Staphylococcal bacteremia in a "Germ-free" unit.

The rate of carriage and infections due to strains of Staphylococcus aureus were evaluated in adults with acute leukemia in isolators characterized by laminar air flow and barrier isolation. Patients were randomly given antimicrobial prophylaxis with oral nonabsorbed antibiotics and a nasal antibiotic ointment. In four years S aureus was isolated from the nostrils or other sites in 36 patients. Persistent isolation was noted in 24 patients. Suppression of gut flora was associated with a higher carriage rate of S aureus. Five episodes of bacteremia due to S aureus occurred at the nadir of leukopenia induced by chemotherapy. Death occurred within five days in the three patients whose peripheral white blood cell count did not rise. Patient isolation and suppression of gut flora helped reduce infections due to Pseudomonas sp and fungi, but S aureus emerged as a life-threatening pathogen.     

Association of methicillin-resistant Staphylococcus aureus (MRSA) colonization with high-risk sexual behaviors in persons infected with human immunodeficiency virus (HIV)

Methicillin-resistant Staphylococcus aureus (MRSA) infections are an important cause of morbidity, especially among human immunodeficiency virus (HIV)-infected persons. Since an increasing number of MRSA skin and soft tissue infections involve the perigenital areas, some have suggested that these infections may be sexually transmitted. We performed a cross-sectional study among HIV-infected adults from 4 geographically diverse United States military HIV clinics to determine the prevalence of and the factors (including sexual practices) associated with MRSA colonization. Swabs were collected from the nares, throat, axillae, groin area, and perirectal area for S. aureus colonization. Data on sociodemographic characteristics, medical conditions, and sexual history were collected. Multivariate logistic regression models evaluated factors associated with carriage. We studied 550 HIV-infected adults with a median age of 42 years; 93% were male; and race/ethnicity was white for 46%, African American for 35%, and other for 19%. Median CD4 count was 529 cells/mm, 11% had a history of a MRSA infection, and 21% had a sexually transmitted infection within the last year, including 8% with syphilis. One hundred eighty (33%) were colonized with S. aureus and 22 (4%) with MRSA. The most common location for carriage was the nares, followed by the perigenital area (groin or perirectal area). Factors associated with MRSA carriage in the multivariate analyses included a sexually transmitted infection in the last year (odds ratio [OR], 4.2; p<0.01), history of MRSA infection (OR, 9.4; p<0.01), and African American compared with white race/ethnicity (OR, 3.5; p=0.01). In separate multivariate models, syphilis, nongonococcal urethritis, and public bath use were also associated with MRSA carriage (all p<0.01). In conclusion, a history of recent sexually transmitted infections, including syphilis and urethritis, was associated with MRSA carriage. These data suggest that high-risk sexual activities may play a role in MRSA transmission.     

The role of nasal carriage in Staphylococcus aureus infections

Staphylococcus aureus is a frequent cause of infections in both the community and hospital. Worldwide, the increasing resistance of this pathogen to various antibiotics complicates treatment of S aureus infections. Effective measures to prevent S aureus infections are therefore urgently needed. It has been shown that nasal carriers of S aureus have an increased risk of acquiring an infection with this pathogen. The nose is the main ecological niche where S aureus resides in human beings, but the determinants of the carrier state are incompletely understood. Eradication of S aureus from nasal carriers prevents infection in specific patient categories-eg, haemodialysis and general surgery patients. However, recent randomised clinical trials in orthopaedic and non-surgical patients failed to show the efficacy of eliminating S aureus from the nose to prevent subsequent infection. Thus we must elucidate the mechanisms behind S aureus nasal carriage and infection to be able to develop new preventive strategies. We present an overview of the current knowledge of the determinants (both human and bacterial) and risks of S aureus nasal carriage. Studies on the population dynamics of S aureus are also summarised.     

