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PubMed2005

Rapid investigation of hepatitis A virus outbreak by single strand conformation polymorphism analysis.

Investigation of hepatitis A virus (HAV) outbreaks often implies nucleotide sequence analysis. As an alternative method for the identification of related strains, single strand conformation polymorphism method (SSCP) was compared to sequence analysis. Twenty-three strains from sporadic and outbreak cases were studied retrospectively. SSCP, sequence identity and phylogenetic analyses were conducted on a 267 bp fragment of the VP1-2A variable region. The results of SSCP pattern comparison and sequence identity were highly correlated (r = 0.92, P < 0.001). If SSCP showed similar patterns, the VP1-2A fragments had a high and significant probability to have a sequence identity over 99.6%. Results were concordant for outbreak strains. The only discordant result concerned a cluster of three sporadic cases evidenced by phylogenetic analysis while SSCP showed similar patterns for only two of these three cases. A prospective SSCP analysis of a recent HAV outbreak confirmed the reliability of this technique. SSCP may thus provide a rapid and cost-effective tool for preliminary investigation of HAV outbreaks, before undertaking exhaustive nucleotide sequence analysis.

Adolescent↗

PubMed2005

Evidence of the etiological predominance of norovirus in gastroenteritis outbreaks--emerging new-variant and recombinant noroviruses in Hungary.

Between January 2001 and December 2003, stool specimens from 262 (45%) of 581 reported outbreaks of gastroenteritis were investigated for noroviruses in Hungary. Specimens collected from outbreaks of non-bacterial gastroenteritis were examined by reverse-transcription polymerase chain reaction and enzyme immunoassay. In 253 (97%) of 262 outbreaks, norovirus was detected and confirmed by sequencing in 211 (81%). Hospitals (35%), day care centers (30%), and elderly homes (27%) were the most common settings. Diversity and frequency of the genotypes changed over time but with predominance (95%) of genogroup (GG) II strains. Strains grouped into 11 genotypes including an epidemic spread of new-variant GGII4 (Lordsdale virus) and a recently emerged group of natural recombinant strains (GGIIb/Hilversum polymerase) with four capsid types (Hawaii, Mexico, Snow Mountain, and Lordsdale). Clusters of epidemics including food-borne outbreaks were detected. According to this study, noroviruses are the predominant etiological agents causing gastroenteritis outbreaks in Hungary.

Caliciviridae Infections↗

PubMed2006

Serological and molecular epidemiology of measles virus outbreaks reported in Ethiopia during 2000-2004.

Twenty-eight outbreaks in six regions and two major cities in Ethiopia from 2000 to 2004 were investigated, with the collection of 207 venous blood and/or oral fluid samples. Measles diagnosis was confirmed by detection of measles-specific IgM and/or detection of measles virus by polymerase chain reaction (PCR). Of 176 suspected cases tested for specific measles IgM, 142 (81%) were IgM positive. Suspected cases in vaccinated children were much less likely to be laboratory confirmed than in unvaccinated children (42% vs. 83%, P < 0.0001). Of 197 samples analyzed by RT-PCR measles virus genome was detected in 84 (43%). A total of 58 wild-type measles viruses were characterized by nucleic acid sequence analysis of the nucleoprotein (N) and hemagglutinin (H) genes. Two recognized genotypes (D4 and B3) were identified. Each outbreak comprised only a single genotype and outbreaks of each genotype tended to occur in distinct geographical locations. B3 was first observed in 2002, and has now been the cause of three documented outbreaks near to the border of Sudan. D4 genotype was previously observed in an outbreak in 1999 and occurs in more diverse locations throughout the country. These data yield insights into geographical and age-related sources of continued transmission. Refinement of measles control measures might include targeting older age groups (5-14 years) and strengthening routine immunization particularly where importation of cases is a concern.

Adolescent↗

PubMed1994

Analysis of nosocomial outbreaks with multiply and methicillin-resistant Staphylococcus aureus (MRSA) in Germany: implications for hospital hygiene.

