Methicillin-Resistant FREE

MMWR. 2001;50:919-922

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On October 25, 2000, the Mississippi State Department of Health (MSDH) notified CDC that, since November 1999, 31 inmates had acquired methicillin-resistant Staphylococcus aureus (MRSA) skin or soft tissue infections at a state prison. During November 1998–October 1999, no MRSA infections had been reported at the prison, which houses approximately 1,200 female and 1,800 male inmates. This report summarizes the case investigation and the nasal culture prevalence survey conducted by MSDH and CDC during November 2000. Findings indicate that MRSA infections were transmitted person-to-person within the prison, and that the number of asymptomatic carriers was unexpectedly high for a nonhealth-care setting. Correctional facilities can reduce the increasing prevalence of MRSA disease by identifying and appropriately treating infected persons and by instituting prevention measures.

A case of MRSA infection was defined as a skin or soft tissue lesion occurring in a state prison inmate with symptoms (e.g., pus, pain, warmth, or tenderness) and with MRSA cultured from the site of infection during November 1999–November 2000. Cases were identified by interviews with physicians and inmates and a review of the prison's medical, laboratory, and pharmacy records. Fifty-nine inmates had an illness that met the case definition; 46 (78%) were women, and the median age was 33 years (range: 19-70 years). The median length of incarceration was 397 days (range: 3-3,717 days).

Records of 45 (76%) infected inmates were reviewed. Three (7%) had been hospitalized during the year preceding infection. Twenty-six (58%) had infections on the legs and seven (16%) on the arms. Fifteen (33%) were diagnosed with furuncles, 12 (27%) with skin abscesses, and 11 (24%) with open wounds; 21 (47%) had cellulitis, and two (4%) had systemic infections requiring hospitalization. Infections resolved after a median of 3 weeks (range: 1-36 weeks). Systemic antimicrobials were used to treat 44 (98%) infected inmates, 35 (78%) received topical antimicrobials, six (13%) required incision and drainage, and wound dressing was prescribed for 21 (47%). Nineteen (90%) of the 21 infected inmates with wound dressings changed their dressings themselves. During interviews, 15 (33%) infected inmates reported helping or being helped by other inmates with wound care or dressing changes. Twenty-six (58%) reported lancing their own boils or other inmates' boils with fingernails or tweezers; 40 (89%) shared personal items (e.g., linen, pillows, clothing, and tweezers) that potentially were contaminated by wound drainage.

To assess the extent of MRSA carriage among the inmates, swab specimens of both anterior nares were collected from all female and a one third systematic sample of male inmates. Of 1,757 inmates sampled, 86 (4.9%) were MRSA carriers. More women (73 of 1,241 [5.9%]) were carriers than men (13 of 516 [2.5%]) (p = 0.003), and inmates who had been incarcerated for >60 days were more likely to be carriers (84 of 1,565 [5.4%]) than those who had served less time (one of 142 [0.7%]) (p = 0.01).

Of the 59 infection-associated isolates, 41 (69%) were tested and genotyped at CDC. All 41 isolates were confirmed as MRSA and 40 (98%) were susceptible to gentamicin, rifampin, trimethoprim-sulfamethoxazole, clindamycin, vancomycin, and chloramphenicol; three (7%) were resistant to levofloxacin. Pulsed-field gel electrophoresis of isolates revealed that three MRSA strains predominated: genotype A (24 [59%]), genotype B (seven [17%]), and genotype C (four [10%]).

During December 2000, CDC and MSDH provided the Mississippi State Department of Corrections and the prison with control measures such as optimizing antimicrobial treatment of infected inmates, reinforcing infection control practices (e.g., implementing Standard Precautions¹ at prison clinics, educating inmates in personal hygiene and wound care), using antibacterial soap, and establishing an MRSA skin infection surveillance system.

R Culpepper, MD, R Nolan, MD, S Chapman, MD, Univ of Mississippi Medical Center, Jackson; A Kennedy, MPH, M Currier, MD, State Epidemiologist, Mississippi State Dept of Health. Div of Healthcare Quality Promotion, National Center for Infectious Diseases; and an EIS Officer, CDC.