CD4 counts as predictors of opportunistic pneumonias in human immunodeficiency virus (HIV) infection

STUDY OBJECTIVE: To determine if circulating CD4+ lymphocyte counts are predictive of specific infectious or neoplastic processes causing pulmonary dysfunction. DESIGN: Retrospective, consecutive sample study. SETTING: Referral-based clinic and wards. PATIENTS: We studied 100 patients infected with human immunodeficiency virus (HIV) who had had 119 episodes of pulmonary dysfunction within 60 days after CD4 lymphocyte determinations. MEASUREMENTS AND MAIN RESULTS: Circulating CD4 counts were less than 0.200 X 10(9) cells/L (200 cells/mm3) before 46 of 49 episodes of pneumocystis pneumonia, 8 of 8 episodes of cytomegalovirus pneumonia, and 7 of 7 episodes and 19 of 21 episodes of infection with Cryptococcus neoformans and Mycobacterium avium-intracellulare, respectively. In contrast, circulating CD4 counts before episodes of nonspecific interstitial pneumonia were quite variable: Of 41 episodes, 11 occurred when CD4 counts were greater than 0.200 X 10(9) cells/L. The percent of circulating lymphocytes that were CD4+ had a predictive value equal to that of CD4 counts. Serum p24 antigen levels had no predictive value. CONCLUSIONS: Pneumocystis pneumonia, cytomegalovirus pneumonia, and pulmonary infection caused by C. neoformans or M. avium-intracellulare are unlikely to occur in HIV-infected patients who have had a CD4 count above 0.200 to 0.250 X 10(9) cells/L (200 to 250 cells/mm3) or a CD4 percent above 20% to 25% in the 60 days before pulmonary evaluation. Patients infected with HIV who have a CD4 count below 0.200 X 10(9) cells/L (or less than 20% CD4 cells) are especially likely to benefit from antipneumocystis prophylaxis.     

High Staphylococcus aureus nasal carriage rate in patients with acquired immunodeficiency syndrome or AIDS-related complex

Staphylococcus aureus has been reported to cause a high number of infections and septicemias, often related to intravenous catheters, in patients with acquired immunodeficiency syndrome (AIDS). Our objective was to assess the frequency of S. aureus nasal carriage among patients with AIDS or AIDS-related complex (ARC). The nasal carriage rate of S. aureus was determined within 24 hours of admission in 64 consecutively hospitalized patients with AIDS or ARC. Intravenous drug abusers were excluded. A control group of 64 patients with other diseases was also tested. Of 64 patients with AIDS or ARC, 35 (55%) were nasal carriers of S. aureus, compared with 18 (28%) of 64 control patients. Recent hospitalization did not influence carriage rate, nor did the recent use of antibiotics or zidovudine. The significant S. aureus carriage rate in patients with AIDS or ARC may contribute to the high incidence of intravenous catheter-related S. aureus infections in this population.     

Staphylococcus aureus nasal carriage in 104 cirrhotic and control patients. A prospective study

BACKGROUND/AIMS: Bacterial infections, specially Staphylococcus aureus (S. aureus) septicemia, remain a leading cause of death following liver transplantation. It has been demonstrated that nasal carriage of S. aureus is associated with invasive infections in patients undergoing hemodialysis and could be decreased by use of antibiotic nasal ointment. However, in cirrhotic patients, the frequency of nasal carriage is unknown. The aims of this study were to determine the prevalence of S. aureus nasal carriage in cirrhotic patients and to assess nosocomial contamination. METHODS: One hundred and four patients were included in a prospective study, 52 cirrhotic and 52 control (hospitalized patients without cirrhosis or disease which might increase the rate of nasal carriage of S. aureus). On admission and after a few days of hospitalization, nasal specimens from each anterior naris were obtained for culture. S. aureus was identified by the gram strain, positive catalase and coagulase reactions; antibiotic susceptibility was determined using a disk-diffusion test. RESULTS: Both groups were similar with regard to age and sex. The prevalence of nasal colonization on hospital admission was 56% in cirrhotic patients and 13% in control patients (p = 0.001). After an average of 4 days, 42% of cirrhotics and 8% of control patients were colonized (p = 0.001), without any nosocomial contamination. Three strains out of 29 were oxacillin-resistant in cirrhotic patients, and none in controls (p>0.05). There was no statistical difference in carriage rate according to sex, age, cause of cirrhosis and Child-Pugh score. Previous hospitalization (OR, 6.3; 95% CI, 2.3 to 19.9; p = 0.0006) and cirrhosis (OR, 4.4; 95% CI, 1.5 to 13.4; p = 0.0048) were independent predictors of colonization. CONCLUSION: Cirrhotic patients had a higher S. aureus nasal carriage rate than control subjects. Previous hospitalization and cirrhosis diagnosis were correlated to nasal colonization. Further studies are necessary to determine if nasal decontamination could reduce S. aureus infections after liver transplantation.     

