Rapid Emergence of Co-colonization with Community-acquired and Hospital-Acquired Methicillin-Resistant Staphylococcus aureus Strains in the Hospital Setting

Background: Community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA), a novel strain of MRSA, has recently emerged and rapidly spread in the community. Invasion into the hospital setting with replacement of the hospital-acquired MRSA (HA-MRSA) has also been documented. Co-colonization with both CA-MRSA and HA-MRSA would have important clinical implications given differences in antimicrobial susceptibility profiles and the potential for exchange of genetic information. Methods: A deterministic mathematical model was developed to characterize the transmission dynamics of HA-MRSA and CA-MRSA in the hospital setting and to quantify the emergence of co-colonization with both strains Results: The model analysis shows that the state of co-colonization becomes endemic over time and that typically there is no competitive exclusion of either strain. Increasing the length of stay or rate of hospital entry among patients colonized with CA-MRSA leads to a rapid increase in the co-colonized state. Compared to MRSA decolonization strategy, improving hand hygiene compliance has the greatest impact on decreasing the prevalence of HA-MRSA, CA-MRSA and the co-colonized state. Conclusions: The model predicts that with the expanding community reservoir of CA-MRSA, the majority of hospitalized patients will become colonized with both CA-MRSA and HA-MRSA

The effect of co-colonization with community-acquired and hospital-acquired methicillin-resistant Staphylococcus aureus strains on competitive exclusion

We investigate the in-hospital transmission dynamics of two methicillin-resistant Staphylococcus aureus(MRSA) strains: hospital-acquired methicillin resistant S. aureus (HA-MRSA) and community-acquired methicillin-resistant S. aureus (CA-MRSA). Under the assumption that patients can only be colonized with one strain of MRSA at a time, global results show that competitive exclusion occurs between HA-MRSA and CA-MRSA strains; the strain with the larger basic reproduction ratio will become endemic while the other is extinguished due to competition. Because new studies suggest that patients can be concurrently colonized with multiple strains of MRSA, we extend the model to allow patients to be co-colonized with HA-MRSA and CA-MRSA. Using the extended model, we explore the effect of co-colonization on competitive exclusion by determining the invasion reproduction ratios of the boundary equilibria. In contrast to results derived from the assumption that co-colonization does not occur, the extended model rarely exhibits competitive exclusion. More commonly, both strains become endemic in the hospital. When transmission rates are assumed equal and decolonization measures act equally on all strains, competitive exclusion never occurs. Other interesting phenomena are exhibited. For example, solutions can tend toward a co-existence equilibrium, even when the basic reproduction ratio of one of the strains is less than one

Mitochondrial diversity in Gonionemus (Trachylina:Hydrozoa) and its implications for understanding the origins of clinging jellyfish in the Northwest Atlantic Ocean

© The Author(s), 2017. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PeerJ 5 (2017): e3205, doi:10.7717/peerj.3205.Determining whether a population is introduced or native to a region can be challenging due to inadequate taxonomy, the presence of cryptic lineages, and poor historical documentation. For taxa with resting stages that bloom episodically, determining origin can be especially challenging as an environmentally-triggered abrupt appearance of the taxa may be confused with an anthropogenic introduction. Here, we assess diversity in mitochondrial cytochrome oxidase I sequences obtained from multiple Atlantic and Pacific locations, and discuss the implications of our findings for understanding the origin of clinging jellyfish Gonionemus in the Northwest Atlantic. Clinging jellyfish are known for clinging to seagrasses and seaweeds, and have complex life cycles that include resting stages. They are especially notorious as some, although not all, populations are associated with severe sting reactions. The worldwide distribution of Gonionemus has been aptly called a “zoogeographic puzzle” and our results refine rather than resolve the puzzle. We find a relatively deep divergence that may indicate cryptic speciation between Gonionemus from the Northeast Pacific and Northwest Pacific/Northwest Atlantic. Within the Northwest Pacific/Northwest Atlantic clade, we find haplotypes unique to each region. We also find one haplotype that is shared between highly toxic Vladivostok-area populations and some Northwest Atlantic populations. Our results are consistent with multiple scenarios that involve both native and anthropogenic processes. We evaluate each scenario and discuss critical directions for future research, including improving the resolution of population genetic structure, identifying possible lineage admixture, and better characterizing and quantifying the toxicity phenotype.This work was supported by the Woods Hole Sea Grant, the Town of Oak Bluffs Community Preservation Committee, the Nantucket Biodiversity Initiative, the Kathleen M. and Peter E. Naktenis Family Foundation, and the Russian Science Foundation (No. 14-50-00034)

Phylogeographic structure and northward range expansion in the barnacle Chthamalus fragilis

