A hospital-acquired outbreak of methicillin-resistant Staphylococcus aureus infection initiated by a surgeon carrier

Methicillin-resistant Staphylococcus aureus (MRSA) has become an important hospital-acquired pathogen, infection with which often leads to major morbidity and mortality. The principal mode of transmission for MRSA is transfer of the organism from a carrier or infected patient to uninfected patients by the hands or clothing of staff. From January 16 1997 to April 2 1997, five patients who had undergone open-heart surgery in a hospital located in northern Taiwan, developed surgical wound infections and mediastinitis caused by MRSA. All patients were hospitalized in two adjacent surgical intensive care units (ICUs) following their respective operations. Consequently, the hospital's infection control team commenced investigation of the outbreak. Pulsed-field gel electrophoresis (PFGE) has been shown to be a good technique for epidemiological typing. By analysing cultures taken from staff by PFGE, it was demonstrated that this outbreak was most likely to be initiated by a surgeon with MRSA carriage. After elimination of the carrier state using topical mupirocin treatment, the outbreak was controlled without further incident.

[Hepatitis E virus infection in Albania]

Acute HEV in Albania make up 35.7% of acute non A-non B hepatitis and 2.4% of all acute viral hepatitis cases, affecting women more with a 2:1 ratio, and are described more frequently in adults (73.3%) older than 35 years. In the general population (control group), the prevalence of anti-HEV antibodies increases progressively with age, from 1.2% in the younger than 9 years, to 17.7% among the over 60, in general the average is of 9.7%. A statistical comparison of anti-HEV antibodies in healthy persons younger than 20, and those 20 years old and over is significant (p < 0.0001). HEV transmission by blood transfusion, mentioned by some authors, could be related to the infection of blood donors. We have not found any positive cases in thalassemic children who received between 24 and 169 transfusions. The prevalence of anti-HEV antibodies in pregnant women is lower than in the general population (p < 0.0001). In patients with chronic liver disease, in comparison with the general population (control group), there is no statistical significant difference (p = NS).

Nosocomial Candida albicans acquisition in a geriatric unit: epidemiology and evidence for person-to-person transmission

This prospective study, which included 69 patients over a two-month period, was conducted to evaluate the incidence of community-acquired carriage and hospital-acquired yeasts in elderly patients hospitalized in a short stay care unit. Furthermore, possible person-to-person transmission was investigated by means of genotyping the Candida albicans isolates obtained from samples (throat swabs, urine and stools) systematically taken from the patients at different times during the hospitalization and from healthcare workers (throat swabs and handwashes) in the middle of the observation period. This study showed a high prevalence rate of 64% for community-acquired yeast carriage and a 40% incidence rate for hospital- acquired yeasts. Mycological analysis of the samples from the healthcare workers revealed eight of them to be colonized in the oral cavity. In addition, pulsed field gel electrophoresis and mitochondrial DNA analysis of the C. albicans isolates demonstrated person-to-person transmission. This study suggests that regular mycological sampling should be done as hospitalized elderly patients are frequently colonized by yeasts. Likewise, oropharyngeal swabs from healthcare workers may be helpful in this setting.

A purpose built MRSA cohort unit

The control of hospital-acquired infection, in particular methicillin-resistant Staphylococcus aureus (MRSA) remains a challenge. Our hospital has established a purpose built 11-bed cohort unit with on-site rehabilitation for care of patients colonized with MRSA, in an attempt to improve their quality of care. Prior to the opening of this unit a number of concerns were voiced and the aim of this study was to address these. First, to establish if patient cohorting reduces the likelihood of successful decolonization, second, to evaluate the risk of staff colonization, and finally to see if successful environmental control of MRSA is possible.A patient database was established detailing patient demographics, infection rates, eradication and reacquisition rates. Staff screening was performed weekly, at the start of a period of duty. Sixty environmental sites were screened before unit opening, at 48h, six weeks and at six months. There were 88 admissions in the first six months; 62 patients were colonized with MRSA, and 26 patients (10 surgical, 16 medical) had MRSA infections. Twenty-three of 88 patients (26%) were successfully decolonized, which compares favourably with an eradication rate of 20% for the rest of the hospital. Twenty staff members participated in weekly screening. Five staff members colonized with MRSA were detected and all were successfully decolonized. Environmental control was achieved with a combination of a daily detergent clean and a once weekly clean with phenolic disinfectant. Our preliminary data suggest that, despite cohorting patients colonized with MRSA, with proper education and supervised cleaning protocols, it is possible to control environmental MRSA load, successfully decolonize patients and limit the risk of staff colonization.