Immune restoration disease after the treatment of immunodeficient HIV-infected patients with highly active antiretroviral therapy

Background To determine if infectious disease events in HIV-infected patients treated with highly active antiretroviral therapy (HAART) are a consequence of the restoration of pathogen-specific immune responses, a single-centre retrospective study of all HIV-infected patients commencing HAART prior to 1 July 1997 was undertaken to determine the incidence, characteristics and time of onset of disease episodes in HAART responders (decrease in plasma HIV RNA of > 1 log₁₀ copies/mL).
Methods Baseline and post-therapy changes in CD4 T-cell counts and HIV RNA were compared in patients with and without disease and delayed-type hypersensitivity responses to mycobacterial antigens were measured in selected patients.
Results Thirty-three of 132 HAART responders (25%) exhibited one or more disease episodes after HAART, related to a pre-existent or subclinical infection by an opportunistic pathogen. Disease episodes were most often related to infections by mycobacteria or herpesviruses but hepatitis C virus (HCV), molluscum contagiosum virus and human papilloma virus were also implicated. They were most common in patients with a baseline CD4 T-cell count of < 50/uL and occurred most often during the first 2 months of therapy and when CD4 T-cell counts were increasing. Mycobacteria- and HCV-related diseases were associated with restoration of pathogen-specific immune responses.
Conclusions We conclude that improved immune function in immunodeficient patients treated with HAART may restore pathogen-specific immune responses and cause inflammation in tissues infected by those pathogens.     

Population dynamics of nasal strains of methicillin-resistant Staphylococcus aureus--and their relation to community-associated disease activity

BACKGROUND: Nasal carriage of methicillin-resistant Staphylococcus aureus (MRSA) plays a key role in the epidemiology and pathogenesis of disease. The purpose of this study was to determine the characteristics and dynamics of nasal strains of MRSA, as well as their relation to community-associated disease activity. METHODS: This study is a cross-sectional survey and molecular epidemiologic analysis of nasal colonization by S. aureus in homeless and runaway youths, an underserved population at high risk for staphylococcal disease. RESULTS: Of the 308 study participants, 27.6% carried S. aureus, and 6.2% carried MRSA. Subgroups of individuals with increased MRSA carriage rates were also at highest risk for community-associated MRSA infection; these subgroups included individuals with either HIV infection or AIDS, injection drug users, patients with abscesses, and those recently hospitalized. Multilocus sequence typing and pulsed-field gel electrophoresis identified 2 genotypes--ST59:P (USA1000) and ST8:S (USA300)--that accounted for 84.2% (16/19) of the MRSA isolates carried. The genotypes were distinct from nosocomial genotypes endemic in the hospital, although they originated from individuals with prior exposure to health care. CONCLUSIONS: Comparison of MRSA strains from asymptomatic carriers versus concurrently collected community-associated clinical strains from patients treated at local health-care facilities allowed for the identification of 3 population dynamics of nasal strains of MRSA: (1) endemic clones--for example, ST8:C and ST59:P--sustained asymptomatic carriage and infection over prolonged periods; (2) an epidemic clone, ST8:S, demonstrated enhanced capacity for rapid transmission and widespread infections; and (3) an outbreak clone, ST30:Z (USA1100), was highly infectious but exhibited poor asymptomatic transmission.     

