CHEST INTUBATION, INCENTIVES, TRACHEOSTOMY & SPIROMETRY., Summaries of Surgical Pathology

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NURSING

MEDICAL MICROBIOLOGY 1

Table of Contents

• Chlamydia
• The treatment of Chlamydia
• Side effects of Chlamydia treatment................................................................................
• Diagnosis of Chlamydia...................................................................................................
• Pathogenesis of Chlamydia
• Strains of Chlamydia
• RICKETTSIA
• Treatment of Rickettsia
• Diagnosis of Rickettsia
  • Molecular methods
  • Cell structure isolation
• Pathogenesis of Rickettsia
• Strains of Rickettsia.......................................................................................................
• References

Side effects of Chlamydia treatment

Chlamydia treatment can have side effects on the patient, some of the side effects are

 Stomach problems like feeling sick, throwing up, diarrhea, or belly pain  Headaches  Feeling dizzy  Getting a rash or irritated skin  Being more sensitive to the sun  Getting a yeast infection in your vagina (for girls) There are some rare but serious side effects:  Having an allergic reaction like getting hives, swelling, or having trouble breathing  Having problems with your liver or kidneys  Getting colitis, which is when your colon gets inflamed because of the antibiotics

Tips to help with side effects:

 Take the medicine with food to avoid stomach problems.  Drink lots of water and get enough rest.  Using medicine that can be bought without a prescription for headaches or a fever.

Diagnosis of Chlamydia

Chlamydia is a type of organism that lives inside cells. The main goal is to collect samples from host cells that have this organism. A special solution called 0.2M sucrose in phosphate buffered saline is used for this purpose. Tissue culture is a method used to preserve tissue. Different scientists have used various techniques for tissue culture. For example, Gordon used irradiated McCoy cells to show the first cell culture for C. trachomatis. To culture the organism, patient samples are put onto cell layers. This technique is very accurate, but not as sensitive as DNA amplification. Some cell lines, like BGMK and McCoy cells, have been used to grow C. trachomatis. Before cultivation, high-frequency sound waves are used to break down bacterial cells and release the chlamydial bodies.

Pathogenesis of Chlamydia

The cause of severe and often debilitating post-infection complications is not clear, but it is believed to involve the immune system. Research on human trachoma and nonhuman primates with eye infections has led to this hypothesis. Studies have shown that prior vaccination with killed chlamydia bacteria can make trachoma worse when a person is infected again. Some people with trachoma have chlamydia antigens and DNA in their eye tissue even when live

chlamydia bacteria can’t be found. This supports the idea that the immune system plays a role in causing the disease.

In nonhuman primates infected with C. trachomatis and guinea pigs infected with C. psittaci, researchers have found good models for studying how chlamydia infections develop. Previous studies using these models have shown that repeated exposure to the bacteria is needed to cause the chronic inflammation seen in trachoma.

Interestingly, when animals are repeatedly exposed to chlamydia bacteria, they can develop a shorter but more severe infection that is hard to detect. This suggests that the immune response may be protective in some ways, but harmful in others. Repeated infections lead to a buildup of immune cells in the tissue, similar to what is seen in people with trachoma.

Collectively the human and animal study argue for a delayed hypersensitivity role in Chlamydial disease. The most direct evidence for DH in pathogenesis of chlamydial disease comes from the observations that a crude extract of viable chlamydiae elicits severe ocular inflammation in immune animals (17, 18). In immune guinea pigs, this extract produces an ocular inflammatory response whose histopathology is consistent with human trachoma and chlamydial-induced tubal infertility.

Subsequently, we identified and isolated the DH-evoking component, a 57-kD chlamydial protein. Those results support the hypothesis that the host’s immune response to chlamydial infection is, in part, deleterious. In this study, the chlamydial gene that encodes the 57-kD protein was cloned, and the recombinant protein elicited an ocular DH response in immune guinea pigs. The sequence reveals a close relatedness to the heat-shock or stress proteins GroEL of Escherichia coli, HtpB of Coxiella burnetii, 65k of Mycobacterium tuberculosis, and Hsp60 of Saccharomyces cerevisiae.

