Emergence of community-acquired methicillin-resistant Staphylococcus aureus USA 300 clone as the predominant cause of skin and soft-tissue infections

BACKGROUND

Studies have shown that community-acquired methicillin-resistant Staphylococcus aureus (MRSA) causes S. aureus skin and soft-tissue infection in selected populations.

OBJECTIVE

To determine the proportion of infections caused by community-acquired MRSA, the clinical characteristics associated with community-acquired MRSA, and the molecular epidemiology of community-acquired MRSA among persons with community-onset S. aureus skin and soft-tissue infection.

DESIGN

Active, prospective laboratory surveillance to identify S. aureus recovered from skin and soft-tissue sources.

SETTING

1000-bed urban hospital and its affiliated outpatient clinics in Atlanta, Georgia.

PATIENTS

384 persons with microbiologically confirmed community-onset S. aureus skin and soft-tissue infection.

MEASUREMENTS

Proportion of infections caused by and clinical factors associated with community-acquired MRSA among persons with community-onset S. aureus skin and soft-tissue infection. Pulsed-field gel electrophoresis and antimicrobial susceptibility patterns were used to epidemiologically classify community-onset S. aureus infections. Community-acquired MRSA was defined by MRSA isolates that either demonstrated a USA 300 or USA 400 pulsed-field type or had a susceptibility pattern showing resistance only to beta-lactams and erythromycin (for isolates not available for pulsed-field gel electrophoresis).

RESULTS

Community-onset skin and soft-tissue infection due to S. aureus was identified in 389 episodes, with MRSA accounting for 72% (279 of 389 episodes). Among all S. aureus isolates, 63% (244 of 389 isolates) were community-acquired MRSA. Among MRSA isolates, 87% (244 of 279 isolates) were community-acquired MRSA. When analysis was restricted only to MRSA isolates that were available for pulsed-field gel electrophoresis, 91% (159 of 175 isolates) had a pulsed-field type consistent with community-acquired MRSA; of these, 99% (157 of 159 isolates) were the MRSA USA 300 clone. Factors independently associated with community-acquired MRSA infection were black race (prevalence ratio, 1.53 [95% CI, 1.16 to 2.02]), female sex (prevalence ratio, 1.16 [CI, 1.02 to 1.32]), and hospitalization within the previous 12 months (prevalence ratio, 0.80 [CI, 0.66 to 0.97]). Inadequate initial antibiotic therapy was statistically significantly more common among those with community-acquired MRSA (65%) than among those with methicillin-susceptible S. aureus skin and soft-tissue infection (1%).

LIMITATIONS

Some MRSA isolates were not available for molecular typing.

CONCLUSIONS

The community-acquired MRSA USA 300 clone was the predominant cause of community-onset S. aureus skin and soft-tissue infection. Empirical use of agents active against community-acquired MRSA is warranted for patients presenting with serious skin and soft-tissue infections.

Increased efficiency in evaluating patients with suspected tuberculosis by use of a dedicated airborne infection isolation unit

BACKGROUND

The resurgence of tuberculosis (TB) in the 1980s and early 1990s in the United States was also accompanied by numerous hospital outbreaks of TB and nosocomial transmission to health care workers.

OBJECTIVE

To determine whether a dedicated airborne infection isolation (AII) unit improves efficiency in "ruling-out" patients suspected of having pulmonary TB. This is important because, to prevent nosocomial transmission of TB, the number and ratio of patients isolated who are subsequently found to have TB is much higher than those "ruled out" and have TB excluded.

METHODS

A prospective cohort study was conducted of all patients 18 years and older admitted to respiratory isolation during 3 separate time periods before and after opening of an 26-bed AII unit in a 1000-bed, public, university-affiliated, innercity hospital.

RESULTS

A total of 879 patients were admitted during the 3 study periods. Most were black and males (87%, 72%, respectively). The median age was 42 years, and 70% of patients included in the study were HIV positive. Among patients who "ruled out," ie, TB was excluded by having 3 negative AFB smears of respiratory specimens for TB, there was a significant decrease in time from 5.0 days in period I to 3.3 days in period III (P < .0001). In period III, patients who were admitted to rule out TB in areas outside of the AII unit in other wards of the hospital required a significantly longer period to have TB excluded: 5.9 days compared with 3.5 on the AII unit (P = .0015).