Asymptomatic oral carriage of Candida species in HIV-infected patients in the highly active antiretroviral therapy era

Oropharyngeal candidiasis is the most common opportunistic fungal infection in individuals infected with human immunodeficiency virus. CD4+ lymphocytes count and the quantification of viral RNA in blood plasma have been found to be the main markers of HIV disease progression. The present study was conducted to evaluate Candida sp. diversity in the oral cavity of HIV-infected patients and to determine whether there was association of CD4+ cell count and viral load with asymptomatic oral Candida carriage. Out of 99 HIV-positive patients studied, 62 (62.6%) had positive culture for Candida (oral carriage) and 37 patients (37.4%) had Candida negative culture (no oral carriage). The etiologic agents most common were C. albicans and C. tropicalis. The range of CD4+ was 6-2305 cells/mm3 in colonized patients and 3-839 cells/mm3 for non-colonized patients, while the viral load was 60-90016 copies/mL for colonized patients and 75-110488 copies/mL for non colonized patients. The viral load was undetectable in 15 colonized patients and in 12 non colonized patients. Our results showed that there was no significant difference of the variables CD4+ cell count and viral load between oral candida carriage and no oral candida carriage patients.     

Tuberculosis infection in HIV-infected Indian patients

Individuals with HIV infection are at increased risk for tuberculosis (TB). The altered CD4 T-cell homeostasis induced by HIV infection may play a key role in the development of tuberculosis in HIV-infected patients. In this retrospective analysis, lymphocyte profiles (CD4 and CD8 count) of subjects infected with HIV, with or without TB, were evaluated. The influence of tuberculosis treatment on the CD4 count in dually infected patients was analyzed in a subset of patients available for follow-up. Of 421 subjects with HIV infection studied, 105 (24.9%) were positive for TB (HIV+TB+). A statistically significant difference (p = 0.0001) was found in the median CD4+ counts between the HIV+TB- (297.5 per microliter) and HIV+TB+ (181 per microliter) groups. TB was found to be the indicator disease for HIV infection in 36 (34.2%). In 65.7% of HIV-infected patients, TB was the first AIDS-defining disease. Of 72 patients who were receiving TB treatment, 33 (45.9%) showed an increase in CD4 counts, but this was statistically not significant. None of these patients was undergoing antiretroviral therapy prior to TB treatment. We conclude from this retrospective study that TB, a common HIV-related opportunistic infection in Indian subjects, is associated with lower CD4+ counts. The influence of TB therapy on CD4 counts in the patients needs to be further investigated.     

Association between nasal carriage of Staphylococcus aureus and infection in liver transplant recipients.

We reviewed the records of 87 patients who underwent liver transplantation and who were screened by use of nasal swabs on the day before surgery. Twenty-four patients harbored methicillin-susceptible Staphylococcus aureus (MSSA), and 8 harbored methicillin-resistant S. aureus (MRSA). MSSA infection occurred in 3 (12.5%) of 24 MSSA carriers and in 2 (3.2%) of 63 noncarriers (nonsignificant). In contrast, MRSA infection occurred more frequently in MRSA carriers (7 [87.5%] of 8) than in MRSA noncarriers (8 [10.1%] of 79; P<.001). Nasal carriage of MRSA is associated with a very high risk of MRSA infection in liver transplant recipients.     

Risk and outcome of nosocomial Staphylococcus aureus bacteraemia in nasal carriers versus non-carriers

Staphylococcus aureus is the second most frequent cause of nosocomial blood infections. We screened 14008 non-bacteraemic, non-surgical patients for S aureus nasal carriage at admission, and monitored them for development of bacteraemia. Nosocomial S aureus bacteraemia was three times more frequent in S aureus carriers (40/3420, 1.2%) than in non-carriers (41/10588, 0.4%; relative risk 3.0, 95% CI 2.0-4.7). However, in bacteraemic patients, all-cause mortality was significantly higher in non-carriers (19/41, 46%) than in carriers (seven/40, 18%, p=0.005). Additionally, S aureus bacteraemia-related death was significantly higher in non-carriers than in carriers (13/41 [32%] vs three/40 [8%], p=0.006). S aureus nasal carriers and non-carriers differ significantly in risk and outcome of nosocomial S aureus bacteraemia. Genotyping revealed that 80% of strains causing bacteraemia in carriers were endogenous.     