MRSA carriage: the relationship between community and healthcare setting. A study in an Italian hospital

From May 1997 to June 1998, all patients admitted to the study institution were screened at entry for MRSA carriage (both colonization and infection). Eighty-six MRSA carriers were identified; of these, 85 were nasal carriers. Risk factors were compared to those of 86 controls. Although the vast majority of both carriers and controls had at least one previous hospital stay, carriers were less likely than controls to be referred from a community setting, and had resided within the community for a shorter time before the current admission. The number of underlying conditions was comparable in the two groups, but those infected were more likely to have cancer than the controls. While community-acquired MRSA carriage is rare, exposure to a health care setting (particularly if repeated) within six months from the current admission, is a risk factor for MRSA carriage and introduction of the organism into an institution.

Carriers of foot-and-mouth disease virus: a review

This review describes current knowledge about persistent foot-and-mouth disease virus (FMDV) infections, the available methods to detect carrier animals, the properties of persisting virus, the immunological mechanisms, and the risk of transmission. In particular, knowledge about the carrier state, the period in which virus can be isolated from animals 28 days or longer post infection, is important, because the risk that animals may carry the virus will influence the diagnostic and preventive measures that need to be taken. Although many years of research have led to much knowledge about foot-and mouth disease and its causative agent, there are still numerous aspects of the virus and the disease that are not yet fully understood. Areas for further research on persistence of FMDV are discussed.

Preventing the spread of vancomycin-resistant enterococci in a long-term care facility

OBJECTIVES

To test the hypothesis that infection control practices can prevent the spread of vancomycin-resistant enterococci (VRE) to residents of a long-term care facility (LCF) from an affiliated acute care facility with a high endemic rate of colonization.

DESIGN

Point prevalence study of the rate of rectal colonization.

SETTING

A state-supported veterans nursing home and an acute care veterans hospital.

PARTICIPANTS

Residents in a state veterans home.

INTERVENTIONS

Identification of patients with rectal colonization by VRE before transfer to the state veterans home, contact isolation for colonized veterans, use of oral bacitracin to eliminate colonization.

MEASUREMENTS

Rectal swab and culture for VRE, review of clinical records and recording of presumptive risk factors for VRE colonization. The risk factors were age, gender, length of stay at nursing home, treatment with vancomycin or oral antibiotics, prior hospitalization at the acute care facility during the prior year, use of indwelling urethral catheters, presence of diarrhea, and fecal or urinary incontinence.

RESULTS

Sixty-nine of 200 residents were cultured in the first study (1996) and 130 of 230 residents were cultured in the second study (1998). Residents who consented to culture differed from those who did not only with regards to gender (2 vs 7, P = .012). In neither study were any residents found to be colonized with VRE who had not already been identified as positive on admission.

CONCLUSIONS

Adherence to infection control practices by the patient care staff of the LTCF was associated with the absence of transmission of VRE colonization among its residents. The presence of rectal colonization with VRE in an acute care patient should not be a barrier to acceptance in a nursing home.

Horizontal transmission of HBV infection among students in Turkey

In this study, the HBsAg carrier state and the role of horizontal transmission were investigated among primary and high school students in southeastern Anatolia where HBsAg seropositivity is remarkably high. In total, 350 students from primary school first grade, 350 students from fifth grade, 400 students from high school eleventh grade and 400 healthy adults as a control group were studied. In all cases HBsAg and anti-HBs were screened by ELISA. HBsAg positivity was 2.4% in first grade, 6.1% in fifth and 6.7% in eleventh grade students. Anti-HBs positivity was 14% in first grade, 20% in fifth and 21% in eleventh grade students. HBsAg positivity was 9% and anti-HBs, 49% in the control group. There is a significant difference between first and fifth grade students for HBsAg positivity (2.1% vs 6.1% and P<0.05). This difference decreased during the high school years (6.2% and P>0.05). There is also a similar statistically significant difference for anti-HBs positivity during the primary school years (14% vs 20%, P<0.05). These findings show that the risk of horizontal transmission of HBV is especially important during elementary school years between the ages of 7 and 11 y. All infants or at least elementary school first grade students in Turkey should have HBV vaccinations.