Two outbreaks of nosocomial infections with MRSA, one in a urological unit in connection with transurethral prostatectomy and the other in an orthopaedic clinic with infections after implantation of prosthetic hips, have been analyzed on the basis of typing MRSA by phage-patterns, plasmid profiles and genomic DNA fragment patterns. Main reasons for these outbreaks were obviously mistakes in hospital hygiene and an inappropriate antibiotic prophylaxis (in the first outbreak a quinolone over about 7 days, in the second a third generation cephalosporin). Both outbreaks could be stopped by measures of hospital hygiene including isolated or cohort nursing of affected patients, and change in antibiotic prophylaxis. Intensive care units (ICUs) are more often affected by MRSA than other clinical settings. As described by the example of an outbreak with MRSA in a municipal hospital, ICUs can play a special role in intrahospital spread of MRSA. The recently observed inter-regional clonal interhospital dissemination of MRSA in Germany is mainly due to a transfer of patients between hospitals; prewarning of the hospital of destination and a number of hygiene measures can prevent further spread.

Anti-Bacterial Agents↗

PubMed2002

Investigation of a slaughterhouse-related outbreak of Q fever in the French Alps.

The aim of the study presented here was to describe the different epidemiological methods used to investigate an outbreak of Q fever that occurred in the spring of 1996 among inhabitants of Briançon, a small town in the French Alps. Three approaches were used: (i) a comparison between a 2-month exhaustive serological survey among blood donors and a retrospective serological survey performed on frozen plasma collected by the transfusion centre in the spring of 1995; (ii) a serological survey performed in the general population by cluster sampling, using dried blood on blotting paper; and (iii) a case-control study. A total of 29 cases of acute Q fever were diagnosed by physicians during hospitalisations of the patients or ambulatory care. The case-con-trol study suggested that the outbreak resulted from airborne transmission of contaminated sheep waste, which had been left uncovered in the slaughterhouse area. Such transmission may have been facilitated by the nearby heliport. The comparison between the cumulative incidence of Q fever among blood donors during the spring seasons of 1995 and 1996 confirmed the outbreak (0.38% vs. 2.58%, respectively; P<0.0001). Health authorities promptly decided to close the slaughterhouse. The use of complementary epidemiological methods allows investigators to focus on major issues related to an outbreak: timely detection of cases, identification of the source, estimations of incidence, and public health intervention. Rapid recognition and management of outbreaks in the general population of a rural region need to be improved, particularly at a time when airborne agents could be used as biological weapons.

Abattoirs↗

PubMed2005

Evaluation of a commercial enzyme immunoassay for detection of norovirus in outbreak specimens.

The aim of the study presented here was to use faeces from 41 gastroenteritis outbreaks (130 specimens) in Victoria, Australia, to evaluate the sensitivity and specificity of the RIDASCREEN norovirus enzyme immunoassay (EIA) kit relative to reverse transcription-polymerase chain reaction and/or electron microscopy. Seven specimens known to contain sapovirus, adenovirus, astrovirus and rotavirus were also tested. For single-specimen diagnosis the kit gave a specificity and sensitivity of 47% and 71%, respectively; altering the positivity cut-off to give a specificity of 73% reduced the sensitivity to 44%. Thus, the kit cannot be recommended for single-specimen diagnosis. One specimen containing adenovirus but not norovirus was identified as non-specifically positive by the EIA kit. If the criterion used for outbreak positivity was at least one EIA-positive specimen per outbreak, the kit's outbreak sensitivity was 94% but the outbreak specificity was only 60%.

Caliciviridae Infections↗

PubMed2002

Nosocomial neonatal outbreak of Serratia marcescens--analysis of pathogens by pulsed field gel electrophoresis and polymerase chain reaction.