Spread of Staphylococcus aureus in hospitals: causes and prevention

Methicillin-resistant Staphylococcus aureus (MRSA) has become a major nosocomial pathogen in many hospitals worldwide. Even more alarming, MRSA strains that are vancomycin intermediate-susceptible are isolated with increasing frequency, making therapy for staphylococcal infections even more difficult and prevention more important than ever. Spread of S. aureus in hospitals and infection control measures are reviewed. The major sources of S. aureus in hospitals are septic lesions and carriage sites of patients and personnel. Carriage often precedes infection. The anterior nares are the most consistent carriage site, followed by the perineal area. Skin contamination and aerial dissemination vary markedly between carriers and are most pronounced for combined nasal and perineal carriers. The principal mode of transmission is via transiently contaminated hands of hospital personnel. Airborne transmission seems important in the acquisition of nasal carriage. Infection control strategies include screening and isolation of newly admitted patients suspected of carrying MRSA or S. aureus with intermediáte resistance to vancomycin, implementation of an infection control program to prevent transmission of resistant strains between patients and hospital personnel, and institution of a proper antibiotic policy to minimize antibiotic resistance development. MRSA carriers should be treated with intranasal antibiotics, e.g. mupirocin, and skin disinfectants to eliminate carriage. Education of hospital personnel is essential. Improved knowledge about the best ways to ensure favourable infection control practices is needed. Active intervention against the spread of MRSA is important.     

Sinusitis in HIV-infected patients: a clinical and radiographic review.

PURPOSE: To describe the clinical, radiographic, and laboratory features of sinus disease in human immunodeficiency virus (HIV)-infected individuals. PATIENTS: Seventy-two patients with a history of sinusitis identified from 1,461 consecutive admissions (667 patients) to the HIV ward at The Johns Hopkins Hospital. METHODS: Retrospective chart review. SETTING: The Johns Hopkins Hospital. RESULTS: Sinusitis was identified in 72 HIV-infected patients, predominantly individuals with a CD4 cell count of less than 200/mm3. A history of respiratory infections such as bacterial pneumonia, bronchitis, and otitis media was common. Although nasal congestion and postnasal drainage were found in the majority of patients, symptoms of sinusitis were often nonspecific and the diagnosis was incidental in 28 patients (33%). Magnetic resonance imaging or computed tomography was significantly more sensitive than plain radiography (p less than 0.001) in defining the extent of the disease, particularly with posterior sinus involvement, which occurred in the majority of the patients. The number of radiologically abnormal sinuses correlated inversely with the CD4 count. Although the majority of patients responded at least partially to antibiotic therapy, only 15% had complete resolution of clinical symptoms. Fifty-eight percent of patients had clinical and/or radiographic evidence of recurrent/persistent sinus infection, and chronicity correlated with a CD4 count less than 200/mm3 (p less than 0.001). CONCLUSIONS: Sinusitis in HIV-infected patients is common, severe, and difficult to treat. Patients with CD4 counts less than 200/mm3 are prone to disease involving multiple sinuses that responds incompletely to antibiotic therapy, often resulting in chronic sinusitis. Unlike the immunocompetent host, the majority of the HIV-infected patients with advanced immunodeficiency develop posterior sinus disease.     

Musculoskeletal manifestations in patients positive for human immunodeficiency virus: correlation with CD4 count

OBJECTIVE: To determine the relationship between the CD4+ lymphocyte count and musculoskeletal manifestations of human immunodeficiency virus (HIV) infection. METHODS: All patients from 1991 to 1998 who were positive for HIV with osteoarticular manifestations were reviewed retrospectively. HIV positivity was confirmed by ELISA and Western blot. CD4 count was performed by flow cytometry. RESULTS: We studied 74 patients with osteoarticular manifestations. The study group comprised 61 men (82.4%) and 13 women (17.5%) with a mean age of 34.2 years (range 17-62). Fifty-two patients were iv drug users (70.3%). Septic arthritis was present in 20 cases (23.0%), soft tissue infections in 9 cases (12.2%), spondyloarthropathies in 6 cases (8.1%), lymphomas in 9 cases (12.2%), osteomyelitis in 6 (8.1%), and 24 miscellaneous cases (32.4%). The mean CD4 count was as follows: septic arthritis 164.7 cells/mm3, soft tissue involvement 127.1 cells/mm3, spondyloarthropathies 245.8 cells/mm3, lymphoma 132.8 cells/mm3, and osteomyelitis 233.6 cells/mm3. CONCLUSION: Osteoarticular manifestations in the setting of HIV infection tend to be predominantly infectious. S. aureus is the microorganism most frequently involved. Ostearticular infections always appeared when the CD4 count was < 200 and pyomyositis and lymphoma appeared when CD4 was < 150. CD4 counts may be useful predictors to determine the type of musculoskeletal manifestation.     