Transmission of Pneumocystis carinii disease from immunocompetent contacts of infected hosts to susceptible hosts

Pneumocystis carinii organisms constitute a large group of heterogeneous atypical microscopic fungi that are able to infect immunocompromised mammals by an airborne route and to proliferate in their lungs, inducing Pneumocystis carinii pneumonia. This pneumonia remains a crucial epidemiological challenge, since neither the source of Pneumocystis carinii infection in humans nor the process by which humans become infected has been clearly established. Polymerase chain reaction (PCR) assays have shown that profoundly immunosuppressed patients without pneumocystosis can be subclinically infected with Pneumocystis. Other PCR-based studies have suggested that healthy immunocompetent hosts are not latent carriers of the parasite. However, recent reports have indicated that Pneumocystis carinii can persist for limited periods in the lungs of convalescent rats after recovery from corticosteroid-induced pneumocystosis, and also that immunocompetent mammals can be transiently parasitized by Pneumocystis carinii after close contact with hosts with Pneumocystis carinii pneumonia. Can transiently parasitized hosts be a source of infection for immunosuppressed hosts? In order to investigate this important clinical question, the ability of immunocompetent BALB/c mice, which were carrying subclinical levels of Pneumocystis carinii, to transmit the infection by the airborne route to highly susceptible, uninfected mice with severe combined immunodeficiency was studied. The results indicated that the immunocompetent mice, transiently parasitized by Pneumocystis carinii organisms after close contact with Pneumocystis carinii-infected mice, were able to transmit the infection to Pneumocystis carinii-free mice with severe combined immunodeficiency.

Carriage of N. lactamica in a population at high risk of meningococcal disease

Carriage of Neisseria lactamica among household contacts of meningococcal disease (MCD) cases was investigated during an epidemic in Auckland, New Zealand. The overall carriage rate for N. lactamica was 10.5% (95% CI 7.4-13.5%) with a peak carriage rate in 2-year-olds of 61.5% (95% CI 26.6-88.1%). Factors associated with a significant (P < 0.05) increase in the likelihood of carriage included runny nose, the number of people per bedroom and youth. Genetic analysis of isolates revealed a striking correlation of strains within the same household but a high level of diversity between households, suggesting that household contact is an important factor in acquisition. For household contacts aged less than 5 years, there was a higher rate of carriage amongst those in contact with MCD cases under 8 years old than for contacts of cases aged 8 years and over. It is likely that development of MCD is a reflection of the nature and intensity of the exposure to a virulent strain of N. meningitidis, coupled with an absence of host resistance among those individuals not carrying N. lactamica.

Detection and characterization of Shiga toxin-producing Escherichia coli from seagulls

Shiga toxin (Stx)-producing Escherichia coli (STEC) strains isolated from a seagull in Japan were examined. A total of 50 faecal samples was collected on a harbour bank in Hokkaido, Japan, in July 1998. Two different STEC strains, whose serotypes were O136:H16 and O153:H-, were isolated from the same individual by PCR screening; both of them were confirmed by ELISA and Vero cell cytotoxicity assay to be producing active Stx2 and Stx1, respectively. They harboured large plasmids, but did not carry the haemolysin or eaeA genes of STEC O157:H7. Based on their plasmid profiles, antibiotic resistance patterns, pulsed-field gel electrophoresis analysis (PFGE), and the stx genes sequences, the isolates were different. Phylogenic analysis of the deduced Stx amino acid sequences demonstrated that the Stx toxins of seagull-origin STEC were closely associated with those of the human-origin, but not those of other animal-origin STEC. In addition, Stx2phi-K7 phage purified from O136 STEC resembled Stx2phi-II from human-origin O157:H7, and was able to convert non-toxigenic E. coli to STEC. These results suggest that birds may be one of the important carriers in terms of the distribution of STEC.

Methicillin-resistant Staphylococcus aureus. Nosocomial acquisition and carrier state in a wound care center

OBJECTIVE

To assess methicillin-resistant Staphylococcus aureus (MRSA) nosocomial acquisition and carrier state in a wound care center.

DESIGN AND SETTING

The results of an intervention to control MRSA were compared with those of historical controls at the wound care center of university-based Hôpital Broussais, Paris, France.

PATIENTS

Patients admitted for specific care of chronic ulcers and surgical wounds.

MAIN OUTCOME MEASURES

Incidence rates of MRSA carriers and acquisition in wounds.

RESULTS

Of 88 patients admitted during a 3-month preintervention period in 1993, 18 (21%) were MRSA carriers. Of 334 patients admitted in 1994 and 395 in 1996, 65 (19.5%) and 81 (20.5%) were MRSA carriers, respectively (P=.80). In 1993, 6 (9%) of 70 patients without MRSA acquired MRSA wound infections; the corresponding numbers were 6 (2.2%) of 269 in 1994 and 3 (0.9%) of 314 in 1996. Despite that the number of MRSA carriers remained stable at admission to the wound care center, the rate of MRSA infections in wounds per 100 noncarriers decreased significantly between the preintervention period and subsequent years: 1994 (P=.02) and 1996 (P=.002).