S. aureus is an important and common pathogen in humans. It is found in the nose or on the skin of many healthy, asymptomatic persons (i.e., carriers) and can cause infections with clinical manifestations ranging from pustules to sepsis and death. Most transmission occurs through the contaminated hands of a person infected with or carrying S. aureus. MRSA infections frequently are encountered in health-care settings.² Since the 1960s, treatment of these infections has become more difficult because S. aureus has progressively acquired resistance to previously effective antimicrobial agents.² In 1999, 2,538 (53.5%) of 4,744 intensive care unit patients with hospital-acquired S. aureus–associated infection had MRSA.³ Less information is available on long-term-care facilities, where prevalence of MRSA carriage may range from zero to 33% of the residents.⁴

Risk factors for infection with MRSA in health-care settings include prolonged hospital stay, exposure to multiple or prolonged broad-spectrum antimicrobial therapy, stay in an intensive care or burn unit, proximity to patients colonized or infected with MRSA, use of invasive devices, surgical procedures, underlying illnesses, and MRSA nasal carriage.⁵

Although community-onset MRSA infections have been reported recently,⁶ little is known about their epidemiology or prevalence of carriage. Community outbreaks have occurred among injection-drug users; aboriginals in Canada, New Zealand, and Australia; Native Americans/Alaska Natives in the United States; and players of close-contact sports.⁶ Reported most commonly have been uncomplicated skin infections; however, community-acquired MRSA infections can be severe. Four deaths from community-acquired MRSA in children were reported in Minnesota and North Dakota in 1999.⁷

Disease transmission can occur easily among inmates at correctional facilities. In 1999, approximately two million persons were incarcerated in the United States.⁸ Skin or soft tissue infections are recognized problems in these facilities.⁹ MRSA disease in prisons can be controlled or prevented using several approaches. First, severe skin disease or treatment failures of presumed S. aureus skin infection should be evaluated with appropriate cultures or other diagnostic tests. Efforts to monitor the etiology of skin disease should be linked to these data to determine whether MRSA is a problem in the facility. MRSA outbreaks can be reported to CDC (telephone [800] 893-0485) through state departments of corrections and state health departments. Second, optimal treatment of MRSA disease should be based on the infecting organism's antimicrobial susceptibility result and, when available, input by infectious disease expertise. Third, close contact among inmates may place them at increased risk for transmission of skin-colonizing or skin-infecting organisms. To prevent skin disease, all inmates should practice good personal hygiene, including daily showers. Inmates should avoid touching wounds or drainage of others and should have access to sinks and plain soap (in this setting, the usefulness of antibacterial soap is unknown). Hands should be washed with soap as soon as possible after touching wounds or dressings. Personnel that provide wound care should follow Standard Precautions.¹

MMWR. 2001;50:1029-1033

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Since 1990, the republic of Guinea (2000 population: 7.5 million) has accepted 390,000-450,000 refugees from Sierra Leone and Liberia.^1- 2 During this 10-year period, refugees have lived in small villages scattered throughout rural southeastern Guinea.³ During September-December 2000, attacks by armed factions in Guinea led to the widespread displacement of refugees living in the southeastern camps; the refugees subsequently were transferred to safer camps in the northwest. Approximately 280,000 refugees initially were estimated to have been displaced.⁴ After the attacks, the number of refugees relocated was approximately 58,000. This report demonstrates methods used to calculate mortality rates when large populations are displaced. The findings indicate that the number of refugees in Guinea before the relocation probably was overestimated. The mortality rates calculated using conservative denominator numbers did not meet the definition of an emergency phase* of a complex emergency,† and mortality rates were lower for refugees compared with baseline rates for the local population. Accurate methods are needed to estimate population size in complex emergencies to provide resources to vulnerable groups.

In camps that were accessible to site visits by international agencies, nongovernmental organizations (NGOs)‡ collected and reported camp mortality data from NGOs and government health posts, camp health-care workers, the referral hospital, and burial workers. Deaths were line listed (i.e., one line for each death), and duplications of reported deaths were deleted. Estimates of camp populations were provided by the government of Guinea, the United Nations High Commissioner for Refugees (UNHCR), NGOs, and refugee and other organizations. Because these estimates varied widely, the lowest estimates for all camps were used to calculate mortality rates. Nutrition surveys could not be conducted in less accessible camps; the prevalence of acute malnutrition among children aged 6-49 months was estimated using nutrition screening data collected from all children entering new camps in northwestern Guinea. Monthly camp death rates usually are calculated by dividing the sum of all deaths in the camps by the sum of each camp's midpoint population size and then dividing by the number of days in the month or by the mean number of days the camps were open. However, using this approach would have underrepresented camps that were not open for the entire month.

