[Cavernous Nontuberculous Mycobacterial Lung Infection in an HIV-positive Patient]. / Kavernöse nichttuberkulöse Mykobakteriose der Lunge durch M. heckeshornense bei einem HIV-infizierten Patienten.

Since we first described Mycobacterium heckeshornense, a rare species of mycobacteria in 2000, only 21 cases of infection with this mycobacterium have been described in humans. We relate the diagnosis and therapy of another case of this uncommon nontuberculous mycobacterium in an immune-suppressed patient.

Long Persistence of a Streptococcus pneumoniae 23F Clone in a Cystic Fibrosis Patient.

Streptococcus pneumoniae isolates of serotype 23F with intermediate penicillin resistance were recovered on seven occasions over a period of 37 months from a cystic fibrosis patient in Berlin. All isolates expressed the same multilocus sequence type (ST), ST10523. The genome sequences of the first and last isolates, D122 and D141, revealed the absence of two phage-related gene clusters compared to the genome of another ST10523 strain, D219, isolated earlier at a different place in Germany. Genomes of all three strains carried the same novel mosaic penicillin-binding protein (PBP) genes, pbp2x, pbp2b, and pbp1a; these genes were distinct from those of other penicillin-resistant S. pneumoniae strains except for pbp1a of a Romanian S. pneumoniae isolate. All PBPs contained mutations that have been associated with the penicillin resistance phenotype. Most interestingly, a mosaic block identical to an internal pbp2x sequence of ST10523 was present in pbp2x of Streptococcus mitis strain B93-4, which was isolated from the same patient. This suggests interspecies gene transfer from S. pneumoniae to S. mitis within the host. Nearly all genes expressing surface proteins, which represent major virulence factors of S. pneumoniae and are typical for this species, were present in the genome of ST10523. One exception was the hyaluronidase gene hlyA, which contained a 12-nucleotide deletion within the promoter region and an internal stop codon. The lack of a functional hyaluronidase might contribute to the ability to persist in the host for an unusually long period of time. IMPORTANCEStreptococcus pneumoniae is a common resident in the human nasopharynx. However, carriage can result in severe diseases due to a unique repertoire of pathogenicity factors that are rare in closely related commensal streptococci. We investigated a penicillin-resistant S. pneumoniae clone of serotype 23F isolated from a cystic fibrosis patient on multiple occasions over an unusually long period of over 3 years that was present without causing disease. Genome comparisons revealed an apparent nonfunctional pneumococcus-specific gene encoding a hyaluronidase, supporting the view that this enzyme adds to the virulence potential of the bacterium. The 23F clone harbored unique mosaic genes encoding penicillin resistance determinants, the product of horizontal gene transfer involving the commensal S. mitis as donor species. Sequences identical to one such mosaic gene were identified in an S. mitis strain from the same patient, suggesting that in this case S. pneumoniae played the role of donor.

Neuroleptic drugs in the treatment of tuberculosis: Minimal inhibitory concentrations of different phenothiazines against Mycobacterium tuberculosis.

Due to an increase of drug resistant TB, alternative drugs that are not currently listed in the WHO guidelines on MDR TB treatment are currently being evaluated. Our group tested 100 susceptible, 20 MDR and 2 XDR Mtb strains against the phenothiazine derivatives thioridazine, trifluoperazine and triflupromazine. MIC testing was performed on Middlebrook 7H10 agar and was defined as the lowest drug concentration that inhibits ≥99% of the bacterial population. We confirm very good in vitro activity of phenothiazines against Mycobacterium tuberculosis. In >77% of all strains MICs of ≤10 µg/ml were found.

Minimal inhibitory concentrations of first-line drugs of multidrug-resistant tuberculosis isolates.

CONTEXT: The treatment of multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis (TB) is consistently difficult. Besides resistances, drug availability can be problematic and costs for therapy are high. AIMS: Our aim was to evaluate alternatives in treatment of MDR and XDR TB other than using second-line drugs. MATERIALS AND METHODS: We analyzed retrospectively the minimal inhibitory concentrations (MICs) of first-line drugs for 44 multidrug-resistant Mycobacterium tuberculosis isolates determined in our institute over a period of 20 years (1990 - 2010, n = 44). Drug susceptibility testing (DST) was performed using the proportion method on Lowenstein-Jensen Medium or Middlebrook 7H10 agar. MICs were defined as the lowest drug concentration after two-fold serially diluted concentration of the drugs that inhibits growth of more than 99.0% of a bacterial proportion of the tested M. tuberculosis within 14 to 21 days of incubation at 37°C. STATISTICAL ANALYSIS USED: Summation. RESULTS: The MICs of isoniazid and ethambutol were equal or slightly above the critical concentration in most of the strains (92% and 84%, respectively), defined as "low-level resistance". Rifampicin and streptomycin exhibited very high MICs in most of the strains (100% and 77%, respectively), indicating a "high-level resistance". CONCLUSION: Our results indicate that isoniazid and ethambutol could still play a role in treating MDR and XDR TB patients if low-level resistance is detected. Quantitative DST seems to be promising for the recognition of residual drug activity, but has to be confirmed by clinical studies.

