Community-acquired methicillin-resistant Staphylococcus aureus colonization in healthy children attending an outpatient pediatric clinic

Prevalence of nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) in children a multicenter cross-sectional study

In this cross-sectional multicenter study, we determined the rate of nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) in children admitted to 9 training hospitals in Switzerland during 1 month. From 1337 patients, 1363 nasal swabs were obtained (mean age 6.1 years, median 4.7 years, interquartile range 1.3-10.4 years) and 562 (41.3%) grew S. aureus. Only one isolate was MRSA (0.18%) which encoded mecA and femA genes as well as SCCmec type IV, whereas Panton-Valentine leukocidin (PVL) was absent.

Carriage of methicillin-resistant Staphylococcus aureus in children in Brazil

The extent of methicillin-resistant Staphylococcus aureus (MRSA) carriage in Brazilian infants is largely unknown. We evaluated the presence of MRSA nasopharyngeal (NP) carriage in 686 children younger than 5 years with respiratory tract infection (609) and meningitis (77). S. aureus was isolated in 93 (13.5%) NP specimens of which 7 (1.02%) were identified as MRSA (oxacillin MIC, >256 microg/mL) harboring SCCmec type III. The dendrogram derived from the pulsed-field gel electrophoresis gel images showed that the MRSA strains diverged from the Brazilian endemic hospital-acquired clones from 10.4% to 21.7%. Although the MRSA strains were recovered from children within the first 6 h of their admission to hospital, the presence of SCCmec type III along with the multidrug-resistant profile of the isolates raises the hypotheses that these MRSA strains may have hospital origin and are now spreading into the pediatric community as colonizing pathogens.

Changing patterns of acute hematogenous osteomyelitis and septic arthritis: emergence of community-associated methicillin-resistant Staphylococcus aureus

INTRODUCTION

An increase in the incidence and severity of acute osteoarticular infections in children was perceived after the emergence of community-associated methicillin-resistant Staphylococcus aureus (MRSA) in our community. This study was performed to describe changes in the epidemiology and clinical features of acute osteoarticular infections.

METHODS

The records of patients discharged from Le Bonheur Children's Medical Center with a diagnosis of acute osteoarticular infection between 2000 and 2004 were reviewed. Data regarding signs and symptoms, diagnostic testing, therapeutics, surgery, and hospital course were collected.

RESULTS

There were 158 cases of acute osteoarticular infection. The incidence increased from 2.6 to 6.0 per 1000 admissions between 2000 and 2004. The proportion of infections caused by methicillin-susceptible S. aureus (MSSA) remained constant (10%-13%) and that caused by MRSA rose from 4% to 40%. There was no difference between MRSA and MSSA patients in the duration of fever or pain before diagnosis. Seventy-one percent of patients with MRSA had subperiosteal abscesses compared with 38% with MSSA (P = 0.02). Ninety-one percent of MRSA patients required a surgical procedure compared with 62% of MSSA patients (P < 0.001). Median hospital stay was 7 days for MSSA patients and 10 days for MRSA patients (P = 0.0001). Three patients developed chronic osteomyelitis, 2 with MRSA. There was no association between a delay in institution of appropriate antibiotic therapy and presence of subperiosteal abscess (P = 0.8).

CONCLUSIONS

There has been an increase in the incidence and severity of acute osteoarticular infections in Memphis. Patients with community-associated MRSA infections are at higher risk of subperiosteal abscess requiring surgical intervention.

Low prevalence of methicillin-resistant Staphylococcus aureus (MRSA) in a southwestern region of Germany

INTRODUCTION

Methicillin-resistant Staphylococcus aureus (MRSA) has developed into an important human pathogen and is increasingly being found to be the cause of skin and soft tissue infections or invasive infections in many communities. We have determined the prevalence of MRSA among S. aureus isolates from pediatric in- and outpatients of the University Children's Hospital of Freiburg, from children attending primary care pediatricians and from healthy children entering school in a prospective study carried out in a southwestern region of Germany. Of the healthy children tested, all between 5 and 7 years of age, 25.8% were intra-nasally colonized with S. aureus. A total of 1455 S. aureus isolates were tested for antibiotic susceptibility. Apart from penicillin resistance (82.1%), an overall high susceptibility of S. aureus to antibiotics, including clindamycin, was common, while resistance among the S. aureus isolates to erythromycin and clindamycin had even significantly decreased from 2002 to 2004. Methicillin-resistance was exceedingly rare (0.3%).

CONCLUSION

In the southwestern region of Germany, about one quarter of the healthy children tested at school entry were found to be colonized with S. aureus. The prevalence of MRSA among healthy as well as hospitalized children colonized with S. aureus is still extremely rare in this region.

Incidence and epidemiology of methicillin-resistant Staphylococcus aureus infection in a Saudi Arabian Hospital, 1999-2003

During 1999-2003 in a Saudi Arabian Hospital, methicillin-resistant Staphylococcus aureus constituted 6% of all S. aureus isolates; the proportion had increased from 2% in 1999, to 9.7% in 2002, to 8% in 2003. Of all MRSA isolates, 62% represented community-acquired infection, 20.4% represented healthcare-associated infection, and 17.6% represented nosocomial infection. The proportion of community-acquired isolates increased from 41.7% in 1999 to 66.6% in 2002, and the proportion representing nosocomial infection decreased from 33% in 1999 to 19% in 2003. Isolates representing nosocomial infection showed higher rates of resistance to ciprofloxacin (76.6%), clindamycin (76.6%), erythromycin (68%) and trimethoprim-sulfamethoxazole (68%) than did isolates in the other categories (P<.001).

Carriage of methicillin-resistant Staphylococcus aureus in a Queensland Indigenous community

OBJECTIVE

To determine the prevalence of community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) carriage and infection among children living in an Indigenous community in Queensland.

DESIGN, SETTING AND PARTICIPANTS

Swabs for culture of S. aureus were collected from the nose, throat and skin wounds of primary school children.

MAIN OUTCOME MEASURES

MRSA carriage, antibiotic sensitivity, genotype, and presence of the virulence factor Panton-Valentine leukocidin (PVL); and epidemiological risk factors for MRSA carriage.

RESULTS

92 (59%) of 157 eligible children were included in the study. Twenty-seven (29%) carried S. aureus; 14 of these (15% of total) carried MRSA. MRSA was isolated from 29% of wound swabs, 8% of nose swabs, and 1% of throat swabs. Fourteen of 15 MRSA isolates were sensitive to all non-beta-lactam antibiotics tested. Eight children (9%) carried CA-MRSA clonal types: six carried the Queensland clone (ST93), and two carried the South West Pacific clone (ST30). All these isolates carried the virulence factor PVL. The remaining six children carried a hospital-associated MRSA strain (ST5), negative for PVL.

CONCLUSIONS

We have identified a high prevalence of CA-MRSA carriage in school children from a Queensland Indigenous community. In this setting, antibiotics with activity against CA-MRSA should be considered for empiric therapy of suspected staphylococcal infection. Larger community-based studies are needed to improve our understanding of the epidemiology of CA-MRSA, and to assist in the development of therapeutic guidelines for this important infection.

