Summary
Background
Staphylococcus aureus is increasingly implicated as a possible causal factor in the pathogenesis of atopic dermatitis (AD). However, the reported prevalence rates of skin and nasal ...colonization in the literature vary widely.
Objectives
This study evaluates the prevalence and odds of skin and nasal colonization with S. aureus in patients with AD.
Methods
A systematic literature search was conducted. Odds ratios (ORs) for colonization in patients vs. controls and the prevalence of colonization in patients were pooled using the random‐effects model.
Results
Overall, 95 observational studies were included, of which 30 had a control group. The Newcastle–Ottawa Scale was used to assess study quality, with the majority of studies being of fair to poor quality. Patients with AD were more likely to be colonized with S. aureus than healthy controls OR 19·74, 95% confidence interval (CI) 10·88–35·81. Differences were smaller in nonlesional skin (OR 7·77, 95% CI 3·82–15·82) and in the nose (OR 4·50, 95% CI 3·00–6·75). The pooled prevalence of S. aureus colonization among patients was 70% for lesional skin, 39% for nonlesional skin and 62% for the nose. In lesional skin, meta‐regression showed that the prevalence of colonization increased with disease severity. Study heterogeneity should be taken into consideration when interpreting the results.
Conclusions
These results demonstrate the importance of colonization with S. aureus in AD. Further evaluation of the mechanisms by which S. aureus influences inflammation is required in addition to the development of targeted strategies to decrease skin and nasal S. aureus load.
What's already known about this topic?
Staphylococcus aureus colonizes the skin of patients with atopic dermatitis.
What does this study add?
For the first time, data on S. aureus colonization in atopic dermatitis are systematically summarized showing an increased risk of colonization of lesional skin, nonlesional skin and the nose in patients vs. healthy controls.
Guillain–Barré syndrome (GBS) is a post-infectious disease in which the human peripheral nervous system is affected after infection by specific pathogenic bacteria, including
Campylobacter jejuni
. ...GBS is suggested to be provoked by molecular mimicry between sialylated lipooligosaccharide (LOS) structures on the cell envelope of these bacteria and ganglioside epitopes on the human peripheral nerves, resulting in autoimmune-driven nerve destruction. Earlier, the
C. jejuni
sialyltransferase (Cst-II) was found to be linked to GBS and demonstrated to be involved in the biosynthesis of the ganglioside-like LOS structures. Apart from a role in pathogenicity, we report here that Cst-II-generated ganglioside-like LOS structures confer efficient bacteriophage resistance in
C. jejuni
. By bioinformatic analysis, it is revealed that the presence of sialyltransferases in
C. jejuni
and other potential GBS-related pathogens correlated significantly with the apparent degeneration of an alternative anti-virus system: type II
C
lusters of
R
egularly
I
nterspaced
S
hort
P
alindromic
R
epeat and
as
sociated genes (CRISPR-Cas). Molecular analysis of the
C. jejuni
CRISPR-Cas system confirmed the bioinformatic investigation. CRISPR degeneration and mutations in the
cas
genes
cas2
,
cas1
and
csn1
were found to correlate with Cst-II sialyltransferase presence (
p
< 0.0001). Remarkably, type II CRISPR-Cas systems are mainly found in mammalian pathogens. To study the potential involvement of this system in pathogenicity, we inactivated the type II CRISPR-Cas marker gene
csn1
, which effectively reduced virulence in primarily
cst
-II-positive
C. jejuni
isolates. Our findings indicate a novel link between viral defence, virulence and GBS in a pathogenic bacterium.