Individual camp mortality rates were calculated based on the number of days each camp was open during the month. Several sites were transit camps; opening and closing of these camps depended on refugee migration patterns. The mean mortality rates weighted by population were used to calculate overall camp mortality rates by month; mortality rates of each camp were weighted using the overall population and totaled. Only camps reporting data for the entire time they were open during each month were included in the overall monthly mortality rates. The same weighting method was used to calculate the overall crude mortality rate (CMR) and the mortality rate for children aged <5 years (<5MR) during January-May 2001.

The number of camps included in the health information systems (HIS) during January-May 2001 varied from four to 15 camps sheltering approximately 34,000-89,500 persons because of large population movements and changing security conditions. Before relocation, an estimated 280,000 refugees were housed in approximately 43 camps. However, in three HIS camps, census or relocation numbers determined by UNHCR were 1.6-3.9 times higher than original estimates of 280,000. If the overestimation ratios of 1.6-3.9 are applied to the original population estimate, the actual refugee population in southeastern Guinea may have ranged from 72,000 to 175,000 persons. Camps represented in the HIS tended to be larger and more accessible to UN and NGO health workers. All children aged 6 months–15 years were vaccinated for measles on entry to the new camps§.

During January-May 2001, a total of 304 deaths were reported; 173 (57%) were among children aged <5 years. The CMR and <5MR of 0.3 and 0.9 deaths per 10,000 per day, respectively, were well below the levels used to define the emergency phase of a complex emergency.^5- 6 These rates also were lower than the CMR and <5MR reported for the Guinean population (0.5 and 1.3 deaths per 10,000 per day, respectively).⁷ The CMR and <5MR monthly trends were higher at the beginning of relocation in January and after most refugees had been transferred in May. Mortality rates decreased then stabilized from February to April as refugees who arrived in secure camps were provided with services. In May, however, mortality rates increased⁵ NGOs anecdotally reported an increase in malnutrition in some of the less accessible camps. However, of 4,771 children who were screened in the new camps using weight-for-height during February-May, 119 (2.5%) were acutely malnourished.

In response to the increase in mortality rates among refugees in Guinea during May, UN agencies and NGOs (1) accelerated efforts to move the refugees in the new camps from crowded temporary shelters to permanent family structures, (2) enhanced communicable disease surveillance, (3) improved water and sanitation provisions in the new camps, (4) stockpiled cholera-control supplies, and (5) increased the number of health posts.

T Doumbia, MD, B Massakumbo, MD, A Barry, MD, M Deppner, MD, United Nations High Commissioner for Refugees, Geneva, Switzerland. International Emergency and Refugee Health Br, Div of Emergency Environmental Health Svcs, National Center for Environmental Health, CDC.

During complex emergencies, agencies must resolve immediate health questions affecting tens of thousands of refugees, despite the uncertainty of population size and the inaccuracy of data. This report used methods to calculate rates that suggest an effective response to the 2001 Guinea refugee crisis in which large populations were displaced. Mortality rates might have been kept below emergency threshold rates because of the prompt engagement of international agencies together with sufficient resources and coping mechanisms developed by the refugees during the 10 years in Guinea preceding the latest crisis. The increase in mortality after most refugees were relocated into the new camps might have occurred because some refugees were not relocated to individual family shelters as quickly as planned, causing overcrowding of temporary shelters and overburdening of existing facilities. This increase demonstrates the need to ensure that adequate human and material resources and programs are in place before large transfers of persons occur.

Lower mortality rates among refugees than among host populations have been documented in postemergency settings^8- 9; in Guinea during the displacement, the refugee population had lower mortality rates than those of the baseline population in Guinea. The lack of mortality data for the local and internally displaced populations during the refugee crisis suggests that organizations whose mandates cover nonrefugee populations need to be included early in the process of emergency response.