Contrasting pediatric and adult methicillin-resistant Staphylococcus aureus isolates

Children may share a reservoir of MRSA strains that have an antimicrobial drug resistance profile distinct from that of adults.

We performed a prospective study of all inpatient and outpatient methicillin-resistant Staphylococcus aureus (MRSA) isolates identified at the University of Chicago Hospitals from November 2003 through November 2004. Differences in resistance to non–β-lactam antimicrobial drugs were determined after stratification of the 578 MRSA isolates into 4 groups by patient age (pediatric vs. adult) and onset location (community vs. hospital). Non–β-lactam resistance was significantly greater among the 288 adult than the 177 pediatric community-associated isolates for erythromycin (93.2 vs. 87.0%, p = 0.03), clindamycin (51.8 vs. 7.3%, p<0.001), ciprofloxacin (62.1 vs. 10.7%, p<0.001), gentamicin (11.1 vs. 1.1%, p<0.001), and tetracycline (19.9 vs. 6.4%, p<0.001). In contrast, hospital-associated MRSA isolates from children and adults had similar rates of non–β-lactam antimicrobial drug resistance. In our region, clindamycin is an appropriate empiric therapy of community-associated MRSA infection in children but should be used with caution in adults.

Prevalence of methicillin-resistant Staphylococcus aureus nasal carriage in patients admitted to Driscoll Children's Hospital

A nasal swab specimen was collected for culture within 48 hours of admission and a questionnaire was completed using a convenience sample of 350 patients admitted to Driscoll Children's Hospital between February 15 and March 15, 2005. Of the 350 patients enrolled, 125 (36%) patients were colonized with Staphylococcus. aureus and 76 (61%) of the 125 S. aureus isolates were methicillin-resistant.

Early burn related gram positive systemic infection in children admitted to a pediatric surgical ward

BACKGROUND

Gram positive infections, including toxic shock syndrome (TSS), may be an early complication following burns, especially in children.

OBJECTIVE

To identify risk factors associated with early burn related gram positive systemic infection (EBGI) in children admitted to a Pediatric Surgical Ward.

METHODS

A retrospective analysis of the records of all EBGI patients treated from January 1995 to December 2004. EBGI patients were defined as having systemic signs of infection appearing in the first 48 h following the burn and associated with: (1) clinical signs of toxin mediated illness and/or (2) positive blood culture of either Staphylococcus aureus or group A beta hemolytic Streptococcus. Demographic and clinical data were also collected from the charts of 150 randomly selected burn patients admitted during the study period.

RESULTS

We identified 13 cases of EBGI (2.5%) among 518 children admitted for thermal burns (mean age: 2.4 years). Three had bacteremia without rash. The 10 other patients were diagnosed as having a toxin mediated disease. S. aureus grew from the burn wound in six patients. All EBGI patients recovered following antibiotic therapy. Significant differences between the groups included: percentage of burned body surface area (6.9% versus 3.9%), and head and face localization (64% versus 31%) in the EBGI and control groups, respectively.

CONCLUSIONS

EBGI is not rare even in pediatric patients with minor-moderate burns. Burns localized to the face or the head may be predisposing factor for such an infection.

Staphylococcal skin infections in children: rational drug therapy recommendations

Staphylococcus aureus remains one of the most common and troublesome of bacteria causing disease in humans, despite the development of effective antibacterials and improvement in hygiene. The organism is responsible for over 70% of all skin and soft tissue infections in children and accounts for up to one-fifth of all visits to pediatric clinics. Skin and soft tissue infections that are predominantly caused by S. aureus include bullous and non-bullous impetigo, folliculitis, furunculosis, carbunculosis, cellulitis, surgical and traumatic wound infections, mastitis, and neonatal omphalitis. Other skin and soft tissue infections may also be caused by S. aureus but are often polymicrobial in origin and require special consideration. These include burns, decubitus ulcers (particularly in the perianal region), puncture wounds of the foot, as well as human and mammalian bites. Treatment of staphylococcal skin infections varies from topical antiseptics to prolonged intravenous antibacterials, depending on severity of the lesions and the health of the child. The treatment of choice for oral antibacterials remains the penicillinase-resistant penicillins such as flucloxacillin. Cefalexin and erythromycin are suitable cost-effective alternatives with broader cover, although care must be taken with the use of macrolides because of development of resistance to multiple families of antibacterials, particularly the lincosamides. Other cephalosporins such as cefadroxil and cefprozil are also effective, can be given once daily and have a better tolerability profile -- while azithromycin has a further advantage of a 3-day course. However, all of these agents are more expensive. Although the antibacterials have been given for 10 days in most clinical trials, there is no evidence that this duration is more effective than a 7-day course. In children requiring intravenous therapy, ceftriaxone has a major advantage over other antibacterials such as sulbactam/ampicillin and cefuroxime in that it can be given once daily and may, therefore, be suitable for outpatient treatment of moderate-to-severe skin infections. Newer-generation cephalosporins and loracarbef are also effective and have a broader spectrum of activity, but do not offer any added benefit and are significantly more expensive. Skin and soft tissue infections due to methicillin-resistant S. aureus (MRSA) are still relatively uncommon in children. Well children with community-acquired MRSA infections can be treated with clindamycin or trimethoprim-sulfamethoxazole (cotrimoxazole), but must be observed closely for potentially severe adverse effects. In severe infections, vancomycin remains the treatment of choice, while intravenous teicoplanin and clindamycin are suitable alternatives. Linezolid and quinupristin/dalfopristin are currently showing great promise for the treatment of multi-resistant Gram-positive infections. While the choice of antibacterial is important, supportive management, including removal of any infected foreign bodies, surgical drainage of walled-off lesions, and regular wound cleaning, play a vital role in ensuring cure.

Clinical and molecular epidemiology of community-acquired methicillin-resistant Staphylococcus aureus infections among children with risk factors for health care-associated infection: 2001-2003

BACKGROUND

Methicillin-resistant Staphylococcus aureus (MRSA) has recently emerged as a common cause of infection in children in many parts of the world. The epidemiology of community-acquired MRSA (CA-MRSA) among healthy children has been recently described. However, little is known about CA-MRSA in children with underlying medical conditions.

OBJECTIVE

To compare the clinical and molecular epidemiology of CA-MRSA in children with and without risk factors for health care-associated infections (RF-HAI).

METHODS

We conducted a 3-year retrospective cohort study of children with CA-MRSA infection. RF-HAI, including hospitalization within the past year, indwelling medical devices or chronic medical condition, were identified by chart review. Genetic relatedness of CA-MRSA strains was assessed by pulsed field gel electrophoresis. Polymerase chain reaction was used to detect Panton-Valentine leukocidin and determine staphylococcal chromosomal cassette carrying the mecA methicillin-resistant gene (SCCmec) type.