Development of new antibiotics is declining whereas antibiotic resistance is rising, heralding a post-antibiotic era. Antimicrobial peptides such as gramicidin S (GS), exclusively topically used due ...to its hemolytic side-effect, could still be interesting as therapeutic compounds. By modifying the amino-acid composition of GS, we synthesized GS analogues. We now show that derivative VK7 has a lower MIC (7.8–31.2 μg/ml, median 15.6 μg/ml) against strains of multi-drug resistant (MDR)
Klebsiella pneumoniae, Acinetobacter baumannii
, and
Pseudomonas aeruginosa
than GS has (3.9–62.5 μg/ml, median 31.3 μg/ml). Low MICs for both VK7 and GS were observed for
Staphylococcus aureus
and
Enterococcus faecium
. VK7 showed reduced haemolysis and less lactate dehydrogenase release. All compounds were fully bactericidal at MIC values. Modification of GS enables production of novel derivatives potentially useful for systemic treatment of human infections.
Aims
In the previous work, following a pressure treatment with wild‐type Staphylococcus aureus, we obtained piezotolerant isolates showing altered phenotypic characteristics. This work focuses on ...understanding the genetic background of their altered phenotype.
Methods and Results
AK23, a representative piezotolerant isolate was subjected to DNA microarrays, corroborated by PCR product sequencing and revealed 10‐gene deletion. All other piezotolerant isolates possessed the mutation encompassing the region from SAR0665 to SAR0674 genes (9351 bp) which was most likely the result of recombination between two homologous loci (ATTGCGGGTG) present in both genes. RNA microarray transcriptomic analysis showed that due to partial deletion of the low‐affinity phosphate transporter pitA, the high‐affinity PhoU‐PstABCS operon was upregulated in AK23 which could be the reason for piezotolerance. Furthermore, AK23 showed low levels of the virulence gene regulator rnaIII resulting in the downregulation of several agr system genes explaining the impaired virulence characteristics of the mutant.
Conclusions
Naturally occurring mutations can result in piezotolerance which can be of a concern for high hydrostatic pressure‐treated foods.
Significance and Impact of the Study
A locus has been identified in piezotolerant S. aureus mutants providing insight into possible mechanisms associated with phenotypic characteristics of S. aureus. Further work should study each individual gene of the locus.
MCR: modern colistin resistance Caniaux, I.; van Belkum, A.; Zambardi, G. ...
European Journal of Clinical Microbiology and Infectious Diseases,
03/2017, Letnik:
36, Številka:
3
Journal Article, Book Review
Recenzirano
Odprti dostop
Recently, plasmid-mediated and, therefore, transferable bacterial polymyxin resistance was discovered in strains from both humans and animals. Such a trait may widely spread geographically, while ...simultaneously crossing microbial species barriers. This may ultimately render the “last resort” polymyxin antibiotics therapeutically useless. Colistin is currently used to treat infections caused by Gram-negative carbapenemase producers and colistin resistance may lead to practical pan-antibiotic resistance. We here analyzed the medical and diagnostic consequences of (emerging) colistin resistance and propose pathways toward adequate diagnostics for timely detection of both asymptomatic carriage and infection. Culture-based testing using chromogenic and selective media for screening clinical (and veterinary) specimens may constitute key tools for that purpose. Relevant molecular tests are also discussed.
A total of 103 group B streptococci (GBS) including 22 invasive, 21 non-invasive, and 60 colonizing isolates were collected in a Malaysian hospital (June 2010–October 2011). Isolates were ...characterized by conventional and molecular serotyping and analyzed for
scpB
,
lmb
,
hylB
,
cylE
,
bac
,
bca
and
rib
gene content. Antimicrobial susceptibility to penicillins, macrolides, lincosamides, quinolones and tetracyclines was determined using disk diffusion and the MICs for penicillin were determined by E-test. Molecular serotyping for all eight serotypes (Ia, Ib, II–VII) was in full accordance with conventional serotyping. Overall, taking CS and MS together, serotype VI was the most common capsular type (22.3 %) followed by VII (21.4 %), III (20.4 %), Ia (17.5 %), V (9.7 %), II (7.7 %) and IV (1 %). Susceptibility to beta-lactam antimicrobials was prevalent (100 %). Resistance rates for erythromycin, clindamycin and tetracycline were 23.3 %, 17.5 % and 71.8 %, respectively. PCR-virulence gene screening showed the presence of
cylE
,
lmb
,
scpB
and
hylB
in almost all the isolates while
rib
,
bca
, and
bac
genes were found in 29.1 %, 14.6 % and 9.7 % of the isolates. Certain genes were significantly associated with specific serotypes, namely,
rib
with serotypes Ia, II, III and VI;
bca
and
bac
with serotypes II and III. Furthermore, serotype Ia was significantly more common among patients with invasive infections (
p
< 0.01) and serotype VI isolates were significantly more common among carriers (
p
< 0.05). In summary, serotype distribution correlates with virulence gene content will be useful in epidemiological studies and design of vaccines.