BACKGROUND: We investigated an outbreak of Serratia marcescens in the neonatal intensive care unit (NICU) and the pediatric intensive care unit (ICU) of the University Children's Hospital Leipzig, Germany. PATIENTS AND METHODS: From September to November 1998 15 patients were infected or colonized by S. marcescens. During the outbreak swabs from eye, blood, throat and nose were taken from every patient hospitalized in the ICUs. RESULTS: In 15 cases (14 from the NICU and one from the pediatric ICU) the cultures yielded S. marcescens. All strains were investigated by pulsed field gel electrophoresis (PFGE) as well as by polymerase chain reaction (PCR) fingerprinting. Both molecular typing methods revealed corresponding fingerprint patterns in all of the 15 isolates. Typing results of the outbreak-related isolates demonstrated that two epidemic strains of distinct genotypes were associated with cross-infections of a group of five and a group of ten patients, respectively. The three invasive and seven of the colonizing isolates were related genotypically. CONCLUSION: This survey shows that PCR and PFGE are comparable in respect to the discrimination and reproducibility for epidemiological studies of S. marcescens strains in nosocomial outbreaks. Genotypic fingerprinting of bacterial isolates is useful and important to limit nosocomial infections. Fingerprinting sources of nosocomial infections can be traced both by PFGE and PCR. All patients infected recovered completely and the nosocomial outbreak could be stopped rapidly.

Cross Infection↗

PubMedDate not supplied

A second community outbreak of waterborne giardiasis in Canada and serological investigation of patients.

A waterborne outbreak of giardiasis which occurred 5 years after another in the same town in Canada was investigated. Sera from residents defined as cases or non-cases were tested by enzyme-linked immunosorbent assay (ELISA) and compared with sera from symptomatic and asymptomatic control groups. The outbreak-associated Giardia isolate was retrieved from contaminated drinking water and antigen from this strain was used in the serological investigation. Up to 84% of cases were identified by ELISA. More cases were identified by elevated immunoglobulin (Ig) G than by either elevated anti-Giardia IgA or IgM levels. Residents of the community infected during the first outbreak were significantly less likely to have been reinfected during the second outbreak. This is the first report of a second waterborne outbreak occurring in a community and results of the investigations are consistent with an acquired, protective immunity lasting at least 5 years.

Adolescent↗

PubMed1984

Silver staining of DNA restriction fragments for the rapid identification of adenovirus isolates: application during nosocomial outbreaks.

The ultrasensitive photochemical silver stain for nucleic acids, described by Beidler et al. (1982), has been applied to the detection of adenovirus restriction fragments as a relatively rapid technique for the identification of virus isolates. In this study, restriction enzyme cleavage analysis was used to characterize adenovirus isolates from what appeared to be two nosocomial outbreaks. The first outbreak was thus shown to include two clusters of patients, and involved two serotypes Ad7c and Ad40. The second outbreak was unrelated and involved Ad35. Although restriction analysis does not replace serum neutralization as a routine method for typing adenoviruses, it is a much more rapid means of discriminating between different patient isolates, providing a current rather than retrospective analysis of a nosocomial outbreak. During the first outbreak, restriction analysis identified two distinct adenovirus serotypes from one patient--Ad7c from a nasopharyngeal aspirate and Ad41 from a stool specimen. Restriction analysis is also valuable for the sub-typing of virus isolates. In this study, the Ad40 and Ad41 isolates were shown to be variants of the respective prototype strains.

Adenoviridae Infections↗

PubMed1987

A hospital outbreak caused by a chlorhexidine and antibiotic-resistant Proteus mirabilis.

An outbreak of urinary-tract infection involving a strain of Proteus mirabilis resistant to gentamicin and several other antibiotics affected 90 patients in Southampton between July 1980 and May 1985. The outbreak strain was also resistant to chlorhexidine and this, in combination with the antibiogram and Dienes' test, permitted differentiation from other P. mirabilis strains. The outbreak had features in common with other Enterobacteriaceae outbreaks, although certain aspects of the population involved have made it particularly difficult to control. The outbreak commenced shortly after the introduction of a catheter care policy which involved the use of chlorhexidine, and although the majority of the cases were colonized before this policy was enforced, chlorhexidine had been used extensively for other procedures within the district. Preliminary evidence suggests that there is no genetic linkage between the chlorhexidine and multiple antibiotic resistance.

Age Factors↗

PubMed1989

Outbreaks of astrovirus type 1 and rotavirus gastroenteritis in a geriatric in-patient population.

