinolones were not.
However, the authors acknowledge several limitations of the 2009 study. In addition, they note that "other studies have not found such risks among other populations or when using different epidemiologic methods."
According to the authors, antibiotics "should be prescribed for pregnant women only for appropriate indications and for the shortest effective duration."
They add that many urine cultures show bacterial contaminants that do not represent true infection. However, when selecting an antibiotic for a true infection during the first trimester, "health care providers should consider and discuss with patients the benefits as well as the potential unknown risks of teratogenesis and maternal adverse reactions."
They suggest that prescribing sulfonamides or nitrofurantoins in the first trimester is still considered appropriate when no other suitable alternative antibiotics are available.
"During the second and third trimesters, sulfonamides and nitrofurantoins may continue to be used as first-line agents for the treatment and prevention of urinary tract infections and other infections caused by susceptible organisms," they write.
They also caution that "pregnant women should not be denied appropriate treatment for infections because untreated infections can commonly lead to serious maternal and fetal complications."
Obstet Gynecol. 2011;117:1484-1485.
Related Link
The National Women’s Health Information Center, a service of the US Department of Health and Human Service’s Office on Women’s Health, provides a comprehensive Web site, useful for patient education, on the subject of Pregnancy and Medicines.
Clinical Context
Antibiotics are often prescribed in pregnancy, resulting in considerable pharmacoepidemiologic evidence regarding the association of prenatal antibiotic exposure and birth defects. Teratogenesis caused by drugs or other agents is most likely to occur during the first trimester, when organs and nervous systems are forming. A National Birth Defects Prevention Study report published in 2009 suggested that nitrofurans and sulfonamides, which are 2 antibiotic classes often prescribed for urinary tract infections, may increase the risk for birth defects when taken during the first trimester.
Therefore, ACOG reviewed available evidence on maternal use of nitrofurans, sulfonamides, and other specific antibiotics during pregnancy and subsequent development of birth defects in the offspring. ACOG noted several methodologic limitations in research linking nitrofuran and sulfonamide use to birth defects, and it also found data supporting the safety of various other antibiotics used appropriately in pregnant women. The goals of this ACOG Committee Opinion were to summarize the current evidence linking prenatal antibiotic exposure with birth defects and to issue evidence-based recommendations for use of antibiotics during pregnancy.
Study Highlights
•This ACOG Committee Opinion summarized current evidence linking prenatal antibiotic exposure with birth defects and offered evidence-based guidelines for antibiotic use during pregnancy.
•A population-based case-control study, published in 2009, of the association between antibiotics and birth defects used data from the National Birth Defects Prevention Study.
•This study showed that nitrofuran derivatives and sulfonamides were significantly associated with multiple categories of birth defects.
•Limitations of this study include recall bias, lack of confirmation of antibiotic prescription by the medical record, inability of roughly one third of patients to recall the specific product name, and observational design with confounding.
•Some other studies of the association between prenatal exposure to these antibiotics and birth defects showed potential fetal risks, whereas still other studies did not show these risks in other populations or when using different epidemiologic methods.
•In the 2009 study, penicillins, erythromycin, cephalosporins, and quinolones were not associated with an increased risk for birth defects.
•Many other studies corroborate these findings, with no increased risk for birth defects associated with prenatal exposure to penicillin, ampicillin, amoxicillin/clavulanate, pivampicillin, cephalosporins, gentamicin, oxacillin, erythromycin, metronidazole, and quinolones.
•For pregnant women, as for all patients, antibiotics should be prescribed only for appropriate indications and for the shortest effective duration.
•Bacterial contaminants of urine cultures are common in pregnancy and do not reflect the actual infection.
•Organisms in urine cultures that may be presumed to be contaminants and therefore not treated are mixed gram-positive bacteria, lactobacilli, and Staphylococcus species other than S saprophyticus.
•For true infections occurring in the first trimester of pregnancy, clinicians should consider the benefits and potential unknown risks for teratogenesis and maternal adverse reactions, and they should discuss these with patients.
•In the first trimester, prescribing sulfonamides or nitrofurantoins is still considered appropriate when there are no other suitable alternative antibiotics.
•Sulfonamides and nitrofurantoins may continue to be used during the second and third trimesters as first-line agents to treat and prevent urinary tract and other infections caused by susceptible organisms.
•Untreated infections may cause serious maternal and fetal complications, and pregnant women therefore should not be denied appropriate treatment.
Clinical Implications
•The evidence linking prenatal exposure to nitrofurans and sulfonamides with birth defects is mixed. Penicillins, erythromycin, cephalosporins, and other commonly used antibiotics have not been found to be associated with an increased risk for birth defects.
•During the second and third trimesters, sulfonamides and nitrofurantoins may continue to be used as first-line agents to treat and prevent urinary tract and other infections caused by susceptible organisms. Even in the first trimester, prescribing sulfonamides or nitrofurantoins is still considered appropriate when no other suitable alternative antibiotics are available.
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