Throat and Sputum Lab

This week in lab we looked at throat cultures, a quick throat screen, sputum culture and sputum gram stains. We were given three throat swabs along with media that had already been plated out. There were two isolates on the SBA. The first was beta hemolytic translucent, white and glistened. The second was small, white, opaque and convex. The presumptive ID on number one was a beta hemolytic Streptococcus because the catalase test was negative. A PYR test was also done and was negative. From this I determined that a PathoDx should be done and was "C" positive indicating Streptococcus dysgalactiae subsp. Equisimilis. Notice from the picture below this looks like group A strep, and the PYR and PathoDx are what differentiate them. Isolate 2 was determined to be normal flora and was a coagulase negative Staph. The throat screens were very simple to do, and one of mine was positive for group A Streptococcal antigen, indicating the patient should be treated. The other was negative, so a culture should be done.

Streptococcus dysgalactiae subsp. Equisimilis (group G strep) beta hemolysis

The sputum cultures also had 2 isolates. On SBA, number 1 was mucoid, gray, and opaque while number 2 was small white and opaque. Number 1 grew on SBA, MAC, and Chocolate meaning it was a negative rod and was a SLF. An oxidase test was done and was negative so an API 20E gave results of Klebsiella pneumonia. The other isolate was coagulase negative Staphlococcus. This finding of K. pneumoniae was consistant with the case given that the patient had a cough producing thick bloody phlegm ("currant jelly"). He also had lower lobe infiltrate and a pulmonary abscess.

Lower Respiratory Infections

This week in class we finished discussing lower respiratory infections (LRI). The two most common infections seen and heard are bronchitis and pneumonia. Bronchitis can be either acute or chronic, each having a large impact on the individual invaded by the bacteria or virus. The most common bacteria see in bronchitis are S. pneomoniae, H. influenza, and M. catarrhalis. Pneumonia can be categorized into community-acquired and nosocomial (hospital) acquired. Many bacteria can be responsible for nosocomial  infections including Klebsiella, Enterobacteriacae, P. aeruginosa, S. aureus, S. pneumonia, Anaerbes, and Legionella. Another common infection is Mycoplasma. This is usually caused from M. pneumonia, which is often called walking pneumonia. Serology is most often used to confirm the infection and can be done by ELISA/IFA. The last bacterial agent I want to review is Chlamydophila. Chlamydophila psittaci is often referred to as atypical pneumonia, is transmitted to man via birds, and is classified as a category B biological warfare agent. Serology is the most commonly used method used to identify this agent. Chlamydophila pneumonia is asymptomatic and is major cause of community acquired pneumonia. This is also associated with coronary artery disease. I have had mycoplasma pneumonia and am interested in it, and as a result I have researched and attached a link to a journal article that looks at pneumonia in children with asthma.

http://ajrccm.atsjournals.org/cgi/reprint/172/9/1078

Lab- Urines and CSF

This week in lab we looked at urines and spinal fluids. The case I was given for CSF was a 13-month old child who was admitted a grand mal seizure, temperature, increased pulse and respiratory rate. He was lethargic, irritable, and a stiff neck. A lumbar puncture was performed and the WBC count of 4,650/ µL with 95% neutrophils, glucose of 48 mg/dL and protein of 107 mg/dL. I first gram stained the primary smear and quantitated the bacteria seen. There were more than 30 bacteria seen in each field observed (average), and they were described as some short rods, some pleomorphic rods, with some coccobacilli. The SBA media had pinpoint, grayish, translucent colonies satelliting with a quantitation of 4+. The chocolate agar also was quantitated at 4+ with smooth translucent gray colonies. We also gram stained a slide from the inoculated thioglycollate broth. This showed a possible contaminate because along with the long pleomorphic rods expected, there were gram positive cocci seen. With these findings, an API NH was done with a presumptive ID of Haemophilus. The API strip confirmed the child had an infection due to Haemophilus influenzae.