RESULTS

We identified 446 episodes of community-acquired S. aureus infections, of which 134 (30%) were caused by MRSA. During the 3-year study period, the proportion of S. aureus infections caused by MRSA rose from 15% (12 of 80) to 40% (93 of 235) (P < 0.001) with the increase noted predominately in children with skin and soft tissue infections. RF-HAI were identified in 56 (42%) patients with CA-MRSA. Among subjects with CA-MRSA, children with RF-HAI were more likely to have had an invasive infection than healthy children (32% versus 5%; P < 0.001). CA-MRSA isolates from children with RF-HAI were similar to those without RF-HAI; all laboratory-retained CA-MRSA isolates harbored the SCCmec type IV cassette, and almost all isolates were susceptible to trimethoprim-sulfamethoxazole and clindamycin. However, pulsed field gel electrophoresis revealed greater molecular diversity among CA-MRSA isolates recovered from children with RF-HAI compared with those from otherwise healthy children (P = 0.001). Additionally CA-MRSA isolates from children with RF-HAI were less likely to contain sequences for Panton-Valentine leukocidin (P < 0.001) and more likely to be resistant to 3 or more classes of antibiotics (P = 0.033).

CONCLUSION

CA-MRSA strains recovered from children with RF-HAI were phenotypically similar to those recovered from healthy children The absence of SCCmec type II or III MRSA among children with RF-HAI suggests that CA-MRSA strains might have become endemic within pediatric health care facilities.

Successful multiresistant community-associated methicillin-resistant Staphylococcus aureus lineage from Taipei, Taiwan, that carries either the novel Staphylococcal chromosome cassette mec (SCCmec) type VT or SCCmec type IV

Methicillin-resistant Staphylococcus aureus (MRSA) isolates carry the methicillin resistance gene (mecA) on a horizontally transferred genetic element called the staphylococcal chromosome cassette mec (SCCmec). Community-acquired MRSA (CAMRSA) isolates usually carry SCCmec type IV. We previously reported that 76% of 17 CAMRSA isolates (multilocus sequence type 59) obtained from pediatric patients with skin and soft tissue infections (SSTI) from Taipei did not carry SCCmec types I to IV. We used DNA sequence analysis to determine that the element harbored by these nontypeable isolates is a novel subtype of SCCmec V called SCCmec V(T.) It contains a ccrC recombinase gene variant (ccrC2) and mec complex C2. One SSTI isolate contained molecular features of SCCmec IV but also contained ccrC2 (a feature of SCCmec V(T)), suggesting that it may harbor a composite SCCmec element. The genes lukS-PV and lukF-PV encoding the Panton-Valentine leukocidin (PVL) were present in all CAMRSA SSTI isolates whether they contained SCCmec type IV or V(T). SCCmec V(T) was also present in 5 of 34 (14.7%) CAMRSA colonization isolates collected from healthy children from Taipei who lacked MRSA risk factors. Four (80%) of the these isolates contained lukS-PV and lukF-PV, as did 1 of 27 (3.7%) SCCmec IV-containing colonization isolates. A total of 63% (10 of 16) of the SSTI isolates and 61.7% (21 of 34) of the colonization isolates tested were resistant to at least four classes of non-beta-lactam antimicrobials. SCCmec V(T) is a novel SCCmec variant that is found in multiply resistant CAMRSA strains with sequence type 59 in Taipei in association with the PVL leukotoxin genes.

Community-associated methicillin-resistant Staphylococcus aureus, Canada

A total of 184 methicillin-resistant Staphylococcus aureus (MRSA) strains were collected from patients who sought treatment primarily for skin and soft tissue infections from January 1, 1999, to March 31, 2002, in east-central Saskatchewan, Canada. Molecular subtyping analysis using pulsed-field gel electrophoresis showed 2 major clusters. Cluster A (n = 55) was composed of a multidrug-resistant MRSA strain associated with a long-term care facility and was similar to the previously reported nosocomial Canadian epidemic strain labeled CMRSA-2. Cluster B (n = 125) was associated with cases identified at community health centers and was indistinguishable from a community-associated (CA)-MRSA strain identified previously in the United States (USA400). Cluster B remained susceptible to a number of classes of antimicrobial agents and harbored the lukF-PV and lukS-PV toxin genes. Over 50% of both clonal groups displayed high-level resistance to mupirocin. This is the first report of the USA400 strain harboring the lukF-PV and lukS-PV toxin genes in Canada.

Dissemination of methicillin-resistant staphylococci among healthy Japanese children

Methicillin-resistant Staphylococcus aureus (MRSA), regarded as a tenacious pathogen in the hospital, has recently become increasingly prevalent as a community pathogen. We evaluated the prevalence and characteristics of methicillin-resistant staphylococci in the Japanese community by testing nasal samples of 818 children of five day care centers and two kindergartens in three districts. We found that methicillin-resistant staphylococci are already prevalent among healthy children. Among 818 children, 35 children (4.3%) carried MRSA and 231 children (28.2%) carried methicillin-resistant coagulase-negative staphylococci (MRC-NS). The types of staphylococcal cassette chromosome mec (SCCmec) found among 44 MRSA isolates were as follows: type IIa, 11 isolates; type IIb, 19 isolates; and type IV, 14 isolates. The type IIb SCCmec element was a new SCCmec element found in this study. Eleven (25%) strains which belonged to clonal complex 5 (CC5) carried type IIa SCCmec, and they produced type 2 coagulase and toxic shock syndrome toxin 1. They were indistinguishable from health care-associated MRSA (H-MRSA) strains in Japan, represented by strain N315. On the other hand, 33 (75%) strains, most of which belonged to CC78 or CC91, carried small SCCmec elements, such as type IIb or type IV, and they produced type 1 or type 3 coagulase and exfoliative toxin. The data indicated that MRSA clones distinct from H-MRSA have disseminated in healthy children. The fact that MRC-NS strains were prevalent in the community suggested that they might serve as a reservoir for the SCCmec element carried by MRSA strains disseminated in the community.

Increasing rates of nasal carriage of methicillin-resistant Staphylococcus aureus in healthy children

BACKGROUND

Prior studies, including one from our institution performed in 2001, suggest that nasal colonization with methicillin-resistant Staphylococcus aureus (MRSA) occurs infrequently in the healthy pediatric population (0.2-2.2%). However, infections caused by community-associated MRSA have increased remarkably in recent years. As a result, we restudied the prevalence of MRSA nasal colonization in healthy children, comparing results from 2001 and 2004.

PATIENTS AND METHODS

Nasal swabs were collected from 500 children presenting for health maintenance visits. Samples were cultured quantitatively, and MRSA isolates were confirmed by growth on selective media, coagulase testing and the presence of the mecA resistance gene. MRSA isolates were further analyzed for antibiotic susceptibilities, genetic relatedness by pulsed field gel electrophoresis and polymerase chain reaction for the detection of the gene encoding Panton-Valentine leukocidin.

RESULTS

There were 182 children (36.4%) colonized with S. aureus, and 46 (9.2%) colonized with MRSA. This is significantly higher than the MRSA colonization rate in 2001 (0.8%; P < 0.001). There were no significant associations between potential risk factors and MRSA colonization except for having a family member work in a hospital (odds ratio, 2.0; 95% confidence interval, 1.03-4.1). Pulsed field gel electrophoresis revealed heterogeneity of circulating strains, and the Panton-Valentine leukocidin gene locus was detected in 10 of 46 MRSA isolates (22%).

CONCLUSION

Nasal MRSA colonization in healthy children in Nashville has increased significantly in the past 3 years. As colonization typically precedes infection, this increase may be a major factor in the emergence of community-associated MRSA as a pathogen of healthy children.

