Epidemiology, Treatment, and Prevention of Community-Acquired Methicillin-Resistant Staphylococcus aureus Infections

doi:10.4065/80.9.1201

Mayo Clinic Proceedings

Volume 80, Issue 9, September 2005, Pages 1201-1208

https://doi.org/10.4065/80.9.1201 Get rights and content

Since first described in 1961, methicillin-resistant Staphylococcus aureus (MRSA) has become a common nosocomial pathogen. Substantial increases in MRSA infections among nonhospitalized patients are being reported. Methicillin-resistant S aureus is the most common isolate from skin and soft tissue infections in selected centers in the United States. Community-acquired MRSA strains differ from nosocomial strains in clinically relevant ways, such as in their propensity to cause skin and soft tissue infection and severe necrotizing pneumonia. Clinicians in numerous specialties, particularly primary care physicians, will likely evaluate patients presenting with community-acquired MRSA and should become familiar with the epidemiology and clinical characteristics of and evolving therapeutic and preventive strategies for this infection.

Section snippets

THE CHANGING FACE OF S AUREUS

Shortly after the introduction of penicillin in the 1940s, penicillin-resistant S aureus isolates were described first in hospitals and subsequently in the community.¹ Today, the vast majority of staphylococcal isolates carry plasmids encoding a penicillinase-rendering penicillin resistance.

Methicillin, a penicillinase-resistant semisynthetic penicillin, was introduced in 1961. Less than 1 year later, MRSA was reported.¹ Today, MRSA is a common nosocomial isolate and accounts for more than 50%

WHAT CONSTITUTES CA-MRSA?

There is no universally accepted definition of what constitutes CA-MRSA. Epidemiologically oriented studies base the definition on the timing of MRSA isolation in culture relative to hospital admission (ie, <24–72 hours), with or without excluding patients with established MRSA risk factors (recent hospitalization, hemodialysis, indwelling catheters, etc).⁸ Numerous epidemiological studies have suggested that hospitals were the primary MRSA reservoir and that hospital contact accounted for most

POPULATIONS AT RISK

The incidence of CA-MRSA varies regionally, but comprehensive epidemiological studies have not been published recently. Local prevalence data and antibiograms should be updated and monitored. Attendant to this, clinicians need to culture appropriate sources (furuncles, soft tissue abscesses, etc). The incidence of CA-MRSA varies also by age and is reported consistently in younger patients than is nosocomial MRSA.¹⁵ Outbreaks have occurred in several discrete patient populations. Identified

CLINICAL SYNDROMES

Skin and soft tissue infections and lower respiratory infections account for much of the current clinical literature about CA-MRSA. Community-acquired MRSA has been reported less frequently in endocarditis, brain abscesses, bacteremia, sinusitis, and musculoskeletal infections.30, 31, 32, 33, 34 Recent reports about CA-MRSA causing necrotizing fasciitis, myositis, osteomyelitis, prosthetic joint infection, and complicated parapneumonic effusions highlight the various clinical settings and

Skin and Soft Tissue Infections

When choosing an empirical antimicrobial for skin and soft tissue infections, one should consider the likelihood that MRSA is the etiologic agent, the severity of the infection, and pertinent host factors including immunologic status (eg, diabetes mellitus and human immunodeficiency virus), allergies, and factors that may impede follow-up. β-Lactam agents currently remain the antimicrobial of choice for most skin and soft tissue infections in many if not most parts of the country. If CA-MRSA is

PREVENTION

There is great interest in measures to abort and prevent CA-MRSA outbreaks. Education of health care providers, patients, caregivers, high-risk populations, and appropriate organizations about CA-MRSA and adherence to basic infection-control principles are key to preventive strategies. Informed physicians are in a better position to recognize, treat, and appropriately counsel patients with CA-MRSA. Data are limited about which specific control interventions may be most effective. Measures that

CONCLUSIONS

Community-acquired MRSA is an emerging infectious cause of morbidity and mortality among previously healthy persons in the United States and worldwide. Accumulating evidence suggests that these heterogeneous strains are particularly suited to community survival and spread. It remains to be seen whether CA-MRSA will become the predominant staphylococcal phenotype in the community, as penicillin-resistant S aureus did. If so, CA-MRSA promises to affect nearly every medical specialty. Primary care

Questions About CA-MRSA

1.
Which one of the following patient populations is not associated with CA-MRSA outbreaks?
- a.
  Prisoners
- b.
  Teachers
- c.
  Soldiers
- d.
  Athletes
- e.
  Alaska Natives
2.
Which one of the following clinical manifestations is not associated with the PVL toxin?
- a.
  Endocarditis
- b.
  Cellulitis
- c.
  Furunculosis
- d.
  Necrotizing pneumonia
- e.
  Cutaneous abscesses
3.
Which one of the following statements about CA-MRSA therapy is true?
- a.
  TMP-SMX monotherapy is adequate when β-hemolytic streptococci infection also is suspected
- b.
  Clindamycin is

