Intraocular Foreign Body: Ultrasound and CT Findings

History of present illness: A 36-year-old male with no past medical history presented to the emergency department with left eye pain. Earlier that day, the patient reported pounding a metal object with a metal hammer, when a piece flicked up and struck his eye. He was not wearing eye protection. He noted mild pain. He described his vision as being “dirty water-stained,” seeing “black, floating clouds” and “squiggly lines.” He also described the sensation of something being “stuck” in his eye. On physical exam, his vision was 20/30 in the left eye and 20/20 in the right. His extraocular movements were intact; lid and lash eversion did not reveal a foreign body. There was mild left conjunctival injection, but no tearing or purulent discharge. There was 3 mm of linear corneal fluorescein stain uptake over the anterior chamber. Significant findings: Point of care ultrasound revealed a mobile, radiolucent hyperechoic structure (see red arrow) with reverberation within the posterior chamber (see blue arrow), likely a metallic foreign body. Linear areas of mobile hyperechoic material revealed possible vitreous hemorrhage (see purple circular area). Orbital non-contrast CT confirmed a 3 mm metallic focus within the dependent portion of the left globe, lodged in the posterior sclera, with some vitreous hemorrhage but no evidence of globe rupture. Ophthalmology was consulted and the patient was taken to surgery later that night. Discussion: Patients presenting with intraocular foreign body (IOFB) can be easily missed, as they may not complain of vision loss or severe pain. Only a small entry wound may be found on careful examination. However, these seemingly harmless injuries may be vision threatening.1 The IOFB must be removed surgically in the majority of cases (>90%). 2 Bedside ultrasound is a useful tool in looking for metallic objects. Orbital CT continues to be the exam of choice.

Intraocular Foreign Body: Ultrasound and CT Findings

History of present illness: A 36-year-old male with no past medical history presented to the emergency department with left eye pain. Earlier that day, the patient reported pounding a metal object with a metal hammer, when a piece flicked up and struck his eye. He was not wearing eye protection. He noted mild pain. He described his vision as being “dirty water-stained,” seeing “black, floating clouds” and “squiggly lines.” He also described the sensation of something being “stuck” in his eye. On physical exam, his vision was 20/30 in the left eye and 20/20 in the right. His extraocular movements were intact; lid and lash eversion did not reveal a foreign body. There was mild left conjunctival injection, but no tearing or purulent discharge. There was 3 mm of linear corneal fluorescein stain uptake over the anterior chamber. Significant findings: Point of care ultrasound revealed a mobile, radiolucent hyperechoic structure (see red arrow) with reverberation within the posterior chamber (see blue arrow), likely a metallic foreign body. Linear areas of mobile hyperechoic material revealed possible vitreous hemorrhage (see purple circular area). Orbital non-contrast CT confirmed a 3 mm metallic focus within the dependent portion of the left globe, lodged in the posterior sclera, with some vitreous hemorrhage but no evidence of globe rupture. Ophthalmology was consulted and the patient was taken to surgery later that night. Discussion: Patients presenting with intraocular foreign body (IOFB) can be easily missed, as they may not complain of vision loss or severe pain. Only a small entry wound may be found on careful examination. However, these seemingly harmless injuries may be vision threatening.1 The IOFB must be removed surgically in the majority of cases (>90%). 2 Bedside ultrasound is a useful tool in looking for metallic objects. Orbital CT continues to be the exam of choice.

Plasmodium falciparum K76T pfcrt Gene Mutations and Parasite Population Structure, Haiti, 2006–2009

Hispaniola is the only Caribbean island to which Plasmodium falciparum malaria remains endemic. Resistance to the antimalarial drug chloroquine has rarely been reported in Haiti, which is located on Hispaniola, but the K76T pfcrt (P. falciparum chloroquine resistance transporter) gene mutation that confers chloroquine resistance has been detected intermittently. We analyzed 901 patient samples collected during 2006–2009 and found 2 samples showed possible mixed parasite infections of genetically chloroquine-resistant and -sensitive parasites. Direct sequencing of the pfcrt resistance locus and single-nucleotide polymorphism barcoding did not definitively identify a resistant population, suggesting that sustained propagation of chloroquine-resistant parasites was not occurring in Haiti during the study period. Comparison of parasites from Haiti with those from Colombia, Panama, and Venezuela reveals a geographically distinct population with highly related parasites. Our findings indicate low genetic diversity in the parasite population and low levels of chloroquine resistance in Haiti, raising the possibility that reported cases may be of exogenous origin

A Multiplex PCR/LDR Assay for the Simultaneous Identification of Category A Infectious Pathogens: Agents of Viral Hemorrhagic Fever and Variola Virus.