CONCLUSIONS

Although our results are limited by the use of historical controls, they showed that simple infection control measures, such as the use of soap and water and barrier precautions associated with staff education, seemed to significantly reduce MRSA infection rates in patients with chronic skin breaks.

An outbreak of multiply resistant Serratia marcescens: the importance of persistent carriage

An outbreak of multi-resistant Serratia marcescens involving 24 patients occurred in a bone marrow transplant and oncology unit, from September 1998 to June 1999, of whom 14 developed serious infection. This is the first such outbreak described in a BMT unit. All isolates demonstrated the same antimicrobial susceptibility pattern and were the same unusual serotype O21:K14. The antimicrobial susceptibility profile showed reduced susceptibility to ciprofloxacin, gentamicin and piperacillin-tazobactam. As the latter two antimicrobials are part of our empiric therapy for febrile neutropenia, they were substituted with meropenem and amikacin during the outbreak. Investigation revealed breaches in infection control practices. Subsequently, the outbreak was contained following implementation of strict infection control measures. A prominent feature of the outbreak was prolonged carriage in some patients. These patients may have acted as reservoirs for cross-infection. This report also indicates that patients who become colonised with Serratia marcescens may subsequently develop invasive infection during neutropenic periods.

[Monitoring of Staphylococcus aureus colonization in students of a course for nurses aides during their professional education]

Considering our goal of understanding the colonization by Staphylococcus aureus in students from a nursing auxiliary program, during their professional formation, we collected material from the nasal cavity (N), right (Md) and left (Me) hands from 42 students on different moments of their formation relating the levels of colonization to the activities developed during the program. Results showed an oscillation in the colonization rate in different moments and the possibility of agent reciprocal transmission between the students and the taken care receptors, considering the type of contact.

Urine from chronic hepatitis B virus carriers: implications for infectivity

Horizontal transmission of hepatitis B virus (HBV) without apparent sexual or parenteral exposure is common in hyperendemic areas. In most cases, the route of transmission is unknown. To investigate urine as a potential source of infection, serum and urine from 56 chronic hepatitis B surface antigen (HBsAg) carriers were examined for the presence of HBV DNA using the polymerase chain reaction (PCR). Thirty-four of the patients were anti-hepatitis B e antigen (anti-HBe) positive and 22 were hepatitis B e antigen (HBeAg) positive. HBV DNA was detected in serum from 46 patients (82%) and in urine from 28 patients (50%). Most HBeAg-positive patients had HBV DNA detectable in urine (91%), whereas urine samples from anti-HBe-positive patients were found to contain HBV DNA to a lesser extent (24%). When comparing HBV DNA from serum and urine by an end-point titration PCR, a titration difference averaging 10(3) was found between serum and urine. A significant female predominance was also noted among the positive urine samples (P < 0.05), which was not correlated to the presence of haematuria. Detection of HBV DNA may indicate active viral replication, and thereby infectivity. Because a high proportion of chronic HBV carriers were found to have HBV DNA in urine, it is suggested that irrespective of HBeAg/anti-HBe status, urine should be regarded as a potential route of transmission and therefore be investigated further as a means of horizontal and nosocomial transmission of HBV.

Fecal and oral shedding of Helicobacter pylori from healthy infected adults

CONTEXT

Helicobacter pylori commonly infects humans; however, its mode of transmission remains unknown.

OBJECTIVE

To determine how humans-the primary host for H pylori-shed the organism into the environment.

DESIGN

Controlled clinical experimental study conducted from February through December 1998.

SETTING

Clinical research unit of a hospital in northern California.

PATIENTS

Sixteen asymptomatic H pylori-infected and 10 uninfected adults.

INTERVENTION

A cathartic (sodium phosphate) and an emetic (ipecac) were given to all infected subjects and an emetic was given to 1 uninfected subject.

MAIN OUTCOME MEASURE

Confirmed H pylori isolates cultured from stool, air, or saliva before and after catharsis and emesis and from vomitus during emesis. Isolates were fingerprinted using repetitive extragenic palindromic (REP) polymerase chain reaction and species identity was confirmed by sequencing the 16s ribosomal RNA gene.