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New real-time PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus directly from specimens containing a mixture of staphylococci

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Community-adapted methicillin-resistant Staphylococcus aureus (MRSA): population dynamics of an expanding community reservoir of MRSA

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Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection

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Hospital transmission of community-acquired methicillin-resistant Staphylococcus aureus among post-partum women

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Multidrug-resistant (MDR) gram-positive bacteria are an inevitable source of infection for hospitalized patients and one of the reasons for the increased proportion of severe diseases. Therefore, constructing smart agents for specific and effective combating infections in vivo caused by MDR gram-positive strains is very urgent. Herein, we reported a structure-oriented design strategy (SODS) to reasonably construct an organic photo-antimicrobial near-infrared (NIR) AIEgen BDPTV equipped with a phenylboronic acid moiety, which could be bound to the thick peptidoglycan layer of MDR gram-positive bacteria, resulting in a tight distribution with the cell wall in a confined space. Compared to the contrast compounds DQVTA and DPTVN, upon photoirradiation of AIEgen BDPTV, the generation of abundant and highly toxic reactive oxygen species (ROS) irreversibly destroys MDR gram-positive bacteria through photodynamic therapy, which is better than commercial photosensitizers (including methylene blue, chlorin e6, and protoporphyrin IX) and antibiotic (cefoxitin). As a proof of concept, in vitro experimental results showed that methicillin-resistant Staphylococcus aureus (MRSA) were completely killed using AIEgen BDPTV. More importantly, AIEgen BDPTV was capable of successfully combating MRSA-infected wounds of mice, but not Escherichia coli (E. coli)-infected wounds. We hope that this strategy could provide a new method to design powerful AIEgens to avoid the overuse and misuse of antibiotics.
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Managing CAP patients at risk of clinical failure
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Community-acquired pneumonia (CAP) is a curable disease. Both the European and American clinical practice guidelines provide algorithms how to manage patients with CAP.
However, as populations worldwide are ageing and bacteria are becoming multidrug resistant, it is necessary to address the major factors that put patients at risk of poor outcome. These may include age, comorbidities, the settings where pneumonia was acquired or treated, the need for hospitalisation or ICU admission, likely causative pathogen (bacteria or virus) in a certain region and their local susceptibility pattern. One complicating fact is the lack of definite causative pathogen in approximately 50% of patients making it difficult to choose the most appropriate antibiotic treatment. When risk factors are present simultaneously in patients, fewer treatment options could be rather challenging for physicians. For example, the presence of comorbidities (renal, cardiac, hepatic) may exclude certain antibiotics due to potential adverse events.
Assessing the severity of the disease and monitoring biomarkers, however, could help physicians to estimate patient prognosis once diagnosis is confirmed and treatment has been initiated. This review article addresses the most important risk factors of poor outcome in CAP patients.
Skin infections caused by community-acquired methicillin-resistant staphylococcus aureus: Clinical and microbiological characteristics of 11 cases
2014, Actas Dermo-Sifiliograficas
Staphylococcus aureus resistente a meticilina de adquisición comunitaria (SARM-CO) constituye un patógeno emergente como agente productor de infecciones de piel y partes blandas.
Describir las características clínicas de las infecciones cutáneas causadas por SARM-CO, así como su correlación con los datos demográficos y microbiológicos disponibles.
Se realizó un estudio descriptivo de los pacientes con diagnóstico de infección microbiológicamente confirmada por SARM-CO en el Servicio de Dermatología desde junio de 2009 a diciembre de 2011. Se recogieron los datos demográficos de los pacientes, las características clínicas de las lesiones y los tratamientos realizados.
Se reclutaron 11 pacientes, 5 hombres y 6 mujeres. El 91% tenía menos de 40 años y no presentaba antecedentes médicos de interés. El absceso cutáneo (asociado o no a celulitis) fue la forma más frecuente de presentación. Tras su drenaje se observó una cantidad escasa o nula de exudado purulento junto a un componente de necrosis tisular marcado en todas estas lesiones. El 50% de los abscesos había recibido tratamiento previo con antibióticos betalactámicos y el drenaje quirúrgico, asociado en el 63% a quinolonas o cotrimoxazol, aseguró la resolución de los mismos.
Actualmente las infecciones cutáneas causadas por SARM-CO se presentan en individuos jóvenes, sanos, deportistas, sin contacto con el ámbito sanitario. Los abscesos cutáneos, su forma más frecuente de presentación, se caracterizan por una marcada necrosis tisular, con escaso o nulo exudado purulento. Ante estos hallazgos en pacientes susceptibles debe sospecharse la implicación de SARM-CO como agente causal. El drenaje de los abscesos se realizará siempre que sea posible, y cuando resulte necesario añadir tratamiento antibiótico deberá evitarse el uso de betalactámicos de forma empírica.
Community-acquired methicillin-resistant Staphylococcus aureus (CA-MRSA) is an emerging pathogen that causes skin and soft-tissue infections.
To describe the clinical characteristics of skin infections caused by CA-MRSA and correlations with the available demographic and microbiological data.