Predominance of staphylococcal cassette chromosome mec (SCCmec) type IV among methicillin-resistant Staphylococcus aureus (MRSA) in a Swedish county and presence of unknown SCCmec types with Panton-Valentine leukocidin genes

Methicillin-resistant Staphylococcus aureus (MRSA) is an established nosocomial pathogen, but has recently begun to appear in the community. The clones in the community may not have originated in the hospital setting, and are referred to as community-acquired MRSA (CA-MRSA). Resistance to methicillin is mediated by the gene mecA, which is carried by the mobile genetic element staphylococcal cassette chromosome mec (SCCmec). SCCmec typing (I-IV) of all clinical isolates of MRSA (n = 92) from 1987 to 2004 in Orebro County, Sweden, was performed by real-time LightCycler PCR to detect the essential genetic components mecA, mecR1, IS1272, ccrA and ccrB. Forty-one isolates harboured type IV SCCmec, of which ten could be classified further as subtype IVa, and 27 as subtype IVc. No isolates belonged to subtype IVb, but four isolates could not be subtyped, and may be examples of novel type IV SCCmec subtypes. Thirty-five MRSA isolates, assigned to six different pulsotypes by pulsed-field gel electrophoresis, did not belong to SCCmec types I-IV. The Panton-Valentine leukocidin (PVL) genes were identified in two of these pulsotypes. Only SCCmec type IV has been associated previously with the PVL toxin, but the results suggest that new PVL-positive clones with novel SCCmec types may be arising and disseminating in the community.

Nasal carriage of methicillin-resistant Staphylococcus aureus in school children without identifiable risk factors in northern taiwan

In a nasal culture survey of school children, 5 (1.9%) of 262 school children and 18 (13%) of 137 health care workers (HCWs) were colonized with methicillin-resistant Staphylococcus aureus (MRSA). One common genotype accounted for most isolates from the school children and from the HCWs. Based on genotyping, MRSA strains circulating in the community in Taiwan were similar to the hospital strains.

Amoxicillin-clavulanate therapy increases childhood nasal colonization by methicillin-susceptible Staphylococcus aureus strains producing high levels of penicillinase

We examined factors associated with penicillinase production by nasal carriage Staphylococcus aureus strains in 648 children aged 3 to 6 years attending 20 randomly sampled playschools. The children were prospectively monitored for drug use and medical events for 6 months and were then screened for S. aureus carriage. Isolates were tested for their susceptibility to penicillin G and methicillin, and penicillinase production by methicillin-susceptible, penicillin-resistant strains was quantified. S. aureus was isolated from 166 children (25.6%). Exposure to amoxicillin-clavulanate during the previous 3 months was associated with higher penicillinase production by penicillin-resistant, methicillin-susceptible strains (odds ratio, 3.6; P = 0.03). These results suggest that use of the amoxicillin-clavulanate combination could induce a herd selection process of S. aureus strains producing higher levels of penicillinase.

Evolution of the antimicrobial resistance of Staphylococcus spp. in Spain: five nationwide prevalence studies, 1986 to 2002

Data regarding the evolution of Staphylococcus resistance in a whole country have a definite influence on the design of empirical treatment regimens. Nevertheless, incidence studies over long periods of time are expensive and very difficult to carry out. In order to ascertain the present situation of the antimicrobial resistance of Staphylococcus in Spain and the change of this resistance over time, we performed five point prevalence studies (1986 to 2002) in a large group of Spanish hospitals (from 68 institutions in 1986 to 143 in 2002) collecting all Staphylococcus strains isolated on a single selected day. All microorganisms were identified in the five studies at the same laboratory, and antimicrobial susceptibility testing was performed against 17 antimicrobial agents by the agar dilution method and a microdilution method. During this period, there was an overall increase in resistance to most antimicrobials among Staphylococcus aureus/coagulase-negative staphylococci, mainly to oxacillin (1.5%/32.5% in 1986 versus 31.2%/61.3% in 2002) (P < 0.001), erythromycin (7%/41.1% in 1986 versus 31.7%/63% in 2002) (P < 0.001), gentamicin (5.2%/25.4% in 1986 versus 16.9%/27.8% in 2002) (P < 0.001; P = 0.5), and ciprofloxacin (0.6%/1.1% in 1986 versus 33.9%/44.9% in 2002) (P < 0.001). All of the isolates were uniformly susceptible to glycopeptides, linezolid, and quinupristin/dalfopristin. Resistance of S. aureus to trimethoprim/sulfamethoxazole was very low (from 0.5% to 2.1%) (P = 0.152). Periodic performance of prevalence studies is a useful, inexpensive, and easy tool to know the nationwide situation of a microorganism and its resistance to antimicrobials; it also helps us assess the emergence and spread of antimicrobial resistance.

Nasal carriage of methicillin-resistant Staphylococcus aureus in contacts of an adolescent with community-acquired disseminated disease

OBJECTIVES

To assess the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) carriage in contacts after the diagnosis of community-acquired MRSA bacteremia, hip arthritis, pyomyositis and pulmonary septic emboli with necrotizing pneumonia and empyema in a previously healthy female adolescent in Taiwan.

MATERIALS AND METHODS

A nasal culture survey of the 4 household members, 30 classmates and 5 teachers of the index case (class A), 28 classmates of her brother's (class B), as well as 76 health care workers (HCWs), including 58 nurses, 16 doctors and 2 assistants, working in the ordinary wards were performed 1 month after the onset. The clinical isolates from bloodstream and synovial fluid of the index case as well as all the colonized isolates, if identified, were collected and genotyped with pulsed field gel electrophoresis.

RESULTS

A total of 15 subjects, including the case patient, her brother, 2 adolescents (6.7%) in class A, 6 children (21.4%) in class B and 5 HCWs (6.6%), were colonized with MRSA. Of the 15 colonizing and 2 clinical MRSA isolates, 4 genotypes with 2 major types were identified. Except for 2 isolates, the remaining 15 isolates were genotype C or D. Both clinical isolates, the isolate from her brother, 3 isolates from the children in class B and 2 isolates from the HCWs belonged to genotype D. Two isolates from the adolescents in class A, the other 3 isolates from the children in class B and 2 isolates from the HCWs were genotype C. The colonized strain from the index case was genotype A.

CONCLUSIONS

Carriage of MRSA can be identified in a substantial proportion of school children without apparent risk factors in Taiwan. With transmissibility, the carriage of MRSA in school children can accelerate the spread of MRSA in the community.

Antibiotic resistance in Staphylococcus aureus colonising the intestines of Swedish infants

Staphylococcus aureus has become a frequent coloniser of the intestinal tract of infants, but the health effects of such colonisation are not clear. In this study, the antibiotic resistance patterns of 116 S. aureus strains from the commensal intestinal microflora were determined. The strains were obtained from 81 Swedish infants who had been followed with regular stool samples and registration of antibiotic usage during their first year of life. The faecal population levels of the individual strains and the duration of their persistence in the microflora had been determined previously. The prevalence of antibiotic resistance among the 116 strains was modest: methicillin, 0%; penicillin G, 78%; erythromycin A, 3%; tetracycline, 2%; clindamycin, 0.9%; and fusidic acid, 0.9%. Colonisation by antibiotic-resistant strains was unrelated to antibiotic consumption by individual infants. Antibiotic-resistant strains were as capable of persisting in the intestinal microflora and reaching high faecal population levels as fully susceptible strains. No strain lost or acquired resistance during the colonisation period. Thus, antibiotic-resistant strains of S. aureus seem to be as fit for competition in the large bowel microflora as susceptible strains, even in the absence of selective pressure from antibiotics. This may aggravate the ecological consequences of antibiotic resistance development.

