Prospective surveillance of bacterial colonization and primary sepsis: findings of a tertiary neonatal intensive and intermediate care unit.

BACKGROUND: Preterm infants and critically ill neonates are predisposed to nosocomial infections as sepsis. Moreover, these infants acquire commensal bacteria, which might become potentially harmful. On-ward transmission of these bacteria can cause outbreaks. AIM: To report the findings of a prospective surveillance of bacterial colonization and primary sepsis in preterm infants and neonates. METHODS: The results of the surveillance of bacterial colonization of the gut and the respiratory tract, targeting meticillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE) and Gram-negative bacteria from November 2016 to March 2018 were analysed. Bacterial colonization was compared to surveillance of sepsis. FINDINGS: Six-hundred and seventy-one patients were admitted and 87.0 % (N=584) of the patients were screened; 48.3% (N=282) of the patients screened were colonized with at least one of the bacteria included in the screening; 26.2% of them (N=74) had multi-drug-resistant strains. A total of 534 bacterial isolates were found. The most frequently found species were Escherichia coli, Enterobacter cloacae, Klebsiella oxytoca and Klebsiella pneumoniae. Three MRSA but no VRE were detected. The surveillance detected a K. pneumoniae cluster involving nine patients. There were 23 blood-culture-confirmed sepsis episodes; 60.9% (N=14) were caused by staphylococci. Gram-negative bacteria (one Klebsiella aerogenes and two E. cloacae) caused three sepsis episodes which were preceded by colonization with the respective isolates. CONCLUSIONS: Surveillance of colonization provided a comprehensive overview of species and antibiotic resistance patterns. It allowed early detection of a colonization cluster. Knowledge of colonization and surveillance of sepsis is useful for guiding infection control measures and antibiotic treatment.

Infection control in german-speaking burn centres: results of an online survey.

To systematically evaluate which infection control measures are in place in burn units, we conducted an online survey among 43 German-speaking burn units. The 29 units that responded and agreed to publication represented more than 125 patient beds. All units were located in advanced care hospitals. A total of 14 units provided single rooms only, and 22 units had a nurse-to-patient ratio of at least 1:2. Infection control practices included pre-emptive barrier precautions (29 units), the use of sterile filters for tap water supply (29 units), and an antibiotic stewardship program (24 units). Microbial screening of the patients on admission (23 units), regular prevalence screening (26 units) and surveillance of nosocomial infections (21 units) were also widely used. The high reply rate to the survey indicates the special relevance of infection control for burn units. Our survey shows that great efforts and several measures are being undertaken to address infection control challenges in burn patient care, but it also underlines the need for increased interdisciplinary infection control and antibiotic stewardship activities.

Afin d'évaluer les mesures préventives des infections déployées, nous avons réalisé une enquête en ligne auprès de 43 Centres de Traitement des Brûlés germanophones. Les 29 CTB ayant répondu (et accepté la publication) représentent 125 lits. Tous les CTB étaient situés dans des hôpitaux de référence. Quatorze CTB n'avaient que des chambres seules, 22 avaient un ratio infirmière/patient de1/2. Les mesures préventives comprenaient les précautions barrière (29), des filtres aux points d'eau (29), un programme d'évaluation de l'antibiothérapie (24). La cartographie bactérienne à l'entrée (23), la surveillance de la prévalence des infections (26) et des infections nosocomiales (21) étaient aussi régulièrement déployées. Le taux de réponse élevé pour ce type d'étude montre l'intérêt porté à la prévention des infections en CTB. Cette étude montre que les CTB portent une attention particulière à la prévention et à la surveillance des infections. Elle démontre aussi l'intérêt d'une approche multidisciplinaire et de la mise en place de programmes d'évaluation de l'antibiothérapie.

A multimodal infection control concept in a burn intensive care unit - lessons learnt from a meticillin-resistant Staphylococcus aureus outbreak.

