Download The bacterial flora of acute appendicitis at the Port Moresby General

PNG Med J 2012 Mar-Dec;55(1-4):12-15
The bacterial flora of acute appendicitis at the Port Moresby General
Hospital in Papua New Guinea
Damien J. Hasola1,2, Ray Dutta3, Cecil Darrell3, George Gende1,
William Kaptigau1, Osborne Liko1 and Ikau Kevau1
Surgery Department and Pathology and Microbiology Department, Port Moresby
General Hospital, Papua New Guinea
sUmmary
Acute appendicitis is a common cause of acute abdomen requiring an emergency
appendicectomy. Complications such as perforation and peritoneal contamination leading
to peritonitis can result from delay in presentation and an emergency operation. This
study prospectively recruited 101 patients diagnosed with acute appendicitis to correlate
the bacterial flora with the severity of appendicitis. The results show that 90 patients had
acutely inflamed or gangrenous appendicitis and 11 had perforated appendicitis. The
ages ranged from 6 to 49 years with a median of 20 years. There were 59 females and 42
males. The commonest isolates were aerobic bacteria such as Escherichia coli, Group
D streptococci and Klebsiella pneumoniae. Mixed infection with anaerobes such as
Bacteroides fragilis was seen only in perforated appendicitis. The best choices of antibiotic
were a fluoroquinolone, cephalosporin and aminoglycoside for aerobic organisms and
metronidazole for anaerobes.
Introduction
initiates but at present this is only speculative
(1).
Appendicitis is a disease of antiquity but
acquired prominence when it was recognized
as a clinical and pathological entity requiring
surgical therapy in 1886. Before this in the
16th century it was known as perityphlitis, a
‘fatal suppurative disease of the caecal region’
(1).
It was only as recently as 1938 that bacterial
infection was documented by Altemeier in
appendicitis (2). Since then it is known that
from 4 to 10 different species which act in
synergism can be isolated. Most studies (2-5)
show that bacterial invasion is secondary and
that the isolates are mainly Escherichia coli,
streptococci groups and Bacteroides fragilis.
The basic pathological process in
appendicitis is obstruction, usually by a
faecolith. The progressive nature of the
inflammation results from a sudden rise in
intraluminal hydrostatic pressure with vascular
obstruction and bacterial invasion of the
appendicular wall. Perforation occurs at the
weakest point, which is at the antimesenteric
border. There are other intriguing causes such
as orange seeds, ascarids and pins that have
lodged themselves in the caecal appendix but
they are extremely rare. The equivalent of
the Peyer’s patches in the appendix has been
suggested as the place where the process
In Papua New Guinea no such study has
been done to date to establish the microbiology
of appendicitis. The aim of this study was
to establish the bacterial profile in acute
appendicitis and the antibiotic susceptibilities
of the bacteria and to correlate these findings
with the severity of the disease.
Materials and Methods
101 patients with clinical and histologically
proven acute appendicitis were recruited into
1 S
urgery Department, Port Moresby General Hospital, Free Mail Bag, Boroko, National Capital District 111, Papua
New Guinea
2 P
resent address: Department of General Surgery, Buka General Hospital, Autonomous Region of Bougainville
[email protected]
3 P
athology and Microbiology Department, Port Moresby General Hospital, Free Mail Bag, Boroko, National Capital
District 111, Papua New Guinea
12
Papua New Guinea Medical Journal
Volume 55, No 1-4, Mar-Dec 2012
incubated at 36-37°C for 48 hours under aerobic
and anaerobic conditions with anaerobic gas
pack for another 48 hours. Positive colonies
were Gram stained and any Gram-negative
rods were tested against metronidazole and
gentamicin discs. The first subculture after 48
hours on to MacConkey agar was incubated in
an aerobic environment at 35-37°C for 18-48
hours. Positive colonies were Gram stained
and tested using the Analytical Profile Index
(API – Oxide bioMérieux Inc, USA) to identify
the different isolates.
the study. All patients were operated on at the
Port Moresby General Hospital from March to
December 2009. Before operation antibiotics
effective against both aerobic and anaerobic
organisms were routinely given. Under general
anaesthesia, the appendicectomies were
mainly done through a Lanz incision except
for patients with peritonitis who had lower
midline laparotomies. Once the abdomen
had been opened the diseased appendix was
amputated and any pus or fibrin sucked out.