RESULTS

All vomitus samples from infected subjects grew H pylori, often in high quantities. Air sampled during vomiting grew H pylori from 6 (37.5%) of the 16 subjects. Saliva before and after emesis grew low quantities of H pylori in 3 (18.8%) and 9 (56.3%) subjects, respectively. No normal stools and only 22 (21.8%) of 101 induced stools grew the organism, although 7 (50.0%) of 14 subjects had at least 1 positive culture (2 stool culture samples were contaminated by fungus and were not included). Fingerprints of isolates within subjects were identical to one another but differed among subjects. No samples from uninfected subjects yielded H pylori.

CONCLUSIONS

Helicobacter pylori can be cultivated uniformly from vomitus and, occasionally, from saliva and cathartic stools. The organism is potentially transmissible during episodes of gastrointestinal tract illness, particularly with vomiting.

[Prevention of viral hepatitis B in exposure to carriers of HBsAG in Plzen in 1998]

In 1998 in five Plzen laboratories 128 HBsAg carrierships were found. In 64.8% the patient was evaluated at the time of sampling as a "healthy carrier". Based on the assessed positivity family contacts of these subjects were offered examination of hepatic markers of free immunization. Most people responded because of personal contact with a HBsAg positive patient. Postinfection markers (HBsAg, anti-HBcAg) were detected in 20.6%, in the control group in 5.1% of the examined subjects. 64% sensitive subjects were immunized. Based on the financial costs of the study, it was calculated that examination and immunization of contacts of HBsAg positive subjects in the whole republic would require a sum of 46 million crowns. If laboratory examinations of family contacts were left out the costs would be cca 75%.

Susceptibility and carrier status of impala, sable, and tsessebe for Cowdria ruminantium infection (heartwater)

Three species of wild African ruminants, impala (Aepyceros melampus), sable (Hippotragus equinus), and tsessebe (Damaliscus lunatus), were experimentally inoculated with in vitro culture-derived Cowdria ruminantium organisms, the tick-borne causative agent of heartwater in domestic ruminants, to determine their susceptibility to infection. No clinical disease was observed in any of the ruminants. However, C. ruminantium was detected in the sable by the transmission of heartwater to susceptible sheep, through the tick vector Amblyomma hebraeum, at 10 and 37 days postinfection (PI). Attempts to detect infection in the impala and tsessebe by tick transmission at 54 days PI failed. The impala and tsessebe were reinoculated with C. ruminantium organisms at 146 days after the first inoculation; however, a tick transmission attempt at 66 days after the reinoculation also failed. Seroconversion, as detected by immunoblotting, was demonstrated in the sable and the tsessebe but not in the impala. The results demonstrate that sable can be carriers of C. ruminantium. The susceptibility of tsessebe and impala, however, remains undetermined.

Group A Streptococcus carriage among close contacts of patients with invasive infections

During the past few years, the incidence of invasive group A Streptococcus (GAS) infection has been increasing. However, there are presently no clear recommendations regarding antibiotic prophylaxis for close contacts of index patients. The aims of this study were 1) to determine the prevalence of carriage of the same GAS strain as the patient's among contacts of patients with invasive infections and 2) to assess the importance of exposure duration. From March 1995 to March 1996, the authors prospectively included in the study all patients with invasive GAS infection, as defined by the Working Group on Severe Streptococcal Infections, who came to Hôpital Maisonneuve-Rosemont in Montreal, Quebec, Canada. An epidemiologic investigation was systematically carried out for each index case. Contacts were divided into two groups: those who had spent 24 hours or more with the index patient during the week preceding the beginning of his or her illness and those who had spent 12-24 hours with the index patient during that week. Strains of GAS were examined by serotyping (proteins M and T and the presence or absence of the serum opacity factor) and by characterization of streptococcal pyrogenic exotoxins (exotoxins A, B, and C). One hundred and two contacts of 17 index cases with invasive GAS infection were systematically screened. Contacts were considered positive if they carried the same strain of the bacterium and the same streptococcal pyrogenic exotoxin as the index case. Among the contacts who had spent at least 24 hours per week with their respective index cases, 13 out of 48 (27%) were found to be harboring the same serotype of GAS as the index patient (95% confidence interval 14.5-39.5). By comparison, only one of the 54 contacts in the 12- to 24-hour group (1.8%) was found to be carrying the same strain of the bacterium (95% confidence interval 0-5.3). This difference between the two groups was statistically significant (p<0.001). The median age of the positive carriers (10 years) was significantly lower than the median age of the noncarriers (39 years) (p< or =0.0005). This study showed that close contacts who had spent 12-24 hours with the index patient were rarely colonized with GAS. If antibiotic prophylaxis against GAS is recommended, it should probably target contacts who spent at least 24 hours with an infected patient during the week preceding illness onset.