CONCLUSION

The decrease in isolation time after the opening of the dedicated AII unit demonstrates that a concerted effort to rule patients out by having nurses and respiratory therapists trained in tuberculosis control is efficacious and efficient and results in significant cost savings.

West Nile Virus among Hospitalized, Febrile Patients: A Case for Expanding Diagnostic Testing

In Georgia, most individuals reported with West Nile virus (WNV) disease have been diagnosed with West Nile neuroinvasive disease (WNND). Relatively few cases of West Nile Fever (WNF) are reported, and the burden of illness due to WNV is likely underestimated. From July through October 2003, WNV serologic testing was performed on enrolled patients>or=18 years of age with fever admitted to a large, urban hospital in Atlanta, Georgia through the emergency department (ED). Patients' history, clinical, and laboratory data were recorded. Residual blood drawn in the ED was tested to determine the presence of WNV IgG and IgM antibodies. Of 254 patients tested for WNV, four (1.6%) patients were positive for WNV IgM and IgG antibodies, and had a clinical illness compatible with WNV. None of the four positive patients were clinically suspected of having WNV infection; discharge diagnoses included pneumonia, migraine, stroke, and gout. These four patients accounted for 80% of all WNV diagnosed in this hospital, 44% of all cases in Fulton County, and 7% of all cases reported in Georgia in 2003. The occurrence of WNV disease may be substantially greater than currently reflected in disease statistics in Georgia and many other states. When indicators of WNV activity are present and patients are likely to have had intensive mosquito exposure, WNV should be considered in the differential diagnosis of seriously ill, febrile patients.

Emergence of Community-Associated Methicillin-Resistant Staphylococcus aureus USA300 Genotype as a Major Cause of Health Care--Associated Blood Stream Infections

BACKGROUND

Whether community-associated methicillin-resistant Staphylococcus aureus (MRSA) genotypes (e.g., USA300) are a major cause of bloodstream infections (BSIs) and health care-associated infections has been poorly defined.

METHODS

Consecutive MRSA isolates recovered from patients with BSIs were prospectively collected at an urban public hospital. Molecular typing studies were performed. Prevalence and risk factors for the MRSA USA300 genotype were assessed.

RESULTS

One hundred thirty-two cases of MRSA BSI were documented over 7.5 months in 2004 (incidence, 6.79 per 1000 admissions); 116 isolates were available for genotyping. Characteristics of the 116 evaluable cases included: a mean age 47 years; 62% were male, 82% were African American, and 22% were HIV seropositive. The crude in-hospital mortality rate was 22%. In 107 cases (92%), there was contact with a health care facility within the year prior to infection, and a nosocomial infection (defined as positive blood culture results obtained >48 h after admission) occurred in 49 cases (42%). PFGE demonstrated that 39 (34%) of the 116 isolates were the MRSA USA300 genotype; 34 (29%) were USA100; 42 (36%) were USA500; and 1 (1%) was USA800. MRSA USA300 accounted for 28% of health care-associated BSIs and 20% of nosocomial MRSA BSIs. In multivariate analysis, isolation of the USA300 genotype was associated with injectiondrug use (OR, 3.67; 95% CI, 1.10-12.28) and skin and soft tissue infection (OR, 4.26; 95% CI, 1.08-16.84). Patients who resided in long-term care facilities (OR, 0.09; 95% CI, 0.01-0.82) and those who were treated with antimicrobials in the prior year were less likely to have MRSA USA300 genotype recovered (OR, 0.10; 95% CI, 0.02-0.49).

CONCLUSIONS

MRSA USA300 genotype, the predominant cause of community-associated MRSA infections in our area (Atlanta, GA), has now emerged as a significant cause of health care-associated and nosocomial BSI. MRSA USA300 as a nosocomial pathogen presents new challenges to infection control programs.