Despite all refugees being offered transportation, far fewer relocated to the new camps than had been anticipated. Populations commonly are overestimated in refugee crises because food distribution is linked to camp size. In Guinea, internally displaced and local persons sought to be counted as refugees to receive food aid and other services; distinguishing among the three groups, where refugees came from the same ethnic group and lived among the local population, was particularly difficult.

The findings in this report are subject to at least five limitations. First, data were unavailable from inaccessible camps where mortality rates may have been higher than in more accessible camps. Second, population denominators for camps that did not have a recent census probably overestimated population sizes. Third, underreporting and underestimates of mortality might have occurred in camps with limited access. Fourth, only camps with data for 1 month were included in the monthly HIS calculations. The changing number of camps with data available for an entire month and the opening and closing of some transit camps make the comparison of monthly rates difficult, because the same sites and populations were not represented each month. Finally, midpoint rather than the mean population size was used as the denominator in calculating mortality rates. The preferred method is unclear because of the constant changes in population throughout this period.¹⁰

Difficulties arise when estimating mortality and nutrition rates among displaced populations that are moving at different rates in areas with varying accessibility.¹⁰ In Guinea, some approaches to these challenges were (1) including mortality data only for the days in which individual camps were open for each month throughout the 5-month reporting period, (2) using the lowest population estimates and applying them retro-spectively when appropriate, and (3) calculating overall mortality rates using population-weighted mean rates to allow for an unbiased estimate from camps being open for different numbers of days within a month.

*Crude mortality rate of ≥1 death per 10,000 population per day or a mortality rate of ≥2-4 deaths per 10,000 children aged <5 years per day.

†Relatively acute situations affecting large civilian populations, usually involving a combination of war or civil strife, food shortages, and population displacement, resulting in excess mortality.

‡Action Against Hunger, American Refugee Committee, International Federation of the Red Cross and Crescent, Doctors of the World, and Doctors Without Borders.

§Provided by United Nations Children's Fund and the government of Guinea.

MMWR. 2001;50:1087

Environmental sampling to ascertain the presence of Bacillus anthracis spores in buildings is an important tool for assessing risk for exposure. Similar to diagnostic testing, culture with positive identification of B. anthracis (CDC culture method) is the confirmatory test. Laboratory-based polymerase chain reaction (PCR) methods for detecting genetic material of B. anthracis can be used in preliminary assessments and as adjuncts to microbiologic methods. Although these tests are consistent with culture results, PCR methods are not approved by the Food and Drug Administration, and results should not be the basis for clinical decisions.

Rapid-assay devices that can provide results within minutes are used for onsite detection of environmental contamination. Some of these devices are PCR-based assays, and others are immune-based assays for B. anthracis. CDC has not obtained validation data for rapid-assay devices. A recent CDC evaluation of B. anthracis contamination at the Brentwood postal facility in the District of Columbia included use of one onsite PCR-based device and CDC culture method. Of 107 samples analyzed using CDC culture method and the PCR-based device, 95 (89%) were negative by both methods. Of six samples identified as positive by CDC culture method, two were positive using the PCR-based device. Of eight samples identified as positive by the PCR-based device, two were positive by CDC culture method. Although these results indicate a poor agreement between results from the onsite PCR-based device and CDC culture method, this assessment was not intended as a formal validation test because of limited capacity to implement adequate quality-control measures and the small number of B. anthracis positive samples.

The apparently poor agreement of the onsite PCR-based device could be attributed to several factors such as the concentration of spores on contaminated surfaces, sample collection and preparation procedures, sample splitting, and the methods used for removing the sample from collection material. Furthermore, PCR- or immune-based tests do not distinguish viable from nonviable spores and can produce positive scores for samples that culture methods would define as negative. As a result, these methods are not useful for evaluating the success of disinfection techniques that do not remove nonviable spores.

Public health officials are urged to understand the limitations of onsite, rapid technologies for B. anthracis before using them for public health decision making. Until validation testing is complete and guidelines for effective use are developed, PCR- or immune-based assay results for B. anthracis should not be used alone, but should be confirmed with samples analyzed by culture methods to make public health decisions. Danila, PhD, HF Hull, MD, State Epidemiologist, Minnesota Dept of Health. Div of Healthcare Quality Promotion, National Center for Infectious Diseases; and EIS officers, CDC.

This article was corrected on January 9, 2002.