Title
Post-operative wound infection by Nontuberculous Mycobacteria; case
series in Dhaka Medical College Hospital of Bangladesh.
Introduction: Nontuberculous Mycobacteria (NTM) are ubiquitous
group of bacteria that include mycobacterial species other
than Mycobacterium tuberculosis complex and Mycobacterium
leprae (1). NTM are the diverse group of organisms that are isolated
from environmental sources like soil, water, dust, lakes, rivers,
streams and also from municipal water sources like water that people
drink or shower (2). Mycobacterium chelonae , Mycobacterium
abscessus , Mycobacterium fortuitum, and Mycobacterium
smegmatis are most often linked with NTM infections after surgical
intervention worldwide (3). Usually, Ziehl-Neelsen (Z-N) staining and
mycobacterial cultures are not routinely performed, that’s why the
detection of NTM is missed and the burden is increasing (4). Resistance
to common antiseptics and disinfectant solutions used in hospital
settings is also making these illnesses a growing threat. Inaccurate
sterilization of instruments used in operation theater (OT) is usually
responsible for such types of infections and makes it a great problem
mainly affecting developing countries (5). Thus, proper sterilization of
such instruments is essential to prevent the occurrence of
post-laparoscopic wound infections with atypical Mycobacterium. NTM can
produce biofilms which are collections of microorganisms that stick to
each other, adhere to the surfaces of moist environments, become
resistant to antibiotics, are difficult to eliminate, and ultimately
increase the likelihood of chronic infection (3,6). Globally, in the
last few years nosocomial post-operative wound infections by NTM have
been increasing (7). NTM is becoming more common day by day yet it may
be difficult to diagnose and long-term medication with lowered tolerance
make it more challenging to treat effectively (8). Since treatment
differs from species to species, species and sub-variants should be
identified and even must be recognized from environmental NTM (9).
Materials methods: We collected data on such infections from
February 2021 to July 2022 from the patients who presented with
complaints of chronic serous discharge from the post-operative wound.
The cases were examined, detailed history was taken, and wound discharge
was collected for microbiological laboratory testing at the Microbiology
department of Dhaka Medical College, Bangladesh. To detect NTM from
these cases, Gram stain, ZN stain, fungal microscopy of the samples,
culture, Gene-Xpert and, polymerase chain reaction (PCR) tests were
done. We identified three patients with post-operative skin and soft
tissue infections caused by NTM.
In the microbiology department, with proper aseptic technique discharge
was collected by sterile swab sticks from all the cases. Wet-film
preparation for fungal microscopy, Gram stain, Z-N stain, Gene-Xpert,
culture, and PCR were done from wound discharge. Discharge was
inoculated and incubated on blood agar media and MacConkey agar media
for 7 days, and Lowenstein Jensen (LJ) media for up to 6 weeks at 37°C
aerobically. Written informed consent was taken from each patient.
Detailed information about the operation history, the treatment regimens
of antibiotics, duration of therapy that is completed or running,
follow-up, and the ultimate outcome were collected from patients. In
other cases, where NTM were suspected but not identified from the
samples, were treated with another treatment protocol advised by
Microbiology department of Dhaka Medical College.
Results: On Gram staining, in some cases, few to moderate
amounts of pus cells and sometimes gram-positive cocci were seen under
the microscope. Z-N stained smear revealed acid-fast bacilli (AFB) in
all the cases (Fig-1). No fungal element was found in any sample on
microscopic examination of the discharge. No Mycobacterium
tuberculosis was detected in GeneXpert for MTB from any case.
Culture on LJ media and MacConkey agar media did not show any growth but
in on Blood agar media pale and opaque colored colonies were found in
two samples after 4 days of incubation at 37°C (Fig-2) which became
yellow-pink after 7 days of incubation. Again, Z-N stain was done from
culture isolates and revealed AFB. PCR was done, and NTM was detected in
two specimens. In one sample, culture yielded additional growth of
Methicillin-resistant Staphylococcus aureus (MRSA) on blood agar
media after 24 hours of incubation. The patients were treated initially
for 6 weeks with 4 drugs regimen (clarithromycin 500 mg 12 hourly,
ciprofloxacin 500 mg 12 hourly, linezolid 400 mg 12 hourly, and,
amikacin 500 mg 12 hourly) for 6 weeks, followed by 5 months with 3
drugs regimen (clarithromycin 500 mg 12 hourly, ciprofloxacin 500 mg 12
hourly and linezolid 400 mg 12 hourly) as a maintenance dose. Follow-up
was done in every case after the completion of the proposed drug
regimens. Cessation of discharge occurred within 3-4 weeks after
starting treatment and the wound was also healed or healing in most of
the cases (fig-3, 4).