Controlling tuberculosis in the United States. Recommendations from the American Thoracic Society, CDC, and the Infectious Diseases Society of America

During 1993-2003, incidence of tuberculosis (TB) in the United States decreased 44% and is now occurring at a historic low level (14,874 cases in 2003). The Advisory Council for the Elimination of Tuberculosis has called for a renewed commitment to eliminating TB in the United States, and the Institute of Medicine has published a detailed plan for achieving that goal. In this statement, the American Thoracic Society (ATS), CDC, and the Infectious Diseases Society of America (IDSA) propose recommendations to improve the control and prevention of TB in the United States and to progress toward its elimination. This statement is one in a series issued periodically by the sponsoring organizations to guide the diagnosis, treatment, control, and prevention of TB. This statement supersedes the previous statement by ATS and CDC, which was also supported by IDSA and the American Academy of Pediatrics (AAP). This statement was drafted, after an evidence-based review of the subject, by a panel of representatives of the three sponsoring organizations. AAP, the National Tuberculosis Controllers Association, and the Canadian Thoracic Society were also represented on the panel. This statement integrates recent scientific advances with current epidemiologic data, other recent guidelines from this series, and other sources into a coherent and practical approach to the control of TB in the United States. Although drafted to apply to TB control activities in the United States, this statement might be of use in other countries in which persons with TB generally have access to medical and public health services and resources necessary to make a precise diagnosis of the disease; achieve curative medical treatment; and otherwise provide substantial science-based protection of the population against TB. This statement is aimed at all persons who advocate, plan, and work at controlling and preventing TB in the United States, including persons who formulate public health policy and make decisions about allocation of resources for disease control and health maintenance and directors and staff members of state, county, and local public health agencies throughout the United States charged with control of TB. The audience also includes the full range of medical practitioners, organizations, and institutions involved in the health care of persons in the United States who are at risk for TB.

Pre-event willingness to receive smallpox vaccine among physicians and public safety personnel

BACKGROUND

Planning for voluntary smallpox vaccination of health and safety officials began in December 2002.

MATERIALS AND METHODS

Surveys were conducted among physicians and fire and police department personnel in Atlanta, Georgia. Information on demographics, willingness to receive smallpox vaccine, self-reported knowledge level, and potential vaccine contraindications was analyzed.

RESULTS

Forty-one percent of physicians (n = 199) were undecided on vaccination (32% would receive vaccine and 27% would not). Forty-eight percent of firefighters (n = 343) and 41% of police (n = 466) were undecided; 23% and 41% would receive vaccine, whereas 28% and 18% would not (fire and police, respectively). Absence of contraindications was associated with physicians' willingness to be vaccinated (P = 0.006). Many physicians (66%) and most public safety personnel (88%) considered themselves inadequately informed on smallpox vaccine. In a multivariate analysis, inadequately informed respondents were more likely to be undecided (OR = 2.23, CI = 1.39 to 3.56).

CONCLUSIONS

Before implementation of the smallpox vaccination program, self-assessed knowledge about smallpox disease and vaccine were poor.

Emergence of community-associated methicillin-resistant Staphylococcus aureus USA 300 clone as a cause of health care-associated infections among patients with prosthetic joint infections

BACKGROUND

Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) has emerged as an important cause of staphylococcal infections, but there have been little data on whether CA-MRSA causes health care-associated infections.

METHODS

A case-control study was performed to identify risk factors for prosthetic joint infections (PJI). Antibiograms of isolates associated with PJI were reviewed. Molecular typing of available MRSA isolates was done using pulsed field gel electrophoresis (PFGE). Nares cultures of health care workers who provided care to those orthopedic patients were obtained.