This was a descriptive study of patients with a microbiologically confirmed diagnosis of CA-MRSA infection treated in a dermatology department between June 2009 and December 2011. We recorded demographic details, the clinical characteristics of lesions, and the treatments used.
We studied 11 patients (5 men and 6 women); 91% were under 40 years of age and had no relevant past medical history. The most common presentation was a skin abscess (with or without cellulitis). In all such cases, marked tissue necrosis and little or no purulent exudate was observed when the abscess was drained. Fifty percent of these abscesses had been treated previously with β-lactam antibiotics, and in all cases the lesions resolved after surgical drainage, which was combined in 63% of cases with quinolones or cotrimoxazole.
Today, skin infections due to CA-MRSA affect healthy young athletes who have no contact with healthcare settings. The most common presentation is a skin abscess characterized by marked tissue necrosis and little or no purulent exudate. In cases with these characteristics in susceptible patients, the involvement of CA-MRSA as the causative agent should be suspected. The abscesses should be drained whenever possible and, if necessary, antibiotic treatment should be prescribed; empirical use of β-lactam antibiotics should be avoided.
Antibiotics for methicillin-resistant Staphylococcus aureus skin and soft tissue infections: The challenge of outpatient therapy
2014, American Journal of Emergency Medicine
Citation Excerpt :
Our study focused on the evolution of antimicrobial resistance in response to commonly prescribed antibiotics, which in our hospital consists of a combination or single-drug regimen of TMP/SMX, cephalexin, and clindamycin. Cephalexin is known to be ineffective against MRSA [3,4,8,9,11,19], and it was likely given as coverage for the possibility of streptococcal infection. Resistance to TMP/SMX was first identified in 2006; the proportion of MRSA isolates resistant to TMP/SMX remained low overall but slowly increased over the years.
Methicillin-resistant Staphylococcus aureus (MRSA) infections are becoming increasingly prevalent in both community and hospital settings. Certain strains are notorious for causing skin and soft tissue infections in patients with no established risk factors. In this article, we report our findings on the dynamic antibiotic resistance pattern of MRSA and outpatient prescription trend for skin and soft tissue infections within our community.
We conducted a retrospective medical record review of 1876 patients evaluated in the emergency department of an urban community hospital from 2003 to 2012. Data regarding culture isolates and associated antimicrobial resistance, antibiotic treatment, site of specimen collection, age, race, and sex were collected and analyzed.
Analysis of 1879 culture specimens yielded 2193 isolates. In some cases, a single specimen yielded polymicrobial growth. Staphylococcus aureus represented 996 isolates (45.4%); 463 were methicillin-susceptible (21.1%) and 533 (24.3%) were methicillin-resistant. Most patients were prescribed a single- or poly-drug regimen of trimethoprim/sulfamethoxazole, cephalexin, and clindamycin. Antimicrobial resistance analysis indicated that MRSA became increasingly resistant to the aforementioned antibiotics over time: 10% and 6% in 2012 vs 3.5% and 3.4% in 2007 for clindamycin and trimethoprim/sulfamethoxazole, respectively.
Methicillin-resistant Staphylococcus aureus is a particularly virulent, rapidly adaptive pathogen that is becoming increasingly difficult to combat with existing antibiotics. Care must be taken to ensure appropriate treatment and follow-up of patients with known MRSA infections.
Trends in ophthalmic manifestations of methicillin-resistant Staphylococcus aureus (MRSA) in a northern California pediatric population
2013, Journal of AAPOS
To determine pediatric clinical trends of ocular and periocular methicillin-resistant Staphylococcus aureus (MRSA) in a large northern California healthcare system.
This study was a retrospective cross-sectional review of all pediatric cases (aged 0-18) with culture-positive ophthalmic MRSA isolates identified between January 2002 and December 2009. Medical record review included history, presentation, infection site, acquisition (community or nosocomial), antibiotic sensitivity/resistance, treatment, and clinical outcome. Incidence was classified by year, sex, and age. Parameters were analyzed for statistical significance by trend and χ² analysis.
A total of 399 ocular and periocular MRSA cases were included. Cases trended upward from 2002 to 2009, peaking in 2006. Of the 137 pediatric cases (0-18 years), 58% were community acquired. Conjunctivitis was the predominant presentation (40%), followed by stye/chalazion (25%), orbital cellulitis/abscess (19%), dacryocystitis (11%) and brow abscess (3%). Significant predictors for ocular infection with MRSA included male sex (61%), neonates (38%), and multiple infection sites on the body (38%). Resistance was high to bacitracin (80.9%) and ofloxacin (48.3%) but remained low for trimethoprim/sulfamethoxazole (8.7%). Topical therapy was effective in 29% of cases; oral antibiotics, in 47%. Intravenous therapy was required in 12% of cases and incision/drainage or surgery in 19%. Initial oral antibiotic treatment, primarily cephalosporins (24%), was ineffective in 37% of patients. There was a significant increase in resistance to antibiotic therapy (P < 0.001) during the study period. No patients developed permanent visual impairment.
Pediatric ocular and periocular MRSA is increasing in incidence and resistance in our patient population. Outcomes can be improved by early recognition, proper antibiotic selection, and obtaining cultures and sensitivities when resistant or severe ocular infections are present.

