MRSA Infection in Neonatal Care Units

Running Head: MRSA INFECTION
MRSA INFECTION IN NEONATAL CARE UNITS
Name of the Student
Name of the University
Author’s Note

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Suspected MRSA infected infants and their diagnosis in Neonatal Intensive Care Unit
A 7 year old male infant was suffering from fever so he got transferred to the neonatal intensive
care unit (NICU) as the case study will be focusing on this infant. He was receiving pumped
breast feeding from the time he was born but then later on he started refusing to feed on the milk
because he was having some systemic infection (Lawrence and Lawrence 2004). The symptoms
were swelling and redness in the umbilical cord stump, fast breathing of more than 20 bpm and
fast heart rate of more than 100 bpm. The symptoms can be easily diagnosed as sepsis. The
newborn had to give 9 ml blood because there was a suspicion about systemic infection, so the
blood sample was inoculated in the blood culture bottles. The samples were used for testing in
microbiology laboratory specifically for BACTEC blood culture analyser and the results
displayed that a gram positive coccus was seen. The NICU was free of any infections initially
when the newborn child was admitted but two nurses (N1, N2), a doctor (D1) and two infants
turned out to be positive as an MRSA carriage (Kock et al. 2010).
A bacteria known as Staphylococcus aureus, which is gram positive is found in skin and mucous
membrane and the normal human flora. It is usually found around the nasal area but it does not
cause infection. It can cause infections when it enters the blood stream or internal tissues. This
bacteria is found in two types that is methicillin-sensitive Staphylococcus aureus (MSSA) and
Staphylococcus aureus (MRSA). The MRSA is resistant to antibiotics and it can cause life
threatening infections, which makes it necessary for this infection to get detected in hospital so
that cannot elevate cross infections (Taylor and Unakal 2019).

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Aim
The aim of this study is to diagnose an infant so that a suitable treatment can be planned for the
same and to identify the microorganism that has caused the infection. It also focuses on the
reason of the outbreak in the NICU and how it can be kept under check (Hassoun, Linden and
Friedman 2017).
Materials and Methods
The practical schedules in the blackboard was used as a guide for the methods.
Results
The agar plates have been examined macroscopically.
A swab was taken from the umbilical cord and it was given into the culture media for
inoculation. In the same way, the collection and inoculation of the blood sample was done in the
blood culture bottles and then it was given for incubation. After an incubation period of 18 hours,
the colonies of the same morphology on the nutrient agar media of the umbilical cord and the
blood culture were observed. The microscopic results of the MRSA chromogenic media with the
umbilical cord and blood culture showed denim blue stained colonies of small cocci (Cherkaoui
et al. 2007). In both the samples, blood agar plates displayed beta haemolysis and cocci colonies
and the nutrients in the agar plates showed the colonies in yellow/creamy color with a cocci
shape.
Gram Staining

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Both the samples went through the gram staining technique by using the nutrient agar plate. The
results for the blood culture and umbilical cord were identical and it showed clusters of gram
positive cocci. The presence of staphylococcus genus was indicated in the morphology but the
determination of species will only be done by latex agglutination test.
Biochemical identification test
The results of the biochemical tests were identical for both the samples.
Table 1 shows that the bacterial stains, which were unknown turned out to be non-motile and that
means that the flagella was present. In facultative conditions the bacteria started growing, which
meant that the bacteria was capable of growing with or without the presence of oxygen. The
formation of bubbles in the tube was found in the catalase tests that proved that it had a positive
reaction. Pink color was found in the glucose test, which suggests a positive reaction. In the
carbohydrate test the sample showed a yellow coloration that suggests the growth of bacteria that
is fermented that means that this bacteria is able enough to grow in aerobic condition while the
tube is open and during anaerobic condition while the tube is closed (Kullar et al. 2016).
Latex agglutination test
The species of staphylococcus was found with the help of latex agglutination test.
Table 2. It also helped in identifying the presence of staphylococcus aureus.
Antimicrobial sensitivity test (AST)
This test was performed to find out if the antibiotic was effective towards staphylococcus aureus.
Table 3. This table shows the result of the disc susceptibility and if the antibiotic treatments
testing is effective on the strain for blood culture.