RESULTS

Over a 13-month period (January 2003-January 2004), 9.5% of patients with prosthetic hip (THA) or knee (TKA) joint surgery developed PJI (7 TKA and 2 THA). The mean time to development of PJI was 20 days. Five infections were caused by CA-MRSA and 3 by methicillin-susceptible S aureus; one was culture negative. All CA-MRSA isolates had identical antibiograms (resistant to beta-lactams and erythromycin; susceptible to clindamycin, trimethoprim-sulfamethoxazole, rifampin, gentamicin, levofloxacin, and vancomycin). Molecular typing of 2 available CA-MRSA isolates revealed that these were the USA300 clone; these isolates were PVL+ and carried SCCmec IV. CA-MRSA was not recovered from nares cultures from 31 health care workers. In multivariate analysis, TKA (OR, 8.1; 95% CI: 1.3-48.1) and surgery time >180 minutes (OR, 7.4; 95% CI: 1.4-39.6) were associated with PJI.

CONCLUSION

We have demonstrated that the CA-MRSA USA300 clone is no longer just a cause of community-acquired infections but has also emerged as a cause of health care-associated infections, causing PJI at our institution.

Update on the treatment of tuberculosis and latent tuberculosis infection

Tuberculosis (TB) has emerged as a global public health epidemic. Despite decreasing numbers of cases in the United States since 1992, TB remains a serious public health problem among certain patient populations and is highly prevalent in many urban areas. The responsibility for prescribing an appropriate drug regimen and ensuring that treatment is completed is assigned to the public health program or the clinician not to the patient. The initial prescribed regimen for the treatment of TB usually consists of 4 drugs: isoniazid, rifampin, pyrazinamide, and ethambutol. The minimum length for the treatment of drug-susceptible TB with a rifampin-based regimen is 6 to 9 months. Providing medications directly to the patient and watching him/her swallow the anti-TB drugs, which is termed directly observed therapy, is recommended for all patients diagnosed with TB and can help ensure higher completion rates, prevent the emergence of drug resistant TB, and enhance TB control. There has been renewed interest in the treatment of those with latent TB infection as a TB-control strategy in the United States for eliminating the large reservoir of individuals at risk for progression to TB. The 2 broad categories of persons who should be tested for latent TB infection are those who are likely to have been recently infected (such as contacts to infectious TB cases) and persons who are at increased risk of progression to TB disease following infection with Mycobacterium tuberculosis (eg, human immunodeficiency virus infection and selected medical conditions; recent immigrants to the United States from high TB-burden countries). The preferred regimen for the treatment of latent TB infection is 9 months of isoniazid. There is now renewed interest in and great need for the development of new drugs to treat TB and latent TB infection.

Risk factors for colonization with methicillin-resistant Staphylococcus aureus (MRSA) in patients admitted to an urban hospital: emergence of community-associated MRSA nasal carriage

BACKGROUND

Surveillance cultures performed at hospital admission have been recommended to identify patients colonized with methicillin-resistant Staphylococcus aureus (MRSA) but require substantial resources. We determined the prevalence of and risk factors for MRSA colonization at the time of hospital admission among patients cared for at a public urban hospital.

METHODS

Anterior nares cultures were obtained within 48 h after admission during a 1-month period. A case-control study and molecular typing studies were performed.

RESULTS

A total of 53 (7.3%) of 726 patients had a nares culture positive for MRSA, and 119 (16.4%) had a nares culture that was positive for methicillin-susceptible S. aureus. In multivariate analysis, risk factors for MRSA colonization included antibiotic use within 3 months before admission (odds ratio [OR], 2.5; 95% confidence interval [CI], 1.2-5.0), hospitalization during the past 12 months (OR, 4.0; 95% CI, 2.0-8.2), diagnosis of skin or soft-tissue infection at admission (OR, 3.4; 95% CI, 1.5-7.9), and HIV infection. A total of 47 (89%) of 53 case patients colonized with MRSA had at least 1 of these independent risk factors, in contrast to 343 (51%) of 673 control patients (OR, 7.5; 95% CI, 3.2 -17.9). Molecular typing demonstrated that 16 (30%) of 53 MRSA nares isolates (2.2% of the 726 isolates) belonged to the USA300 community-associated MRSA (CA-MRSA) genotype.

CONCLUSION

The prevalence of MRSA colonization at the time of patient admission was high (>7%). Limiting surveillance cultures to patients with >or=1 of the identified risk factors may allow for targeted screening. The emergence of CA-MRSA colonization represents a new, unrecognized reservoir of MRSA within hospitals, potentially increasing the risk for horizontal transmission.