Two outbreaks of viral gastroenteritis occurred in seven psychogeriatric wards of a 469-bed psychiatric hospital. The outbreaks occurred over an eight-week period; the first affected 30 people and rotavirus was detected in 12 of 14 persons from whom faecal specimens were available. The second affected 32 people (15 of whom were affected in the previous outbreak) and astrovirus was detected in 5 of the 24 people from whom specimens were available. Specific IgM to astrovirus was demonstrated in 3 patients. The rotavirus outbreak was characterised by a longer duration of illness (mean 4 days), and more severe symptoms; two elderly female patients had severe symptoms over a 14-15 day period but recovered. In the astrovirus outbreak the duration of illness was shorter and symptoms were milder although the attack rate was higher than that observed for rotavirus.

Adult↗

PubMed1992

Costs of an outbreak of wound infections in an orthopaedic ward.

An outbreak of serious wound infections occurring in an orthopaedic ward is reported. The outbreak involved 10 patients, all of whom had undergone clean, orthopaedic operative procedures. The outbreak was eventually terminated by discarding five damaged and contaminated mattresses. The costs incurred during this outbreak were calculated using a retrospective comparative study. The infected patients had an average increased hospital stay of 17 days and average increased costs of 2220 pounds. The outbreak demonstrated the high costs of hospital-acquired infection and the need for further investment in infection control programmes.

Beds↗

PubMed1994

An outbreak of group C streptococcal infection in a maternity unit.

An outbreak of Group C streptococcal infection (Streptococcus equisimilis serotype T204) occurred in a Maternity Unit in Durham over a 2-week period. The outbreak strain possessed an M-protein antigen identical to that found in a previously reported Maternity Unit outbreak. Seven patients in total were affected, and in two patients infected perineal wounds took several weeks to heal. The source of the outbreak appeared to be a patient who developed a perineal wound infection and who subsequently returned to the ward for reassessment. Environmental contamination is likely to have been the reservoir of infection for the subsequent patients. The outbreak was controlled by applying strict infection control procedures and establishing a high standard of routine cleaning.

Cross Infection↗

PubMed1995

A major outbreak of methicillin-resistant Staphylococcus aureus caused by a new phage-type (EMRSA-16)

An outbreak of methicillin-resistant Staphylococcus aureus (MRSA) infection caused by a novel phage-type (now designated EMRSA-16) occurred in three hospitals in East Northamptonshire over a 21-month period (April 1991--December 1992). Four hundred patients were colonized or infected. Seven patients died as a direct result of infection. Chest infections were significantly associated with the outbreak strain when compared with methicillin-sensitive S. aureus. Twenty-seven staff and two relatives who cared for patients were also colonized. A 'search and destroy' strategy, as advocated in the current UK guidelines for control of epidemic MRSA was implemented after detection of the first case. Despite extensive screening of staff and patients and isolation of colonized and infected patients, the outbreak strain spread to all wards of the three hospitals except paediatrics and maternity. A high incidence of throat colonization (51%) was observed. Failure to recognize the importance of this until late in the outbreak contributed to the delay in containing its spread. Key parts of the strategy which eventually contained the local outbreak were the establishment of isolation wards in two hospitals, treatment of all colonized patients and staff to eradicate carriage and screening of all patients upon discharge from wards where MRSA had ever been detected. EMRSA-16 spread to neighbouring hospitals by early 1992 and to London and the South of England by 1993. It is distinguished from other epidemic strains by its characteristic phage-type, antibiogram (susceptibility to tetracycline and resistance to ciprofloxacin), and in the pattern given on pulse field electrophoresis.

Adolescent↗

PubMed1982

Progressive resistance in a single strain of Acinetobacter calcoaceticus recovered during a nosocomial outbreak.

A study was undertaken to investigate a nosocomial outbreak of acinetobacter calcoaceticus. The outbreak occurred in a shock-trauma intensive care unit (ICU) during a 6-month period and involved a total of 37 cases. Although no deaths were attributable to Acinetobacter, 60% of patients from whom Acinetobacter was isolated were determined to have a lower respiratory tract infection. A significant difference (p less than 0.05) was noted between the length to stay in the unit of patients who acquired Acinetobacter (mean 23.9 days) and of those who remained free of the organism (mean 2.58 days). The average day on which cultures first became positive was 14.85. During the last 3 months of the outbreak, the ICU Acinetobacter isolates developed an unusual pattern of aminoglycoside resistance that differed significantly (p less than 0.001) from the sensitivities of non-ICU Acinetobacter isolates. No plasmids could be detected in selected aminoglycoside-resistance Acinetobacter. Pseudomonas aeruginosa isolated concurrently from patients with Acinetobacter showed no abnormal variation in antimicrobial sensitivities. These findings were interpreted to mean that the outbreak was the result of the persistence of a single strain of A. calcoaceticus within the ICU. Termination of the outbreak was attributed to initiation of control measures.