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Table 4. This table shows the disc susceptibility and the antibiotic treatments testing on the strain
for umbilical cord.
Disc susceptibility and semi confluent bacterial growth was identified in both the samples. The
inhibition zone was compared to the clinical breakpoint value, this would indicate that the
bacteria was resistance if the clinical breakpoint value was larger than zone of inhibition. The
bacteria was sensitive if the clinical breakpoint value was smaller than the zone of inhibition.
The susceptibility of the bacteria in the blood culture was towards the Fusidic acid antibiotics
and it was resistant to other antibiotics, and the susceptibility of the bacteria in the umbilical cord
was also towards Fusidic acid antibiotics and it was also resistant to other bacteria (Dobie and
Gray 2004).
Table 5. The result of MIC was demonstrated of the antibiotics for blood culture versus case
study strain in this table.
Table 6. The result of the MIC was demonstrated of the antibiotics for umbilical cord versus case
study strain.
Table 5 and 6 showed the minimum inhibitory concentrations tests results. The MRSA was
confirmed in the bacterial strain as the values of oxacillin was more than 256mg/l for umbilical
cord and blood samples. This suggested that the bacterial strain was resistant. The value was
0.5ml/g for vancomycin that suggested that it was minimum concentration needed to stop the
bacterial growth (Rudine and Jennifer 2011).
Cross infection analysis of NICU
Table 7. The MRSA sensitivity test was done for nurses, babies and the doctors in the NICU.

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Table 8. shows that there was resistance in the bacterial strain to all the antibiotics but not the fus
acid. The results in this table was similar to table no 5.
MRSA phage types from healthcare workers and patients in NICU.
Table 9. This table illustrated the results from the NICU of the MRSA phage type.
Table 9 shows the isolation of the healthcare workers and the MRSA sources of the patients. The
phage type was similar to each other such as 3, 7a, 17. This shows that there is possibility of the
infants being the reason for cross infection amongst the staff in NICU as the MRSA strain was
same.
Rapid MRSA screening using real time PCR.
The real time PCR was used for the rapid screening of MRSA, it was done in the NICU because
there was an emergency admission of an infant. However, there was no association between the
child and the case study.
Figure 1. It shows the real time PCR DNA samples that were collected from the nose (PN) and
the skin (PS) including the negative and positive controls were displayed. It also carried out the
SCCmecA region carried out by the PCR targeting.
Table 10. The samples used in figure 1 was presented and the Ct value of the unknown.
The results for the PS and PN were positive for MRSA, which was supported by the values of
the Ct in the table 10.
The extraction of the genomic DNA was done from the blood isolates and umbilical cord of the
infant that were put through the whole genome sequencing (WGS). 100% similarity was seen in
the BLAST results that were displayed. Similarly, silico analysis was performed to determine if

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the staphylococcus Aureus was resistant or sensitive to methicillin antibiotic. It was done by
identifying the presence of MecA cone using BLAST and the results were 100% similar. Thus,
the methicillin antibiotic was not effective to Staphylococcus Aureus.
Determination of antimicrobial resistance through in silico analysis.
The umbilical isolates has the complete genome depicted here
The blood isolates has the complete genome depicted here
Figure 2. It demonstrated the antimicrobial resistance gene found in the silico analysis for the
blood isolates and umbilical cord, the resistant antibiotics are depicted in green and the sensitive
antibiotics are in red.
Figure 2 shows the number of antibiotics such as aminoglycoside, beta-lactam and macrolide,
which are the resistance gene and the antibiotics are such as rifampicin, tetracycline and fusidic
acid that are identified as sensitive.
Epidemiological investigation of MRSA outbreak in the NICU.
The determination of the epidemiological relation was done through the epidemiological
investigation amongst all the isolates to find if there was any single outbreak in the NICU or if
the isolates of the MRSA carriage was found to be separated cases in the hospital (Denys et al.
2013).
Figure 3. It shows a molecular phylogenetic tree founded on SNPs. The representation of the
isolates shows that the infant had sepsis and the reference of the gene (REF) and isolates of the
carriage (N1, N2, D1, F1, and F2). The historical MRSA isolates includes 2 hospital acquired