Delineation of the Endemic and Sporadic Methicillin-Resistant Staphylococcus aureus Clones in a Czech Hospital

The aim of this study was to define the endemic clones of methicillin-resistant Staphylococcus aureus (MRSA) among strains collected between September, 2001, and February, 2003, at the regional hospital of Nový Jicín, Czech Republic. The isolates were characterized by susceptibility tests, HindIII ribotyping, and pulsed-field gel electrophoresis. Representatives of each clonal type were analyzed by multilocus sequence typing and staphylococcal cassette chromosome mec (SCCmec) typing. The prevalence of the most important macrolide (ermA, ermB, ermC, and msrA) and aminoglycoside (aac6'-aph2", aph3', and ant4') resistance genes was evaluated as well. Our results document the existence of two international MRSA clones: (1) the Iberian clone (ST247:SCCmec IA:PFGE A:ribotype H2), endemic in the hospital and associated to a single multiresistant phenotype; and (2) clone EMRSA-15 (ST22:SCCmec IV:PFGE H-ribotype H7), appearing in the beginning of 2002 and associated with three phenotypes. These two clones could be distinguished by antibiogram, distribution of macrolide and aminoglycoside resistance genes (ermA, aac6'-aph2", ant4' versus ermC and msrA in a few isolates), production of beta-lactamase, and presence of enterotoxin A (in the Iberian clone).

Availability of antibiotics without prescription in New York City

Misuse of antibiotics in the community has been associated with emergence of increasingly antibiotic-resistant bacterial strains. Although antibiotics in the United States are to be prescribed by a health care provider, the extent to which they are obtained by other means is not known. The purpose of this article is to describe a survey of the availability of nonprescription antibiotics in neighborhood independent businesses in several Manhattan, New York, neighborhoods. A survey was conducted of 101 stores in three neighborhoods--one primarily Hispanic; one primarily black, non-Hispanic; and one primarily white, non-Hispanic. Antibiotics were available in all stores in the Hispanic neighborhood (n = 34), but in none of the others (P < .001). If efforts to rationalize the use of antibiotics are to be successful, the beliefs and cultural norms of subpopulations must be considered, and interventions must be culturally relevant.

Surveillance of methicillin-resistant Staphylococcus aureus in a pediatric hospital in Mexico City during a 7-year period (1997 to 2003): clonal evolution and impact of infection control

Between 1997 and 2000 a single multidrug-susceptible methicillin-resistant Staphylococcus aureus clone, M (sequence type 30 [ST30]-staphylococcal cassette chromosome mec [SCCmec] type IV), was present in a pediatric hospital in Mexico City, Mexico. In 2001 the international multidrug-resistant New York-Japan clone (ST5-SCCmec type II) was introduced into the hospital, completely replacing clone M by 2002.

Origins of community strains of methicillin-resistant Staphylococcus aureus

To characterize methicillin-resistant Staphylococcus aureus (MRSA) strains circulating in the community, we identified predictors of isolating community MRSA and genotyped a sample of MRSA collected from a community-based, high-risk population. Computerized databases of the Community Health Network of San Francisco and the Clinical Microbiology Laboratory were searched electronically for the years 1992-1999 to identify community-onset infections caused by MRSA. Sequential analyses were performed to identify predictors of MRSA strains. The majority (58%) of infections were caused by strains traceable to the hospital or to long-term care facilities. Injection drug use was associated with infections that were not associated with health care settings. Genotypes for 20 of 35 MRSA isolates recovered from injection drug users did not match any of >600 genotypes of clinical isolates. In a nonoutbreak setting, the hospital was the main source of community MRSA; however, the presence of genetically distinct and diverse MRSA strains indicates MRSA strains now also originate from the community.

Antimicrobial resistance among gram-positive organisms in the intensive care unit

PURPOSE OF REVIEW

The epidemiology of gram-positive pathogens in the intensive care unit are reviewed, recent trends in antimicrobial resistance among these organisms are discussed, and the significance of these data with respect to treatment are considered.

RECENT FINDINGS

Results of surveillance studies published in 2001 and 2002 have demonstrated that gram-positive organisms such as Staphylococcus aureus, coagulase-negative staphylococci, and enterococci are among the most common bacteria infecting patients in intensive care units. Furthermore, these organisms are becoming increasingly resistant to available antimicrobial agents, and 2002 has ushered in worrisome developments such as the appearance of vancomycin-resistant S. aureus. Community-acquired methicillin-resistant S. aureus and the rise in incidence of vancomycin-resistant enterococci are other problems of great concern. Novel antibiotics such as quinupristin/dalfopristin and linezolid have activity against these agents, but resistance may develop to these agents as well. Studies have shown that infections caused by antibiotic-resistant organisms may be associated with increased morbidity, mortality, and costs. Exposure to antibiotics is a major risk factor for producing antibiotic resistance in patients, and methods to limit the spread of these organisms include restriction of antibiotic use, infection control, surveillance programs, and isolation procedures.

SUMMARY

An awareness of the prevalence and patterns of resistance among gram-positive nosocomial pathogens is vital for the appropriate treatment of hospitalized patients. In addition, efforts must be made to minimize the selection and spread of these organisms.

Spider Bites Presenting with Methicillin-ResistantStaphylococcus aureusSoft Tissue Infection Require Early Aggressive Treatment

BACKGROUND

Occasionally, spider bites result in necrotizing soft tissue infections that require aggressive surgical debridement and treatment with intravenous antibiotics. With the rise of microbial resistance in the community, management with standard gram-positive intravenous antibiotic coverage may be ineffective. Our objective was to determine the infectious organisms cultured following wide local excision of soft tissue infections caused by spider bites. We hypothesized that the majority of isolated organisms would be sensitive to penicillin based antibiotics.

METHODS

From March 2000 to November 2001, the medical records were reviewed of patients who presented to a tertiary care hospital with serious soft tissue infections secondary to spider bites that required surgical treatment. For each patient, demographics, symptoms, size, time to surgical evaluation (TTSE), temperature, white blood cell (WBC) count, surgical procedure, and culture data were collected. Data are presented as mean +/- SEM.

RESULTS

Thirty-eight patients presented with serious soft tissue infections secondary to spider bites that required surgical debridement and treatment with intravenous antibiotics. Twenty-nine percent (11 of 38) of these patients had failed initial outpatient therapy with penicillin-based oral antibiotics. The mean TTSE was 5.0 +/- 0.5 days (range = 2-14 days; median = 4.5 days). The most common presenting symptoms were pain and erythema surrounding the bite site. The mean temperature was 98.8 +/- 0.6 degrees F (range = 97.2-102.2 degrees F; median = 99.2 degrees F). The mean WBC count was 12.6 +/- 0.8 mm3. All patients required wide surgical debridement of the infected area. The mean size of the excised tissue was 26 +/- 4 cm2 (range = 4-120 cm2; median = 16 cm2). Every patient had cultures that grew Staphylococcus aureus. In 86.8% of patients, S. aureus was found to be methicillin-resistant (MRSA). All isolated organisms were sensitive to trimethoprim-sulfamethoxazole.