Acinetobacter↗

PubMedDate not supplied

Epidemiologic typing of Enterobacter sakazakii in two neonatal nosocomial outbreaks.

Two unrelated hospital outbreaks of Enterobacter sakazakii, involving meningitis, bacteremia, and colonization of neonates, were investigated. In each of these outbreaks, E. sakazakii was isolated from both patients and dried infant formula. In previous outbreaks, the source and mode of transmission of E. sakazakii in neonatal infections was not determined. In this study, we used a combination of typing methods (plasmid analysis, antibiograms, chromosomal restriction endonuclease analysis, ribotyping, and multilocus enzyme electrophoresis) to evaluate the isolates from each outbreak as to their relatedness. The typing results differed among outbreaks, but in each one, patient and formula isolates shared the same typing pattern. The only exceptions were disk antibiograms, which often varied among colonies selected from each of the isolates. Plasmid analysis, chromosomal restriction endonuclease analysis, ribotyping, and multilocus enzyme electrophoresis all were effective as epidemiological typing methods for E. sakazakii, especially when used in combination. By using this typing scheme, we have confirmed that E. sakazakii from intrinsically contaminated dried infant formula was the source of neonatal infection.

Anti-Bacterial Agents↗

PubMed2006

Delayed recognition of a pseudo-outbreak of Mycobacterium terrae.

Pseudo-outbreaks of mycobacteria are difficult to recognize because of long incubation periods for growth and species identification. We report our experience with one clinical microbiology laboratory that isolated a species of nontuberculous mycobacteria from 14 patient specimens. These specimens came from 12 patients at 2 hospitals over a 6-day period and included 6 different fluids or tissues. Because of the delay between mycobacterial specimen submission and growth in culture, the outbreak was not noted until more than a month later. Initial species determination by a reference laboratory indicated that these isolates were Mycobacterium fortuitum. One patient received treatment for presumed M fortuitum brain infection, and it was not effective in changing her clinical course. The isolates were sent to the Centers for Disease Control and Prevention (CDC) for identification and typing by pulsed-field gel electrophoresis. The CDC determined that the isolates were an identical strain of M terrae, thus confirming a pseudo-outbreak. Combining pseudo-outbreak isolates with those correctly identified initially as M terrae during the 6-day period in question, there were 22 samples from 20 patients with M terrae. Since the pseudo-outbreak, the number of cultures of M terrae in the clinical laboratory has returned to baseline levels without any specific intervention.

Bacterial Typing Techniques↗

PubMed2006

Outbreak of epidemic methicillin-resistant Staphylococcus aureus in a regional burns unit: management and implications.

Colonization of burn patients with methicillin-resistant Staphylococcus aureus (MRSA) is not uncommon, however an outbreak that necessitates closure of a burns unit is relatively rare. The objective of this study was to present the experience of a regional adult burns unit where an outbreak of epidemic MRSA-15 (EMRSA-15) took place. During the studied period, 176 patients were admitted to the unit, 52 with burns, 48 for elective plastic surgery procedures while the remainder belonged to other specialties. Patients admitted under burns and plastic surgery were investigated together with 46 staff members to control the outbreak. MRSA was isolated in 18 patients out of which 12 had EMRSA-15. Among the staff members, MRSA was isolated in nine of which five had EMRSA-15. The burns unit was closed to all admissions to terminate this outbreak. The MRSA positive staff members were sent on "special leave" and underwent treatment with nasal mupirocin and triclosan body wash. All staff members were able to return to work after one week's treatment. The burns unit underwent re-furbishment and decontamination while it was closed. In conclusion, the study shows that an outbreak of EMRSA was controlled successfully, however, it highlights the implications of such an event for a regional burn service with regard to staff, patients and guidelines for management.

Adult↗