Explosive COVID-19 outbreak in a German nursing home and the possible role of the air ventilation system.

BACKGROUND: Most COVID-19 outbreaks in nursing homes are explained by transmission of SARS-CoV-2 from nurses or visitors. METHODS AND RESULTS: We describe an outbreak with 64 of the 67 residents identified as COVID-19 cases within two weeks (34 in nursing block 1, 30 in nursing block 2), at least 32 of them had relevant symptoms of COVID-19. Thirteen of the residents' deaths were associated with COVID-19. In addition, 27 of approximately 60 staff members were identified as COVID-19 cases, 23 of them had relevant symptoms. In none of the samples from residents or staff was a mutation of SARS-CoV-2 detected. Quarantine of the residents was already in force at the beginning of the outbreak. A common source among the staff was considered to be unlikely because the two nursing home blocks had no staff rotation and the staff had to wear FFP2 masks during contact with residents. Three months after the outbreak the RNA of SARS-CoV-2 was detected on 14 of 39 sampled indoor surfaces of the air ventilation system with Ct values between 34.9 and 41.9, but only at the air supply in the corridor (11 of 24 samples) and the air overflow in the door between the corridor and the residents' rooms (three of 11 samples) but not at the air exhaust in the residents' bathrooms. CONCLUSIONS: The air ventilation system and an inversion weather situation three days before the first confirmed case may have enhanced viral spread inside the nursing home assuming that a common source with a high viral load had existed at the time of outbreak.

Outbreak of carbapenem-resistant Acinetobacter baumannii in the intensive care unit: a multi-level strategic management approach.

An outbreak of carbapenem-resistant Acinetobacter baumannii (CRAb) occurred in an interdisciplinary intensive care unit, affecting 10 patients. Within hours of recognition of the spread of CRAb an intervention team was instituted for collection of available data, decision-making, communication and monitoring of all interventions performed, including cohorting, temporary stop of admissions, staff education, and enforcement of infection control measures. An area was defined for cohortation of patients colonized with CRAb, with a separate nursing team and a second set of mobile equipment. New transmissions were no longer observed after only four days into the institution of enhanced infection control measures.

Monitoring bacterial contamination of blood components in Germany: effect of contamination reduction measures.

BACKGROUND AND OBJECTIVES: National guidelines for monitoring bacterial contamination of blood components were introduced in Germany in 1997. Between 1998 and 2002, numerous measures were implemented to prevent bacterial contamination. This study investigates their impact on contamination rates. MATERIALS AND METHODS: Culture-based testing for bacterial detection on a random sample of blood components is part of routine quality control in German blood establishments. Using standardized questionnaires, data from the production periods 1998, 2001 and 2005/2006 were collected and analysed. RESULTS: The bacterial contamination rate of RBCs was reduced from 0·157% in 1998 to 0·029% in 2005/2006 (P<0·001). While the contamination rate of apheresis PCs remained nearly unchanged over the years, it dramatically decreased for pooled PCs by 70% to a contamination rate of 0·158% (P=0·001) within the last observation period, similar to that of apheresis PCs. The contamination rate of plasma decreased from 0·100% in 1998 to 0·019% in 2005/2006 (P=0·002). CONCLUSIONS: Precautionary measures significantly reduced bacterial contamination rates of blood components. Long-term monitoring with standardized methods is appropriate to evaluate the cumulative effect of contamination-preventing measures.

Bacterial contamination of platelet concentrates prepared by different methods: results of standardized sterility testing in Germany.

BACKGROUND AND OBJECTIVES: National guidelines for monitoring the bacterial contamination rate of blood components were introduced in Germany in 1997. The objective of this study was to present and evaluate the results of sterility testing of platelet concentrates (PCs) prepared by different methods. MATERIALS AND METHODS: The analysis of results of sterility testing of blood component production from transfusion medicine centres in Germany in 1998 and 2001 was based on information collected using standardized questionnaires. RESULTS: The bacterial contamination rates for single-donor PCs derived from whole blood and apheresis (0.210% vs. 0.156%) were comparable and showed no significant difference. However, pooled PCs produced from four buffy coats using the sterile docking procedure showed a significantly higher bacterial contamination rate compared with single-donor PCs derived from whole blood and apheresis (0.184% vs. 0.604%). CONCLUSIONS: Use of standardized methods for sterility monitoring is sufficient to assess collection and production processes in terms of hygiene and yields reliable data on bacterial contamination rates of blood components. The methods described are suitable for using to analyse the efficiency of newly introduced methods to reduce bacterial contamination rates of blood components (e.g. diversion, bacteria screening and pathogen inactivation).

Household cleaning and surface disinfection: new insights and strategies.

Recently, new insights into the persistence of pathogens, their transfer from inanimate surfaces to humans and the risk of contamination and dissemination of pathogens by detergents have been gained. Furthermore, new experimental data on the interruption of chains of infection by disinfectants as well as results of outbreak-control studies are now available. Hence it has become necessary to reassess the potential benefits using disinfectants to prevent and control nosocomial infections. Based on the new findings and in view of the increasing incidence of nosocomial infections and antibiotic resistances, the German Robert-Koch-Institut has issued completely revised recommendations on Household Cleaning and Surface Disinfection. With respect to these recommendations we developed a new test method, which allows comparison of the efficacy of disinfection in reducing the microbial loads and their dissemination with that of cleaning procedures under practical conditions. In a multi-factor approach, mechanical properties (wet mop technique), utensils (different mop materials) and active agents (disinfectant, detergent) were taken into consideration. We found that under the given conditions, dissemination of the test organism Staphylococcus aureus did not take place when using aldehydes and peroxides, it did take place, however, when water, surfactants, and the disinfectants glycol derivatives, quaternary ammonium compounds and alkylamines were used.