© The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PeerJ 3 (2015): e926, doi:10.7717/peerj.926.The barnacle Chthamalus fragilis is found along the US Atlantic seaboard historically from the Chesapeake Bay southward, and in the Gulf of Mexico. It appeared in New England circa 1900 coincident with warming temperatures, and is now a conspicuous member of rocky intertidal communities extending through the northern shore of Cape Cod, Massachusetts. The origin of northern C. fragilis is debated. It may have spread to New England from the northern end of its historic range through larval transport by ocean currents, possibly mediated by the construction of piers, marinas, and other anthropogenic structures that provided new hard substrate habitat. Alternatively, it may have been introduced by fouling on ships originating farther south in its historic distribution. Here we examine mitochondrial cytochrome c oxidase I sequence diversity and the distribution of mitochondrial haplotypes of C. fragilis from 11 localities ranging from Cape Cod, to Tampa Bay, Florida. We found significant genetic structure between northern and southern populations. Phylogenetic analysis revealed three well-supported reciprocally monophyletic haplogroups, including one haplogroup that is restricted to New England and Virginia populations. While the distances between clades do not suggest cryptic speciation, selection and dispersal barriers may be driving the observed structure. Our data are consistent with an expansion of C. fragilis from the northern end of its mid-19th century range into Massachusetts.Funding was provided by the Woods Hole Oceanographic Institution in an Independent Study Award to J Pineda and AF Govindarajan, a WHOI summer fellowship to F Bukša, and NSF Biological Oceanography #1029526 to JP Wares

Surveillance of drug-resistant tuberculosis in the state of Gujarat, India

BACKGROUND: Limited information about the prevalence of drug-resistant tuberculosis (TB) has been reported from India, the country with the world’s highest burden of TB. We conducted a representative state-wide survey in the state of Gujarat (2005 population: 56 million). METHODS: Mycobacterium tuberculosis isolates from a representative sample of new and previously treated smear-positive pulmonary TB (PTB) cases were subjected to drug susceptibility testing (DST) against fi rst-line drugs at a World Health Organization supranational reference laboratory. Isolates found to have at least both isoniazid (INH) and rifampicin (RMP) resistance (i.e., multidrugresistant TB [MDR-TB]) were subjected to second-line DST. RESULTS: Of 1571 isolates from new patients, 1236 (78.7%) were susceptible to all fi rst-line drugs, 173 (11%) had any INH resistance and MDR-TB was found in 37 (2.4%, 95%CI 1.6–3.1). Of 1047 isolates from previously treated patients, 564 (54%) were susceptible to all fi rst-line drugs, 387 (37%) had any INH resistance and MDR-TB was found in 182 (17.4%, 95%CI 15.0–19.7%). Among 216 MDR-TB isolates, 52 (24%) were ofl oxacin (OFX) resistant; seven cases of extensively drug-resistant TB (XDR-TB) were found, all of whom were previously treated cases. CONCLUSION: MDR-TB prevalence remains low among new TB patients in Gujarat, but is more common among previously treated patients. Among MDR-TB isolates, the alarmingly high prevalence of OFX resistance may threaten the success of the expanding efforts to treat and control MDR-TB

Feasibility of an Alcohol Intervention Programme for TB Patients with Alcohol Use Disorder (AUD) - A Qualitative Study from Chennai, South India

The negative influences of alcohol on TB management with regard to delays in seeking care as well as non compliance for treatment has been well documented. This study is part of a larger study on the prevalence of AUD (Alcohol Use Disorder) among TB patients which revealed that almost a quarter of TB patients who consumed alcohol could be classified as those who had AUD. However there is dearth of any effective alcohol intervention programme for TB patients with Alcohol Use Disorder (AUD).This qualitative study using the ecological system model was done to gain insights into the perceived effect of alcohol use on TB treatment and perceived necessity of an intervention programme for TB patients with AUD. We used purposive sampling to select 44 men from 73 TB patients with an AUDIT score >8. Focus group discussions (FGDs) and interviews were conducted with TB patients with AUD, their family members and health providers.TB patients with AUD report excessive alcohol intake as one of the reasons for their vulnerability for TB. Peer pressure has been reported by many as the main reason for alcohol consumption. The influences of alcohol use on TB treatment has been elaborated especially with regard to the fears around the adverse effects of alcohol on TB drugs and the fear of being reprimanded by health providers. The need for alcohol intervention programs was expressed by the TB patients, their families and health providers. Suggestions for the intervention programmes included individual and group sessions, involvement of family members, audiovisual aids and the importance of sensitization by health staff.The findings call for urgent need based interventions which need to be pilot tested with a randomized control trial to bring out a model intervention programme for TB patients with AUD

Safety and Availability of Clofazimine in the Treatment of Multidrug and Extensively Drug-Resistant Tuberculosis: Analysis of Published Guidance and Meta-Analysis of Cohort Studies