The use of interferon gamma release assays in the diagnosis of active tuberculosis.

Interferon gamma release assays (IGRAs) are in vitro immunologic diagnostic tests used to identify Mycobacterium tuberculosis infection. They cannot differentiate between latent and active infections. The cutoff suggested by the manufacturer is 0.35 IU/mL for latent tuberculosis. As IGRA tests were recently approved for the differential diagnosis of active tuberculosis, we assessed the diagnostic accuracy of the latest generation IGRA for detection of active tuberculosis in a low-incidence area in Germany. Our consecutive case series includes 61 HIV negative, Mycobacterium tuberculosis culture positive patients, as well as 234 control patients. The retrospective analysis was performed over a period of two years. In 11/61 patients with active tuberculosis (18.0%) the test result was <0.35 IU/mL, resulting in a sensitivity of 0.82. We recommend establishing a new cut-off value for the differential diagnosis of active tuberculosis assessed by prospective clinical studies and in various regions with high and low prevalence of tuberculosis.

Early bactericidal activity of moxifloxacin in treatment of pulmonary tuberculosis: a prospective, randomized study.

Moxifloxacin is the most active fluoroquinolone against Mycobacterium tuberculosis in vitro. However, data about the efficacy in patients are not available. We enrolled 17 patients with tuberculosis in a prospective, randomized study. After 5 days of monotherapy with either moxifloxacin or isoniazid, we detected significant decreases in mean CFU per milliliter in sputum in both groups. The calculated early bactericidal activities for isoniazid and moxifloxacin were 0.209 and 0.273 log(10) CFU per ml of sputum per day, respectively. According to the data from our study, moxifloxacin exhibits an early bactericidal activity that is comparable to that of isoniazid.

Optimizing ceftazidime pharmacodynamics in patients with acute exacerbation of severe chronic bronchitis.

OBJECTIVES: Implementation of current pharmacodynamic knowledge could enhance clinical results, avoid resistance development and reduce treatment costs. In this open, randomized, multicentre study, we evaluated the clinical and bacteriological outcome and pharmacokinetic as well as pharmacodynamic parameters of two ceftazidime therapy regimens in patients with acute exacerbation of severe chronic bronchitis (AECB). METHODS: Eighty-one patients (56 males, 25 females, age 65.3 +/- 10.1 years) with AECB were included. A subgroup of 21 patients underwent pharmacokinetic and pharmacodynamic examination. The patients received either ceftazidime 2 g every 8 h (C3 x 2) or ceftazidime 2 g as a loading dose, followed by ceftazidime 2 g over 7 h every 12 h (C2 x 2) for 8-14 days. Clinical and bacteriological responses were monitored at day 8 or 9, and 72 h after the end of therapy (EOT). RESULTS: At EOT, clinical success was recorded in 90% and 90.2% of clinically evaluable patients receiving C3 x 2 and C2 x 2, respectively. Bacteriological success at EOT was achieved in 87.5% and 90.2% of evaluable patients treated with C3 x 2 and C2 x 2, respectively. C(max) (mg/L) varied between 168.9 +/- 34.1 and 144.0 +/- 9.8 in the C3 x 2 group, and between 60.1 +/- 34.1 and 54.2 +/- 30.4 at steady-state in the C2 x 2 group. Minimal concentrations were between 9.1 and 13.4 mg/L in the C3 x 2 group, and between 16.6 and 17.7 mg/L in the C2 x 2 group. Concentrations >4-5 x MIC were seen in all pathogens, except Staphylococcus aureus, during 100% of infusion time. CONCLUSION: The 2 x 7 h infusion of ceftazidime 2 g (C2 x 2) was clinically and bacteriologically as effective as the usual 3 x 2 g ceftazidime short-term infusion in the treatment of AECB, and demonstrated advantages in terms of pharmacodynamic parameters compared with the C3 x 2 regimen.

Phylogeny of the genus Nocardia based on reassessed 16S rRNA gene sequences reveals underspeciation and division of strains classified as Nocardia asteroides into three established species and two unnamed taxons.