BACKGROUND: Meticillin-resistant Staphylococcus aureus (MRSA) is a frequently encountered pathogen in burn units. Burn patients are especially susceptible to MRSA acquisition and MRSA spread may cause outbreaks in burn units. AIM: To report the characteristics and successful control of an MRSA outbreak and to demonstrate a multimodal infection control concept. METHODS: In addition to a pre-existing infection control concept, several control measures were implemented including weekly prevalence screenings for MRSA, reinforcement of disinfection, restriction of admissions, and short-term unit closure. Epidemiologic investigation and environmental examinations were performed. The outbreak isolates were analysed by pulsed-field gel electrophoresis and spa-typing. A PubMed search was conducted, focusing on MRSA outbreaks in burn units. FINDINGS: This outbreak of hospital-acquired MRSA affected eight patients during a seven-month period, yielding an attack rate of 8%. Epidemiologic and environmental examinations suggested patient-to-patient transmission, which was confirmed by molecular analysis of bacterial isolates revealing a monoclonal pattern. In accordance with findings from other outbreaks in burn units, the implemented measures including patient screening and temporary unit closure resulted in successful control of the outbreak. CONCLUSION: A comprehensive concept is required to control the spread of all multidrug-resistant micro-organisms including MRSA on a burn unit. Where patients colonized or infected with MRSA appear to be the main reservoir, transfer of these patients to other units, or temporary closure of the unit, accompanied by intensive cleaning are very effective measures to stop transmission events.

Serum procalcitonin levels in the postmortem diagnosis of sepsis.

Procalcitonin is regarded as a valuable marker for sepsis in living persons and even in post-mortem investigations. At the Institute of Legal Medicine, 25 autopsy cases with suspected bacterial infectious diseases or sepsis were examined using the semi-quantitative PCT-Q(®)-test (B.R.A.H.M.S., Germany) in 2010 and 2011. As controls, 75 cadavers were used for which there was no suspicion of a bacterial infectious disease or sepsis. Femoral blood was cultured from the cases and from controls, and samples from the brain, heart, lungs, liver, spleen and kidneys were examined histologically for findings seen in sepsis. Twelve cases in the sepsis/infectious disease group (48%) were classifiable as sepsis following synopsis of PCT levels, autopsy results, and histopathological and microbiological findings. This study shows that the semi-quantitative PCT-Q(®)-test is a useful supplementary marker in routine autopsy investigations, capable of classifying death as due to sepsis.

A fatal case of AIDS-defining meningoencephalitis by C. neoformans, sensitive to antifungal therapy.

Cryptococcus neoformans is the most common cause of life threatening meningoencephalitis in HIV-infected patients. Diagnosis is based on tests for cryptoccocal antigen in serum and cerebrospinal fluid, and on culture of the organism. We present a case of AIDS-related cryptococcal meningoencephalitis unresponsive to antifungal combination therapy, despite of evidence of fungal susceptibility in vitro. Significant decreases in cryptococcal antigen titers in serum and cerebrospinal fluid did not correlate with progress in disease and fatal outcome.

Costs of nosocomial pneumonia caused by meticillin-resistant Staphylococcus aureus.

Nosocomial infections with meticillin-resistant Staphylococcus aureus (MRSA) lead to increased health and economic costs. The purpose of this study was to determine costs for nosocomial MRSA pneumonia compared with meticillin-susceptible S. aureus (MSSA) pneumonia. A case-control study was conducted with patients who acquired nosocomial pneumonia with either MRSA or MSSA between January 2005 and December 2007. Patients were matched for age, severity of underlying disease, stay on intensive care units and non-intensive care units, admission and discharge within the same year, and in-hospital stay at least as long as that of cases before MRSA pneumonia. Our analysis includes 82 patients (41 cases, 41 controls). The overall costs for patients with nosocomial MRSA pneumonia were significantly higher than for patients with MSSA pneumonia (€60,684 vs €38,731; P=0.01). The attributable costs for MRSA pneumonia per patient were €17,282 (P<0.001). The financial loss was higher for patients with MRSA pneumonia than for patients with MSSA pneumonia (€11,704 vs €2,662; P=0.002). More cases died than controls while in the hospital (13 vs 1 death, P<0.001). Hospital personnel should be aware of the attributable costs of MRSA pneumonia, and should implement control measures to prevent MRSA transmission.

[Reactivation of tuberculosis with Mycobacterium bovis infection of the oral mucosa during immunosuppression]. / Tuberkulosereaktivierung mit Mycobacterium-bovis-Infektion der Mundschleimhaut unter Immunsuppression.