CONCLUSIONS

In our experience, patients who presented with soft tissue infections as result of spider bites predominantly had methicillin-resistant S. aureus infections, corresponding to the increased incidence of MRSA reported in the community. Therefore, a more aggressive approach to the management of spider bites presenting with severe cellulitis is warranted. Routine treatment should include aggressive surgical debridement, intraoperative wound cultures, the empiric use of antibiotics with activity against MRSA, and adjustment of antimicrobial therapy based on culture and sensitivity data.

Susceptibility trends in bacteraemias: analyses of 7544 patient-unique bacteraemic episodes spanning 11 years (1990–2000)

The aim of the present study was to design more accurate tools for the selection of appropriate antimicrobial therapy for hospitalized patients with suspected sepsis. We created a large database comprising data on all patient-unique blood cultures obtained over an 11 year period (1 January, 1990 through 31 December, 2000). Improved statistical tools were applied to assess the trends in in vitro activity of individual antibiotic agents against various bacteria over time, and to calculate susceptibility rates of subsets of organisms. During the 11 year study period, 173571 blood cultures were obtained, of which 17703 (10.2%) were positive, with 7544 patient-unique blood cultures (4.3%). The mean annual number of positive, patient-unique cultures was 686 (standard deviation=79). The 10 most frequently isolated organisms were: Escherichia coli (1494), Staphylococcus aureus (1240), Klebsiella pneumoniae (779), Enterococcus spp. (631), Pseudomonas aeruginosa (488), Streptococcus pneumoniae (447), Enterobacter spp. (338), Acinetobacter spp. (298), Proteus mirabilis (260) and Candida spp. (254). No significant change was detected in the annual rates (means, standard deviations) per 1000 admissions of these organisms: the highest was E. coli (5.5, 1), the lowest was Candida (1, 0.3). Forty percent of organisms (N=2943) were obtained from patients in the emergency department (ED), 23% (1744) in medical departments, 15% (1134) in paediatric units, 13% (998) on surgical wards and 9% (709) in intensive care units (ICUs). Trend statistical analysis revealed a significant decrease in susceptibility in ED Enterobacteriaceae to eight of 15 (53%) tested antimicrobials, with a mean annual decrease of 1.6%+/-0.6%, in the ICU isolates, a significant decrease was detected in only five (33%) of the tested antimicrobials, with a mean annual decrease of 2.5%+/-1.3%. The difference in susceptibility between ED and ICU isolates was significant for all antimicrobials (P<0.001). A significant decrease in the susceptibility of E coli to nine of 15 drugs (60%) was detected, ranging from 0.7% to 2.7% annually. In K. pneumoniae a significant decrease in susceptibility of K. pneumoniae was detected with only two agents. Pseudomonas spp. isolates remained highly sensitive to all traditional anti-pseudomonal agents, without significant decay in sensitivity rates over time. Susceptibility of S. aureus to methicillin decreased significantly for several subsets of patients (P<0.001). Marked differences in susceptibility rates between the departments were detected. Trend statistical analyses, when appropriately applied to multi-year databases of microbial susceptibilities, may yield susceptibility tables that are significantly more accurate than traditional semi-annual or annual tables.

Severe Staphylococcus aureus infections caused by clonally related community-acquired methicillin-susceptible and methicillin-resistant isolates

We investigated the genetic relatedness of 5 community-acquired (CA) Staphylococcus aureus isolates obtained from 4 consecutive pediatric patients presenting with sepsis syndrome and severe pneumonia during a 3-week period in 2000. Two patients were infected with methicillin-susceptible S. aureus (MSSA), and 2 were infected with methicillin-resistant S. aureus (MRSA). The pulsed-field gel electrophoresis patterns for the 2 CA-MRSA isolates were identical to each other, as were the patterns for the 3 CA-MSSA isolates. A 2-band difference reflecting the presence of a staphylococcal cassette chromosome mec (SCCmec) element distinguished the CA-MRSA isolates from the CA-MSSA isolates. The small, mobile type IV SCCmec element was present in the CA-MRSA isolates. These data suggest that an insertion or, less likely, a deletion of the SCCmec type IV element occurred in a highly virulent S. aureus background. Staphylococcal toxin genes sea, seh, lukS-PV, and lukF-PV were detected in all isolates. Also, in all isolates, was a partial homolog of seo (seo'). The relationship among these patient isolates strengthens the assumption that CA-MRSA infections may be caused by isolates closely related to MSSA isolates.

Antibacterial cleaning and hygiene products as an emerging risk factor for antibiotic resistance in the community

Antibiotic resistance within the community setting is an emerging public-health concern. Infection with antibiotic-resistant organisms in the community among people lacking traditional risk factors has been reported. In addition, prevalence studies have identified individuals carrying antibiotic-resistant organisms in the absence of known risk factors. These studies strongly suggest the presence of contributing factors that have yet to be identified. In this paper we review the burden of antibiotic resistance and known risk factors within the community setting, assess the potential role of antibacterial cleaning and hygiene products containing triclosan in the emergence of resistance, and recommend future research on the assessment of household cleaning and hygiene products containing triclosan.

Epidemiology of methicillin-resistant Staphylococcus aureus at a children's hospital

OBJECTIVE

To describe the relative contribution of and risk factors for both community-acquired and nosocomial methicillin-resistant Staphylococcus aureus (MRSA) infections.

DESIGN

Retrospective cohort study.

SETTING

270-bed, tertiary-care children's hospital.

PARTICIPANTS

All MRSA-infected children from whom MRSA was recovered between October 1, 1999, and September 30, 2001.

METHODS

Demographic, clinical, and risk factor data were abstracted from medical records. Categorical variables were analyzed using the chi-square or Fisher's exact test and continuous variables were analyzed using the Mann-Whitney test.

RESULTS

Of the 62 patients with new MRSA infection, 37 had community-acquired MRSA and 25 had nosocomial MRSA. Most community-acquired MRSA infections were of the skin and soft tissue, the middle ear, and the lower respiratory tract. Nosocomial MRSA infections occurred in the lower respiratory tract, the skin and soft tissue, and the blood. Risk factors for infection, including underlying medical illness, prior hospitalization, and prior surgery, were similar for patients with community-acquired MRSA and nosocomial MRSA. History of central venous catheterization and previous endotracheal intubation was more common in patients with nosocomial MRSA. Only 3 patients with community-acquired MRSA had no identifiable risk factor other than recent antibiotic use. Resistance for clindamycin, erythromycin, and levofloxacin was similar between strains of community-acquired MRSA and nosocomial MRSA.

CONCLUSIONS

Similarities in patient risk factors and resistance patterns of isolates of both community-acquired and nosocomial MRSA suggest healthcare acquisition of most MRSA. Thus, classifying MRSA as either community acquired or nosocomial underestimates the amount of healthcare-associated MRSA.