Experimental hepatitis A virus infection in guinea pigs.

Although many of the properties of hepatitis A virus (HAV) are known, several aspects of HAV pathogenesis are still not understood, such as the mechanism underlying the hepatotropism or HAV replication in extrahepatic sites. Detailed studies of these aspects were hampered mostly by the lack of accessible animal models, since only nonhuman primates are susceptible to experimental infections. An alternative animal model would also be of interest to assess the primary replication site and for the evaluation of the safety and efficacy of vaccines. A study was undertaken to determine whether HAV can infect guinea pigs and whether they are useful as a model for studying aspects of HAV pathogenesis and for the evaluation of vaccines. HAV variants adapted to primate or guinea pig tissue culture were used to inoculate guinea pigs intraperitoneally and by the oral route. The animals were observed for clinical disease, shedding of HAV in stools, viremia, seroconversion, evidence for liver damage by biochemical liver function tests, virus presence in the liver, development of hepatic histopathological changes, and occurrence of HAV in extrahepatic organs. The animals developed an active, clinically inapparent infection with specific histopathological changes in the liver. Although virus replication occurred, as shown by RT-PCR and isolation of infectious virus from feces and serum, it seems unlikely that guinea pigs are suitable for studying the clinical features of hepatitis A, because the clinical and laboratory parameters remained normal. However, guinea pigs appear useful for studying some aspects of HAV pathogenesis and for testing the safety of vaccines.

Perinuclear accumulation of hepatitis A virus proteins, RNA, and particles and ultrastructural alterations in infected cells.

The exact intracellular site of hepatitis A virus (HAV) production is unknown, possibly due to its usually slow and inefficient replication. Using immunocytochemistry and in-situ RT-PCR, we show that in cells infected with the rapidly replicating HAV strain HAS-15, viral proteins and RNA are scattered throughout the cytoplasm and accumulate in the perinuclear cytoplasmic area. Various ultrastructural alterations were found in infected cells, such as large polyribosomes, swelling of the perinuclear space and the ER, and dilatation of Golgi cisternae. In addition, HAV infection induced the formation of large arrays of annulate lamellae. Direct visualization of HAV particles was scarce. The various ultrastructural alterations described here might represent different phases of the replicative cycle of HAV that is asynchronous in the infected cell layer.

Systemic infection of an immunocompromised patient with Methylobacterium zatmanii.

We describe the identification of Methylobacterium zatmanii as the causative agent of bacteremia and fever in an immunocompromised patient. The patient, a 60-year-old man, had a 5-month history of acute myeloid leukemia and had been on chemotherapy throughout this period. Seven days after the onset of neutropenia, the patient developed fever. The combination of ciprofloxacin, co-trimoxazole, imipenem, amikacin, and vancomycin led to a complete defervescence. On subculture from six positive blood cultures, the organism grew only on buffered charcoal yeast extract agar and not on standard agars. Identification by universal PCR and subsequent sequence analysis of the amplified 16S rRNA gene segment was achieved. This identification by molecular biology techniques was confirmed by conventional biochemical tests. To our knowledge, this is the first description of M. zatmanii isolated from patient material.

[Disturbed neutrophil activation in pneumonia during medicinal immunosuppression]. / Gestörte Neutrophilenrekrutierung bei Pneumonie im Rahmen einer medikamentösen Immunsuppression.

BACKGROUND: In medically immunosuppressed patients with pneumonia, the BAL cell differential and neutrophils secretion products were determined and compared to patients with pneumonia without defined immunodeficiency in order to define a possibly deficient neutrophil function. PATIENTS AND METHODS: Forty-eight medically immunosuppressed patients were studied: 24 pts. after renal transplantation receiving threefold immunosuppression (cyclosporine, azathioprine, prednisolone), 14 pts. with non-Hodgkin-lymphoma receiving polychemotherapy and 10 pts. with rheumatologic disorders (rheumatoid arthritis n = 3, M. Wegener n = 5 und SLE n = 2) receiving cyclophosphamide or methotrexate. For comparison, 116 patients without defined immunodeficiency and pneumonia and 16 healthy adults were studied. In addition to the cell differential the BALF concentrations of the neutrophil degranulation products myeloperoxidase (MPO) and lactoferrin were determined using immunoluminometric assays. For identification of microorganisms semiquantitative cultures were used. RESULTS: Neutrophilia > 5% in BAL was present in only 36% of the immunosuppressed pts. in contrast to 91.3% of the immunocompetent pts. (p < 0.01). The same pathogen was found in 14 pts. of each group, so that a pathogen matched comparison was possible. The neutrophil percentage and the BALF concentration of lactoferrin was significantly lower in the immunosuppressed group. In blood there was no difference with regard to the neutrophil count between the groups. CONCLUSIONS: BAL characteristics of immunosuppressed pts. are different from those of immunocompetent pts. with pneumonia. The pathogen-matched comparison proved that this is not due to different pathogens. Medically immunosuppressed patients with pneumonia exhibit a disturbed neutrophil recruitment. A neutrophil percentage < 5% in BAL of medically immunosuppressed patients does not preclude a bacterial infection.