Conventional identification of Nocardia in the routine laboratory remains problematic due to a paucity of reliable phenotypic tests and due to the yet-unresolved taxonomy of strains classified as belonging to the species Nocardia asteroides, which comprises the type strain and isolates with drug pattern types II and VI. The 16S rRNA gene of 74 representative strains of the genus Nocardia, encompassing 25 established species, was sequenced in order to provide a molecular basis for accurate species identification and with the aim of reassessing the phylogeny of taxons assigned to the species N. asteroides. The result of this phylogenetic analysis confirms that the interspecies heterogeneity of closely related nocardial species can be considerably low (a sequence divergence of only 0.5% was found between N. paucivorans and N. brevicatena). We observed a sequence microheterogeneity (sequence divergence of fewer than five bases) in 8 of 11 species of which more than one strain in the species was studied. At least 10 taxons were found that merit description as new species. Strains previously classified as N. asteroides fell into five distinct phylogenetic groups: the type strain cluster (N. asteroides sensu strictu), N. abscessus, N. cyriacigeorgica, and two clusters closely related to N. carnea or N. flavorosea. The strains within the latter two groups probably represent new species, pending further genetic and phenotypic evaluation. Restricted phenotypic data revealed that N. abscessus, N. cyriacigeorgica, and the two Nocardia species taxons are equivalent to drug patterns I, VI, and II, respectively. In the future, these data will help in finding species-specific markers after adoption of a more precise nomenclature for isolates closely related to N. asteroides and unravel confusing phenotypic data obtained in the past for unresolved groups of strains that definitely belong to separate taxons from a phylogenetic point of view.

Differentiation between Mycobacterium farcinogenes and Mycobacterium senegalense strains based on 16S-23S ribosomal DNA internal transcribed spacer sequences.

16S ribosomal DNA (rDNA) and 16S-23S internal transcribed spacer rDNA sequence analyses were performed on Mycobacterium farcinogenes and M. senegalense strains and 26 strains of other rapidly growing mycobacteria to investigate the phylogenetic structure of bovine farcy mycobacteria within the M. fortuitum complex. M. farcinogenes and M. senegalense were indistinguishable in their 5"-end 16S rDNA but showed both considerable interspecies spacer sequence divergence and a high level of intraspecies sequence stability. A rapid detection assay using PCR and hybridization with species-specific probes was developed. The assay was specific among 46 species other than M. farcinogenes and M. senegalense and correctly identified all M. farcinogenes and M. senegalense strains. PCR- and 16S-23S rDNA sequence-based detection will be a valuable approach for diagnosis of the causal agents of African bovine farcy in cattle.

Nosocomial pneumonia: epidemiology, pathogenesis, diagnosis, treatment and prevention.

Nosocomial pneumonia is the second most common nosocomial infection and the leading cause of death from hospital-acquired infection. Supine body position in mechanically ventilated patients, and cardiopulmonary resuscitation and continuous sedation are significant risk factors for developing nosocomial pneumonia. During the past 2 years some new therapeutic approaches for nosocomial pneumonia and modifications to established therapies have been described, such as optimal pharmacodynamic evaluations, monotherapy versus combination therapy, computer-assisted management programmes and antibiotic rotations.

Diagnosis of acute respiratory tract infections: serology and new methods.

No test is available that can identify all potential pathogens in acute respiratory tract infections. Each diagnostic test is associated with limitations with respect to sensitivity and/or specificity and/or speed, and thus a combination of tests has to be used. Even so, no etiologic agent is found in 30--60% of cases. The following methods are recommended for use in the routine laboratory for the diagnosis of infections: (1) Legionella --- direct immunofluorescence test, culture, serology and antigen detection (available only in specialized laboratories); (2) Chlamydia pneumoniae --- micro-immunofluorescence test, complement fixation, but not direct antigen detection by immunofluorescence; (3) Mycoplasma pneumoniae - complement fixation and/or particle agglutination or other evaluated methods; (4) Coxiella burnetii --- immunofluorescence test (IgG and IgM) and complement fixation; (5) viruses --- complement fixation or other similar test (ELISAs often lack adequate evaluation). Culture for Chlamydia, Mycoplasma pneumoniae, Coxiella burnetii and viruses should only be performed by very experienced laboratories. Most procedures deliver results only retrospectively or too late. The most promising diagnostic tools for the future are nucleic acid amplification techniques (NAT) or PCR, which could solve many of the problems connected with conventional techniques, but there are enormous contamination problems. Further research and worldwide aid in the development of standardized NAT, especially by industrial companies, is urgently encouraged to improve the laboratory diagnosis of these pneumonias.