A randomized clinical trial of mupirocin in the eradication of Staphylococcus aureus nasal carriage in human immunodeficiency virus disease.

Seventy-six human immunodeficiency virus (HIV)-infected patients with Staphylococcus aureus nasal carriage were randomized to treatment groups receiving intranasal mupirocin or placebo twice daily for 5 days. Nasal cultures for S. aureus were obtained at 1, 2, 6, and 10 weeks after therapy. At 1 week, 88% of mupirocin-treated patients had negative nasal cultures compared with 8% in placebo patients (P<.001). The percentage of mupirocin-treated patients with persistently negative nasal cultures decreased over time (63%, 45%, and 29% at 2, 6, and 10 weeks, respectively) but remained significantly greater than the placebo group (3% at 2, 6, and 10 weeks). In mupirocin-treated patients, most (16/19) instances of nasal recolonization were with pretreatment strains (determined by means of by pulsed field gel electrophoresis); mupirocin resistance was not observed. Five days of treatment with mupirocin eliminated S. aureus nasal carriage in HIV-infected patients for several weeks; however, since the effect waned over time, intermittent dosing regimens should be considered for long-term eradication.     

Investigation of colonization with methicillin-resistant and methicillin-susceptible Staphylococcus aureus in an outpatient population in Turkey

Methicillin-resistant Staphylococcus aureus (MRSA), known as a nosocomial pathogen, has been isolated from community-acquired infections since the 1980s. It has been reported that there are carriers of MRSA in the community although the rate of carriers is low and the most important risk factor of community-acquired carriage is hospitalization or referral to healthcare facilities. We attempted to investigate methicillin-resistant and methicillin-susceptible S. aureus colonization, respectively, in nasal and axillary swabs obtained from 500 patients without a history of hospitalization who were admitted to outpatient clinics and from 102 healthcare workers chosen as a control group. Of the patients, 9.4% had nasal S. aureus colonization without methicillin-resistant strains. Of the health care workers, 8.8% had S. aureus colonization without methicillin-resistant strains and only one worker had MRSA. The nasal carriage ratio of S. aureus in children was found to be 19.1% (22 of 115), and that in adults was 6.5% (25 of 385). The difference between the two age groups was determined as statistically significant (P = 0.006).     

Staphylococcus aureus nasal colonization among HIV-infected adults in Botswana: prevalence and risk factors

We sought to determine the clinical and epidemiologic determinants of Staphylococcus aureus nasal colonization in HIV-infected individuals at two outpatient centers in southern Botswana. Standard microbiologic techniques were used to identify S. aureus and methicillin-resistant S. aureus (MRSA). In a sample of 404 HIV-infected adults, prevalence of S. aureus nasal carriage was 36.9% (n?=?152) and was associated with domestic overcrowding and lower CD4 cell count. MRSA prevalence was low (n?=?13, 3.2%), but more common among individuals with asthma and eczema. The implications of these findings for HIV management are discussed.     

Associations between Staphylococcus aureus Genotype, Infection, and In-Hospital Mortality: A Nested Case-Control Study

We screened 14,008 adult nonsurgical patients for Staphylococcus aureus nasal carriage at hospital admission and assessed them for invasive S. aureus disease and in-hospital mortality. Multilocus sequence typing was performed on endogenous invasive strains and nasal strains of matched asymptomatic carriers to investigate whether virulent clones could be identified in nasal carriers. Clonal complex (CC) 45 was significantly underrepresented (odds ratio [OR], 0.16 [95% confidence interval {CI}, 0.04-0.59]) and CC30 was overrepresented (not statistically significant) among invasive strains (OR, 1.91 [95% CI, 0.91-4.0]). The distribution of CCs of invasive S. aureus strains in noncarriers did not differ from that in carriers. Those infected with S. aureus strains belonging to a CC had higher mortality than those infected with strains not belonging to a CC (P<.05), which indicates the coevolution of S. aureus virulence and spread in humans.