HISTORY: A 70-year-old woman who had for five years been treated with tumour necrosis factor (TNF)-a-inhibitors for rheumatoid arthritis was admitted because of treatment-refractory oral ulcerations and persisting considerable soft-tissue swelling over the left maxilla. INVESTIGATIONS AND DIAGNOSIS: Multiple mucosal biopsies from the left maxillary sinus revealed necrotizing granulomatous inflammation suspicious of mycobacterial infection. This was subsequently confirmed in concurrent microbiological cultures and ultimately identified as Mycobacterium bovis. This species of the mycobacterium tuberculosis complex has in recent times rarely been seen in clinical practice in Germany. On further questioning the patient reported that she had been treated for "lung disease" as a schoolgirl. TREATMENT AND COURSE: The patient was isolated and quadruple therapy with isoniazide (INH), rifampin (RMP), ethambutol (EMB) and pyrazinamide (PZA) was initiated. Rapid improvement of her condition occurred within two weeks. When microbiological sub-typing using 16s-RNA sequencing had confirmed M. bovis, PZA was replaced by moxifloxacin. CONCLUSION: When investigating the cause of treatment-refractory infections and ulcerations, particularly among immunosuppressed patients, consideration should always be given to mycobacterial infections. Detailed and targeted history-taking is vital.

Of guinea pigs and men--an unusual case of jaundice.

A 21-year-old male presented at the emergency room with jaundice, itching, dry cough, malaise and weight loss of 10 kg during the preceding four weeks. Eighteen months earlier, the patient had suffered an automobile accident leading to polytrauma. Serological markers for viral or other causes of hepatitis were absent. For suspected secondary sclerosing cholangitis, ultrasound and ERCP were performed but failed to reveal pathological findings. A liver biopsy showed cholestatic liver disease without signs of portal field-associated hepatitis. Hepato-biliary scintigraphy demonstrated hepatocellular dysfunction. The patient finally mentioned his guinea pig farm with around 50 animals, 20 of which had recently died for unknown reasons. The patient and three of his guinea pigs were subsequently tested for serological evidence of leptospirosis. IgG and IgM antibodies reacting with Leptospira interrogans were detected in the patient's serum, and all 3 guinea pigs were serologically positive for serovar Bratislava. Bacterial culture was not successful, and also PCR tests remained negative. The clinical symptoms quickly resolved after the initiation of antibiotic therapy with amoxicillin.

Oxygen status of lung granulomas in Mycobacterium tuberculosis-infected mice.

It is often assumed that Mycobacterium tuberculosis (Mtb)-induced granulomatous lesions, particularly those undergoing central caseation, are anoxic, and that the survival of Mtb in these lesions requires the integrity of its non-oxidative respiratory pathways. Using the hypoxia marker pimonidazole, we now provide immunohistochemical evidence that in the most frequently used animal model system of inbred mice Mtb-induced granulomas, even after more than one year of aerogenic infection, are not severely hypoxic. In contrast, chronic aerosol infection with M. avium strain TMC724 was associated with hypoxia surrounding necrotizing granuloma centres. Direct measurements of oxygen tension with a flexible microelectrode in mouse lungs chronically infected with Mtb disclosed a wide range of oxygen partial pressures in different parts of the lungs which, however, rarely approached the anoxic conditions consistently found in necrotizing tumours. We further show that an Mtb mutant, defective in nitrate reductase (narG) necessary for survival under anaerobic conditions in vitro, can persist in the lungs of chronically infected mice to a similar extent as wild-type Mtb. These findings have important implications for the use of the mouse model of Mtb infection in developing eradication chemotherapy and for evaluating putative mechanisms of chronic persistence and latency of Mtb.

The species Mycobacterium africanum in the light of new molecular markers.

