الفهرس 
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Abstract
.aeruginosa is one of the most important bacterial pathogens involved
in nosocomial infections with a wide spectrum of clinical diseases ranging from infection of
drainage sites, to septicaemia and meningitis, possibly due to its prevalence in the environment
and its ability to colonize infection sites. Infection with this organism is a major cause of
morbidity and mortality among hospital ized patients with altered immune defenses and patients with
different mal ignancies.
In our study, we aimed mainly at characterizing P.aeruginosa isolates by several typing methods
including biotyping, serotyping, antibiotyping and SDS PAGE in an attempt to find any relation
between serotypes and protein patterns with the resistance of P.aeruginosa. We also aimed at
investigating P.aeruginosa susceptibi lity to a new quinolone, trovafloxacin,
One hundred and forty clinical isolates, sent to the Microbiology Laboratory by the managi ng
physician from the Alexandria main University Hospital were collected throughout a period of 6
months. Thirty non-cli nical isolates from amongst specimens taken from the hospital environment
were also collected. These specimens were taken to prove whether or not the hospital environment
was a source of nosocomial infection.
Identi fication of the isolates was done by observing the characteristic colonial morphology,
pigment production, together with the characteristic grape like smell of aminoacetophenone and a
posi tive oxidase test. Further identification was done by culture on cetrimide agar and incubation
at 42°C.
Amongst the 140 clinical isolates, the most common source was sputum (46.4%), followed by pus and
urine (27.1% and 23.7% respecti vely). Regardi ng the depa11ments, the most common was the ICU
(25%) followed by internal
med icine department, emergency department and chest department (23.6%,
10.7% and 9.3% respecti vely).
Antibiotic sensitivity was done by the Bauer Kirby technique for all the isolates. P.aeruginosa was
most resistant to AMP, CTX, C and RD, it was most sensitive to MEM and IPM. It also proved to be
50% resistant to TVA. There was a statistically significant difference between clinical and non-cli
nical isolates as regards resistance to most antibiotics.
We were able to divide the isolates into 6 antibiotypes according to the total number of
antibiotics to which they are resistant (antibiotype I being the most resistant).
In comparing resistance of clinical isolates to TVA with the other antibiotics, most of them showed
a statistically significant difference (AMP, CB, CTX, C, DO, CN, RD, and TOB showing more
resistance and IPM and MEM showing more sensitiv ity) except for 5 anti bi otics (AK, CFP, CIP, NOR
and SCF). Only 5 antibiotics showed a statisti cally significant difference regardi ng the non-cli
nical isolates (CB, CTX, C, RD and SCF), and all showed more resistance.
We performed the MIC of TVA to P.aeruginosa by the tube titration method followed by estimating the
MBC. The MIC50 was 2 µg/ml while the MIC90 was 4 µg/ml. The MBC was 16 µg/ml.
In order to find the relation between the antibiotic sensitivity and the other typing methods, 40
clinical isolates were selected for biotyping, serotyping and SDS-PAGE and were chosen as follows:
20 were taken from the most resistant isolates and 20 from the most sensitive. Ten non-clinical
isolates were chosen
according to the department from where the majority of the clinical isolates were collected, in
order to compare between them.
Biotyping was done using the API 20 NE system (bioMerieux, France). Regarding the clinical
isolates, 10 showed atypical reaction. As for the non cl i n ical isolates, 3 showed atypical
reactions.
Serotyping was done by slide agglutination method (Sanofi Diagnostics, Pasteur, France) by the
method of HABS. Eighty-two percent of cl inical isol ates were typable wh il e 70o/o of the non-cl
inical i solates were typable.
The most common serotypes of clinical isolates were 11 and 12 (32.5% and 30% respectively). The
most common of the non-clinical isolates were 4 and 1 1 (both 20%). None belonged to serotypes 1,
5, 7, 8, 9, 13, 14 and 16.
SDS-PAGE was carried out using the discontinuous buffer system described by Laemml i . We were
able to separate bands into 3 groups according to their molecular weight (above 67 kDa, between 45
and 67 kDa and below 45 kDa). This differentiation could be usefu l if further study would be
carried out in order to separate certain protei ns and investigate them more.
According to the protei n pattern, the isolates were differentiated into 11 distinct band ing
patterns. These were useful for detecting the relation between the protein pattern and the other
typing techniques.
As regards the antibiotype, 100% of banding pattern I belonged to antibiotype I, which is the most
resistant, and 30.7% of non-specific banding pattern belonged to the same antibiotype, while the
remaining 69.3% belonged to antibiotype VI which is the most sensitive one.
from our results the following was observed: for serotype 1 1, 23% of them gave type I banding
pattern while 38.5% gave non-specific banding pattern. As for serotype 12, 40% gave type II banding pattern, while 30.7% were non
specific. Regarding the non-typable isolates, 42.8% gave type III banding pattern.
As for the source of the isolates, 60% of banding pattern I were isolated from sputum, and 66.6% of
banding pattern III were from pus. As regards the non-specific banding pattern, 53.8% were isolated
from sputum and 30.7% were isolated from urine.
from our results it was also noticed that there was no clear relation between certain banding
patterns and the hospital departments.
Concerning the biotyping, 33.3% with typical biotypes gave non-specific banding pattern, while
13.3% gave type I banding pattern. As for the atypical, 30% gave non-specific banding pattern.
As regards the relation between the antibiotype and the serotype of the clinical isolates, 53.8% of
serotype 11 belonged to the most resistant group, and the rest belonged to the most sensitive. As
for serotype 12, the isolates were divided equally among both groups. For the non-typable strains,
71.4% belonged to the resistant isolates, while the rest belonged to the sensitive ones. For
serotype 3, 25% belonged to the resistant isolates and 75% to the sensitive isolates.
from the above, it was quite apparent that there is probably some relation between the protein
structure of the isolates and their resistance patterns.
As regards the non-clinical isolates, the results showed that there was no relation between them
and the clinical isolates, proving that the hospital environment is probably not an important
source of nosocomial infection.