Spread of methicillin-resistant Staphylococcus aureus (MRSA) among household contacts of individuals with nosocomially acquired MRSA

OBJECTIVE

To determine the frequency with which methicillin-resistant Staphylococcus aureus (MRSA) is spread from colonized or infected patients to their household and community contacts.

DESIGN

Retrospective cohort study.

SETTING

University hospital.

PARTICIPANTS

Household and community contacts of MRSA-colonized or -infected patients for whom MRSA screening cultures were performed.

RESULTS

MRSA was isolated from 25 (14.5%) of 172 individuals. Among the contacts of index patients who had at least one MRSA-colonized contact, those with close contact to the index patient were 7.5 times more likely to be colonized (53% vs 7%; 95% confidence interval, 1.1 to 50.3; P = .002). An analysis of antimicrobial susceptibility and DNA fingerprint patterns suggested person-to-person spread.

CONCLUSIONS

MRSA colonization occurs frequently among household and community contacts of patients with nosocomially acquired MRSA, suggesting that transmission of nosocomially acquired MRSA outside of the healthcare setting may be a substantial source of MRSA colonization and infection in the community.

High levels of fusidic acid-resistant Staphylococcus aureus in dermatology patients

BACKGROUND

Antibiotic resistance is a significant problem both in hospitals and the community. Topical antibiotics are widely used for dermatological problems and this may be leading to the emergence of resistant bacteria.

OBJECTIVE

To assess the level of fusidic acid-resistant Staphylococcus aureus inpatients with dermatological problems.

METHODS

All microbiology samples over a 4-month period were tested for antibiotic sensitivities. Patients with cultures positive for S. aureus were studied.

RESULTS

The study shows 50% of S. aureus isolates from dermatology patients were resistant to fusidic acid. This figure rose to 78% inpatients with atopic eczema. Of patients with fusidic acid-resistant S. aureus isolates, 96% had used a fusidic acid-containing preparation within the previous 6 months. The level of fusidic acid resistance in S. aureus samples cultured from nondermatology patients was only 9.6%, a level significantly below that for dermatology patients (P < 0.001).

CONCLUSIONS

High levels of fusidic acid-resistant S. aureus are found in dermatology patients. Inappropriate use of topical antibiotics in dermatology patients leading to fusidic acid resistance may threaten the efficacy of systemic fusidic acid for the treatment of serious S. aureus infections. Education of health professionals and restriction of the use of fusidic acid is needed.

Staphylococcal resistance revisited: community-acquired methicillin resistant Staphylococcus aureus--an emerging problem for the management of skin and soft tissue infections

PURPOSE OF REVIEW

In the community non-localized or deep staphylococcal skin and soft tissue infections are typically managed with beta-lactamase stable penicillins. The aims of this review are (1) to evaluate the evidence for the emergence of new strains of community-acquired methicillin resistant Staphylococcus aureus (MRSA), (2) to identify the reasons for their significant association with cutaneous infections, and (3) to consider how they arose and how big a threat they pose to the management of such infections outside hospitals.

RECENT FINDINGS

MRSA are emerging as significant community pathogens, especially in previously healthy children with no recognizable risk factors, and are predominantly associated with skin and soft tissue infections (especially abscesses and cellulitis). When present, risk factors are generally similar to those for infection with methicillin susceptible S. aureus. The MRSA isolates associated with such infections may not be entirely 'new', but could represent the displacement of some hospital clones (e.g. EMRSA-15 or variants thereof) to the community as well as the de-novo generation of novel MRSA clones by multiple horizontal transmissions of the mecA gene into methicillin susceptible S. aureus with different genetic backgrounds, some of which are already circulating globally. Community-acquired MRSA from diverse locations are non multiresistant and almost always contain the novel type IV SCCmec commonly found in coagulase-negative staphylococci, but also in hospital-associated gentamicin susceptible MRSA from France, the paediatric clone and in EMRSA-15.

SUMMARY

More local data on CA-MRSA infections are needed so that dermatologists and community physicians can assess the risk of such infections amongst their patients and avoid the inappropriate administration of beta-lactams. No simple change in prescribing practices will entirely alleviate selective pressure for the spread of community-acquired MRSA and not exacerbate resistance in pyogenic streptococci, commonly found together with S. aureus in skin and soft tissue infections. The importance of hygiene in preventing the spread of community-acquired MRSA in the community must be reemphasized.

Linezolid versus cefadroxil in the treatment of skin and skin structure infections in children

BACKGROUND

Skin and skin structure infections are common reasons for visits to pediatricians, accounting for up to 18%. Staphylococcus aureus and Streptococcus pyogenes are the most frequently isolated Gram-positive pathogens in uncomplicated skin infections. Increasingly outpatient infections involve antibiotic-resistant Gram-positive pathogens including methicillin-resistant S. aureus.

METHODS

This randomized, blinded, comparator-controlled, multinational trial compared the efficacy and safety of linezolid and cefadroxil for treatment of uncomplicated skin/skin structure infections in pediatric patients. Children ages 5 to 11 years were to receive linezolid suspension [10 mg/kg (up to 600 mg)] or cefadroxil suspension [15 mg/kg (up to 500 mg)] every 12 h. Patients ages 12 to 17 years were to receive linezolid tablets (600 mg) or cefadroxil capsules (500 mg) every 12 h. Therapy lasted 10 to 21 consecutive days with a follow-up visit 10 to 21 days posttherapy.

RESULTS

Linezolid and cefadroxil were consistently effective treatments across all primary and secondary efficacy assessments. At follow-up cure rates were 88.7% (205 of 231) for linezolid-treated and 86.2% (193 of 224) for cefadroxil-treated intent-to-treat patients; cure rates were 91.0% (201 of 221) for linezolid-treated and 90.0% (189 of 210) for cefadroxil-treated clinically evaluable patients. S. aureus was eradicated in 89.6% (120 of 134) linezolid-treated and 88.8% (111 of 125) cefadroxil-treated microbiologically evaluable patients. Gastrointestinal complaints were the most common adverse events reported, without significant differences between treatment groups, and myelosuppression was not observed in this study.

CONCLUSIONS

Linezolid is well-tolerated and as effective as cefadroxil in treating uncomplicated skin infections in pediatric patients. Linezolid effectively treated infections caused by S. aureus, methicillin-resistant S. aureus and S. pyogenes.

Bacterial resistance--the clinical challenge

Resistance to antibacterial agents has increased among many species of bacterial pathogens in the last two decades. While this has been recognized and has been a matter of concern among those concerned with infectious diseases, it is only relatively recently that prescribing physicians have become aware of the problem. A range of official bodies, both national and international, have proposed a range of strategies for controlling this increase in resistance. The relationship between resistance and clinical efficacy or failure is unclear in many areas, although increasingly resistance can be seen to be associated with a less than optimal clinical response. Although the relationship between antibiotic use and resistance is complex, there is an assumption that excessive use of antibacterials may drive an increase in resistance. The term 'prudent prescribing' is frequently used in official documents, but it is not easy for the prescriber to determine exactly what is prudent prescribing. There have been efforts to reduce the unnecessary use of antibacterials in the treatment of many community respiratory infections where the etiological agent is likely to be viral. Guidelines for prescribing have been drawn up by governments and professional societies but their impact can be variable. They need to take account of the changing patterns of resistance, for example the rise in high-level penicillin resistance among pneumococci. They also need to be readily accessible to the practicing clinician. Surveillance systems are available in abundance and these may be local, national, or international. They often, however, suffer from drawbacks and are frequently selective. Frequently the prescriber does not have ready access to the most appropriate data. Integrated strategies to control resistance are urgently needed, as are improved rapid diagnostic facilities.