Strains of Chlamydia

Chlamydia is a common infection that spreads through sexual contact and is caused by the bacterium Chlamydia trachomatis. If not treated, it can cause serious health problems like infertility and ectopic pregnancy. The main way to tell different strains of chlamydia apart is by looking at the major outer membrane protein (MOMP), with serovars D and E being the most common strains worldwide. Although there isn’t a clear difference in how harmful the different strains are, it’s crucial to treat any chlamydia infection right away with antibiotics to avoid complications.

Some strains lf Chlamydia include;

Ocular strain -Chlamydia trachomatis can cause eye infections like inclusion conjunctivitis and trachoma, which can lead to scarring of the inner eyelid and blindness. These infections can be spread through direct or indirect contact and can be treated with antibiotics.

crowded settings, such as schools, college residence halls, military barracks, long-term care facilities, hospitals, and prisons1.

Symptoms of a C. pneumoniae infection usually begin 3 to 4 weeks after exposure and can include:

i. Cough ii. Fever iii. Sore throat iv. Difficulty breathing

People of all ages can get sick from C. pneumoniae, but reinfection is most common in older adults, who are also at increased risk for severe disease caused by the infection1.

For diagnosis, healthcare providers may use respiratory specimens, and treatment typically involves antibiotics. It’s important for individuals with respiratory symptoms to seek medical advice for proper diagnosis and treatment.

Serovars E and F: These strains can cause respiratory infections, such as pneumonia, in newborns. It’s important to note that the different strains of Chlamydia trachomatis can have varying levels of virulence, transmission rates, and associated complications. Accurate diagnosis and appropriate treatment are crucial to manage and prevent the spread of chlamydia infections

RICKETTSIA

Rickettsiae are a variety of Gram-negative bacteria that must live inside cells. They can be found in ticks, lice, fleas, mites, chiggers, and mammals. This group includes Rickettsiae, Ehrlichia, Orientia, and Coxiella. These bacteria can spread infections through the blood to different parts of the body.

Rickettsia felis is seen as a new germ that can make people sick and cause flea-borne rickettsiosis, also known as flea-borne spotted fever and cat flea typhus. Rickettsioses are diseases spread by bugs and caused by a type of bacteria called Rickettsia, which can infect both people and animals. The Rickettsia group has been split into three main groups based on their characteristics: the spotted fever group (SFG), the typhus group (TG), and the ancestral group. While some scientists have suggested a fourth group, the transitional group, to separate certain species, there is still debate over whether this is necessary.

Originally, Rickettsia was thought to be either a virus or an organism that fell somewhere between viruses and bacteria. Much later, it was determined to be a type of bacteria that lives inside cells.

Even though the diseases caused by Rickettsia and the pathogen itself were identified early on, many of the species are considered to be responsible for newly emerging, re-emerging, and/or neglected infections. The increase in infections caused by Rickettsia spp. Could be due to various reasons such as changes in the environment, vegetation, and increased movement of humans and animals. It could also be because of the lack of previous knowledge about studying intracellular bacteria, the fact that the general symptoms of Rickettsia infections are similar to other infections, and changes in the prevalence of other infectious diseases.

Even though more information is available now, the complete understanding of Rickettsia is still not clear. More knowledge is required to monitor new species, make accurate and timely diagnoses, and develop better tools to study the bacteria and their effects on humans and animals.

The first time Rickettsia spp. (specifically Rickettsia helvetica) was found in Swedish ticks was 20 years ago. Since then, awareness of the risk of infection for humans and wild and domestic animals has increased. However, in Sweden, rickettsioses have not gained the same level of public recognition as Lyme borreliosis and tick-borne encephalitis (TBE).

Treatment of Rickettsia

Even though much of this thesis introduction has problematized the difficulty of differentiating between the Rickettsia spp., treatment strategies are generally the same regardless of species.

Doxycycline is the treatment of choice and effective against most rickettsial strains, including R. helvetica and R. felis (281–283). The recommended dose is 100mg twice a day for five to seven days for SFGR or until fever has been absent for three days. In the event of complicating conditions, such as meningitis, a longer treatment course is required (165,284,285). Doxycycline is a tetracycline antibiotic that inhibits the ribosomal protein synthesis, but is contraindicated in children younger than 8 years and pregnant women. The Tetracycline group is contraindicated because it causes deposits in growing bones and tooth enamel, leading to growth retardation, enamel hypoplasia and discoloration of children’s permanent teeth (286,287). Apart from the Tetracyclines, the macrolides such as josamycin, clarithromycin and azithromycin also show effects against Rickettsia spp. In vitro (281,288) and clinical trials have found them to be suitable options for treating children with MSF (R. conorii) (289,290).