The findings of recent studies addressing the molecular characteristics of Mycobacterium tuberculosis complex isolates have initiated a discussion on the classification of M. africanum, especially of those isolates originating from East Africa (cluster F, subtype II) and displaying phenotypic and biochemical characteristics more similar to those of M. tuberculosis. To further address this question, we analyzed a representative collection of 63 M. tuberculosis complex strains comprising 30 M. africanum subtype I strains, 20 M. africanum subtype II strains, 10 randomly chosen M. tuberculosis isolates, and type strains of M. tuberculosis, M. bovis, and M. africanum for the following biochemical and molecular characteristics: single-nucleotide polymorphisms (SNPs) in gyrB and narGHJI and the presence or absence of RD1, RD9, and RD12. For all molecular markers analyzed, subtype II strains were identical to the M. tuberculosis strains tested. In contrast, the subtype I strains as well as the M. africanum type strain showed unique combinations of SNPs in gyrB and genomic deletions (the absence of RD9 and the presence of RD12), which proves their independence from M. tuberculosis and M. bovis. Accordingly, all subtype I strains displayed main biochemical characteristics included in the original species description of M. africanum. We conclude that the isolates from West Africa were proved to be M. africanum with respect to the phenotypic and genetic markers analyzed, while the isolates from East Africa must be regarded as phenotypic variants of M. tuberculosis (genotype Uganda). We propose the addition of the molecular characteristics defined here to the species description of M. africanum, which will allow clearer species differentiation in the future.

LightCycler-based differentiation of Mycobacterium abscessus and Mycobacterium chelonae.

In this study we introduce a rapid procedure to identify Mycobacterium abscessus (types I and II) and M. chelonae using LightCycler-based analysis of the hsp65 gene. Results from 36 clinical strains were compared with hsp65 gene restriction analysis and biochemical profiles of bacilli. As all three methods yielded identical results for each isolate, this procedure offers an excellent alternative to previously established nucleic acid amplification-based techniques for the diagnosis of mycobacterial diseases.

Rapid testing for nitrate reductase activity of Mycobacterium tuberculosis grown in an automated culture system.

In order to reduce the time to detection of nitrate reductase activity, which is arguably the most widely used phenotypic trait to differentiate between Mycobacterium tuberculosis, Mycobacterium bovis and Mycobacterium bovis BCG, the following study was conducted using cultures grown in an automated system. Automated culture systems, which are typically based on liquid medium, have greatly reduced the time-to-recovery of mycobacteria. Yet subsequent testing of isolates for nitrate reductase activity may take several weeks, because culture on solid media is required. Presented here is a procedure to obtain a final result within 24 h for nitrate reductase activity of cultures grown in an automated culture system. Using this procedure, Mycobacterium tuberculosis was rapidly differentiated from Mycobacterium bovis and Mycobacterium bovis BCG.

Improved decontamination method for recovering mycobacteria from patients with cystic fibrosis.

In order to improve the recovery of mycobacteria from patients with cystic fibrosis, the present study evaluated a two-step decontamination procedure for clinical specimens. A total of 920 specimens obtained from 239 patients with cystic fibrosis were treated initially with N-acetyl-L-cysteine/sodium hydroxide. Of these specimens, 31 (3.3%) showed mycobacterial growth and 415 (45.1%) remained contaminated. Contaminated specimens were then subjected to a second round of decontamination, using a combination of N-acetyl-L-cysteine/sodium hydroxide and oxalic acid. Following this second decontamination, the number of specimens overgrown by microorganisms other than mycobacteria was reduced to 7.3%, and an additional 10 specimens positive for mycobacteria were found. The results suggest this two-step protocol could improve the recovery of mycobacteria from heavily contaminated specimens.

[Intestinal tuberculosis: Easier overlooked than diagnosed]. / Darmtuberkulose: leichter zu übersehen als zu sichern.

Intestinal tuberculosis: Easier overlooked than diagnosed. The medical history of two Asian immigrants suffering from intestinal tuberculosis demonstrates the difficulties in finding the correct diagnosis. Intestinal tuberculosis resembles Crohn's disease with regard to clinical symptoms, macroscopic and microscopic intestinal findings. Sonographic, radiologic, endoscopic, and histological examinations facilitate distinguishing both entities. Diagnosis of intestinal tuberculosis is made by identification of the causative microorganism in tissue specimens. As this may be difficult and time-consuming, a therapeutic trial with anti-tuberculous agents may be warranted.

Lack of transmission of mycobacterium abscessus among patients with cystic fibrosis attending a single clinic.