Community-acquired methicillin-resistant Staphylococcus aureus: a meta-analysis of prevalence and risk factors

Reports suggest that carriage of methicillin-resistant Staphylococcus aureus (MRSA) among persons without health care-associated risks has increased. A meta-analysis of studies reporting the prevalence of community-acquired MRSA (CA-MRSA) among MRSA isolates from hospitalized patients or the prevalence of MRSA colonization among community members was conducted. The CA-MRSA prevalence among hospital MRSA was 30.2% in 27 retrospective studies and 37.3% in 5 prospective studies; 85% of all patients with CA-MRSA had > or =1 health care-associated risk. The pooled MRSA colonization rate among community members was 1.3% (95% confidence interval [CI], 1.04%-1.53%), but there was significant heterogeneity among study populations. Community members from whom samples were obtained in health care facilities were more likely to be carrying MRSA than were community members from whom samples were obtained outside of the health care setting (relative risk, 2.35; 95% CI, 1.56-3.53). Among studies that excluded persons with health care contacts, the MRSA prevalence was 0.2%. Moreover, most persons with CA-MRSA had > or =1 health care-associated risk, which suggests that the prevalence of MRSA among persons without risks remains low (< or =0.24%). Effective control of dissemination of MRSA throughout the community likely will require effective control of nosocomial MRSA transmission.

State-of-the-art hand hygiene in community medicine

Hand hygiene becomes more important in community medicine not only since antibiotic resistant bacteria such as MRSA spread within the community. Hands may be colonized with transient microorganism in up to 75%. Among those transient pathogens S. aureus, C. difficile or the hepatitis C virus may be found. During patient care the number of microorganisms on the hands steadily increases. In addition hands may be contaminated with different kinds of germs even if only "clean" activities are carried out. Gloves may be worn but do not provide complete protection from contamination due to leaks. Therefore hands should always be treated after gloves are taken off. State-of-the-art treatment of hands is the hygienic hand disinfection with alcohol-based hand rubs. They are more effective, quicker to carry out, better tolerated by the skin, with a positive effect on compliance, and cost effective in comparison to antiseptic soaps based on chlorhexidine or triclosan and in comparison to normal non-medicated soaps. Healthy skin easily tolerates alcohol-based products from the beginning on. Only health care workers with an underlying irritative contact dermatitis which is often caused by bar or liquid antiseptic soaps may have difficulties to use alcohol-based products initially. In such a case treatment of the underlying skin condition is the way to go and not staying with a preparation which has caused the dermatitis. All this knowledge is now reflected in current guidelines on hand hygiene. Beside liquids alcohol-based gels can be used if they have an antimicrobial activity equal to alcohol-based liquid preparations. Hand hygiene remains the single most important tool to avoid cross transmission of microorganisms between patients. This state-of-the-art hand hygiene should also be emphasized more in community medicine. This review may help to go the first step into this direction.

Prevalence of methicillin-resistant Staphylococcus aureus nasal carriage in the community pediatric population

BACKGROUND

Reports from various geographic regions indicate that the prevalence of community-acquired methicillin-resistant (MRSA) infection is increasing. The primary reservoir is the anterior nares; nasal carriage is a risk factor for infection in a variety of populations. Little is known about MRSA nasal carriage rates among children in Nashville, TN and the associated likelihood of community MRSA transmission.

METHODS

Nasal swabs were collected from 500 children at well-child visits at either a university hospital pediatric clinic or a private pediatric office. Cultures were plated onto selective staphylococcal media, with or without oxacillin. isolates were confirmed by coagulase tube testing. Antibiotic susceptibilities were determined for suspected methicillin-resistant isolates by standard broth microdilution methods (National Committee for Clinical Laboratory Standards). Pulsed field gel electrophoresis was used to evaluate epidemiologic relatedness. PCR testing was done to assess for the gene. A parent questionnaire was administered regarding MRSA risk factors.

RESULTS

Four patients had oxacillin-resistant isolates (MIC >or= 4 microg/ml), and two had borderline resistant isolates (MICs = 1 and 2 microg/ml). One of the borderline-resistant isolates and one of the MRSA isolates had pulsed field gel electrophoresis typing results indicating close relatedness. The gene was present in all resistant isolates and one of the borderline-resistant isolates. Only having a household member employed in a hospital was associated with a greater risk of MRSA nasal carriage (odds ratio, 9.6; P= 0.008).

CONCLUSIONS

MRSA nasal colonization is present within Nashville's healthy pediatric population. Children with household contacts employed in a hospital are significantly more likely to be colonized.

Issues associated with and recommendations for using PCR to detect outbreaks of pertussis

Two outbreaks of respiratory tract illness associated with prolonged cough occurring in 1998 and 1999 in New York State were investigated. A PCR test for Bordetella pertussis was primarily used by a private laboratory to confirm 680 pertussis cases. Several clinical specimens had positive culture results for B. pertussis during both outbreaks, which confirmed that B. pertussis was circulating during the outbreaks. However, testing by the New York State Department of Health reference laboratory suggested that some of the PCR results may have been falsely positive. In addition, features of the outbreak that suggested that B. pertussis may not have been the primary agent of infection included a low attack rate among incompletely vaccinated children and a significant amount of illness among patients testing PCR negative for B. pertussis. These investigations highlight the importance of appropriate clinical laboratory quality assurance programs, of the limitations of the PCR test, and of interpreting laboratory results in context of clinical disease.

New trends in Staphylococcus aureus infections: glycopeptide resistance in hospital and methicillin resistance in the community

PURPOSE OF REVIEW

Methicillin-resistant Staphylococcus aureus is prevalent in hospitals throughout the world, and we have got used to its presence in daily clinical practice. However, methicillin-resistant S. aureus has not remained static over the past four decades, but seems to be evolving in unfamiliar directions. This review focuses on recent findings on two directions of methicillin-resistant S. aureus evolution: the acquisition of multiple antibiotic resistance in the hospital and the trend towards methicillin-resistant S. aureus as a community pathogen.

RECENT FINDINGS

We looked at reports on glycopeptide resistance in S. aureus and those on community-acquired methicillin-resistant S. aureus strains, with some references of historical value to explain the entire picture of this 'new field' of the methicillin-resistant S. aureus problem.

SUMMARY

The references given here (excluding some of low credibility) attest the increasing awareness of the two conspicuous problems concerning methicillin-resistant S. aureus infection. One is the increasing trend of glycopeptide-resistance, making difficult the successful treatment of multi-drug-resistant methicillin-resistant S. aureus infection in the hospital. On the other hand, non-multi-drug-resistant methicillin-resistant S. aureus strains are emerging as novel threats in the community, the genetic analysis of which indicates that they are independent clones from those found in hospitals.