The laboratory diagnosis of tuberculosis usually relies on culture-based isolation of the causative Mycobacterium tuberculosis bacteria. We developed and evaluated the performance of MOD9, a new ...blood-free derivative of the MOD4 solid medium on which we previously reported for the isolation and culture of mycobacteria. First, inoculation of Lowenstein-Jensen medium with 21 M. tuberculosis isolates at 10(5), 10(3), and 10 CFU yielded colonies in 5.7 ± 1.5 days, 7.6 ± 0.8 days, and 10.8 ± 1.7 days versus 1.5 ± 0.4 days, 3.5 ± 0.6 days, and 4.9 ± 1 days in MOD9 (P < 0.05, Student's t test). Further, the time to detectable growth of M. tuberculosis was measured on MOD9 and Lowenstein-Jensen media after duplicate inoculation of 250 clinical specimens decontaminated with 0.7% chlorhexidine. The contamination rate was 1.6% (4/250) on MOD9 versus 4.4% (11/250) on Lowenstein-Jensen medium (P = 0.11, Fisher's exact test). Chlorhexidine-MOD9 yielded 38/250 (15.2%) isolates versus 32/250 (12.8%) isolates for the chlorhexidine-LJ (P = 0.5195, Fisher's exact test). All together, eight M. tuberculosis isolates were cultured solely from chlorhexidine-MOD9, and two M. tuberculosis isolates were cultured solely from chlorhexidine-LJ. The time to detection was 9.8 ± 3.9 (range, 5 to 18) days for chlorhexidine-MOD9 versus 17.4 ± 5.9 (range, 10 to 35) days for chlorhexidine-LJ (P < 0.05, Student's t test). These data indicate the superiority of the MOD9 medium over the standard LJ medium following chlorhexidine decontamination for the recovery of M. tuberculosis.
Staphylococcus aureus
might amplify symptoms in chronic inflammatory skin diseases. This study evaluates skin and mucosal colonization with
S. aureus
in patients with psoriasis, acne and rosacea. A ...systematic literature search was conducted. Both odds ratios (OR) for colonization in patients versus controls and the prevalence of colonization in patients are reported. Fifteen articles about psoriasis and 13 about acne (12 having a control group) were included. No study in rosacea met our inclusion criteria. For psoriasis, one study out of three controlled studies showed increased skin colonization (OR 18.86; 95 % confidence interval CI 2.20–161.99). Three out of the five studies that reported on nasal colonization showed significant ORs varying from 1.73 (95 % CI 1.16–2.58) to 14.64 (95 % CI 2.82–75.95). For acne one of the three studies that evaluated skin colonization reported a significant OR of 4.16 (95 % CI 1.74–9.94). A relation between nasal colonization and acne was not found. Limitations in study design and low sample sizes should be taken into consideration when interpreting the results. Colonisation with
S. aureus
seems to be increased in patients with psoriasis. This bacterial species, known for its potential to induce long-lasting inflammation, might be involved in psoriasis pathogenesis. Information on acne is limited. Prospective controlled studies should further investigate the role of
S. aureus
in chronic inflammatory skin diseases.
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