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isolates known as MRSA 2, MRSA 14, and MRSA 19. The MRSA20 are the 2 strains acquired
from the community.
Figure 3 shows that the infant with photogenic sepsis isolate was taken together into a cluster,
which meant that it was interlinked with all the other isolates with carriage. Therefore, it showed
that the infants were responsible for the outbreak of MRSA amongst the patients in NICU.
Discussion
The agar plates were examined from the macroscopic view and it was revealed that the bacteria
which was identified was also found in umbilical cord and patient’s blood. MRSA has a
chromogenic bacteria that is shown in the denim blue colonies that are the result of activities by
phosphate, which is the enzyme present in all the MRSA (Xu et al. 2016). In the same manner,
biochemical test results and gram staining clarified that the sample had Staphylococcus genus.
Table 1 showed that the results were positive. The latex agglutination test showed positive in the
results for both the samples, which makes it positive that the infant had Staphylococcus aureus
(MRSA). The laboratory carried forward the investigation according to the protocols of MRSA
infection that is necessary to follow to stop the infection to spread. The identification of
causative microorganism, phage typing, antibiotic susceptibility testing, bioinformatics exercise,
and RT PCR were some of the protocols followed.
Tests such as antimicrobial sensitivity and minimum inhibitory concentration are tried to find the
treatment for MRSA infection in patients. The table 3 and 4 showed results that indicated
resistance for erythromycin, Tobramycin, Cefoxitin, Clindamycin, Norfloxacin except for
Fusidic acid. The MIC tests indicated the sensitivity for Vancomycin, which is seen in table 5
and 6. After further testing and results, Vancomycin antibiotics and Fusidic acid were proven to

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be effective for treating patients with MRSA (Schentag et al. 1998). It also prevents
transglucosylases that causes the deterioration of cells, which results to cell lysis. Previously in
Table 9, phage typing results showed that it was present in both the sample of NICU and
patient’s. Moreover, it was displayed that they were linked to the epidemiology that was the
main reason for the outbreak and the possibility of cross infection. Figure 1 indicated that the
non-case related baby had a positive result. Similarly, the real time PCR had a table, which
suggested that an outbreak was found because there were traces of MRSA in the same place (de
la Gandara et al. 2015).
The PCR test was more preferred than the cultural examination as it gave faster results, which is
noteworthy. The isolates were put through the WGS and the results showed that they were 100%
similar and this can indicate two things. First was that the same isolate infected them and second
indicates that both had MRSA strain. When the BLAST was conducted it showed 100%
similarities with MecA genes. This proves that Staphylococcus aureus had traces of MecA genes
that led to the identification of MRSA (Watkins, David and Salata 2012).
Furthermore, the strains of MRSA expresses several factors of virulence that are enzymes,
adhesins, immunomodilators and toxins. The major factor of virulence is Panton-Valentine
leukocidin (PVL), which is a toxin found in skin and soft tissue infections (SSTIs) (Tristan et al.
2007).
The investigation results of epidemiology showed that the sepsis of infants were connected to the
carriages with isolates, which was found in one cluster. Hence, the conclusion came that the
infants had the same MRSA strain, which was also found in other patients of NICU. This
confirmed that he was the reason for the spread of infection amongst other patients in NICU
(Gyawali, Ramakrishna and Dhamoon 2019).

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The risk of transmission of MRSA infection can be avoided by maintaining a habit of washing
hands, use of gloves when going to hospital as this helps to avoid cross contamination. The
healthcare who have been given the duty to care for MRSA patients should use gloves and
aprons while interacting or entering the patient’s room. The patients who are infected with
MRSA should be kept in isolation from other patients so that cross contamination can be avoided
(Nubel et al. 2013).
Human error and misreading the diameter of the inhibition zone could be a reason for limitations
that can negatively impact the results because it will show wrong results for resistance. A sum of
multiple recordings should be done for further investigations, which should be enough to refrain
from any error.
To conclude, Staphylococcus aureus was found in the samples of 7 day old male infant and later
it turned into methicillin resistant (MRSA). As seen in the polygenetic, it was seen that the infant
was the reason for the outbreak of MRSA in the NICU.

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