Gram stain negative pleomorphic rods with coccobacilli



Pseudomonas aeruginosa on SBA

Coagulase negative Staphlococcus

The urine specimen I had was plated on SBA, MAC, and Chromagar. On SBA, there were small white opaque colonies >100,000 CFU/mL, no growth on MAC, and >100,000 CFU/mL of white colonies on Chromagar. The presumptive ID was Staphlococcus. A catalase test was positive, Staphaurex negative, and Novobiocin sensitive. With these results, the final identification was Staphlococcus, coagulase negative. Then we plated/ streaked our urine specimen on to SBA, MAC, and Chromagar. I read the plates on Thursday and the SBA plate was very typical of Pseudomonas (grayish green, beta hemolysis, taco odor). The colonies were clear on MAC, and beige on Chromagar. The oxidase test was positive and spot indole negative and ID was Pseudomonas aeruginosa.

Week 2 UTI/ RTI

In class this week we discussed urinary tract infections along with upper and lower respiratory tract infections. Instead of traditional lecture for UTI, we were given parts of cases in groups and tried to determine what was causing infections in the hypothetical cases. There are five types of bacteriuria. One group was assigned to describe the types of collection of urine specimens, while another described testing done to test and confirm an infection.

On Thursday we discussed upper and lower respiratory infections. One thing that is important to remember about the URT is there is normal flora present. Group A strep (GAS) or S. pyogenes is the leading cause of pharyngitis. I have experienced a rash with a GAS infection and because some other people said so as well I was interested to learn more. I was unable to find a lot of information but I have included a link below to the emedicine website that describes an impetigo rash sometimes seen. One new thing I learned was a CAMP test was described for the detection of A. haemolyticum. I also remember that it is not necessary to do a gram stain on a throat swab or culture throat swabs for anaerobes. Some other pathogens seen are N. gonorrhoeae M. meningitidis B. pertussis C. diptheria, H. influenzae, S. aureus, and C. albicans. I will discuss more about the lower respiratory tract infections next week after we finish discussing it!

Streptococcus Group A Infections

Lab Week 2

In lab, we were able to use the material covered in lecture and actually have a case and 24-hour blood culture to plate onto specific agars and perform rapid and incubated tests. The first thing I did was a gram stain that showed gram positive cocci in pairs (clusters). I then plated the blood onto SBA with a P disk and incubated it in CO2 at 35C. From the P disk and a bile solubility test I determined it was sensitive and therefore Streptococcus pneumoniae. From the information I obtained in lab, I was able to consult several references and write a short statement about the clinical significance of the bacteria and how the patient in the case was likely infected. The picture below is a sheep blood agar with a P disk and positive sensitivity. This is also a review of alpha hemolysis!!

The most challenging part of the class and lab so far is using information I learned last semester. I feel that once I use it more often and become more comfortable with it I will enjoy the class but especially the lab more! Feel free to comment what your organism was and the reactions seen, and we can use it for review.

Bloodstream Infections

This week we discussed bloodstream infections and proper techniques used to isolate organisms from a blood culture bottle. The link below is an article published in the New York Times Health Guide from 2009. It is interesting that the newspaper would publish this, and suggests that there is an interest and need for public awareness. Also, notice the terminology and definitions used in the article, it will probably make you feel like a pro!

We also started discussing CSF and sterile fluids. Both blood and CSF are sterile fluids and therefore no bacteria should be found in them. It is important to remember not to refrigerate the specimen and to always use proper techniques to prevent contamination and the need for a recollect. It is imperative that the collection and storage of specimens be correct, as many of the patients these specimens are coming from are very ill. Meningitis is a situation where CSF would be collected and examined for bacteria or viruses. The causative agents associated with bacterial meningitis were discussed in more detail than viruses.


(The fire drill today was a first experience for me in a university setting!!)

http://health.nytimes.com/health/guides/test/blood-culture/overview.html

WELCOME

Welcome to Jennifer’s Infectious Disease blog created to comment on information covered in the course. I am a CLS student at UAB taking an infectious disease class. The content of the posts will be questions, comments, pictures, articles and anything else relevant to the class. This is designed to both reinforce topics covered in class and introduce new or further information that might be helpful in understanding. Please comment what you find interesting and helpful so we can make this semester a success. Please also feel free to ask questions that we could find answers to together! I will try to post things that I hope you find interesting and helpful!