Objectives: Given the spread of multidrug-resistant tuberculosis (MDR-TB), new therapies are urgently needed, including the repurposing of existing drugs. We aimed to assess key considerations for the clinical and programmatic use of clofazimine (Cfz), a riminophenazine with anti-mycobacterial activity currently used to treat leprosy. Design: Fixed and random effects meta-analysis of cohort studies and systematic review Setting: Electronic and manual searches were combined. Inclusion criteria: Observational studies on treatment of multidrug- and extremely drug- resistant tuberculosis with clofazimine or a clofazimine-containing regimen, and published guidance and documents relating to cost and availability were eligible. Results: Five observational studies enrolled 861 patients, of which 602 received Cfz. The pooled proportion of adverse drug reactions requiring discontinuation of Cfz treatment was 0.1% (95% CI: [0.0, 0.6%]), and the median frequency of all adverse events was 5.1%. Cfz showed in vitro efficacy against Mycobacterium tuberculosis, and Cfz-containing regimens may have had a useful role in the treatment of patients with drug-resistant strains and who had limited alternative treatment options. However, Cfz uptake remains insufficient to meet global needs; there is only one internationally quality-assured manufacturer, which produces a limited quantity of the drug prioritised for treatment of leprosy, the only indication for which the drug is registered. Conclusions: While the data were limited, Cfz was associated with a risk for adverse drug reactions comparable to that of first-line TB treatment, which could be reasonably managed under programmatic conditions. However, low market availability and high cost are important barriers to access to Cfz for MDR-TB patients.Other Research Uni

Management of Multi Drug Resistance Tuberculosis in the Field: Tuberculosis Research Centre Experience

Setting: Multi-drug TB resistant (resistant to isoniazid and rifampicin) patients identified from a rural and urban area. Objective: To study the feasibility of managing MDR TB patients under field conditions where DOTS programme has been implemented Methods: MDR TB Patients identified among patients treated under DOTS in the rural area and from cases referred by the NGO when MDR TB was suspected form the study population. Culture and drug susceptibility testing were done at Tuberculosis Research Centre (TRC). Treatment regimen was decided on individual basis. After a period of initial hospitalization, treatment was continued in the respective peripheral health facility or with the NGO after identifying a DOT provider in the field. Patients attended TRC at monthly intervals for clinical, sociological and bacteriological evaluations. Drugs for the month were pre-packed and handed over to the respective center. Results: A total of 66 MDR TB patients (46 from the rural and 20 from the NGO) started on treatment form the study population and among them 20 (30%) were resistant to one or more second line drugs (Eto, Ofx, Km) including a case of “XDR TB”. Less than half the patients stayed in the hospital for more than 10 days. The treatment was provided partially under supervision. Providing injection was identified to be a major problem. Response to treatment could be correctly predicted based on the 6-month smear results in 40 of 42 regular patients. Successful treatment outcome was observed only in 37% of cases with a high default of 24%. Adverse reactions necessitating modification of treatment was required only for three patients. Implications Despite having reliable DST and drug logistics, the main challenge was to maintain patients on such prolonged treatment by identifying a provider closer to the patient who can also give injection, have social skills and manage of minor adverse reactions

Contact screening and chemoprophylaxis in India’s Revised Tuberculosis Control Programme: a situational analysis

BACKGROUND: India’s Revised National Tuberculosis Control Programme (RNTCP) recommends screening of all household contacts of smear-positive pulmonary tuberculosis (PTB) cases for tuberculosis (TB) disease, and 6-month isoniazid preventive therapy (IPT) for a symptomatic children aged <6 years. OBJECTIVE: To assess the implementation of child contact screening and IPT administration under the RNTCP. METHODS: A cross-sectional study conducted in four randomly selected TB units (TUs), two in an urban (Chennai City) and two in a rural (Vellore District) area of Tamil Nadu, South India, from July to September 2008. The study involved the perusal of TB treatment cards of source cases (new or retreatment smear-positive PTB patients started on treatment), interview of source cases and focus group discussions (FGDs) among health care workers. RESULTS: Interviews of 253 PTB patients revealed that of 220 contacts aged <14 years, only 31 (14%) had been screened for TB, and that of 84 household children aged <6 years, only 16 (19%) had been initiated on IPT. The treatment cards of source cases lacked documentation of contact details. FGDs revealed greater TB awareness among urban health care workers, but a lack of detailed knowledge about procedures. CONCLUSION: Provision for documentation using a separate IPT card and focused training may help improve the implementation of contact screening and IPT. KEY WORDS: contact screening; IPT; RNTCP; chemoprophylaxi

First- and second-line drug resistance patterns among previously treated tuberculosis patients in India

Culture and drug susceptibility testing results of 2816 tuberculosis (TB) patients from across India who had failed repeated treatments from 2001 to 2004 were retrospectively analysed at the Tuberculosis Research Centre, Chennai. Of 1498 (53%) identifi ed as having multidrugresistant TB (MDR-TB), 671 (44.8%) were resistant to ⩾1 second-line drugs (SLDs): 490 (32.7%) to ethionamide, 245 (16.4%) to ofl oxacin and 169 (11.3%) to kanamycin; 69 (4.6%) were extensively drug-resistant TB (XDR-TB). Although from a highly select and nonrepresentative patient group, such high SLD resistance levels, including XDR-TB, among MDR-TB patients is of concern. The prevention of MDR/XDR-TB through quality DOTS services, however, remains the priority. In addition, rapid scale-up of quality programmatic management under the RNTCP is needed, with more control and rational use of SLDs outside the programme. KEY WORDS: drug resistance; previously treated tuberculosis; Indi