We retrospectively analyzed 1062 respiratory specimens from 214 patients with cystic fibrosis, of whom 5 patients had 36 cultures positive for M. abscessus. Results of molecular typing demonstrated that each of these 5 patients carried a single unique strain (genotype), which suggests that it may not be necessary to segregate patients with CF who are colonized or infected with M. abscessus from those who are not.

Anaerobic nitrate reductase (narGHJI) activity of Mycobacterium bovis BCG in vitro and its contribution to virulence in immunodeficient mice.

Mycobacterium tuberculosis and Mycobacterium bovis cause tuberculosis, which is responsible for the deaths of more people each year than any other bacterial infectious disease. Disseminated disease with Mycobacterium bovis BCG, the only currently available vaccine against tuberculosis, occurs in immunocompetent and immunodeficient individuals. Although mycobacteria are obligate aerobes, they are thought to face an anaerobic environment during infection, notably inside abscesses and granulomas. The purpose of this study was to define a metabolic pathway that could allow mycobacteria to exist under these conditions. Recently, the complete genome of M. tuberculosis has been sequenced, and genes homologous to an anaerobic nitrate reductase (narGHJI), an enzyme allowing nitrate respiration when oxygen is absent, were found. Here, we show that the narGHJI cluster of M. tuberculosis is functional as it conferred anaerobic nitrate reductase activity to Mycobacterium smegmatis. A narG mutant of M. bovis BCG was generated by targeted gene deletion. The mutant lacked the ability to reduce nitrate under anaerobic conditions. Both mutant and M. bovis BCG wild type grew equally well under aerobic conditions in vitro. Histology of immunodeficient mice (SCID) infected with M. bovis BCG wild type revealed large granulomas teeming with acid-fast bacilli; all mice showed signs of clinical disease after 50 days and succumbed after 80 days. In contrast, mice infected with the mutant had smaller granulomas containing fewer bacteria; these mice showed no signs of clinical disease after more than 200 days. Thus, it seems that nitrate respiration contributes significantly to virulence of M. bovis BCG in immunodeficient SCID mice.

Recovery of mycobacteria from patients with cystic fibrosis.

Despite decontamination, overgrowth by pseudomonads renders cultural isolation of mycobacteria from respiratory specimens of patients with cystic fibrosis (CF) difficult or impossible. We performed a prospective study by comparing levels of reduction of overgrowth and recovery of mycobacteria using either pretreatment with N-acetyl-L-cysteine (NALC)-NaOH alone or pretreatment with NALC-NaOH and then with oxalic acid. From 406 specimens of 148 CF patients, 11 specimens were positive for mycobacteria, 5 of which grew mycobacteria after decontamination by either procedure. Three specimens grew mycobacteria only after decontamination with NALC-NaOH, whereas three specimens grew mycobacteria only after treatment with NALC-NaOH followed by oxalic acid but were overgrown after decontamination with NALC-NaOH. Thus, inactivation of mycobacteria by the more aggressive oxalic acid treatment offsets its beneficial effect of reducing the proportion of cultures overgrown with microorganisms other than mycobacteria.

Survival of mice infected with Mycobacterium smegmatis containing large DNA fragments from Mycobacterium tuberculosis.

Mycobacterium smegmatis is typically used as a bacterial host for cloning and expressing single genes or genomic libraries of the human pathogen Mycobacterium tuberculosis. To study virulence of M. tuberculosis, we set out to ask the question, whether a genomic library derived from M. tuberculosis H37Rv confers virulence to the non-virulent M. smegmatis. A representative library from the M. tuberculosis H37Rv genome was generated and transformed into wild-type M. smegmatis. Mice were challenged with recombinant clones by intravenous, aerogenic and intranasal infection. We were unable to detect either growth or persistence of recombinant clones in tissues of infected mice; instead, the infection was cleared. Since the concern that virulent traits might be transferred, bio-safety regulations often require the handling of these experiments at bio-safety Level 3. However, we failed to find any evidence that the M. tuberculosis library confers virulence when expressed in M. smegmatis. We suggest that the results, presented here, should fundamentally alter the containment requirements for similar experiments in the future.