The peritoneal cavity was copiously irrigated
with normal saline and the wound repaired in
layers. The layers of skin were approximated
loosely or left open if pus was present and
closed by secondary intention.
Results
Of the 101 patients 59 were females and 42
were males. The youngest was 6 years old and
the oldest 49 years with a median of 20 years.
The duration of illness to the day of operation
ranged from 2 to 6 days with an average of
3 days. 50 patients had acutely inflamed
appendicitis, 40 had gangrenous appendicitis
and 11 had perforated appendicitis (Table 1).
There were no deaths in this series; however,
one patient had a residual abscess that was
drained and improved.
Specimen procurement
The appendix was divided into halves
without entering the lumen. One half was sent
for histological diagnosis and the other for
bacteriological culture. The tissue for culture
was mashed using a sterile plate. Immediately
it was placed in Robertson’s cooked medium
(enriched medium) and sealed with an airtight cap. In the laboratory the samples were
table 1
Aerobic and anaerobic bacteria cultured from early, gangrenous and perforated appendicitis
Bacteria
Early
appendicitis
n = 50
Gangrenous
appendicitis
n = 40
Perforated
appendicitis
n = 11
Total
29
40
11
80
Group D streptococci
3
7
10
20
Klebsiella pneumoniae
3
3
5
11
Citrobacter freundii
1
1
6
8
Proteus mirabilis
1
1
2
4
0
0
3
3
Aerobic (123)
Escherichia coli
Anaerobic (3)
Bacteroides fragilis
13
2/4 (50%)
4
Proteus mirabilis
14
nt = not tested
Total
Bacteroides fragilis
126
nt
7/8 (88%)
8
Citrobacter freundii
3
2/11 (18%)
11
Klebsiella pneumoniae
Anaerobic (3)
15/20 (75%)
20
Group D streptococci
33/80 (41%)
Amoxycillin
80
Number
of
strains
Escherichia coli
Aerobic (123)
Bacteria
nt
3/4 (75%)
7/8 (88%)
8/11 (73%)
19/20 (95%)
61/80 (76%)
Chloramphenicol
0/3 (0%)
3/4 (75%)
8/8 (100%)
11/11 (100%)
15/20 (75%)
76/80 (95%)
Gentamicin
nt
3/4 (75%)
8/8 (100%)
11/11 (100%)
19/20 (95%)
78/80 (98%)
Ceftriaxone
nt
4/4 (100%)
8/8 (100%)
11/11 (100%)
20/20 (100%)
80/80 (100%)
Ciprofloxacin
3/3 (100%)
Metronidazole
The antibiotic susceptibility patterns of isolates from acute appendicitis at Port Moresby General Hospital in 2009
Table 2
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Volume 55, No 1-4, Mar-Dec 2012
Papua New Guinea Medical Journal
Volume 55, No 1-4, Mar-Dec 2012
a reflection of lengthy exposure to many
antibiotics over time (7). Metronidazole has
been shown to reduce mortality and morbidity
from appendicitis and has become the main
prophylactic antibiotic in appendicitis. The
further isolation of Bacteroides species
depends on the laboratory’s capacity to
culture and identify them. Pseudomonas
species were not seen in our study but were
predominant in western studies, which is hard
to explain. Our findings suggest that there are
serious levels of resistance against commonly
used antibiotics in the community. Since this
is the first study for our hospital it will need to
be repeated in the future to monitor resistance
levels for site-specific diseases such as
appendicitis, osteomyelitis and pyelonephritis.
