Surgical infection and outbreaks

Malcolm Richardson PhD, FSB, FRCPathRegional Mycology Reference Centre

University Hospital of South Manchester, andThe University of Manchester

Nosocomially vs. community-acquired IA

Nosocomial• Due to break in, or

contamination of hospital water system

• Due to break in HEPA filtration system

• Due to construction or demolition work in the hospital

Community-acquired• Due to occupational

activities• Due to leisure activities• Due to exposure to

Aspergillus spores (minimum effective dose not known)

Praz-Christinaz et al. Transplant Infect Dis 2007; 9: 175-181

• 53 outbreaks: 1967-2005• 458 affected patients:

– 299 (65.3%) haematological malignancies– Route of transmission: air– Site of primary infection: lower respiratory tract (356 patients)– Surgical site infections (24 patients)– Skin infections (24 patients)

Nosocomial aspergillosis

Outbreaks update 2009Weber et al. Medical Mycology 2009

• >60 English literature

Species distrubution

Infection sites

• Pulmonary• Post-operative

– Cardiac surgery– Ophthalmic surgery– Dental surgery

• Cutaneous

Post-operative aspergillosis

• Dd paper

•>500 cases•Cardiac surgery (n = 188•Ophthalmic surgery (n > 90)•Dental surgery (n = 100)•Wound infection (n = 22)•Bronchial infections (n = 30)•Orthopedic surgery (n = 42)•Vascular prosthetic surgery (n = 22)•Neurosurgery (n = 25)

•Source presumed to be airborne infection

•20 healthy individuals•Conventional and molecular analysis•74 culturable genera•11 non-culturable•Aspergillus species: 35%

2010

•Liver transplant recipient•11-days post-transplant: Aspergillus fumigatus deep-surgical site infection•2 patients: transplantation unit: pulmonary aspergillosis•Debridement and changing of dressings: bioaerosols

CID 2002

Events in the growth of Aspergillus

Aw: Minimum water activity level at 25°C

ERH: Equilibrium relative humidity

Aw < 0.80, ERH <80%

Aw < 0.80-0.90, ERH <80-90%

Aw >0.90, ERH >90%

water

Air as a source of human infection

Inhalation: most common portal of entryTemporal association between hospital-based

outbreaks and constructionVery little data on base-line concentrationsLongitudinal studies show no correlation between

sporadic cases of IA and changes in spore count

Concentrations of airborne Aspergillus compared to the incidence of invasive

aspergillosis: lack of correlation54-week air sampling periodA. fumigatus and A. flavus: mean 1.83 cfu m-3

Individual samples: maximum: 11.6 cfu m-3

No correlation with season or ward6 cases of IPA during sampling periodNo association with fluctuations in air count

Conclusion: “the available data do not provide a firm link between hospital exposure and an increased incidence of aspergillosis”

Hospenthal et al., Medical Mycology 1998.

Heavy excavation!

Ventilation as a source

Source of Aspergillus in the operating theatre

Surgical infection

A thermal ceiling as source of Aspergillus

Dust: a perfect home for Aspergillus!

GM

Dust collection

Ward 9, Dust

0

2

4

6

8

1 2 3 4 5 6 7Weeks

CFU

K9/1 K9/2 K9/3 K9/4 K9/5K9/6 K9/7 K9/8 K9/9 K9/10

Air sampling: SAS Super 100 and Duo

Acceptable levels

• HEPA filtered air: 0• Open ward:?• General hospital areas: ?• Outdoor air: highly variable/seasonal

Efficacy of prevention by HEPA filtration or laminar airflow against Aspergillus airborne contamination during hospital renovation

• Conclusions:– strong association between building renovation and

an increase in environmental contamination– confirmation of the high efficacy of laminar airflow

plus HEPA filtration and a high air-exchange rate– HEPA filtration alone did not prevent contamination

during renovation– ”A standard protocol for aerobiological surveillance is

needed”

Cornet et al. Infect Control Hosp Epidemiol 1999; 20: 508-513.

Invasive aspergillosis related to construction and the utility of air sampling

• 8-bedded BMT unit• 2 cases of IPA• 5 cases of colonisation• Coincided with major construction project on floor

directly below unit• High air counts before cleaning• No isolation after construction stopped and deep

cleaningLai et al., 39th ICAAC, San Francisco 1999

Is air sampling necessary, if so, when?

• Determination of source: outbreaks• occupants have symptoms, but no obvious

building damage• contamination suspected through air from

other parts of the building

Malt extract agar• Heptane• Undecane• Isoprene• 2,4 Hexadiene• 2-Methyl-1,3-pentadiene• 1,3-Octadiene• 2-Methyl-1-butanol• 3-Methyl-1-butanol• 2-Ethyl-1-hexanol

Wood• Methylpyrazine• Acetone• 2-Pentanon• 2-Hexanone• 2-Heptanone• 4-Heptanone• 2-Octanone• 3-Octanone• Acetophenone• -Farnesene

Aspergillus fumigatus

Head-space solid-phase microextraction Fiedler et al. 2001 Int J Hyg Environ Health

•7-year sampling period: weekly: 978 samples

•Aspergillus spp. 16.7%: 1.8 cfu/m3 - 28.3 cfu/m3

•45 cases proven IA (2.29% allo; 0.36% auto HSCT)

•cases of IA analysed 14 and 28-days following high counts

•Conclusion: high counts did not predict risk of developing IA

Rupp et al. JHI 2008.

Particle counting

Hansen et al. JHI 2008; 70: 259-264.

Particle counting

•IQAir Particle Scan Pro Airborne Laser Counter

•0.3m - 5m

•during demolition building was sealed and water sprayed to minimise dust emission

•particle and fungal concentrations monitored before and during demolition

•particle concentrations significantly higher during demolition

•no difference in moulds cultured at 370C before and during demolition

Air quality monitoring of HEPA-filtered hospital rooms by particulate counting

Anttila V-J, Nihtinen A, Kuutamo T, Richardson M. 2008.

Air quality monitoring of HEPA-filtered hospital rooms by particulate counting

Anttila V-J, Nihtinen A, Kuutamo T, Richardson M. 2008.

•Construction of an outbreak curve•Line listing of all infected patients•Evaluation of air ventilation system•Regular particle counting•Water damage/ingress assessment•Possible common source exposure•Air sampling•Water analysis•Settled dust analysis

• AirInSpace: Immunair• 540-640 m3/hr• rapid air decontamination• not sensitive to exterior

movement• <1 cfu/m3

Am J Infect Control 2007; 35: 460-466.

Conclusions

• Overall mortality among patients involved in outbreaks: 50-60%

• Recent outbreaks due to internal construction or renovation with failure to control spread of contaminated dust

• Key interventions: surveillance and engineering controls

• Minimum effective dose of Aspergillus conidia is not known