How many sputum specimens are necessary to diagnose pulmonary tuberculosis?

The definitive diagnosis of pulmonary tuberculosis (PTB) relies on identifying or culturing Mycobacterium tuberculosis from respiratory specimens. National guidelines have recommended obtaining 3 sputum specimens from patients with suspected tuberculosis, but there has been little data on the number of specimens actually needed to support a diagnosis. We retrospectively reviewed all patients diagnosed with PTB at a public inner-city hospital and assessed the sensitivity of the acid-fast bacilli (AFB) smear and the number of smears needed to establish the diagnosis. Between January 1, 1997 and October 1, 2000, 425 patients were diagnosed with culture-proven PTB. Acid-fast bacilli (AFB) smears and cultures were performed on 951 respiratory specimens from 425 patients. The overall sensitivity of a positive AFB smear increased from 67% with 1 sputum collected to 71% and 72%, respectively, with the second and third specimens. The sensitivity of smears from 239 HIV-negative patients was 75%, 79%, and 80% with 1, 2, and 3 smears, respectively, collected compared with 57%, 61%, and 62%, respectively, for 142 HIV-positive patients. In summary, 2 respiratory specimens proved adequate in establishing a diagnosis of tuberculosis, and the third specimen added little additional diagnostic value.

Furunculosis due to Mycobacterium mageritense associated with footbaths at a nail salon

We report two cases of lower-extremity furunculosis caused by Mycobacterium mageritense. Both patients were patrons of the same nail salon, where they received footbaths prior to pedicures. M. mageritense bacteria isolated from two whirlpool footbaths were determined to be closely related to the patient isolates by pulsed-field gel electrophoresis.

Laryngeal Histoplasmosis

Histoplasma capsulatum is an endemic fungus found in moist, fertile soil; in North America, it is most prevalent in the river valleys of the central United States. Most primary infections in the immunocompetent host are asymptomatic or are thought to be a flu-like illness. Disseminated histoplasmosis most commonly occurs in immunosuppressed patients. Histoplasmosis infection involving the larynx is an extremely rare manifestation. Here, we describe the case of an immunocompetent man with symptomatic, acute pulmonary histoplasmosis with laryngeal involvement who presented with a chief complaint of hoarseness. We also review the literature of immunocompetent patients with laryngeal histoplasmosis.

Hospital Water as a Source ofMycobacterium aviumComplex Isolates in Respiratory Specimens

The clinical significance of recovery of Mycobacterium avium complex (MAC) organisms from respiratory specimens is poorly understood. One hundred sixty-one respiratory MAC isolates from 131 patients at Grady Memorial Hospital (Atlanta) and 13 MAC isolates from the hospital's hot water system were examined. Of the 131 patients, 35 (27%) had MAC disease, and 96 (73%) did not; 94 (72%) were human immunodeficiency virus infected. Ten different clusters were identified by pulsed-field gel electrophoresis. Patients without MAC disease were significantly more likely to have clustered isolates than were patients with MAC disease. Of 110 MAC isolates recovered from patients without MAC disease, 72 (65%) were part of a single large cluster that contained isolates recovered from the hospital's hot water system; 13 (25%) of 51 isolates from patients with MAC disease were also in this cluster. We conclude that acquisition of MAC from institutional water systems leads to substantial MAC disease but that most patients with MAC recovered from respiratory specimens have only transient colonization by MAC.

Transmission of methicillin-resistant Staphylococcus aureus in the neonatal intensive care unit from a patient with community-acquired disease

Methicillin-resistant Staphylococcus aureus (MRSA) has traditionally been a nosocomial pathogen. However, several recent studies have noted community-acquired MRSA among young, healthy patients with no risk factors or healthcare system exposure. We report the transmission of a strain of community-acquired MRSA in our neonatal intensive care unit.

Short-course rifampin and pyrazinamide compared with isoniazid for latent tuberculosis infection: a multicenter clinical trial

BACKGROUND

Rifampin and pyrazinamide are recommended for treatment of latent tuberculosis infection in adults without HIV infection, but reports of severe hepatotoxicity have raised concerns about its safety. Clinical trials have not compared this treatment with isoniazid in adults without HIV infection.