However, a recent systematic review has called into question the contraindication for doxycycline, as it lacks support in the scientific literature. The authors’ hypothesis is that the reason doxycycline was considered contraindicated is because it was introduced on the market around the time when other tetracyclines were discovered to have the abovementioned side effects and the specific side effects for doxycycline were never evaluated.

Doxycycline is also an effective antibiotic for treating the other tick-borne infections A. phagocytophilum and Borrelia spp. However due to doxycycline’s broad spectrum nature, it is not the first choice in patients presenting with EM and history of tick bite, but without fever.

Enzyme-linked immunosorbent assay

The ELISA method, similar to IFA, can detect specific antibodies in a serum sample that bind to an antigen. When secondary antibodies, which are anti-human antibodies combined with an enzyme, attach to antibodies from a serum sample and are exposed to a substrate, a measurable enzymatic reaction occurs in a positive sample. The ELISA method has advantages such as the ability to analyze a large number of samples, the chance to study antibody reactions to different protein antigens, and, in comparison to IFA, the enzyme reaction’s absorbance is measured with a spectrophotometer, removing subjective assessment. The ELISA method was quickly adopted for studying serological reactions to Rickettsia spp. And has been proven to be a precise and sensitive tool.

Weil-Felix test

The Weil-Felix test, also known as the agglutination method, has been used since 1916 to diagnose rickettsial infections. This test relies on a reaction between two Proteus vulgaris antigens, one Proteus mirabilis antigen, and antibodies to Rickettsia spp. These antigens help differentiate between different types of rickettsial infections. However, the test has limited sensitivity and specificity, with reported sensitivity as low as 33% and specificity as low as 46%. While this method is no longer commonly used in areas with better resources, it remains the primary diagnostic tool in many low-income settings where rickettsial infections are prevalent.

Molecular methods

Molecular techniques such as PCR play a key role in diagnosing and researching various conditions. These methods involve analyzing DNA from samples like eschar swabs, skin biopsies, cerebrospinal fluid (CSF), and whole blood or serum.

Using PCR-based methods followed by DNA sequencing (263,264) is the easiest way to differentiate between the various Rickettsia spp. And to gain knowledge about the genomic differences within the genus. For diagnostics and screening, the real-time PCR is quick, sensitive and specific Molecular methods are also useful in “diagnosing” the vectors

However, using this method can lead to contamination due to the large amount of PCR-products produced, which may result in false-positive outcomes. Additionally, collecting samples is more challenging compared to serology; if the infection does not show eschar or CNS involvement, swabs, biopsies, and CSF samples cannot be used for diagnosis. Unfortunately, PCR testing on blood and serum is not very sensitive. On the other hand, PCR is a suitable tool for diagnosing acute infections. Samples taken early in the disease, before antibodies develop, are more likely to yield positive results in PCR tests. However, once antibodies are detectable, bacteria are rarely found in the body or at infection sites. Moreover, if antibiotic treatment has started, the sensitivity of PCR tests decreases for the same reasons

Cell structure isolation

To make sure a sample has live Rickettsia bacteria without any doubt, the bacteria must be separated and grown in cell cultures. This method is not commonly used for regular testing because it takes a lot of time, has a low success rate, needs a specific amount of bacteria for inoculation, and grows slowly. Also, some Rickettsia species like R. rickettsii need biosafety level 3 labs for cultivation. Therefore, using this method for regular testing requires having biosafety labs to handle samples from patients who have been to areas where serious Rickettsia species are common. In summary, isolation is not suitable for regular testing.

Rickettsia can grow in many types of cells such as mammalian, amphibian, insect, and tick cell lines. These bacteria are picky and need to be grown in an environment with 5% CO2 at temperatures between 32 and 35 °C, although the temperature can be lower for R. felis depending on the cell line used.

To see the small Rickettsia bacteria that have been grown in cells, they must be labeled with fluorescent antibodies or stained using the Gimenez staining protocol. This staining method was created in the 1960s to stain Rickettsia spp. In yolk sack or cell cultures because they do not stain well with Gram staining. For a closer look at Rickettsia in cell cultures, an electron microscope can also be used.