The 126 bacterial isolates showed an
upward trend in colonization both qualitatively
and quantitatively as the disease worsened.
Escherichia coli, Group D streptococci and
Klebsiella pneumoniae accounted for 90% of
aerobic isolates whereas Bacteroides fragilis
was isolated from 3 patients with perforated
appendicitis (Table 1).
Bacterial susceptibilities showed a variable
pattern of resistance to commonly used
antibiotics ranging from 0 to 82% (Table 2)
in the aerobic pathogens group. All aerobic
organisms were susceptible to ciprofloxacin.
In the anaerobic group, B. fragilis was
completely susceptible to metronidazole.
Discussion
In conclusion, a cephalosporin or
gentamicin combined with metronidazole
should be the first choice for antibiotic
therapy in appendicitis. Ciprofloxacin should
be reserved for cases not responding to
cephalosporin or an aminoglycoside. The
emergency operation should be done the
same day by a trained surgeon to get optimum
results in our setting. It is also important
to have a hospital policy so that there is a
protocol for prescribing antibiotics that is
based on the organisms likely to be found and
their antibiotic resistance levels rather than
‘best guess’.
This study showed that a mixed infection
exists, with aerobic bacteria predominating
in early infection and anaerobic bacteria
appearing in late complicated appendicitis.
E. coli, Group D streptococci, K. pneumoniae
and Citrobacter freundii accounted for 97% of
aerobic bacteria in early acute appendicitis.
This study affirms the position of B. fragilis in
perforated appendicitis.
The antibiotics of first choice are a
fluoroquinolone,
cephalosporin
and
aminoglycoside for aerobic organisms and
metronidazole for anaerobes.
Although
there was no mortality in this study, 1 case
of post-appendicectomy residual abscess
in a perforated appendicitis was seen.
Complications were reduced because of a
tendency to early operation, copious peritoneal
saline wash and antibiotic therapy including
metronidazole (6).
Community-acquired
appendicitis from E. coli, K. pneumoniae and
streptococci had a high level of resistance
to the commonly used antibiotics such as
chloramphenicol and penicillins. This may be
due to indiscriminate prescription patterns in
Papua New Guinea.
references
1 Williams NS, Bulstrode CJK, O’Connell PR, eds.
Bailey and Love’s Short Practice of Surgery. Twentyfifth edition. London: Hodder Arnold, 2008.
2 Altemeier WA. The bacterial flora of acute perforated
appendicitis with peritonitis: a bacteriologic study
based upon one hundred cases.
Ann Surg
1938;107:517-528.
3 Bennion RS, Baron EJ, Thompson JE Jr,
Downes J, Summanen P, Talan DA, Finegold
SM. The bacteriology of gangrenous and perforated
appendicitis – revisited. Ann Surg 1990;211:165-171.
4 Roberts JP. Quantitative bacterial flora of acute
appendicitis. Arch Dis Child 1988;63:536-540.
5 Brook I. Bacterial studies of peritoneal cavity and
postoperative surgical wound drainage following
perforated appendix in children.
Ann Surg
1980;192:208-212.
6 Pinto DJ, Sanderson PJ.
Rational use of
antibiotic therapy after appendicectomy. Br Med J
1980;280:275–277.
7 Berne TV, Yellin AE, Appleman MD, Gill MA,
Chenella FC, Heseltine PN. Surgically treated
gangrenous or perforated appendicitis: a comparison
of aztreonam and clindamycin versus gentamicin and
clindamycin. Ann Surg 1987;205:133-137.
The emergence of multiple drug resistance
in bacteria appears to be a formidable
challenge to our hospitals. Our findings
are supported by other studies in both the
qualitative and quantitative nature of the
bacteria isolated; however, they differ with
respect to the antibiotics used (3,4,6). It is
probable that the use of clindamycin and
gentamicin as the antibiotics of choice is
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