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CONCISE REVIEW FOR CLINICIANSEpidemiology, Treatment, and Prevention of Community-Acquired Methicillin-Resistant Staphylococcus aureus Infections

Section snippets

THE CHANGING FACE OF S AUREUS

WHAT CONSTITUTES CA-MRSA?

POPULATIONS AT RISK

CLINICAL SYNDROMES

Skin and Soft Tissue Infections

PREVENTION

CONCLUSIONS

Questions About CA-MRSA

J Hosp Infect

Lancet

Int J Infect Dis

Chest

Int J Antimicrob Agents

The changing epidemiology of Staphylococcus aureus?

Emerg Infect Dis

National Nosocomial Infections Surveillance (NNIS) System Report, data summary from January 1992 to June 2002, issued August 2002

Am J Infect Control

Methicillin-resistant Staphylococcus aureus: epidemiologic observations during a community-acquired outbreak

Ann Intern Med

Methicillin-resistant Staphylococcus aureus in two child care centers

J Infect Dis

Community-acquired methicillin-resistant Staphylococcus aureus in children with no identified pre-disposing risk

JAMA

Four pediatric deaths from community-acquired methicillin-resistant Staphylococcus aureus—Minnesota and North Dakota, 1997-1999

MMWR Morb Mortal Wkly Rep

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

Clin Infect Dis

Community-acquired and clindamycin-susceptible methicillin-resistant Staphylococcus aureus in children

Pediatr Infect Dis J

A new class of genetic element, staphylococcus cassette chromosome mec, encodes methicillin resistance in Staphylococcus aureus

Antimicrob Agents Chemother

Novel type of staphylococcal cassette chromosome mec identified in community-acquired methicillin-resistant Staphylococcus aureus strains

Antimicrob Agents Chemother

Origins of community strains of methicillin-resistant Staphylococcus aureus [published correction appears in Clin Infect Dis. 2004;39:291]

Clin Infect Dis

New real-time PCR assay for rapid detection of methicillin-resistant Staphylococcus aureus directly from specimens containing a mixture of staphylococci

J Clin Microbiol

Community-adapted methicillin-resistant Staphylococcus aureus (MRSA): population dynamics of an expanding community reservoir of MRSA

J Infect Dis

Comparison of community- and health care-associated methicillin-resistant Staphylococcus aureus infection

JAMA

Hospital transmission of community-acquired methicillin-resistant Staphylococcus aureus among post-partum women

Clin Infect Dis

Community-acquired methicillin-resistant Staphylococcus aureus carrying Panton-Valentine leukocidin genes: worldwide emergence

Emerg Infect Dis

Staphylococcus aureus (including staphylococcal toxic shock)

Community-associated methicillin-resistant Staphylococcus aureus infections in Pacific Islanders—Hawaii, 2001-2003

MMWR Morb Mortal Wkly Rep

Involvement of Panton-Valentine leukocidin-producing Staphylococcus aureus in primary skin infections and pneumonia

Clin Infect Dis

Neutralization of Staphylococcus aureus Panton Valentine leukocidin by intravenous immunoglobulin in vitro

J Infect Dis

Community-acquired methicillin-resistant Staphylococcus aureus isolated in Switzerland contains the Panton-Valentine leukocidin or exfoliative toxin genes

J Clin Microbiol

Natural history of community-acquired methicillin-resistant Staphylococcus aureus colonization and infection in soldiers

Clin Infect Dis

Methicillin-resistant Staphylococcus aureus infections in correctional facilities—Georgia, California, and Texas, 2001-2003

MMWR Morb Mortal Wkly Rep

An epidemic of methicillin-resistant Staphylococcus aureus soft tissue infections among medically underserved patients

Arch Surg

CONCISE REVIEW FOR CLINICIANS
Epidemiology, Treatment, and Prevention of Community-Acquired Methicillin-Resistant Staphylococcus aureus Infections