Pathogenesis of Rickettsia

When an infected tick bites a mammal, it can transmit rickettsia bacteria through its saliva. Similarly, fleas and lice can infect a host when they scratch the itch caused by the bite. Infections with Rickettsia spp. Can result in eschars on the skin, with the severity of the infection often correlating with the species causing the eschars. Mild infections like African tick-bite fever typically lead to eschars, while more severe infections like RMSF or epidemic typhus usually do not. The formation of eschars is a result of inflammation around the bite, which helps prevent the spread of bacteria throughout the body.

Rickettsia tends to target small and medium-sized blood vessels, but can also infect lymphatic vessels, neurons, and phagocytes. Once inside the host’s circulation, rickettsia attaches to the host’s endothelial cells. Certain proteins, such as surface cell antigen (Sca) 0, 1, 2, and 5, play a crucial role in the adherence of rickettsia to host cells. Sca0 and Sca5 are specifically important as they are the rickettsial outer membrane proteins OmpA and OmpB.

The Sca proteins are a family of autotransporters, common in Gram-negative bacteria, and the Rickettsia spp. Have 17 Sca genes, most of which are degraded and non-functioning.

When an infected tick bites a mammal, it can transmit rickettsia bacteria through its saliva. Similarly, fleas and lice can infect a host when they scratch the itch caused by the bite. Infections with Rickettsia spp. Can result in eschars on the skin, with the severity of the infection often

Transitional strain

This refers to a subset of Rickettsia species that share characteristics with both the spotted fever group and the typhus group. A notable example of a transitional group Rickettsia is Rickettsia tillamookensis, which was isolated from the western black-legged tick, Ixodes pacificus.

R. tillamookensis is distinct from other named species within the genus, with a maximum average nucleotide identity of 95.1% to R. asembonensis and a maximum digital DNA-DNA hybridization score similarity to R. felis at 80.1%. It also shows close similarity at the 16S rRNA gene (97.9%) and sca4 (97.5%/97.6% respectively) to Candidatus ‘Rickettsia senegalensis’ and Rickettsia sp. Cf9, both isolated from cat fleas (Ctenocephalides felis)1.

This strain grows aerobically in various cell lines and its growth is rapid at 28 °C and 32 °C, which is significant for understanding its biology and potential pathogenicity. The characterization of R. tillamookensis and other transitional group species helps in expanding our knowledge of the diversity and evolutionary relationships within the Rickettsia genus.

Spotted fever strain

The spotted fever group of Rickettsia includes several strains, with Rickettsia rickettsii being the most well-known as it causes Rocky Mountain spotted fever (RMSF). RMSF is a severe tick- borne illness prevalent in North America and is characterized by symptoms such as fever, headache, and rash. Without prompt antibiotic treatment, mortality rates can be as high as 20 to 30 percent1.

Another strain, Rickettsia parkeri strain Atlantic rainforest, has been identified in Brazil and is associated with the tick Amblyomma ovale. It has been reported to cause a milder form of spotted fever rickettsiosis2.

Spotted fever rickettsiosis encompasses a group of infections that are often difficult to distinguish from one another and include diseases like RMSF, Rickettsia parkeri rickettsiosis, Pacific Coast tick fever, and rickettsialpox3.

Bellii strain

The Rickettsia bellii group represents a basal lineage of rickettsiae that diverged before the pathogenic spotted fever and typhus groups. R. bellii has been found in a variety of hard and soft tick species across the American continent. Studies have revealed distinct lineages of R. bellii in the United States and South America, suggesting that these bacteria have evolved separately within their respective continents.

Despite its wide distribution, R. bellii is not typically associated with human disease, which sets it apart from many other Rickettsia species. However, its presence in ticks and other arthropods indicates its potential role in the ecology of tick-borne diseases. The genotypic characterization

of R. bellii helps in understanding the phylogeographical relationships among strains and provides insights into the coevolution of these bacteria with their tick host.

References

Abdelsamed, H., Peters, J., and Byrne, G.I. 2013. Genetic variation in Chlamydia trachomatis and their hosts: Impact on disease severity and tissue tropism. Future Microbiol., 8, 1129–1146.

Abromaitis, S., and Stephens, R.S. 2009. Attachment and entry of Chlamydia have distinct requirements for host protein disulfide isomerase. PLoS Pathog., 5, e1000357.