OBJECTIVE

To compare the safety and tolerance of a 2-month regimen of rifampin and pyrazinamide with that of a 6-month regimen of isoniazid for treatment of latent tuberculosis infection.

DESIGN

Multicenter, prospective, open-label trial.

SETTING

Three urban public health tuberculosis clinics in the United States.

PATIENTS

589 adults with latent tuberculosis infection who met U.S. criteria for treatment.

INTERVENTION

Patients were assigned in alternate weeks to receive rifampin and pyrazinamide daily for 2 months (n = 307) or isoniazid daily for 6 months (n = 282).

MEASUREMENTS

Primary end points were hepatotoxicity, other adverse events, and percentage of patients who completed treatment.

RESULTS

Sixteen of 207 (7.7%) patients assigned to rifampin and pyrazinamide developed grade 3 or 4 hepatotoxicity compared with 2 of 204 (1%) patients assigned to isoniazid (odds ratio, 8.46 [95% CI, 1.9 to 76.5]; P = 0.001). The rifampin plus pyrazinamide regimen was more likely than the isoniazid regimen to be discontinued because of hepatotoxicity (odds ratio, 5.19; P = 0.033). The overall percentage of nonhepatotoxic adverse events was 20% in the rifampin-pyrazinamide group and 16% in the isoniazid group. The proportion of patients who completed the study treatment was 61% and 57%, respectively.

CONCLUSIONS

A 2-month regimen of rifampin and pyrazinamide was associated with an increased risk for grade 3 or 4 hepatotoxicity compared with a 6-month regimen of isoniazid. Liver enzymes should be measured routinely during treatment to screen for liver injury and prevent progression to severe toxicity.

Risk of tuberculin skin test conversion among health care workers: occupational versus community exposure and infection

A prospective observational cohort study to assess rates of and risk factors for tuberculin skin test (TST) conversion among health care workers (HCWs) was conducted at an urban hospital located in a high tuberculosis-incidence area in 1994-1998. All hospital employees undergoing required testing every 6 months were included. A total of 69 (1.2%) of 5773 susceptible employees had a documented TST conversion (overall rate, 0.38 per 100 person-years worked). No significant difference existed in conversion rates among employees with frequent, limited, or no patient contact. HCWs with a TST conversion lived in zip codes with higher tuberculosis case rates (P< or =.05). In multivariate analysis, TST conversion was associated with history of bacille Calmette-Guérin vaccination (relative risk [RR], 11.63), annual salary <$20,000 (RR, 3.67), and increasing age. In the setting of an effective tuberculosis infection-control program, TST conversion rates were low, and risk of conversion among HCWs was associated most strongly with nonoccupational factors.

Human papillomavirus-associated oral warts among human immunodeficiency virus-seropositive patients in the era of highly active antiretroviral therapy: an emerging infection

Oral warts are a manifestation of human papillomavirus infection that have been noted infrequently in persons with human immunodeficiency virus (HIV). A nested case-control study was conducted to assess rates of and risk factors for oral warts among a cohort of HIV-seropositive patients. From 1997 through 1999, 56 patients with oral warts were identified among 2194 HIV-positive patients attending an urban oral health center (prevalence, 2.6%). Incident cases of oral warts were significantly more likely to have been diagnosed in 1999 than they were in 1997-1998 (P=.001). Multivariate analysis indicated that the risk of oral warts was associated with a >/=1-log(10) decrease in HIV RNA level in the 6 months before diagnosis of oral warts (odds ratio [OR], 2.35; 95% confidence interval [CI], 1.08-5.11) and with serologic evidence of chronic or previous infection with hepatitis B virus (OR, 2.66; 95% CI, 1.31-5.41). The incidence of oral warts in HIV-seropositive patients appears to be increasing in the era of highly active antiretroviral therapy. Oral warts were associated with reductions in virus load, which suggests that this may in part be related to immune reconstitution.