CDC designated category A infectious agents pose a major risk to national security and require special action for public health preparedness. They include viruses that cause viral hemorrhagic fever (VHF) syndrome as well as variola virus, the agent of smallpox. VHF is characterized by hemorrhage and fever with multi-organ failure leading to high morbidity and mortality. Smallpox, a prior scourge, has been eradicated for decades, making it a particularly serious threat if released nefariously in the essentially non-immune world population. Early detection of the causative agents, and the ability to distinguish them from other pathogens, is essential to contain outbreaks, implement proper control measures, and prevent morbidity and mortality. We have developed a multiplex detection assay that uses several species-specific PCR primers to generate amplicons from multiple pathogens; these are then targeted in a ligase detection reaction (LDR). The resultant fluorescently-labeled ligation products are detected on a universal array enabling simultaneous identification of the pathogens. The assay was evaluated on 32 different isolates associated with VHF (ebolavirus, marburgvirus, Crimean Congo hemorrhagic fever virus, Lassa fever virus, Rift Valley fever virus, Dengue virus, and Yellow fever virus) as well as variola virus and vaccinia virus (the agent of smallpox and its vaccine strain, respectively). The assay was able to detect all viruses tested, including 8 sequences representative of different variola virus strains from the CDC repository. It does not cross react with other emerging zoonoses such as monkeypox virus or cowpox virus, or six flaviviruses tested (St. Louis encephalitis virus, Murray Valley encephalitis virus, Powassan virus, Tick-borne encephalitis virus, West Nile virus and Japanese encephalitis virus)

Details of viral cultures and nucleic acids used in the study: RNA viruses.

<p>* The exact sequence of the stock used is not known. The GenBank sequence of the parent strain is indicated.</p><p>Details of viral cultures and nucleic acids used in the study: RNA viruses.</p

The limit of detection of the PCR/LDR/Universal Array assay using <i>in vitro</i> transcribed RNA or whole virus.

<p>ND = Not determined</p><p>Pfu/ml = plaque forming units/ml</p><p>ffu/ml = focus forming units/ml.</p><p>^a PCR/LDR was performed on cloned RNA fragments for all viruses except EBOV and DENV while</p><p>^bdilutions of culture supernatants were used for the latter two viruses. <i>Zaire ebolavirus</i>’95 was used for determination of LOD.</p><p>The limit of detection of the PCR/LDR/Universal Array assay using <i>in vitro</i> transcribed RNA or whole virus.</p

Comparison of universal array profile of viral RNA/DNA tested for the corresponding zip-codes.

<p>Normalized average signal intensity for the zip-codes assigned to each virus are presented. The color bars are the signals obtained with the indicated virus (positives). The black bars are the signals produced by the other ten viruses. A signal was considered positive if the intensity of the zip-code spot was at least 10-fold higher than the uniform background level of fluorescence of the array slide. Although a few other viruses produced low-level positive signals for zip18, this did not result in any false positive results since positive signals from at least two addresses was required for a positive identification. In the future, this issue would be rectified by switching to a different zip-code. The average signal intensity for the positives ranged from 31.2 to 123.4, depending on the virus. The average signal intensity for the negatives ranged from 0.3 to 6.2, thus they were not considered positive signals.</p

Schematic of the PCR/LDR assay for detection of VHF viruses.

<p>For each virus (ebolavirus is shown as a representative virus), 1–2 different regions are amplified by RT-PCR using forward and reverse primers, each with minimal degeneracy and all containing universal tails to prevent the formation of primer dimers. Cy-3 labeled downstream LDR primers and single base-discriminating upstream primers with unique zip-code complements (20-30-mers) are targeted to specific sequences/SNPs within the PCR amplicons. Ligation of two adjacent oligonucleotides annealed to a complementary DNA target occurs in the presence of thermostable ligase only if the nucleotides are perfectly matched at the junction [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138484#pone.0138484.ref054" target="_blank">54</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138484#pone.0138484.ref055" target="_blank">55</a>]. The zip-code complements on the 5’ end of fluorescently labeled LDR products anneal to specific complementary zip-code addresses on a universal array [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138484#pone.0138484.ref056" target="_blank">56</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138484#pone.0138484.ref057" target="_blank">57</a>]. A positive signal on the universal array is detected as a fluorescent spot. Primers for the ligation reaction were designed targeting 2 or 3 areas within each PCR amplicon. Each virus could produce a maximum of six ligation products, except for VAR and VACC, for which there were a maximum of 5 each. The detection of 2 or more ligation products was required for the detection and identification of a virus. Representative arrays that detect and identify <i>Ebola Zaire</i>, Lassa and Yellow fever viruses are shown.</p