Case series: Two males and one female, between the ages of
30-36 years, who underwent various surgery presented with serous
discharge at the site of incision mostly within a few months of the
surgical procedures, which progressed to chronic discharging sinus with
a small opening. Most of the patients had a history of apparently
healthy post-operative wounds and stitches were removed within 7-10 days
after surgery. The discharge from the wounds was thin, serous, and
non-purulent. Most of them did not give any history of high fever, pain,
or any constitutional symptoms associated with the wound discharge but
some had low-grade fever and mild pain by giving pressure on the wound
site.
One case presented with nodular swellings that progressed to chronic
discharging sinus from a small site over the incision sites. On applying
local pressure the discharge from the sinus of the wound site increased.
Those patients gave a history of taking several antibiotics such as
fluoroquinolones, colistin, cefixime, vancomycin, ceftriaxone,
meropenem, and linezolid previously but none was cured. One patient took
anti-MTB drug regimens for several months without any improvement and
could not show any diagnostic evidence for MTB. Detailed clinical
profiles of study cases are shown in Table-1, and investigation profiles
are given in Table-2.
Discussion: In recent years, frequently encountered NTM species
in post-surgical wound infections are M. chelonae and M.
fortuitum (10). NTM are transmitted through aerosol, soil, dust, or
contaminated tap water (11). In our study, all the post-operative wounds
were healed initially within 7-10 days of surgery. Then within the next
1-2 months incision sites became erythematous, and indurated, small
blisters formed, burst out, and started serous discharge in small
quantities. Several antibiotics were recommended for these
wound-infected cases but did not respond to any of them, discharge
continued and persisted for a long time before they were referred to the
Microbiology department. Wound infections due to NTM usually do not
occur as an early postoperative complication. During operation, wounds
are contaminated with NTM from environmental sources and take some time
to make their clinical appearance. After infection with NTM, the
operation scar breaks down and develops a non-healing superficial ulcer
with the sinus tract from which non-purulent serous discharge comes out
(12).
Bhalla et al reported 10.9% of post-operative wound infections occurred
by NTM infections in South India (13). Development of mild fever, small
indurations, with or without mild local pain, and serous discharge from
a tiny opening of post-operative healed wound scar indicates the
initiation of the onset of NTM infection. Specimens from such cases
usually show no pus cell or organism on Gram stain and cultures show no
growth on routine culture media for aerobic and anaerobic organisms.
Hence, all these specimens should be collected through aseptic
precautions, must be stained by the Z-N staining method for acid-fast
bacilli (AFB), and incubated on LJ media and blood agar media to isolate
NTM (14). The aim of accurate and early diagnosis is to formulate an
appropriate treatment regimen that is specific to NTM.
NTM have commonly identified pathogens from post-operative wound
infection patients and require a high suspicion for correct and early
diagnosis (13). Chronic discharge with a prolonged course of expensive
antibiotics makes it a serious type of nosocomial infection. Skin or
soft tissue infection is the most common manifestation seen in
NTM-infected individuals whose wounds may be exposed directly or
indirectly to the soil, colonized tap water, unsterilized operative
instruments, or medical devices contaminated with environmental NTM
after traumatic injury, during surgery, or cosmetic procedures.
Surveillance study of environmental culture from tap water, operation
instruments, wall, floor, basin and operation theatre (OT) may not yield
growth of NTM (11). Strict sterilization of all OT equipment, proper
hand washing, and prevention of wound contamination with dust, soil, and
tap water are needed to prevent wound infections with NTM.
Because of the long duration of treatment, side effects and cost of the
drugs accurate diagnosis is necessary. The most preferred choice is a
varying combination of antibacterial drugs like imipenem, amikacin,
fluorinated quinolones, doxycycline, linezolid, and clarithromycin (15).
However, first-line antitubercular drugs like ethambutol and rifampicin
have a bactericidal effect against NTM but they are not used commonly.
When there is a sudden increase in such cases, it is urgent to conduct
epidemiological studies, collect specimens from the surrounding
environment, and confirm NTM infections whether are identical through
culture studies, PCR, and also need antimicrobial susceptibility
testing. Therefore, although it is not possible to test for NTM in all
patients routinely in developing countries like Bangladesh, it is
advisable to refer cases where the patients had an operation history,
were exposed to contaminated water, dust or soil, and suffered from
discharging post-operative wounds with delayed recovery to detect
whether it is NTM infection or not. Furthermore, in this background,
there is poor communication between clinicians and the laboratory due to
poor awareness, unknown prevalence patterns due to lack of study, and
the absence of standard diagnostic facilities and regimens for
treatment.
Until now, there has been a lack of analysis regarding NTM in
Bangladesh. Therefore, such cases have been treated initially as general
wound infections and sometimes by anti-MTB regimens given without any
diagnosis. Recently NTM infections have attracted more attention from
clinicians due to the increase in such cases but still, there is a lack
of awareness. When chronic discharge from post-operative wound
infections occur after operations that cannot be cured by usual
antibiotics, NTM infections should be suspected and ZN stain, culture,
Gene-Xpert, and PCR must be considered as diagnostic tools.