Risk factors for methicillin-resistance among patients with Staphylococcus aureus bacteremia at the time of hospital admission

BACKGROUND

Community-acquired infections caused by methicillin-resistant Staphylococcus aureus (MRSA) seem to be increasing. Characteristics permitting recognition of patients with such strains would aid infection control efforts and choice of empiric therapy pending culture and susceptibility results.

METHODS

Retrospective review of medical records for all adults seen in the Emergency Care Center at Grady Memorial Hospital, Atlanta, Georgia, whose blood cultures taken within 24 hours of entry yielded S. aureus. Risk factors for the presence of methicillin resistance in S. aureus isolates recovered from patients with staphylococcal bacteremia were assessed.

RESULTS

S. aureus isolates from 118 (40%) of 297 study patients with bacteremia at the time of admission were methicillin-resistant. Multivariate analysis identified hospitalization in the 6 months preceding admission [odds ratio (OR) = 4.4; 95% CI, 2.0-9.8], receipt of antimicrobial agents in the past 3 months (OR = 5.6; 95% CI, 2.6-11.9], presence of indwelling urinary catheter (OR = 7.3; CI, 2.5-20.9), and nursing home residence (OR = 9.9; 95% CI, 3.9-25.6) to be independently associated with the presence of methicillin resistance. All but 4 of the 118 patients with methicillin-resistant strains had at least 1 of these factors and the proportion of resistant isolates progressively increased as more of these features were present.

CONCLUSIONS

The presence of these risk factors should be considered when making decisions about isolation and other infection control procedures as well as empiric antimicrobial therapy with vancomycin for patients with suspected staphylococcal infection at the time of hospital admission. Similar studies could guide practices for dealing with such patients in other centers, because the occurrence of MRSA infections at the time of admission may vary widely by geographic area.

Tuberculosis of the pancreas: report of two cases and review of the literature

Tuberculosis of the pancreas is a clinical entity rarely described in the literature. The pancreas is biologically protected from infection by Mycobacterium tuberculosis, probably because of the presence of pancreatic enzymes that interfere with the seeding of M. tuberculosis. However, when pathogens are able to overcome the resistance, they can have diverse presentations, such as pancreatic masses that can mimic carcinoma, obstructive jaundice, pancreatitis, and gastrointestinal bleeding. Herein we describe 2 cases of pancreatic tuberculosis that presented as multicystic masses, and we review the literature to describe the diverse clinical manifestations of this condition.

Risk factors for Candida species colonization of neonatal intensive care unit patients

BACKGROUND

Candida spp. are increasingly important pathogens in neonatal intensive care units (NICU). Prior colonization is a major risk factor for candidemia, but few studies have focused on risk factors for colonization, particularly in NICU patients.

METHODS

A prospective, multicenter cohort study was performed in six NICUs to determine risk factors for Candida colonization. Infant gastrointestinal tracts were cultured on admission and weekly until NICU discharge and health care worker hands were cultured monthly for Candida spp.

RESULTS

The prevalence of Candida spp. colonization was 23% (486 of 2157 infants); 299 (14%), 151 (7%) and 74 (3%) were colonized with Candida albicans, Candida parapsilosis and other Candida spp., respectively. Multiple logistic regression analysis adjusting for length of stay, birth weight < or = 1000 g and gestational age < 32 weeks revealed that use of third generation cephalosporins was associated with either C. albicans (155 incident cases) or C. parapsilosis (104 incident cases) colonization. Use of central venous catheters or intravenous lipids were risk factors for C. albicans, whereas delivery by cesarean section was protective. Use of H2 blockers was an independent risk factor for C. parapsilosis. Of 2989 cultures from health care workers' hands, 150 (5%) were positive for C. albicans and 575 (19%) for C. parapsilosis, but carriage rates did not correlate with NICU site-specific rates for infant colonization.

CONCLUSIONS

We speculate that NICU patients acquire Candida spp., particularly C. parapsilosis, from the hands of health care workers. H2 blockers, third generation cephalosporins and delayed enteral feedings alter gastrointestinal tract ecology, thereby facilitating colonization.